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At Issue: The Future of Cognitive Rehabilitation of Schizophrenia by Steven M. Silverstein and Sandra M. Wilkniss The At Issue section of the Schizophrenia Bulletin con- tains viewpoints and arguments on controversial issues. Articles published in this section may not meet the strict editorial and scientific standards that are applied to major articles in the Bulletin. In addition, the viewpoints expressed in the following article do not necessarily rep- resent those of the staff or the Editorial Advisory Board of the Bulletin.The Editors. Abstract Cognitive rehabilitation is becoming an increasingly popular intervention in treatment programs for people with schizophrenia. Despite this increased acceptance, however, the evidence base on its effectiveness is not impressive. Moreover, given the evidence of cognitive recovery in treated patients who do not receive cogni- tive rehabilitation—from newer medications and from other evidence-based psychosocial interventions—it is not clear whether cognitive rehabilitation is worth its expense in time and resources. We believe that the slow progress in the field of cognitive rehabilitation of schizophrenia is related to failure to address several critical issues: (1) the importance of manipulating stimulus and context structure in rehabilitative inter- ventions; (2) the need to base a cognitive rehabilitation of schizophrenia on cognitive neuroscience as opposed to neuropsychology; (3) the importance of systemati- cally addressing motivation, self-esteem, and affective factors when designing cognition-enhancing interven- tions; (4) the need to move beyond one-size-fits-all interventions and develop individualized treatments; and (5) the need to address abnormalities in the expe- rience of the self when designing interventions to opti- mize cognitive and behavioral performance. Suggestions for addressing these issues are discussed. Keywords: Schizophrenia, cognitive rehabilita- tion, cognition, treatment. Schizophrenia Bulletin, 30(4):679-692,2004. Over the past 10 years, there has been an increased recog- nition of the importance of cognitive impairments in schizophrenia (Sharma and Antonova 2003). Cognitive deficits have been proposed to be manifestations of core illness mechanisms (Cohen and Servan-Schreiber 1992; Phillips and Silverstein 2003), vulnerability indicators for the development of the illness (Nuechterlein et al. 1994), and strong predictors of treatment response and level of functioning (Green 1996). In response to the increased focus on cognitive deficits in schizophrenia, researchers and clinicians have developed efforts to systematically reduce these cognitive impairments. Psychological treat- ments designed to improve cognition have been generally termed cognitive rehabilitation. The field of cognitive rehabilitation of schizophrenia now includes individual- ized (Sohlberg et al. 2000; Lopez-Luengo and Vasquez 2003) and group (Brenner et al. 1994; Spaulding et al. 1999ft) treatments, as well as computerized (Burda et al. 1994; Bell et al. 2001) and noncomputerized (van der Gaag 1992; Kurtz et al. 2001ft) methods. There have now been enough published reports of cognitive rehabilitation that reviews of the field have begun to appear. The few published reviews range from quite positive (e.g., Kurtz et al. 2001a), to somewhat posi- tive (Twamley et al. 2003), to negative (e.g., Pilling et al. 2002). In many cases, however, these reviews have not addressed critical issues facing the field. Therefore, the main goal of this article is to address the following issues: (1) the question of whether cognitive recovery is possible in schizophrenia, and if so, the necessity of cognitive rehabilitation given the cognitive recovery effects from other interventions; (2) the importance of manipulating stimulus and context structure in rehabilitative interven- tions; (3) the need to ground cognitive rehabilitation Send reprint requests to Dr. S.M. Silverstein, Center for Cognitive Medicine, University of Illinois at Chicago, Department of Psychiatry, 912 South Wood Street, Suite 235, Chicago, IL 60612; e-mail: ssilver- [email protected]. 679 by guest on August 3, 2013 http://schizophreniabulletin.oxfordjournals.org/ Downloaded from
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Page 1: At Issue: The Future of Cognitive Rehabilitation of Schizophrenia

At Issue: The Future of CognitiveRehabilitation of Schizophrenia

by Steven M. Silverstein and Sandra M. Wilkniss

The At Issue section of the Schizophrenia Bulletin con-tains viewpoints and arguments on controversial issues.Articles published in this section may not meet the stricteditorial and scientific standards that are applied tomajor articles in the Bulletin. In addition, the viewpointsexpressed in the following article do not necessarily rep-resent those of the staff or the Editorial Advisory Board ofthe Bulletin.—The Editors.

Abstract

Cognitive rehabilitation is becoming an increasinglypopular intervention in treatment programs for peoplewith schizophrenia. Despite this increased acceptance,however, the evidence base on its effectiveness is notimpressive. Moreover, given the evidence of cognitiverecovery in treated patients who do not receive cogni-tive rehabilitation—from newer medications and fromother evidence-based psychosocial interventions—it isnot clear whether cognitive rehabilitation is worth itsexpense in time and resources. We believe that theslow progress in the field of cognitive rehabilitation ofschizophrenia is related to failure to address severalcritical issues: (1) the importance of manipulatingstimulus and context structure in rehabilitative inter-ventions; (2) the need to base a cognitive rehabilitationof schizophrenia on cognitive neuroscience as opposedto neuropsychology; (3) the importance of systemati-cally addressing motivation, self-esteem, and affectivefactors when designing cognition-enhancing interven-tions; (4) the need to move beyond one-size-fits-allinterventions and develop individualized treatments;and (5) the need to address abnormalities in the expe-rience of the self when designing interventions to opti-mize cognitive and behavioral performance.Suggestions for addressing these issues are discussed.

Keywords: Schizophrenia, cognitive rehabilita-tion, cognition, treatment.

Schizophrenia Bulletin, 30(4):679-692,2004.

Over the past 10 years, there has been an increased recog-nition of the importance of cognitive impairments inschizophrenia (Sharma and Antonova 2003). Cognitivedeficits have been proposed to be manifestations of coreillness mechanisms (Cohen and Servan-Schreiber 1992;Phillips and Silverstein 2003), vulnerability indicators forthe development of the illness (Nuechterlein et al. 1994),and strong predictors of treatment response and level offunctioning (Green 1996). In response to the increasedfocus on cognitive deficits in schizophrenia, researchersand clinicians have developed efforts to systematicallyreduce these cognitive impairments. Psychological treat-ments designed to improve cognition have been generallytermed cognitive rehabilitation. The field of cognitiverehabilitation of schizophrenia now includes individual-ized (Sohlberg et al. 2000; Lopez-Luengo and Vasquez2003) and group (Brenner et al. 1994; Spaulding et al.1999ft) treatments, as well as computerized (Burda et al.1994; Bell et al. 2001) and noncomputerized (van derGaag 1992; Kurtz et al. 2001ft) methods.

There have now been enough published reports ofcognitive rehabilitation that reviews of the field havebegun to appear. The few published reviews range fromquite positive (e.g., Kurtz et al. 2001a), to somewhat posi-tive (Twamley et al. 2003), to negative (e.g., Pilling et al.2002). In many cases, however, these reviews have notaddressed critical issues facing the field. Therefore, themain goal of this article is to address the following issues:(1) the question of whether cognitive recovery is possiblein schizophrenia, and if so, the necessity of cognitiverehabilitation given the cognitive recovery effects fromother interventions; (2) the importance of manipulatingstimulus and context structure in rehabilitative interven-tions; (3) the need to ground cognitive rehabilitation

Send reprint requests to Dr. S.M. Silverstein, Center for CognitiveMedicine, University of Illinois at Chicago, Department of Psychiatry,912 South Wood Street, Suite 235, Chicago, IL 60612; e-mail: [email protected].

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efforts for schizophrenia firmly within cognitive neuro-science as opposed to neuropsychology; (4) the impor-tance of systematically addressing motivation, self-esteem, and affective factors when designingcognition-enhancing interventions; (5) the need todevelop individualized treatments; and (6) the need toaddress abnormalities in the experience of the self.Following a brief discussion of the definition of cognitiverehabilitation, each issue will be considered separately.Each section will necessarily be selective, as a compre-hensive discussion of any of these issues could easily fill aseparate review.

What Is Cognitive Rehabilitation?

As Twamley et al. (2003) and Silverstein (2000) havepointed out, cognitive rehabilitation for people with schiz-ophrenia is a heterogeneous category. For the purposes ofthis review, we are focusing on rehabilitation methods thataim to improve or restore (Twamley et al. 2003) cognitivefunctioning by targeting specific cognitive processes (e.g.,attention, memory, problem-solving skills). These includeany technique that directly focuses on improving cogni-tive functioning, whether through computerized tasks,tasks using other equipment for presenting stimuli, paper-and-pencil tasks, motivational enhancement, or groupexercise. They exclude compensatory and environmentaladaptation strategies, which may lead to improved func-tioning but are not intended to improve functioning out-side of the environmental contexts that are changed.Cognitive-behavioral therapies and other forms of milieu,group, and individual therapy are also excluded.Nevertheless, it is recognized that these treatments mayaffect cognition and that research is necessary to deter-mine whether cognitive rehabilitation produces effectsthat are greater than, or that add to, those of these otherpsychological treatments.

Is Cognitive Recovery Possible inSchizophrenia?

An assumption underlying all cognitive rehabilitationefforts is that cognition can be improved in people withschizophrenia. This assumption is in direct contrast to olderbeliefs that schizophrenia is a disorder involving cognitivedeterioration. It has also been established in well-designedstudies that, at least outside of a rehabilitation context,many cognitive deficits in schizophrenia are stable overtime (Spaulding et al. 1994; Addington and Addington1998, 2002). In this section, we briefly review evidencethat cognitive recovery is possible. Such evidence providesthe context from within which studies of cognitive rehabili-

tation must demonstrate independent/additive or inter-active effects, if cognitive rehabilitation is to be seen asworth the expense in time and resources.

Medication Effects. Early comprehensive reviews of theeffects of second generation antipsychotic medications oncognition (e.g., Meltzer and McGurk 1999) demonstratedpositive outcomes in a number of domains. However,there were also negative findings in close to 40 percent ofthe studies reviewed. A more recent review (Harvey andKeefe 2001) found effect sizes (Cohen's d, weightedbased on n's over 20 studies) ranging from 0.13 for imme-diate memory to 0.42 in verbal fluency. While compelling,data showing the positive effects of any of the newermedications must be viewed cautiously because of designflaws in many of the studies (e.g., low doses of new drugsbeing compared with higher than normal doses of firstgeneration drugs such as haloperidol) and because of thedifficulty in identifying true cognition-enhancing effects,rather than recovery of function due to elimination of cog-nition-interfering side effects (e.g., sedation, akathisia,rigidity) of older drugs (Harvey and Keefe 2001;Carpenter and Gold 2002).

Recent evidence points to the conclusion that newlydeveloped drugs, or older ones being used for the firsttime for schizophrenia, may enhance cognition more thanthe earlier second generation antipsychotic medications.For example, moderate to large effect sizes have beenreported for the cognition-enhancing properties of drugssuch as tandospirone (a 5-HT1A agonist) (Sumiyoshi etal. 2001), mianserin (a 5-HT2A antagonist) (Poyurovskyet al. 2003), quetiapine (Velligan et al. 2003), and CX516(an ampakine) when added to clozapine (Goff et al. 2001).Again, because of small sample sizes, only tentative con-clusions can be drawn about the effects of these medica-tions. However, when results are taken together, a notabletrend toward cognitive recovery is evident.

Still, a major problem with cognitive studies of med-ication is that improvements in adaptive functioning(maybe a true sign of cognitive recovery) have yet to bedemonstrated. For example, a recent study documentingthe cognition-enhancing effects of quetiapine (and report-ing large effect sizes) did not find any significant effectson adaptive functioning, even after 6 months of treatment(Velligan et al. 2003). Bellack et al. (2004) found that nei-ther clozapine nor risperidone improved social role func-tioning or social cognition in patients whose symptomswere improved by these medications. To date there is littleconvincing evidence that adaptive functioning improve-ments follow medication-related improvements on cogni-tive tests or that they occur at all in the absence of psy-chosocial rehabilitation (e.g., Mojtabai et al. 1998;Wahlbeck et al. 1999; Keefe et al. 2003).

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Effects of Structured Psychosocial Treatment. In con-trast to the large number of studies examining the cogni-tion-enhancing effects of medication or cognitive rehabili-tation (see below), little attention has been given to thepotential for psychosocial treatment to improve cognitivefunctioning, even though evidence suggests that it occurs.For example, Spaulding et al. (199%) conducted a 5-yearcontrolled study comparing Brenner et al.'s (1994) inte-grated psychological therapy (IPT) with supportive ther-apy, both conducted within the context of an intensivebehavioral rehabilitation program. In this study, the IPTgroup demonstrated significantly more cognitive improve-ment on only 2 of 13 variables. Of interest, within-grouppaired t tests indicated that the control group improvedsignificantly on 4 of the 13 tests, while the IPT groupimproved on 6 of 13 tests. One conclusion that can bedrawn from these data is that the structured milieu pro-gram had greater effects on cognition than did IPT, whichhad a small additive effect on only two cognitive mea-sures. Further support for this conclusion comes from anearlier study of milieu effects on cognition done by theSpaulding group (Spaulding 1993), prior to the implemen-tation of the behavioral milieu. At that time, with lessstructure in the program environment, no significant cog-nitive changes were observed in patients over time.

Further evidence for the cognition-enhancing effectsof a structured ward milieu comes from a seminal 6-yearstudy by Paul and Lentz (1977) that established the supe-rior effectiveness of an intensive inpatient, social learn-ing-based behavioral rehabilitation program over thera-peutic community and long-term psychiatrictreatment-as-usual milieus. In addition to demonstratingsignificantly higher discharge rates and lower medicationuse in the social learning program group, they demon-strated, on a combined index of adaptive, social, cogni-tive, and instrumental functioning, a greater than 1200percent increase for the social learning group, comparedwith entry-level scores, and a 10-fold increase over thegains demonstrated on the therapeutic community unit(Glynn and Mueser 1986). It is interesting to note that thegains from the latter program, while overshadowed bythose of the social learning unit, were nevertheless com-parable with those from some cognitive rehabilitationstudies (and greater than some as well). The treatment-as-usual program was associated with little or no functionalimprovement.

Similar positive effects on cognition from participat-ing in structured psychiatric rehabilitation programs in theabsence of specific cognitive rehabilitation efforts havealso been reported in the outpatient literature. For exam-ple, Fiszdon et al. (2003) examined verbal memory skillsat 3-month intervals for 1 year among schizophreniapatients participating in a structured day treatment pro-

gram after hospital discharge. For male patients, there wasconsistent improvement from discharge to 1-year postdis-charge, with a near-linear trend over the course of theyear. For female patients, this improvement was notobserved. However, they were basically "recovered" atbaseline, where female patients' performance was approx-imately 70 percent better than that of male patients, andfemale patients' performance remained higher at all timepoints, even with the consistent improvement amongmales.

Environmental Effects. Large improvements in cogni-tive functioning have also been found among stable out-patients as a function of residential setting. Seidman et al.(2003) studied 91 persons with serious and persistentmental illness who were moved from homeless sheltersand then randomly assigned to either group homes orindependent apartments. Neuropsychological functioningimproved across the entire sample. Of interest, executivefunctioning, as measured by the Wisconsin Card SortingTest (WCST), decreased significantly among peoplemoved into independent apartments and increased,although not significantly, among people assigned togroup homes. Seidman et al. (2003) interpreted theseresults as indicating that the structure and stability of per-manent housing improves cognitive functioning in generalamong seriously mentally ill people and that executivefunctioning is affected by the amount of structure in theenvironment, such that living alone can actually worsen it.These results extend earlier findings that living in animpoverished environment (e.g., prison) is associatedwith deterioration in basic cognitive functions (Silvermanet al. 1966). The implications of such studies are that cog-nitive ability is affected by many factors, including envi-ronmental and treatment setting factors that are typicallyignored, not accounted for in interpretations of otherstudy data, or at least not fully made use of, in the cogni-tive treatment of schizophrenia.

Taken together, the results of the studies reviewed inthis section indicate that there can be considerableimprovement in cognitive functioning without specificcognitive rehabilitation interventions. This has been foundamong both outpatients and inpatients and both psychi-atrically stable patients and stabilizing patients. One les-son here is that psychiatric rehabilitation techniques withdemonstrated effectiveness should be more widely used,as these can improve basic living skills as well as cogni-tive functioning (Spaulding et al. 1999&). An added caveatis that cognitive rehabilitation, when used, should be partof an intensive, structured, and comprehensive rehabilita-tion program. Isolated efforts outside of an intensivebehavioral rehabilitation context are likely to produceminimal effects at best, as has been previously demon-

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strated (Benedict et al. 1994). Finally, an important task inthe future development of cognitive rehabilitation ofschizophrenia is to incorporate the cognition-enhancingingredients of psychiatric rehabilitation interventions (seelater section on task and stimulus structure).

Effects of Cognitive Rehabilitation. The evidence pre-sented above suggests that cognitive functioning can beimproved in schizophrenia. But does cognitive rehabilita-tion significantly add to the effects of medications, struc-tured psychosocial programming, or healthy environmentsin terms of improving cognitive abilities in schizophreniapatients?

Pilling et al. (2002), in a meta-analysis of studies ofcognitive rehabilitation of schizophrenia, found no posi-tive effects. While this review did not include all availablestudies, more inclusive reviews have come to similar con-clusions. Suslow et al.'s (2001) meta-analysis (n = 9 stud-ies) concluded that only two of nine investigationsshowed clear positive results, and both of these had smalleffect sizes (a"s). Suslow et al.'s review also found thatthere was no improvement on 19 of 35 outcome variablesand improvement for both (rehabilitation and control)groups on 6 of 35 variables. Of importance, they foundthat improvement associated with cognitive rehabilitationwas demonstrated on measures with low processing loadsand simple structure (e.g., nondegraded continuous per-formance test, simple reaction time, Trail Making Test).There was typically no gain on more demanding measures(e.g., degraded-stimulus continuous performance test).

A more positive review was published by Kurtz et al.(2001a). That review found a mean d of 0.96 for studiesof training in the WCST. This is a very specific trainingprotocol, however, and essentially represents training on aspecific test or problem-solving strategy. It is far fromdemonstrating the more general effects on cognition, letalone real-world behavior, which are the goals of mostforms of cognitive rehabilitation. Moreover, to date, ana-logue studies of training on specific tests such as theWCST have demonstrated either no generalizability(Bellack et al. 1996) or generalizability to only similartests (e.g., Halstead Category Test) (Bellack et al. 2001).Kurtz et al. (2001a) also reviewed effects of cognitivetreatment on attention and found more mixed results, withsome negative findings and no large positive effect sizes.

The most comprehensive review of the cognitiverehabilitation literature in schizophrenia is that ofTwamley et al. (2003). They reviewed 17 randomizedcontrolled trials and concluded that the overall effect issignificant, within the small-to-moderate range. Thisreview was noteworthy for its methodological critiques ofthe evidence base and noted a number of pitfalls that limitthe confidence that can be invested in prior studies. These

included small sample sizes, no control for multiple statis-tical comparisons (including in the most well-designedstudies, where improvement was noted on only 20% to25% of measures, uncontrolled for joint alpha level), lackof measurement of real-world functioning in the studies,and lack of evidence of cost-effectiveness.

In contrast to most studies of cognitive rehabilitationof schizophrenia, a recent study by Bell et al. (2003)found a large effect size associated with cognitive rehabil-itation. A problem with the Bell et al. (2003) study, how-ever, was that the large effect size was reported for onemeasure only (digits backward), and effect sizes for othercognitive measures were not reported. Moreover, all ofthe patients in that study were outpatients who were highfunctioning and motivated enough to attend a vocationalrehabilitation program, and so the generalizability ofthose results to more impaired patients (who typicallybenefit less from cognitive training [Michel et al. 1998])is unknown. Despite these cautions, the Bell et al. studydemonstrates that significant cognitive improvement canoccur in schizophrenia, beyond the cognitive effects oftaking medication and attending a structured treatment(vocational) program. Finding methods to make sucheffects the rule rather than the exception is a major chal-lenge facing the field. In the following sections, wereview conceptual and methodological issues that webelieve must be addressed for such progress to occur.

Finally, the durability of gains from cognitive rehabil-itation has not been convincingly demonstrated. It hasalso rarely been investigated. In a recent 6-month fol-lowup study of this issue, Wykes et al. (2003) found lossof gains on the WCST and Tower of Hanoi, and no differ-ences between the control and rehabilitation groups forcognitive flexibility and planning composite scores. Whilepositive effects were found for digit span and memory,this represented a minority of the measures used. Bell etal. (2003), in the study noted above that observed largeeffect sizes for working memory improvement, found thatthe effect at 6 months posttreatment represented a smalleffect size (0.3) relative to pretreatment performance,among less severely impaired patients. For more severelyimpaired patients, the posttreatment followup effectreflected a moderate effect size (0.5). Because the Bell etal. (2003) and Wykes et al. (2003) studies are the onlycontrolled studies that have looked at durability of treat-ment, more research is clearly needed here. As no treat-ment for schizophrenia has been demonstrated to workonce withdrawn (including medication), however, it isimportant to recognize that the ultimate effects of cogni-tive rehabilitation should not be judged by what happenswhen the treatment is no longer offered. On the otherhand, it remains to be seen whether declining contactintervention, or "booster sessions," as have been found

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effective in other forms of skills training, can maintain thegains made in the full treatment, or whether some type ofcontinued full intervention is necessary to maintain gains.

Importance of Stimulus and ContextStructure in Cognition-EnhancingInterventions

Far more attention has been paid to designing cognitiveexercises to improve specific cognitive functions than tothe overall learning environment within which cognitiveand/or behavior change takes place. Both laboratory andreal-world treatment data exist, however, that suggest thatstimulus presentation and environmental structure/designhave a large impact on cognitive functioning. For exam-ple, schizophrenia patients' impairments in perceptualorganization (Silverstein et al. 1996a, 1998a; Silverstein2000) can be eliminated by structuring the presentation ofstimuli to facilitate consistent stimulus-response mappingand the use of top-down strategies during task perform-ance (Silverstein et al. 1996a, Study 2). A more recentstudy (Silverstein et al., in press) compared the effects ofperforming a task with trials presented in increasing orderof difficulty to the effects of performing a task with trialspresented in a random order. Among nonpatients, whenthe random order was experienced first, the subsequent re-taking of the test in sequential order led to significantimprovements in performance. Among the schizophreniagroup, however, this ability to benefit from the sequentialorder was not observed. When the sequential order waspresented first, however, schizophrenia patients performedlike controls in both conditions. This highlights the impor-tance of beginning tasks with obvious task structure forpatients and the potentially disruptive effects of not doingso (i.e., for patients only, benefit from later structureseemed to be prevented because of initial lack of struc-ture). Evidence for the importance of structure can befound from areas of cognition other than visual and audi-tory perceptual organization. For example, Cromwell(1975) described a study in which the reaction timecrossover effect in schizophrenia was eliminated by train-ing patients in high-level task-relevant skills (e.g., timeestimation) to facilitate adaptive top-down input. There isalso evidence that the abstract thinking abilities of schizo-phrenia patients can improve with task structuring.Blaufarb (1962) presented chronic schizophrenia patientsand nonpatient controls with either single proverbs or setsof three proverbs in which all three had the same meaning(e.g., "strike while the iron is hot," "grab with a quickhand the fruit that passes," and "hoist your sail when thewind is fair") (Chapman and Chapman 1973). Patientsperformed worse than controls on the test of the single

proverbs but scored similarly to controls on the test of thesets of proverbs. This result was later replicated byHamlin et al. (1965), who found that both "open-wardschizophrenics" (but not "closed-ward schizophrenics")and patients in remission performed significantly betterwith the sets of proverbs compared with single presenta-tions. The fact that a significant amount of performancevariance in these studies was explained by the manner ofstimulus presentation indicates that performance is nega-tively affected by context processing deficits, as has beenhypothesized (Cohen and Servan-Schreiber 1992; Phillipsand Silverstein 2003). The data also suggest, however,that performance can be optimized by systematicallystrengthening contextual input in order to maximize thelikelihood of patients' recruiting task-relevant cognitiveoperations. An ultimate goal of any such treatment wouldbe to train patients to, on their own, strengthen their pro-cessing of contextual cues during task performance.

A study of abstract reasoning in schizophrenia (Nahorand Vannicelli 1976) found that schizophrenia patientsdemonstrated abnormal performance on the GorhamProverbs Test when the instructional set required morepersonal involvement in the generation of the responsesbut demonstrated more normal performance when theinstructions required less personal involvement. This isfurther evidence that task conditions can significantlyaffect cognitive task performance in schizophrenia andthat these conditions extend beyond task structure intotask-related affective factors (to be considered more fullyin a later section). These data also suggest that it would beuseful to provide training in affect-monitoring strategiesas part of cognitive rehabilitation for schizophrenia.

The improvements in functions such as perceptualorganization, reaction time, and abstract thinking, whichoccur with task structuring, parallel the reductions inbehavioral disorganization that occur as the result of envi-ronmental structuring. Perhaps the strongest environmen-tal modification, in terms of the provision of structure,that has been studied is the social learning program devel-oped by Paul and Lentz (Paul and Lentz 1977; Mendittoet al. 1996) (mentioned in the previous section because ofits cognition-enhancing effects). This program also led toa 60 percent decrease in bizarre/disorganized behavior. Itis important to note that these effects were interpreted asrestorative changes and not compensatory or environmen-tal changes only, because of the high rate of maintenanceof the behavior changes even after hospital discharge.

The evidence reviewed above suggests that multipleforms of disorganization (e.g., in perception, language,behavior) improve via the use of stimulus and task struc-ture. This could be expected given evidence that (1) nor-mal organization of perceptual, memory, language, andmotor activity has been linked to the operation of a com-

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mon binding mechanism involving contextual coordina-tion (Glezer 1985; Chechile et al. 1996; Phillips andSinger 1997; Stoet and Hommel 1999; Jarrold et al.2000); and (2) multiple forms of disorganization in schiz-ophrenia, including perceptual, linguistic, motor, andbehavioral, have been found to be significantly correlatedand have been theoretically linked to a dysfunction of thishypothesized algorithm and its neural basis in NMDAreceptor functioning (Silverstein et al. 1998a, 2000;Silverstein 2000; Phillips and Silverstein 2003; Silversteinand Phillips 2003; see also Carr and Wale 1986 andBressler 2003 for similar views). This implies that agreater focus on using task and environmental manipula-tions to increase structure, decrease disorganization, andoptimize performance is necessary in future treatment.Teaching patients to structure their perceptions oftask/environmental demands and to monitor affect duringperformance may also be an important goal.

Need To Base Cognitive Rehabilitationof Schizophrenia on CognitiveNeuroscience as Opposed toNeuropsychology

Strauss and Summerfelt (1994) and Keefe (1995) pointedout the shortcomings of the neuropsychological approachfor increasing our understanding of schizophrenia. Amajor issue is that neuropsychology, which developed bystudying patients with well-defined brain lesions, makesinferences about the links between these known lesionsand changes in behavior. In this paradigm, such inferencesare valid. Schizophrenia, however, is likely to result frommultiple disease processes affecting multiple brainregions and their ability to interact and is likely to be neu-rodevelopmental in origin. This makes it invalid and mis-leading to assume localized brain pathology fromobserved behavior because test scores are not likely to bereliable indicators of brain pathology.

Another problem with grounding cognitive rehabilita-tion of schizophrenia within clinical neuropsychology isthat test scores from patients typically cannot differentiatea specific cognitive deficit from other factors that couldcause poor performance (e.g., poor motivation, sedation,akathisia). While profile analysis of multiple scores can beuseful in this regard, it still does not ensure that singleprocesses can be isolated from among other influences ontest performance on any single test and it is still vulnera-ble to psychometric artifacts involving differences in reli-ability and difficulty between the tests. Moreover, thisapproach is rarely used in assessment or retraining. In thepast few years, greater attention has been paid to thisproblem. For example, evidence has accumulated that

poor WCST performance in schizophrenia may reflect ageneralized intellectual deficit (Dieci et al. 1997; Laws1999). Recent work also indicates that impaired theory ofmind ability in schizophrenia might be secondary to othercognitive deficits (Briine 2003) and that up to two-thirdsof the variance in memory deficits found in schizophreniacan be explained by the anticholinergic effects of antipsy-chotic medication (Minzenberg et al. 2004). The obviousimplication of such studies is that, unlike in cases of trau-matic brain injury, where a deficit can be reasonablyinferred to be the result of focal brain dysfunction, infer-ences about isolated cognitive, or structural, pathology inschizophrenia should not be made from test scores alone.While suggestions have been proposed to remedy thisproblem (Knight and Silverstein 2001; MacDonald andCarter 2002), process-specific assessment strategies haveyet to be incorporated into treatment planning or outcomeevaluations in cognitive rehabilitation for schizophrenia.The relevance of this problem for treatment is that (1)using neuropsychological test scores as the basis fordesigning a cognitive rehabilitation program for a schizo-phrenia patient may lead to false assumptions and to theuse of "therapeutic" exercises that are not addressing theprimary contributors to abnormal cognitive functioning(e.g., poor motivation, other cognitive deficits); and (2)any improvement demonstrated on such tests after cogni-tive rehabilitation may be due to multiple factors that falloutside of the conceptual framework of the treatment (seesection on motivation below).

We have argued elsewhere (Phillips and Silverstein2003) that basing cognitive psychiatric concepts tooclosely on cognitive neuropsychology neglects informa-tion from psychopharmacology and cognitive neuro-science. For this reason, and because of the shortcomingsof neuropsychology for understanding schizophrenia(noted above), we suggest that the field of cognitive reha-bilitation of schizophrenia would benefit from a reground-ing in the fields of cognitive psychology and neuro-science. A number of strong theories of schizophreniahave now been proposed from within the cognitive neuro-science perspective (e.g., Gray et al. 1991; Cohen andServan-Schreiber 1992; Friston 1998; Braver et al. 1999;Bressler 2003; Phillips and Silverstein 2003). Theseviews, however, have had minimal, if any, impact on thefield of cognitive rehabilitation of schizophrenia.

Related to this is the need to move away from focus-ing rehabilitation efforts on isolated cognitive processesand toward efforts to integrate cognitive activity. Severaltheories of brain and cognitive functioning view cognitionas involving interactive activity between domains of pro-cessing (Edelman 1992; Fuster 2002), and top-downeffects on basic aspects of perception and cognition arewell known (e.g., Gilbert et al. 2000; Beck and Palmer

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2002), as are failures of these influences in schizophrenia(Silverstein et al. 1996a, 19966; Danion et al. 1999).

Spaulding et al. (1999a) noted that tests whereimprovement has been demonstrated from cognitive reha-bilitation typically involve the interaction of bottom-upand top-down processes, or the executive control of otherprocesses, as opposed to tests of isolated cognitive func-tions. This was supported experimentally by Sonntag etal. (2003), who demonstrated impaired strategic control ofthe contents of conscious awareness, and by Danion et al.(2001a), who found intact implicit learning but impairedexplicit learning in schizophrenia. These data were inter-preted as indicating that it is not memory but consciousawareness of cognitive activity (in this case, duringencoding and recall) that is abnormal, leading to poor per-formance. Such conclusions apply even to higher leveltasks such as those involving theory of mind. For exam-ple, Briine (2003) reported that schizophrenia patients'impairments on a theory of mind task were not due to atrue failure to infer the mental state of others, as is foundin autism. Rather, the problem in schizophrenia appearedto be one of knowing how and when to apply strategicsocial reasoning. These data are consistent with Spauldinget al.'s (1999a) suggestion that recovery of cognitivefunction in schizophrenia involves the ability to recruitthe cognitive functions necessary for a particular task, asopposed to improvements in specific basic processes. Wesuggest that it would be worthwhile, therefore, to focus onthe development of metacognitive techniques to promotethe recruitment of context-appropriate cognitive strate-gies.

Need To Address Motivation, Self'Esteem, and Affective Factors

Cognitive activity is intimately related to affect and moti-vation. The adequacy of functions such as attention andmemory in any given situation is linked to the person'saffective state and level of motivation for performing thetask at hand. This was noted long ago by Kraepelin(1919), who wrote that lack of motivation "is withoutdoubt clearly related to the disorder of attention which wevery frequently find conspicuously developed in ourpatients. It is quite common for them to lose both theinclination and ability on their own initiative to keep theirattention fixed for any length of time" (pp. 5-6).

What methods might be useful for overcoming thishypothesized cognitive-motivational deficit in schizophre-nia? One method that has been successful involvesincreasing the affective salience of the task. Workingmemory performance in schizophrenia has been improvedusing this method. Park et al. (2000) tested schizophrenia

patients using a spatial working memory (SWM) task(spatial delayed response test) that had been used in priorstudies to demonstrate a SWM deficit and that purportedlytaps dorsolateral prefrontal cortex (DLPFC) functioning.Schizophrenia patients performed better when the targetswere pictures of faces compared with when they wereblack dots. The SWM deficit was also reduced when posi-tive feedback was given during the testing session (Parket al. 2003). Finally, they found that the SWM deficitcould be reduced by introducing direct social interactionprior to having the patient complete the task (Park et al.2003). Of interest, the converse of these findings has alsobeen noted: that cognitive functioning in schizophreniapatients worsens with negative affect (Docherty et al.1996). All of this suggests that the cognitive abilities ofschizophrenia patients vary as a function of the level andtype of affective input in the task situation and that itwould be worthwhile when designing cognitive treatmentto determine the level and type of affective input neededfor each patient to perform optimally, in addition to teach-ing affect regulation strategies to enhance performance.

Other methods to more strongly link affect, motiva-tion, and attention in schizophrenia involve increasing thestrength of reinforcers. This can also be viewed as a formof increasing the affective salience of a task. Evidenceconsistently indicates that using monetary rewards andother powerful secondary reinforcers can improve the per-formance of schizophrenia patients on cognitive tasks,including those that are linked to DLPFC dysfunction andthose that have been considered vulnerability markers ofthe illness (Rosenbaum et al. 1957; Karras 1962, 1968;Wagner 1968; Meiselman 1973; Summerfelt et al. 1991;Kern et al. 1995; but see also Green et al. 1992 andHellman et al. 1998 regarding WCST improvements).Reinforcement procedures have also been effective inincreasing attentiveness during social interactions (e.g.,Wallace and Boone 1984; Massel et al. 1991).

In addition, published reports on attention shaping(Spaulding et al. 1986; Menditto et al. 1991; Silverstein etal. 19986, 1999; Bellus et al. 1999) have demonstrateddramatic improvements in attention span by consistentlypairing primary or secondary reinforcers with the behav-ioral response of attentive and participatory behavior,even among so-called treatment-refractory state-hospitalschizophrenia patients (reviewed in Silverstein 2000;Silverstein et al. 2001). These procedures are also effec-tive with outpatients in community settings (Skinner et al.2000). Moreover, while more evidence is needed on thisissue, preliminary data suggest that the gains are main-tained after shaping procedures are withdrawn (Mendittoet al. 1991), possibly because of increases in self-efficacy(see below) and greater social reinforcement for the newbehaviors.

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In addition to external reinforcers, it is possible thatduration of attention to a task could be increased by theuse of intrinsic reinforcers. One such intrinsic reinforceris increased self-efficacy. It is known that people withschizophrenia and schizoaffective disorder have loweredself-esteem (McDermott 1995). Many schizophreniapatients who need cognitive rehabilitation have beentreatment-refractory and have had multiple hospitaliza-tions; thus, they can be considered to be in a state of "self-efficacy deprivation." Linking behavior change toincreased self-efficacy could thus make such an increase apowerful reinforcer. Bandura et al. (1977) suggested thatself-efficacy could be enhanced in therapy by providingopportunities for mastery or success and offering incen-tives for achievement. The attention-shaping approach wehave used meets these requirements. In particular, the suc-cessive approximation approach inherent to shaping pro-vides opportunities for mastery and success, and the useof differential reinforcement provides incentives forachievements that are likely to be met. Errorless learningapproaches (O'Carroll et al. 1999; Kern et al. 2003) alsocan be viewed as promoting self-efficacy; evidence indi-cates that this is another effective approach to improvingcognitive functioning in schizophrenia. While directefforts to improve self-efficacy have not yet beenattempted in cognitive rehabilitation, they have beenreported to mediate gains in medication and symptommanagement programs in schizophrenia (Shon and Park2002).

An underappreciated issue is the need for cognitiverehabilitation exercises to be intrinsically reinforcing.Intrinsic reinforcers are especially important for higherfunctioning patients who do not need extrinsic reinforce-ment to engage in a task. Medalia and colleagues(Medalia and Revheim 1999; Medalia et al. 2000, 2001,2002) are the only group to have focused on the impor-tance of using training tasks that include enjoyable fea-tures and have reported positive effects using this strategy.Taken together, all of these data suggest that (1) whenworking with people with schizophrenia, it is critical toenhance motivation, as this is intimately linked to atten-tion, task engagement, and performance; (2) motivation islikely to be enhanced by using powerful reinforcers; and(3) these are likely to include primary and secondary rein-forcers as well as intrinsic reinforcers involving both taskenjoyment and self-efficacy.

Need To Develop IndividualizedInterventions

Schizophrenia is a heterogeneous condition in manyrespects, including cognition. No single deficit has been

found to exist in all patients, and patients differ widely inthe number, type, and severity levels of their cognitivedeficits (Silverstein 2000; Heinrichs 2001). To date, how-ever, little effort has been invested in developing interven-tions for specific profiles or severity levels of cognitiveimpairment.

An additional issue is that cognitive impairment inschizophrenia can be a primary illness manifestation or asecondary consequence of having prominent positivesymptoms. For example, patients with frequent auditoryhallucinations can have difficulty with sustained andselective attention (Cornblatt et al. 1985), but this canresult from the distracting effects of the voices and shouldnot be assumed to be a core symptom of their illness(Spaulding et al. 1986). There is currently no standardizedform of cognitive rehabilitation that specifically addressesthe effects of severe symptoms on cognitive functioning.Rather, when patients like this have been helped it hasbeen through the development of interventions tailored totheir cognitive difficulties. For example, Spaulding et al.(1986) and Hatashita-Wong and Silverstein (2003)demonstrated that dichotic listening tasks (typically usedto demonstrate selective attention impairments) can beused as a training tool to help patients learn to disattend toirrelevant information, leading to improvements in func-tioning, including a better ability to ignore highly distract-ing auditory hallucinations.

In short, both because most existing cognitive reha-bilitation interventions have demonstrated, at best, smallto moderate effects, and because many patients have diffi-culties that are not addressed by existing interventions,more work is needed to match interventions to patients'needs. This will require the use of better assessments ofcognitive impairments and the conditions under whichthese impairments occur, and a willingness tochoose/develop interventions based on these assessments,as opposed to relying solely on standardized cognitiverehabilitation interventions.

Need To Address Self-Awareness Issuesin Cognitive Rehabilitation

The focus of cognitive rehabilitation efforts in schizophre-nia is typically the cognitive deficits themselves and notthe experience of the person struggling with the deficits.Sass (1992), Sass and Parnas (2003), Minkowski (1927),Blankenburg (1971), Kimura (1992), and other phenome-nologically oriented writers, however, view core problemsin schizophrenia as including a disturbance in the feelingof being the agent of one's own actions. Statements exem-plifying this abnormality include "It is as if I watchedfrom somewhere outside the whole bustle of the world"

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and "If I am going to sit down, for example, I have got tothink of myself and almost see myself sitting down beforeI do it. It's the same with other things like washing, eat-ing, and even dressing—things that I have done at onetime without even bothering or thinking about at all"(McGhie and Chapman 1961, pp. 107-108). Hemsley(1998) proposed that these types of disturbances in thesense of self are related to impaired cognition. Clearly,patients with this sort of disturbance are not approachingcognitive tasks or life demands with a mindset that is con-ducive to peak performance. This highlights the issue thatperformance level is not solely a function of degree ofcognitive skill or level of motivation. To date, however,cognitive interventions have not addressed how to helppeople with these experiences improve their ability tointeract adaptively with their environments.

Several researchers have attempted to empiricallyexamine the cognitive mechanisms operative in phenome-nological disturbances in schizophrenia. Studies havedemonstrated that many patients are impaired in subjec-tively assessing the correctness of their knowledge andthat their behavior is less determined by subjective experi-ence than nonpatients' behavior (although performanceimprovement by incentives still occurs) (Danion et al.2001&). Schizophrenia patients' impaired episodic mem-ory has been attributed to deficient binding of self-aware-ness with sensory input during encoding (Danion et al.1999), and impaired learning has been related to distur-bances in conscious awareness of cognitive activity dur-ing encoding and recall (Danion et al. 2001a). Frith(1995) suggested that self-awareness during task perform-ance is reduced in schizophrenia.

While the remediation of these problems is not partof the mainstream of cognitive rehabilitation efforts, thereare reports that point to possible developments. For exam-ple, Schneider et al. (1992) demonstrated successful oper-ant conditioning (via use of monetary feedback) of slowcortical potentials, reflecting the self-regulation of atten-tional resources and activity in cortical neuronal net-works, by 20 training sessions, in schizophrenia. This waslater replicated and recommended as a therapeutic tech-nique by Gruzelier (2000). On a purely behavioral level,Perry et al. (2001) found WCST performance could beimproved by asking schizophrenia patients to verbalizetheir sorting strategy during the task. These reports indi-cate that it is possible to train people with schizophreniato develop an ability to recruit cognitive and behavioralstrategies to improve adaptive functioning, and thatbiofeedback, and potentially other devices capable ofdelivering real-time feedback, can be useful complementsto the practice-, structure-, and affect/motivation-basedprocedures described earlier.

Conclusions

The development of cognitive rehabilitation interventionsfor schizophrenia reflects a growing recognition that cog-nitive recovery is possible. At the same time, there is littleevidence for the effectiveness of existing interventionsthat goes beyond the demonstration of small effect sizes,let alone for cognitive rehabilitation's durability or gener-alizability. We argued that in order for the field toadvance, cognitive interventions for schizophrenia mustincorporate a number of other features, including (1) afocus on stimulus, task, and environmental structure dur-ing training; (2) a theory base in cognitive neuroscienceas opposed to neuropsychology, and a focus on strength-ening metacognitive skills and integrative cognitive activ-ity, as opposed to focusing only on basic processes; (3) asystematic focus on motivational and affective factorsduring training; (4) the development of individualizedinterventions; and (5) a focus on strengthening linksbetween self-awareness and stimulus encoding. It mustalso be recognized that significant cognitive recovery inschizophrenia can occur through the use of structuredinterventions, and living and treatment environments ingeneral, and possibly through medication. Therefore, afocus on maximizing cognitive recovery through what-ever means (or combination thereof) are possible shouldreplace a focus on single interventions in future researchand practice. Paradoxically, in moving ahead in theseways, the future of cognitive rehabilitation of schizophre-nia will be making use of insights that date back toKraepelin but that have yet to be used for systematicallypromoting cognitive change.

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The Authors

Steven M. Silverstein, Ph.D., is Associate Professor ofPsychiatry, and Sandra M. Wilkniss, Ph.D., is AssistantProfessor of Psychiatry, Department of Psychiatry,University of Illinois at Chicago, Chicago, IL.

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