Reprinted from: Panic and Phobias 2

Reprinted from:

Panic and Phobias 2 Treatments and Variables Affecting Course and Outcome

Edited by Iver Hand and Hans-Ulrich Wittchen

Förcword by G.L.Klerman

Epilogue by I.M.Marks

Springer-Verlag Berlin Heidelberg New York London Paris Tokyo

1988

10. Panic Attacks in Nonclinical Subjects

J. MARGRAF and A. EHLERS

Introduction

Sudden episodes of intense anxiety ac­companied by a number of predominantly somatic symptoms (now usually ca!led panic attacks) are the primary feature of the psychological disturbance termed panic disorder in DSM-IIIR (APA 1987). This diagnosis was introduced based on the idea that panic attacks are a distinct type of anxicty in ncccl of thcir own diagnostic entity. However, recenl research has shown that panic attacks are not specific to panic disorder since thcy also occu r 'icross a wide range of other psychological disorders and evcn in non­clinical popu lations. Barlow et al. ( 1985) studied IOS patients with the DSM-111 diagnoses simple phobia. social phobia, generalized anxiety disorder, panic disor­der. agoraphobia with panic attacks. ob­sessive-compulsive disorder. and major depressive episodes. The great majority of patients in each of these categories (at least 83%) reported having experienced panic attJcks. A.lthough the frequency of a!!acks var!ed across diagnoses. thcre were only fe\\' differences in terms of the symptom p<Htern associated with the :lttacks. Funhermore. symptom severity was similar for patients with situational (prcdictabk. öpcctcd) and spontancous (unpredictable. unexpected) attacks. These results are in line with those of the Munich Follow-Up Study (MFS. Wittch­en 1986) in \\hich panic attacks were obser\·ed in 9.3% of a represcntativc

community sample, a percentage higher than the combined frequencies of panic disorder and agoraphobia with panic at­tacks. If it is established that panic attacks are not specific to people suffering from a specific disorder, il is importanl to study the distribution of the phenornenon in the general population. There have been a first few attempts to approach this qucs­tion using qucsti onnai rc scrccn i ng rnethods. Norton et al. (1985, 1986) initiat­ed this line of resea rch. They fou nd surprisingly high prevalenccs of panic attacks in noncl in ical subjects. About OllC-third of thcir lWü 5amplcs of under­gradt1atC students rcportcd having ex­pcrienccd at least one panic attack in thc past year. Thcy concludcd that panic attacks orten occur in presumably normal peoplc and thal thcse panic attacks sh:1re many similaritics with thosc or paticnts who have well-detincd panic disorders (Norton et al. 1985). Aside from the quest ion of the distribu­tion of" panic attacks in thc population, there are at least two other important reasons to study panic attacks in nonclini­cal su bjects. The tirst reason concerns sampling bias. With the exception of l<1rgc epidemiological studies such as 1he Epi­dc111iological Catchmcnt t\rc;1 Progra 111 (ECA, Regier et al. 1984) or the MFS (\Vittchen 1986) pre vious studies or panic attacks have exclusively investigated clini­cal populations. There are a number of rcasons to cxpcct that thcse sampks

10-1 J. M~1rgraf' and A. Ehlcrs

represen t a biased selection or the total population or persons with panic attacks. Highly symptornatic inclividuals are morc likcly to scck treatrnent or tobe detected in clinical scrcenings, an cfTcct Motulsky ( 1978) termed "asccrtainment bias." This bias incrcascs thc probability or pcrsons with two disorders to be part of clinical samples and thus may lead to mistaken assumptions about the relationship be­tween such disorders. For example, al­most all agoraphobic patients seen in clinical settings liave panic attacks (cf. Mendel and Klein 1969; Thycr and 1-iirnlc 1985). In nonclinical community samples, howcvcr. thc picturc looks quitc clilfcrcnt. Weissman et al. (1986) and Wittchen (1986) founcl that only a small percentage or all subjccts meeting criteria for agora­phobia also exhibitcd panic disorder (ran­ging from 6% to 16% in thc various ECA and MFS sitcs) and only anothcr 17% to 50% showed limited panic symptorns in addition to agoraphohia. Anothcr cxamplc for sarnpling hias is thc postulatcd rclationship betwecn panic disordcr and mitral valve prolapse (MVPJ. \Ve havc argucd elscwherc ( Margrnf et al.. 1988) Lhat the highcr prevalcncc of MVP obsen·ect in some studics of panic disor­der patients rerrcsents a problem or co­morbidity rathcr than a true functional relationship. If thc sampling bias inhercnt in studying clinical samplcs is eliminated, thc association hctwccn p;1nic attacks ancl M\'P vanishcs. This was shown by I-lart­man et al. ( 1982) and Dcvcrcux et al. (1986). 11ho studied MVP patients and their family 111embers who had not sought treatment themseh·es. Family me111bers with and without P.IVP were not different from each othcr 11ith respect to numbcr of panic attacks ancl othcr symptoms: both groups were for less symptomatic than thl.! original samplc of MVP paticnts who hucl been refcrrecl to the clinic. Thus. sampling bias ma1· strongly intluence the r.:sults or r.:se:m:h on clinical samplcs. lt is therefore irnportant to complcment

such research by studies of the charac­teristics or nonclinical subjects with the same disturb:mce. A second important reason to study nonclinical panickers is related to the fact that many of these people are infrequent panickers. T hey experience fewer attacks than patients who seek treatment for the full -blown syndrome. lnfrequent pan­ickers may form the basic population out of which some people will continue to develop the full clinical syndrome. If this is the case, infrequent panickers offer a uniquc opportunity to study possibie vulnerability factors for panic att:icks. Most of our currcnt etiological rcsearch on panic attacks is correlational in the sense that groups of panic patients and controls are compared in cross-sectional designs. True experimental designs would for instance involve attempts to produce panic disorder in previously '' normal" subjects. For obvious reasons such studics cannot bc conductcd. Thus, we cannot makc fi rm statcments about causal antecedcnts of the disorder. If infrequent panickers are the basic popula tion for panic disorder thcy should show 1vhatever diathesis for panic exists. In this case we can assume that characteri stics of patients that are not found in infrequent p:mickers are consequences rather than causes of the disorder. On the other hand. infre­quent panickers may represent a different basic populat ion than frequent panickers (panic disorder pat ients). lt is possible that even though both groups show iden­tical manifest symptoms (panic attacksJ thcy suffer from different undcrlying disturbances. In this case, infrequent panickers shou ld be studied to gain in­sight into such a heterogeneity of the panic atl::ick phenomenon.

Questionnaire Studies

Thc lirst studics of panic at tacks in prcsu­mably normal populations were reported

by Norton et al. (1985, 1986). In their initial sludy, 186 studcnts wcrc sc.:rccncd using the Hopkins Symptom Checklist (HSCL-90, Derogatis et al. 1973) and a specially designed anxiely questionnaire asking for current level s of anxiety as weil as frequ ency and sym1:ito111s of panic attacks. A striking 34.4% of lhe subjects reported having had one or more panic attacks in the past year, and 2.2% reported having had at least threc atlacks in thc past 3 weeks. The symptoms reported lo occur during these attacks were similar to the ones described by clinical samples of panic attack patients (ßarl ow et al. 1985; Margraf et al. 1987). The most severe symptoms were heart pounding, trcm­bling, sweating, tlushing, and dizziness. Subjects describing at least one panic attack in the anxiety questionnaire scored significantly higher than those withoul attacks on the HSCL-90 subscales anxiety, phobic.: anxiety, dcprcssion. intcrpcrsonal sensitivity, somatization. and angcr/hos­tility. There were no significant difTer­ences with respec.:t to obsessive-c.:ompul­siveness. psychoticism, paranoid ideation, or sleep difliculties. In a second study, Norton et al. (1986) screened 256 students with a refined version ot· their questionnaire. now termed th e Panic Attack Questionnairc (PAQ). Suhjects also complctcd thc S1;11c­Trait Anxiety Jnventory (ST AL Spiel­berge r et al. 1970), the Beck Depression Inventory (BOI, Beck et al. 1961). and the Profile of i\lood Stares (POMS. McNair et al. 1981). In :iddition , subjects were either gi\·cn thc Fear Survey Schedule (FSS-111, Arrindell 1980) or the Fear Quest ion naire (fQ. Marks and Math ews 1979). Very similarly lO Lhe first SlUdy, 35.9% oi' thc sampk reported having experienced at least one panic altack in the past year. and 3.lt'O reponed having had at least three attacks in the past 3 weeks. Panickers scored significantly hi gher on state ancl traic :.1nxie1y (STA I, anxicty scale of thc PO~IS). depression (BOI, depression

Panic Altads in Nonclinical Sub.i.:cts I05

scale of thc POMS). littiguc (POMS), ;1nd angcr (POMS). In c.:ontrast. there were no difTerences compared to nonpanickers on any ofthe FSS-111 or FQ subscales (agora­phobia, social phob ia, blood/injury phobiil, aggression, animal phobia) or the

· POMS scales activi ty and confusion. Pan­ickers and nonpanickers were similar in the frequency of reported previous treac­ments for any mental or physical disorder. Similarly, thc two groups wcrc cornpar­able with respect to age, sex, or socioeco­nomic stalus. Panickers reported signifi­cantly more first-degrce relatives who had panic attacks. As in the first study, the most severe symptoms of panic attacks were palpita­tions, trembling, sweating, clizziness. and hot/c.:olc.J Oashes. Other characceristics of panic at tacks included a sucldcn onset in thc majority of cases (59% unclcr 10 min). an average of eight DSM-111 symptoms. anc.J a widc variety or situat ional contcxts in which attacks occurred. especially social Situations. Thc grcat majority or panickers reported havi ng expericnccd at least OllC life Stressor at thc onse t of thc ir panic attacks. Most frequentl y mentioned wcrc dini c.:ult ies at work, fomily c.:rises, and loss of a significant other. Subjects who experienced some unpredictable at­tacks were different from those who cxpcricnc.:cd only prcdic.:tablc atlac.:ks on 9 out of 40 comparisons. Those subjects with unpredic.:table attacks reportcd more attacks in more difTerent situations. as weil as more severe feelings of unrealit y and tachycardia. Together. these studies show that panic attacks may occur in more pcrsons than previously assumccl and that suhjccts \\'ho havc panic attacks rcport 111orc psychop;1-thology than do nonpanickcrs. In add i­tion. the panic attacks experienced by noncli nical panickers an d patients wi th anxiety disorders arc \ery similar. \V hile thesc studies have yielded some l'ascinat­ing clala and initiated an imponant line or researc h, they also pose some ne\\ chal-

106 J. \largrar and A. Ehlcrs

!enges. A tlrst problem is to establ ish the reliability and validity of the PAQ as compared to standard structured inter­view diagnoses. Norton et al. (1986) rcport ed that 22 out of 24 cases, previous­ly identified as nonclinical panickers by the PAQ. also met DSM-JII criteria for panic. attacks in a structured interview. However, they did not give information as to what interview was used, whether interviewers were blind to the qucstion­naire results, and the reliability of their interview and questionnaire methods. A second challenge is to go beyond mere questionnairc asscssmcnt of psychopa­thology and to comparc nondinical pan­ickers. clinical panickcrs. and normal controls 011 psychophysiological variables or the response to strcssors. More recent studies hc.m:~ atternpted to addrcss these issues.

Laboratory studics

13cck and Scolt ( 1987) comparcd ten subjects who had panic disordcr with ten infrequent panickcrs. All subjccts were recruited from thc community using media <Jnnounccments. Infrequent pan­ickers were defined as subjects reporting four of the 12 DSM-111 symptorns during typical attacks. but never having ex­perienced three attacks in 3 consecuti ve weeks. The Screening instrument was thc Anxiety Disorder Interview Schedule (A DIS-R. DiNardo et al. 1983). Laboratory paracligms \\·cre four 2-min tasks (neutral imagcry. hosp italization imagcry, signal detection. paced arithmetic). Assessments included continuous measurcmcnt or trapezious electromyogram (EMG). skin conductance level (SCU. and heart rate. as weil as thought-listing and ratings ol' the DSM-111 panic symptoms immcdiate­ly following each task. Overall. thcre wcre relativcly !°<.:\\' dilTcrcnccs bctwccn panic disordcr subjects' anti inl'rcqucnt pan­ickers· res;ionses to the test paradigms.

Panic disorder subjects showed more EMG and SCL reactivity to the two imagcry tasks, in frcquent pa nickers more EMG and SCL reactivity to paced arith­metic. There were no ditTerences in heart rate react ivity or on the thought-listing measure. With respect to panic symp­toms, panic disorder subjects scored signi­ficantly higher on four and infrequent panickers scored higher on six out of 52 comparisons. Sandler et al. (1987) reported a compari­son of nonclinical panickers and control subjects withoL1t panic attacks. Eighty subjccts were recruited through screening or collegc studcnts with a panic at tack questionnaire. Subsamples included fre­quent panickcrs, infrequcnt panickcrs. and panic-free controls. Cardiovascular reactivity to a psychological (challenge reaction time task) and a physical (cy­cling) Stress task was assessed by measur­ing heart rate and blood pressure at intervals before. during, and after the tasks. All of the measures showed pro­gressive dcclincs during thc prctask basc­linc pcriods. increases during the stress tests. and declines during the post-task rccovery phases. There were no differ­ences bctween groups with respect to cardiovascular reactivity. This is similar to what is seen in most so-called panic induction stud ies of clinical samples (cf. Ehlers et al. l986a. 1986b. 1988: Margraf et al. 1986a). In contrast to these studies. however. differences in baseline heart rate levels were lacking. The only ap­parcnt ditference was some modest cvi­dcncc f"or slowcr rccovery from exercisc in those subjects reporting the most frequent occurrence of panic att<Jcks. lt is interesting to note that neither San­dle r et al. (1987) nor Beck and Scott (1987) found difTerences in cardiovascular reac­tivity. There were few reactivity difTer­cnccs between frequent and infrequcnt panickcrs in 13cck and Scott's study and no rcactivity differenc.es between pan­ickcrs and nonpanickers in Sandler et al. ·s

study. This is in contrast to the consislenl and strong diff erences on several of the questionnaire measures in the two Nor­ton studies. We have recently conducted two studi es rrying to combine question­naire and laboratory measures in a com­parison of nonclinical panickers and con­trols.

The Marburg and Tübingen Studies

·Du ring late 1986 and early 1987 we con­ducted two independent studies of non­clinical panickers. The tirst study (Ehlers and Meisner, in preparation) involved a sample of 170 undergraduate students at Philipps Univcrsity in Marburg in the central parr of West Germany. The second study (Margraf, Wrobel, and Jak­schik, in prcriaration) involvcd a samplc of 136 undergraduate studen ts at the university of Tübingen in southcrn Ger­many. These studies pursued three specif­ic goals:

1. To rcrlicate thc Norton et al. (1985. 1986) lindings using a Gcrman translation or their PAQ

2. To determinc the reliability and validity or thc qucstionnairc S(rccning mcthod ;is comparcd to a stand:ird structurcd interview approad1

3. To comparc nonclinical panickcrs anc.J rnntrols on a 4ucstionnairc battery and a psyd10physiu­logical laborJtory assessment

sc~ee~· r; ~ AO ( Pente Al~!C" ~es~1ortne1re.

t<>rt~ •: ol · 9861

·a11na· 1n terv •,;ws. SCID {Stn:cti.;re-J Cllr ·\:)' l l"J~erv tew

for DSM . So1tze-.l. "' •!11011" 1986)

· e1:~0 · cc:n;ar1son ~uesuonna!r~ :attery, osyc~oonys : : 1091ca 1

taooratory assessment

STUDY l <Narourg)

N• 170 unoergraouat e stuaenc s

N•43 1 aoout SO~ oan1ckers.

sor. co~trol s oy PAO

N•43 SC ID IPAO Jan1ckers

vs contro ls

Panic Attacks in Nonclinical Subjects 107

Tahlc 1. Odinitiun or a pani1.: alla1.:k giv1:11 in the vcrsion or the panic allack qucstionnairc used in thc Gcrman studics

A p:111ic attack (anxiety attack) is a discrete period of suddcn onsct of intcnsc apprl'ltcnsion, fcar, or tcrror, oftcn ;1ssociated with fcc lings ofimpending doom. Thc following symptoms may be ex­pericnccd:

Racing. f11Jl111<li11g. ur irregular lican 1>,·111 Di::iness ur ligl11he1ulecl11e.u Slior1111.>ss of brealh s,.,"a1i11g Cl1es1 pain or disco111/iJn Tre111bli11g or shaking f/01 (f/1(1 cold jlashes Choki11g or s11101heri11g se11sa1io11s N11111b11ess or 1i11gli11g in par1s 11/ 1//e btJdr Fcar of 1~1·i11g Fai11111ess Nausea or abdo111i11al dis1ress Feelings t!F 1111realizr or hci11g dewched fror t!F losi11g comrol ur g11i11g cra:y

The questions on the following pagcs rcf.;r to p;inic attads in situations th;1L werc not li fc­thrcall·nini:. Th1.: atlacks h;1v..: lo be acco111pa11i..:d by al least four of thc Symptoms listcd abovc.

Figure 1 gives an overview of"the studies. Each study consisted or three phascs. First, a !arge group of undcrgraduate students was screcncd using our German translation of thc P/\Q. Thc dclinition of a panic attad givcn to thc suhjccts is shown in Table 1.

STUDY 2 <Tübingen)

N•; 36 Jnoergraouate stuce~:s

1

+

N•SI SC IO/ PAO par.1c~ers

vs controls

re l1a:)l l1 ly

s :va'I

re!1ao11 1ty s:~:y

Fi::. 1. Q,·en i.:" of thc tvlarburg and T iibingcn studies uf pani' :lltads in nondink:il subj.:(ls

108 J. i\largraf und J\. Ehlcrs

In phase two, we selecled subsamples of PAQ determined panickers and nonpani­ckers or "controls" (about 50% each) using slrict critcria (panickers : reporting at least one spontaneous attack, at least four sympto111s, attacks not only in socia l situations: controls: no attacks or anxiety symptoms). We then conducted blind diagnostic interviews to determine th e agreement between the interview and questionnaire methods. The interview was a Gerrnan translation of the Struc­tu red Clinical In terview for DSM (SCID) hy Spitzer and Williams (1986). In the third phasc. subjccts mecting bolh PAQ and SCID criteria for panic attacks ("non­clinical panickers") and controls were com pared using an extensive question­naire battery and a psychophysiological laboratory asscssment involving a base­line and a hyperventilation task. In addi­tion. two substudies assessed the retcst reliabil ity of the PAQ and th e interrater reliabilit~ · of the SCID in our hands. In thc foll owi ng. wc will prcscnt thc rcsults or thc prel i111inary analyses conducted so far. The retest re liabi lity ofthe PAQ provecl to be genera lly good. Similarly, thc intcrrat­er reliability of thc SCID in our hands was good. Table 2 summarizcs the resulls of the re test reliabi lity study.

Information about the occurrence, num­ber, and intensity of attacks as weil as stress at the onset of panic, avoidance behavior, ancl fami ly history was give n rel iably. In contrast, subjects were not able to give reliable information about whether they had ever experi_e_nced un ex­pected ("spontaneous") attacks, panicked only in social situations, or experienced most of their symptoms within 10 min. Table 3 compares the number of subjects reporting panic attacks on the PAQ in our two studies with the numbers reported by Norton et al. (1985, 1986). The mean ages or our samplcs were 24 (study 1) ancl 25 years (study 2), while 69% (study l) and 65% (study 2) of all subjects were female. While we found a somewhat higher percentage of panickers for the past year, resul ts for the past 3 weeks close ly rcsem­bl e those of Norton et al. (1985, 1986). Thus, their finding of a high percen tage of nonclinical panickers is replicated using the questionnaire method. However. whcn using thc structurcd interview ap­proach, a difTerent picture emerge. We found that only 12 out of 23 (study L Marburg) and 15 out of 29 (study 2. Tübin­gen) PAQ-determ ined panickers also met SCID criteria for pan ic attacks. \Vhile we thus had a high rate of false positives. there were only a few false negatives:

Tahlc 2. Rc1c•;t.rcliabili11· or thc Pa nie :\ttack Qucstionnai rc (samplc sizc: II= 39. retest int.:rv:il l.J-28 days with :1 rncan or 20 days)

ltcm (llf gf<lups or itcms)

E1·c r h:td p:1111c ;1ltack E1·cr hau .3 :irtacks in 3 wccks E"er worri<?d for .J wccks aboul attack :\umbcr or .it tacks past yc;1r

:'-lost sympwms wi th in 10 mi n E1·cr had un~xpectcd panic Panics only in social s ituations

Strc·s~ .11 llll<,'I or panic (8 ilcllls) ·\gc or on<c!. lrcalmcnl. sclr-111cdica1ion. fomiliy

his1ory .. ?1 oidancc bcha1·ior ( l.J i1c111s) \\ cr:ti,:c· duralion. ;111\ic11·. numbcr or -~· 111pl0111s

Rcliabi lity cocmcicnt Statistic

0.80 0.80 0.82 0 .85

0.33 0.53 O..J3

0.67- 1.0

0.65- 0. 7:! 0. 70-0. 76

Kappa Kappa K;1ppa Spe;irm:m

Kappa Kappa Kappa

Kappa

Kappa. Spearman · Spear111:111. Pcarson

l'anic Allacks in Nonclinical Subjects 109

Tablc 3. Frequency of panic auacks dcterminctl by lhc Panic Allack Questionnairc (pcrccnt or all sub­jects)

Studr 1: S1udy 2: Norton el al. Marburg Tübingen 1985 1986 (11 = 170) (11 = 136) (11 = 186) (11 = 256)

Panickers 46 59 (last yearJ

Panickers 21 29 (last 3 weeksJ

Three atlacks 12 15.5 in 3 weeks (liferimeJ

Threc auack.s in 2 last 3 weeks

• These results were not rcportetl by Norton et al.

pooled across both studies on ly 4 out of 42 PAQ nonpanickers met SCID criteria for panic. Overall rates of agreement were as low as 74°/o and 65% (kappa: 0.50 and 0.32, studies 1 and 2, respectively). A post hoc analysis of those subjccts who ind icat­ed panic attacks on the PAQ, but dicJ not meet SCID criteria, revealed that dis­agreement was not of a pure "chance" nature. Rather. it secmcd that thcsc folse positives reported milder variants of the same rhenomenon (cf. thc conccpt of limitecJ symptom attacks in IJSM-Il!R) and that the interview had a morc con­servati\·e cut-off bctwcen panic and non­panic. The comparison of nonclinical panickers (P . .\Q and SCI D criteria) and controls on the questionnaire battery yielded a num­b.:r or pronounccd dilTerenc.:cs. Sincc study 2 (Tübingen) used a more compre­hensiYc battery. the pattern of'its rcsults is shown in Fig. 2. Thc rcsults ol' stucJy 1 were generally similar. The question­naires used in study 2 werc the Panic and Agoraphobia Profile (PAP, cf. Margraf and Ehlers 1987), Fear Survey Schedulc (FSS. Arrindell 1980). Symptom Chcck­list-90 (SCL. Derogatis 1977), Sclf'-rcport ln\'entory of somatic symptoms (SISS.

34 36

24 23

* *

2 3

King et al. 1986), state-trait anxiety inven­tory (STAl, Sp iel berger et al. 1970. trai t form), 13eck Depression ln ventory (BOI. Bcck et al. 1981), and the Mobility lnven­tory (MI, Chamblcss et al. 1985). Thc different qucstionnaircs use very different scales. For a standardized pre­sentation, we computed thc difference bctween the mcans of ranickers and controls cJividcd by thc standarcJ c.Jcviation of the control group. The bars in Fig. 2 thus indicate the di!Tcrencc hetween the two groups in units ur lhe stantlarcJ cJevia­tion of the controls. The upper part of Fig. 2 shows those scales 011 which the two groups di!Tered signillcantly ( P < 0.05), the lower part scales without sign iti­cant dilferences. lt is important to note that qucstionnaires mcasuring s i mil~1r

constructs also yiclckd similar rcsulls. Thcrcf'urc. such scaks wc re groupec.J together. Nonclinic.:;tl panickcrs rcportcd cunsillcra­bly higher levels of phobophobia. ago­raphobic kars (but not avoidance beha­vior). somatization. anxiousness. depres­sivencss. and injury phobia than nonpani­ckers of' comparabk agc, sex. and socioe­conornic background. 01· the two depres­sion scales. thc BOI that locusses more on

110 J. Margraf' and A. Ehlcrs

2

stanoara oevlattoos

or control grovP

stanoarc aevlattons

or control grau~

2

0

-

PAP

pnobo­pnobla

MI PAP

avolaance

Slgn!rlcant Olfferences

F5S 5CL 5155 5CL 5155 5CL ST Al BOI SCL SCL FS5

agora- somatlzatlon anxlousness depresston psycno- lnjury pl\Oblc tlclsm pllOt>la rears

No Slgnlflcant Olfferences

FSS SC1. PAP fS.S SCt. PAP SCl FS.S $ISS PAP

soc1a1 host1 11 ty separa- otner varlat>les anxlety aggresslon tlon

anxlely

Fii-!. 2. Cumparison of rianickcrs and controls using a qucstionnaire battery (study 2. Tübingen). The l•on rcrr.:<ent thc diffcrcncc hcl\\een thc scorcs ofthc two groups diviclcd hy lhc standard dcviatinn of the c·11111rol !o!l"OllJl. Sc.::1h:s measuring sinular wnstrucls are groupcd logcthcr. The abbreviations refcmn~ to thc qucsllonnaircs containing the scales arc explaincd in the text. The 11pper half of the Jigurc shows scaks ) iclding signilicant dilf.::rcnccs bctween panickcrs and controls: phobophobia (P:\Pl. a!;orarihob i~1 ( FSSL phobic anxicty (SCLl. total somatization disorder score (SISSl. somatiz:it ion !SCLl. ncurotic symp1oms (SISS). anxicty (SCU. trail anxiety (STAIJ. deprcssion (BDll. depression !SCL>. ps\-choticism (SCU. and blood/injury phobia (FSS). The scales listcd in the lo11·er ha(fof the ligurc ,·ieldc:d no signilicant di!Tcrcnccs bctwccn panickcrs and controls: mobility alone and mobility accompanicd (MI>. gcncral avoidancc {P/\P). social fcars (FSSl. intcrpersonal sensitivity (SCL). fear of social cmb~1rrassmcn1 ( P:\ Pl. aggrcssion (FSS l. hosl ility (SCU. scparation nnxiety ( P.-\Pl. obsessi,·e· rn111puJ,l\c'llC\.'> and paranoid idc:llion (S('I.). :111i111;1i phobia !l'SS). ~art!iuvascular. gastrointcstin:1l. :111t! mus.:ubr :1w;m:ncss (SISS). l'car oi' loss or control :111d J'car uf somatic di$tress (PAP)

the cognitive concomitants of depression yielded a strenger difference than the depression scale of the SCL-90 that con· tains more vegetative sym ptoms. The ditTerence on the SCL-90 · psychoticism scale is probably due to several ambig­uous items that can be interpreted as signs of psychotic ideation as weil as indicating typical panic symptoms (e.g., a fear of going crazy, losing control over one's body, derealization). Somcwhat surprisingly, there were no ditTerences in terms of self-reported avoidance behavior, social anxiety, hostility, or aggression. Separation anxiety, which has been linked causally to the development of panic auacks (Klein 1980; cf. Margraf et al. 1986b for a critique), was not heightened in nonclinic:.il rianickers. lt should be noted that the separation anxiety scale used hcre has bccn shown to be highly sensi­tive to the separation anxicty found in clinical panickcrs as weil as in agorapho· bics (Margraf and Ehlcrs 1987). The results fo r the baseline and hyperven­tilation tasks of the psychophysiological laboratory assessment are summarized in Fig. 3 (study 1) and 4 (study 2). We chose hyperventilation (60 cyc les/mi n, 2 min) as thc strcss task bccausc it has l'requcntly been associated with panic attacks. Sep· arate repcated measures ANOVA's (using the Greenhouse-Geisser correction when appropri:.ite J for the ditTerent dependent variables showed signiticant baseline dif­ferences between panickers and controls in self-reported anxiety and panic symp­toms, but not control symptoms which are not usu:illy associated with anxiety, heart rate. systolic blood pressure, and diastolic blood pressure. Ulood pressure results ;1rc not included in thc ligurcs. The responses to the hyperventilation task were similar in both groups with the exception of a greater increasc in self­r:ited Jn\iety in panickers. In study 2 (Tübingen! the EKG was monitored con­tinuously throughout the .different para­digms and a rath er strong heart rate

Panic Attacks in Nonclinical Subjects III

increase in response to hyperventilation was observed. This was not the case in study 1 (Marburg) because heart rate could not be measured during but only before and after paradigms. Overall, the results of the Marburg and Tübingen studies replicate earlier fin­dings: There is a high numbcr of persons with panic auacks in nonclinical samples. These persons also show more seff. rcported psychopathology, but not thc cardiovascular differences typical for clin­ical cases of panic disorder. These replica­tions are complemented by data on the reliability and validity of the question­naire screening method and results from a more comprehensive battery of question­naires. In addition, hyperventilat ion was again shown to proclucc incrcases in anxiety, panic symptoms, and heart rate. Nonclinical panickcrs showcd high t:!r baseline anxicty anti a greater rcsponse to hypervcntilat ion on the anx iety rating scalc than nonpanickers.

Conclusions

Takcn together, published stud ies of nonclinical or infrcqucnt panickcrs ancl our own prc liminary results suggcst tha1 Norton et al. (1985. 1986) idcntificd a val id phenomenon. Panic attacks occur rela­tivcly frequently in nondinical subjects. As in clinical studies, the exact proportion depends in part on thc rncasures or critcria we use to determine panic attacks. In our studies, at least 501Vo ot· question­naire-determined panickers did not meet SCID criteria ror panic attad;s. This occurred in spite or the fact that the suhjccts invitcd for the interview h;1cl not only indicatcd a panic attack but also reported on the PAQ at least one spon­taneous anack, at least fou r symptorns during att;icks. and panic attacks not only in social situ:llions. Thus. the proport ions or panickcrs givcn in Tablc J arc probably uppcr limits or thc prcvalcncc or panic

112 J. Margraf and /\. Ehlcrs

3

Anxlety Rating

(0- 10)

baseline HV posl

18 -,--------------,

16

14

12

10

8

6

4

2

Panlc Symptoms

(0-18)

0 ~--.-----...,.....----....--'

oasel 1ne HV posl

11

10 Control Symptom5 9 (0-11)

8

7 6

5 4

3 2 1

o.L.-~O----~=-=--=-=-=-=-=--~~~====~o~__J basel 1ne HV post

-II- Noncllnical Panlcl<ers

-0- Controls

HV: hyper.ienttlatlon

54

52 State Anx l ety

50 (20-80]

48 46 44

42

40 38 36

34

32 oase11ne HV post

110 Heart Rate

100 (bpm)

90

80

70

baseline HV post

Fi~. 3. Sc!ected rcsults of thc 11S)'chophysiologic;il laboratory assessment in study J (~brburgl. Shown :1rc sclf·r:ucd an:-;icty (on a 0-10 scalcl. numbcr of panic symrHoms (on a list of 18 symptomsl. state ;111 '\icty <ST ·\I. 20-1-iO ~ca!.:. Spiclbcrgcr ct al. 1970>. numbcr of control symptoms (on a list of 11 symr· !Omsl. anJ hcan rate (in bcats per min) al hasclinc. during hype~cntilation (2 min. 60 cyclcs per minl. and ;1t thc ~nd of thc lahoralory scssion. 1 lcan rate was mcasurcd at baseline. immed iately before and a/rcr h)·pcn cntilation. and al lhc end 01· lhc scssion. Black squarcs represenl paniders. Of1!'1l squarcs rcprcs.:111 't>ntrols

altads in nonclinical subjccts. I n spitc of thc high number or "falsc positive" rcsults. thc low proportion of "falsc ncga­ti\ c„ rc~ults ;tnd ils g.oocJ rctcst rcliabilit~·

makc thc PAQ a valid screening cJevicc.

Howcvcr. if one wants to assure compali­bility \\'ith the diagnost ic standards in clinical stucJies. a·structured inter\'iew has lO complemcnt the questionnairc in its prcsent t'orm. Nevertheless. it may be

5...-------------,

3

2

Anxlety Rating (0-10)

0 ~-r---.---.---.---.---.--'

base l ine HV

18...------------~

16

14

12

10

8

6

4

2

Panic Symptoms CO- 18)

0 ~--,-----.-----.--......J

basel ine hypervent l lat Ion

II ...--------------. 1 o Contra 1 Symptoms g (0-11)

8 7

6

5 4 3

~~ o~--.------T-----r-~

baseline hypervenli lalion

l'anic Allacks in Nonclinirnl Subjc~ts 113

----- Nonclinical Panicl<ers

-D- Controls

HV: hyperventi lat ion

54~------------52 Slate Anxiety 50 (20-80)

48 46 44

42 40 38 36

34 32...._-..-----..-----..-----'

baseline hypervent1lat1on

1 10 T--------------, Hearl Rate

100 (bpm)

go

80~

70

basel tne HV

fig . .J. Sde..:tcd rcsults of the psychophysiological laborawry assessmcnt in study 2 ( fübing..:11). Slww11 are the same 1·anables :is in Fig. 3 du ring a 12-min basclinc and a 2-min hypcr\'cntilation test (60 .:yclcs per minl. For the hyperventilation pmadigm. self-report mcasurcs werc takcn immcdiatcly heforc anti aftcr hypcr\'cn: i:~ tion. hcart rates wcrc c:!lculatcd l'rom thc EKG imm.:diatcly h..:l(>rc allll d11ri11.~ thc: last 20 s of hyper\'en:ilacion. Black squares represent panickcrs. 011e11 s1111arcs reprcscnt con tro ls

possible to de\·elop f uture forms of the PAQ that agree better with instruments such as the SCID. lt is also possible that the low agreement was due to the lad; or reliability of .:enain criteria for the diag-

nosis of panic in DSM-llIR. The fact that information about the "spontant.:it(' and the rapidity of onset of panic altacks was not givcn reliably raises doubt as to the usefulness of these critt!ria.

ll4 J. :vlargrar and A. Ehlcrs

What are nonclinical panickers like? Thcrc arc a numhcr of variahlcs in thc scll~rcport domain thal difl'crcntialc non­clinical panickcrs from cont rols. These are primarily measures of phobophobia, agoraphobic fears, somalization, anxious­ness, and depression. The physio logical variables assessed so far as weil as reactiv­ity to laboratory stressors difTerentiate

· much less weil or not at all between panickers and controls in nonclinical samples. The most consistent ditTerence found in our laboratory assessments were lonicallr clcvatccl levels of sclf-rcportccl anxiety and symptoms. Reactivity to stress tasks ditTerentiated only poorly and cardiovascular measures ditTerentiatcd not at all in our studies and in that of Sandler et al. (1987). Even the signiflcant difTerences on laboratory parametcrs reach a magnitude of only about one Standard deviation (of the control group) ancl arc thus much smallcr than so mc of thc qucstionnairc diffcrenccs. S..:veral or thc fcaturcs of nonclinical panickcrs havc previously been founcl in clinical panic disorder patients (e.g., phobophobia. somatization, gcncral anx­iousness. dcprcssion). Howevcr. further studies arc necded that directly comparc nonclinical and clinical samples. lt is an open question whclhcr thc infrequent panickers stuclied by 13eck and Scott (1987) rcprcscnl a clinical or a nonclinical popu lation since all subjects were recruited through media announcemcnts IOr pcopk with panic attack s. In our experience. infrequcnt panickers who respond 10 such advertisements are more similar to self-selected clinical cases than to noncli nical subjects rccruited from community screenings. This could be one reason for the lack of ditTerences between the two samples rerorted by 13eck and Scott (1987). The results of studics of nonclinical panickers are consistent with the psycho­physiologic:.11. cognitive. or psychological models of ranic proposcd by several

researchers (e.g., Barlow 1986; Clark 1986; Margraf et al. !986a, 1986b; van den Hout, 1988) in showing a number or postulatcd causal factors for the development of panic (c.g., fear of anxiety symptoms. anxiety response to hyperventilation) to be present in this population. They are not consistent with views that assume separation anxiety or active avoidance behavior as necessary an tecedents of panic attacks. If we want to use these results to make more causal statements about the deve­lopment of panic attacks, we need pros­pcctive longitudinal studics. These studies have to determine whether infre­quent panickers are the basic population out of which some subjects go on to develop the full-blown clinical picture of panic disorder or even agoraphobia with panic attacks or whether the phe nomenon of panic is heterogeneous, representing different subgroups of underlying causes. Eithcr possibility is of' high scientific and clinical intcrest. In the first case, we havc a fascinating opportunity to study possible vulnerability factors in subjects at a high risk to develop panic disorder. In the second case. we may gain insights into difTcrential etiologies of panic attacks possibly connected to clinical outcome in the long run. In addition, the longitudinal study of noncl inical panickers may give us information about possiblc factors pro­tecting most of them from becoming clinical "cases". We have recently started such a prospcctive longitudinal follow-up study of infrequent panickers at the Clinical Research Unit ofthe Oepartment of Psychology at Phil ipps University. On the whole. the studies presented in this chapter il lustrate the usefulness of sup­plementing the usual study of clinical samples by investigating of panic attacks in noncl inical subjects.

.-lck110111/edge111e11rs: Preparation of this chapter was supported in part by German Research Foundation grant Eh 97/1- 1.

Additional financial support by the Department of Psychology of Philipps University and the help of 1. Florin, G. Jakschik, W. Lutzenberger, K. Meisner, ß. Rockstroh, F. Schneider, and F. Wrobel is gratefully acknowledged. ·

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