Classification of psychiatric disorders

CLASSIFICATION IN PSYCHIATRY

CONCEPT, RELIABILITY, VALIDITY, ADVANTAGES, DISADVANTAGES,

CONTROVERSIES

Dr AMIT CHOUGULE

OVERVIEW

CLASSIFICATION IN PSYCHIATRY ADVANTAGES DISADVANTAGES APPROACHES TO CLASSIFICATION RELIABILITY VALIDITY CONTROVERSIES

CLASSIFICATION

INTRODUCTION

There is a natural human predilection to categorize and classify

To simplify and organize the wide range of observable phenomena and experiences

Facilitates understanding and their predictability

CLASSIFICATION

Classification is a process by which complex phenomena are reduced by rearranging into categories based on shared characteristics (K. S. Jacob, IJP, 2010)

Classification in science involves forming categories or taxa for ordering natural objects or entities and assigning names to these categories

PRINCIPAL FUNCTIONS OF MEDICAL CLASSIFICATIONS

1. Denomination: Assigning a common name to a group of phenomena

2. Qualification: Enriching the information content of a category by

adding relevant descriptive features3. Prediction:

A statement about the expected course and outcome, as well as the likely response to treatment

UNITS OF CLASSIFICATIONS Disease:

A disease is a particular abnormal condition, a disorder of a structure or function, that affects part or all of an organism

A medical condition associated with specific symptoms and signs

Disorder: Breach of order; disorderly conduct; public disturbance A disturbance in physical or mental health or functions

malady or dysfunction Syndrome:

A group of symptoms which consistently occur together or a condition characterized by a set of associated symptoms


Classification in Psychiatry is different as compared to other biological classifications

The objects classified in psychiatry are not “natural” entities but “man made” explanatory constructs

DSM-5 and ICD-10 are not systematic classifications in the sense in which that term is applied in biology


Social anthropologists claim that current psychiatric classifications are analogous to indigenous or “folk” classifications of animals or plants

They do not consist of mutually exclusive categories, have no hierarchies but have some rules

They are pragmatic and adapted to the needs of everyday life

DISORDER AS A UNIT OF PSYCHIATRIC CLASSIFICATION

The generic term “Disorder” first introduced as a unit of psychiatric classification in DSM-I in 1952

Disorder has no correspondence with concept of disease or syndrome in medical classifications

ADVANTAGES OF CLASSIFICATION IN PSYCHIATRY

To allow mental health practitioners and researchers to communicate more effectively with each other

“Patient has major depressive disorder”1. Conveys a great deal of information in few words2. Mood is a central aspect of the presenting problem3. It is not the kind of “normal” mood fluctuation4. what is not to be found in this patient


To arrive at a diagnosis that has important predictive power

Diagnosis of Bipolar disorder 1. Choice of treatment options2. Certain course may be likely 3. Increased prevalence in family member


Education of current and future practitioners Organization of disorders into diagnostic classes Structure for teaching phenomenology and differential

diagnosis Psychoeducation of patients and their families


To demonstrate to patients that their patterns of symptoms are not mysterious and unique but identified and studied in others

To make decisions about insurance coverage Attorneys in malpractice suits and in other litigation Health care epidemiologists to determine the incidence

and prevalence of disorders

APPROACHES TO CLASSIFICATION

1. Etiological Versus Descriptive2. Syndrome Versus Symptom3. Categorical Versus Dimensional

ETIOLOGICAL VERSUS DESCRIPTIVE

Two fundamental approaches:1. Etiological2. Descriptive (First, 1994) Etiology-based classification systems are organized

around presumed pathogenetic processes Relatively few diagnostic entities Relatively easy to use Very few etiological factors have been elucidated

ETIOLOGICAL APPROACH

16th century Swiss physician Paracelsus developed a classification system

He divided psychotic presentations into three types of disorders based on presumed etiology

VESANIA: Disorders caused by poisons Substance-induced disorders INSANITY: Diseases caused by heredity Schizophrenia and bipolar disorder LUNACY: Periodical condition Influenced by the phases of Moon Has no analogous condition today

ETIOLOGICAL APPROACH

Etiological basis for most psychiatric conditions remains unknown

Based on a particular theories about the causes of mental disorders

Very useful to proponents of that particular theory Less useful for proponents of other etiological

theories

DESCRIPTIVE APPROACH

Descriptive approach to classification defines disorders based on clinical descriptions of presenting symptoms

It has proved to be of greater utility This approach advanced by the work of the nineteenth

century psychiatrist Emil Kraepelin (Kraepelin, 1992) Forms the basis for the current DSM and ICD

classification system

SYNDROME VERSUS SYMPTOM

DSM/ICD lacks a specific etiological conceptualization What is organizing principle of DSM/ICD? The fundamental diagnostic element of the DSM/ICD is

the syndrome Syndrome is a group or pattern of symptoms that

appear together temporally in many individuals These symptoms cluster together in clinically meaningful

way They may reflect a common etiological process, course,

or treatment response

INDIVIDUAL SYMPTOM CLASSIFICATION Psychiatric presentation could be classified by

enumerating all relevant symptoms Historically there have been such symptom-based

classifications Boissier de Sauvages in 18th century proposed a medical

classification system He arranged presenting symptoms into numerous

classes, orders, and genera, comparable to the classification of plants and animals

This approach generated 2400 disorders each of which was essentially a symptom

(Boissier de Sauvages, 2012)

CATEGORICAL VERSUS DIMENSIONAL

Disorders included in DSM/ICD are defined categorically

Diagnostic criteria are provided for each disorder They indicate if a clinical presentation either meets or

does not meet the definitional requirements for a particular disorder

This method of classification is similar to one used in the rest of medicine

Patient either has or does not have pneumonia

CATEGORICAL VERSUS DIMENSIONAL

This tendency to define illnesses in terms of categories reflects basic human thought processes

Use of nouns in everyday speech to indicate categories of “things”

(e.g., chairs, tables, dogs, cats)

DIMENSIONAL CLASSIFICATION

Variation in symptomatology can be represented by a set of dimensions

Blood pressure which is measured along a continuum from low to high

It only becomes a categorical construct when we apply the label “hypertension” to indicate that a patient has a significant elevation in blood pressure above a defined cut-point

DISADVANTAGES OF CATEGORICAL SYSTEM

Basic assumption is that Mental disorders are:1. Discrete entities2. Separated from one another and from normality 3. By recognizably distinct combinations of symptoms

or by demonstrably distinct etiologies True only for a small number of conditions Downs syndrome, fragile X syndrome, Alzheimer’s

disease, Huntington’s disease Little evidence supporting the applicability of this model

for other psychiatric disorders


Validity of the categorical approach has been increasingly questioned

Categorical disorders such as major depressive disorder, anxiety disorders, schizophrenia and bipolar disorder seem to merge imperceptibly both into one another and into normality with no demonstrable natural boundaries

(Goldberg, 1996; Widiger & Samuel, 2005)


The introduction to the DSM-IV-TR makes it clear that “Although a categorical classification is described in

the manual this should not be interpreted as suggesting that the categorical approach is more reliable or valid than a dimensional approach toward classification”

ADVANTAGES OF DIMENSIONAL APPROACH

Commonly observed phenomena:1. Excessive comorbidity2. An individual receiving multiple simultaneous DSM

diagnoses Direct result of having a categorical system with more

than 250 narrowly defined discrete categories Dimensional approach indicates the extent of psychiatric

symptomatology across a number of dimensions Virtually eliminates apparent comorbidity (First, 2005b)


Individual who presents with depression, anxiety, and social avoidance

Using the DSM-5 categorical system, criteria might be met for three diagnoses

A dimensional approach may simply indicate that the person has elevated values on the depression, anxiety and social avoidance dimensions


Dimensional approach avoids setting of a particular thresholds for distinguishing between pathology and normality

Categorically individual has major depressive disorder only if the threshold of five depressive symptoms is met or exceeded

Dimensional approach might say that the person is high on the depression dimension


Research studies using dimensional scales have greater power to detect differences in groups

(Cohen, 1983; Kraemer et al., 2004)

Continuous dimensions more closely model the lack of sharp boundaries between disorders and between disorder and normality

Facilitate research into the underlying etiology and path-physiology of mental disorders

(Goldberg, 1996; Smoller & Tsuang, 1998)


Dimensions can be helpful in indicating the severity of the disorder

The range of appropriate treatments is related to the severity of the disorder

Cognitive therapy by itself would not be an appropriate option for the treatment of severe forms of major depressive disorder

(Andrews et al., 2007)

DISADVANTAGES OF DIMENSIONAL APPROACH

Clinicians are accustomed to thinking in terms of diagnostic categories

Existing knowledge base about the presentation, etiology, epidemiology, course, prognosis, and treatment is based on these categories

Decisions about the management of individual patients are easier to make if the patient is thought of as having a particular disorder

(First, 2005a)

DISADVANTAGES OF DIMENSIONAL APPROACH

The value of dimensions in terms of communicating information from one clinician to another is likely to be quite limited

As Phillips (2013) noted in his review of The

Conceptual Evolution of DSM-5 (Regier et al., 2011), one clinician communicates with another by saying something like, ‘this is a bad case of depression and so far intractable to treatment,’ not by saying, ‘on dimensional scales x, y, and z the patient has such and such scores’

VALIDITY It is defined as “well founded and applicable; sound and

to the point; against which no objection can fairly be brought”

When applied to measuring instruments: “validity refers to how well the instrument measures

what it is supposed to measure” When applied to a disease entity such as bacterial

pneumonia “validity refers to the evidence that bacteria is the

cause”

TYPES OF VALIDITY

The types of validity currently employed in the context of psychiatric diagnosis

1. Content2. Criterion 3. Construct4. Predictive

CONTENT VALIDITY

Content validity refers to the degree to which an empirical measurement reflects a specific domain of content

In medicine and psychiatry, clinicians agree on important features that make up a disease, a syndrome, or a disorder

Psychiatrists agree that a patient with schizophrenia has delusions, hallucinations, disorganization, and bizarre behavior

The items that represent the domain or disorder are derived from the consensus of experts in the field

ADVANTAGES OF CONTENT VALIDITY

Content validity facilitates communication among clinicians

It provides an initial framework for further validation The worldwide use of the DSM and ICD diagnostic

criteria reflects great progress with regard to content validity

Clinicians across the globe use the same nomenclature of mental disorders

CRITERION VALIDITY

Criterion validity is measuring something that is external to the measuring instrument itself called the criterion

Physicians agree that DM has four main symptoms: Polyuria, polyphagia, polydipsia, and unexplained

weight loss (content validity) In criterion validity, an external measure is used to

validate the diagnosis that is made by content validity (e.g Fasting blood sugar)

CRITERION VALIDITY IN PSYCHIATRY

A biological marker was defined by Buchsbaum as a measurable indicator of a disease

Several biological markers have been studied in psychiatry:

1. Platelet monoamine oxidase (MAO)2. Dexamethasone suppression test3. Metabolites of serotonin and noradrenaline in the

cerebrospinal fluid No single biological marker has been unequivocally

identified as a marker for mental disorders

LEAD STANDARD BY SPITZER

Spitzer proposed the LEAD standard (longitudinal evaluation)

The LEAD standard gives best estimate diagnosis by expert clinicians by utilizing all the available data over time

Limited use of LEAD:1. The requirement of expert clinicians to make

independent assessments2. Discuss diagnostic disagreement3. Make a consensus diagnosis

CONSTRUCT VALIDITY

Construct validity refers to the extent to which a particular measure relates to other measures consistent with theoretically derived hypotheses

Construct of diagnosis of schizophrenia relies on the young age onset, the presence of psychosis, the absence of organic cause of psychosis, and positive family history of schizophrenia

Robins and Guze actually were the first to articulate the elements of construct validity in psychiatry

ROBINS AND GUZE FIVE PHASES TO ACHIEVE VALID CLASSIFICATION

In 1970 they proposed five phases to achieve valid classification of mental disorders:

1. Clinical description 2.Laboratory study 3. Exclusion of other disorders 4.Follow-up study 5. Family study They applied the criteria to schizophrenia and

concluded that good prognosis schizophrenia is not a mild schizophrenia but a different illness

CONSTRUCT VALIDITY

Construct validity consisting of validity criteria, is the core of psychiatry

Clinicians should use as many validity criteria as possible to improve the validity of their diagnosis

Researchers and clinicians should utilize construct validity to revisit and redefine content validity of psychiatric disorders

PROCEDURAL VALIDITY

Procedural validity refers to the adequacy of a new diagnostic procedure in replacing or simulating some existing procedure

One may use a structured interview to replace the existing procedure of an open ended interview by a clinician

It is very important to remember what Spitzer said: “Procedural validity speaks only to the issue of the

validity of the evaluation procedure and not to the validity of the diagnostic categories themselves”

VALIDITY VS UTILITY

A diagnostic category is said to possess utility if it provides information about:

Prognosis Likely treatment outcomes Testable propositions about biological and social

correlates

UTILITY IN PSYCHIATRIC CLASSIFICATION

The term utility was first used by Meehl There is significant etiological and prognostic

homogeneity among patients belonging to a given diagnostic group

Assignment of a patient to a group has probability implications which is clinically unsound to ignore

PROPOSAL TO IMPROVE THE VALIDITY SKILLS OF CLINICIANS

Aboraya and Compton proposed the acronym DR.SEEK D= Data R= Reference definitions S= Standardized instruments E= Clinical experience E= External validators K=Knowledge to improve the accuracy of making

psychiatric diagnoses

RELIABILITY Reliability refers to the extent to which an experiment,

test, or any measuring procedure yields the same results on repeated trials

A valid measurement or a system is reliable by definition

There is no guarantee that a reliable system is also valid

Such a system could be reliably incorrect and would therefore be invalid

RELIABILITY OF PSYCHIATRIC DIAGNOSIS- SERIOUS CHALLENGE

Dohrenwend described three generations of psychiatric epidemiology studies since the turn of the 20th century

FIRST GENERATION- FROM THE TURN OF THE 20TH CENTURY TO WORLD WAR II

Clinicians were not interested in making psychiatric diagnoses

Dominance of psychoanalysis Traditional psychoanalytic thought considered

psychiatric diagnosis irrelevant American Psychiatry was influenced by Adolf Meyer A prominent psychiatrist and advocate of social

psychiatry

Social psychiatrists feared that psychiatric nomenclature would lead to ignoring or minimizing the importance of environmental and social factors on the etiology of mental illness

Progress toward psychiatric nomenclature in this era was minimal

SECOND GENERATION- FROM WORLD WAR II TO THE PUBLICATION OF DSM-III IN 1980

Psychiatric nomenclature and diagnosis expanded with the publications of ICD and DSM

Studies of this generation relied on direct interviews with subjects

Psychiatric nomenclature developed by the WHO and APA was utilized

Reliability of psychiatric diagnoses was studied Results were disappointing

RESULTS OF THE RELIABILITY STUDIES

Sandifer, et al., conducted a study that involved 91 cases that were diagnosed by 10 experienced psychiatrists

The overall likelihood of a second opinion agreeing with the first was 57%

A review of six studies between 1956 and 1972 by Spitzer and Fleiss showed that the reliability of psychiatric diagnoses is a major problem

ROBERT SPITZER AND DSM-III

American psychiatrists were dissatisfied with the 1975 ICD-9

Robert Spitzer headed a group to develop DSMIII in 1980

The DSM-III represented a benchmark in the history of psychiatric nomenclature:

1. It included explicit and specific criteria of many psychiatric disorders

2. Marked the beginning of psychiatric epidemiology studies

THIRD GENERATION- FROM THE PUBLICATION OF DSM-III IN 1980 TO THE PRESENT

Publication of the DSM-III, DSM-IIIR, DSM-IV, DSM-5 as well as the ICD-10

Studies on the reliability of psychiatric diagnosis expanded greatly

The reliability of psychiatric diagnoses of this generation has improved due to the use of:1. Stringent design2. Diagnostic criteria3. Structured interviews

CAUSES OF UNRELIABILITY OF PSYCHIATRIC DIAGNOSIS

Ward, et al., conducted a study to pinpoint the reasons for diagnostic disagreement among psychiatrists

One experienced psychiatrist interviewed the patient first and a second psychiatrist interviewed the patient after a resting period of few minutes

CAUSES OF UNRELIABILITY OF PSYCHIATRIC DIAGNOSIS

After the second interview, both psychiatrists met, discussed their diagnosis and established reasons for disagreement

The three main reasons for diagnostic disagreement were:

1. Inconstancy of the patient (5%)2. Inconstancy of the clinician (32.5%)3. Inadequacy of the nomenclature (62.5%)

PATIENT FACTORS- PATIENT’S PSYCHOLOGICAL STATE

Patients may forget important information Patients unable to provide useful information Patients may omit information due to shame, denial,

fear of legal consequences Patients with personality disorders may make an

effort to manipulate the clinician

PATIENT FACTORS—THE USE OF PROXY INFORMATION

Clinician has to depend on proxy information The individual providing the proxy information may

have a vested interest in minimizing or exaggerating elements of the history

ATYPICAL PRESENTATIONS OF PSYCHIATRIC DISORDERS

Typical presentation can be defined as the psychiatric disorder that meets the criteria specified in the DSM or the ICD manuals

Majority of patients do not fit the classic psychiatric diagnoses

Diagnostician is forced to choose among the categories

CLINICIAN FACTORS—THE CLINICIAN INTERVIEW

Clinicians with good interviewing skills establish a therapeutic rapport

Most clinicians use an open form type of interview in routine psychiatric evaluation

The workload and time constraints of clinicians Clinicians are pressured by institutional requirements

and financial incentives to make diagnoses that reimburse at a higher rate

CLINICIAN FACTORS—CLINICIAN TRAINING, EXPERIENCE AND SCHOOL OF THOUGHTS

The reliance on the patient’s subjective symptoms Clinician’s interpretation of the symptoms and the

absence of objective measure Use of clinical data derived from direct observation is

a core component in any mental status examination

STUDY: COOPER ET AL. (1972) THE US-UK DIAGNOSTIC PROJECT

The aim of the study was to investigate reliability of diagnosis of depression and schizophrenia

The British psychiatrists diagnosed the patients in the interview to be clinically depressed twice as often

The American psychiatrists diagnosed the same patients to be suffering from schizophrenia twice as often

The results indicated that the same cases did not result in similar diagnosis in the two countries

Problems of reliability Cultural differences in interpretation of symptoms and

making a diagnosis

CLINICIAN FACTORS— PSYCHIATRIC NOMENCLATURE

Ward, et al., found that inadequacy of the psychiatric nomenclature is the main reason for diagnostic unreliability (62.5%)

The dissatisfaction with the DSM-I and -II and ICD-9 sparked major efforts by prominent psychiatrists and researchers and eventually led to the publication of the DSMIII in 1980

EVOLUTION OF DSM-III

The criteria developed by the St. Louis group (Feighner criteria) included the diagnostic criteria for 15 psychiatric conditions

Spitzer and others subsequently developed the Research Diagnostic Criteria (RDC)

RDC was an expansion and modification of the Feighner criteria

RDC included descriptions of 25 diagnostic categories

DSM-III AND RELIABILITY OF PSYCHIATRIC DIAGNOSIS

APA Task Force on Nomenclature and Statistics recommended using diagnostic criteria and categories that can serve both research and clinical purposes

To meet this goal, the Research Diagnostic Criteria (RDC) was expanded and modified and resulted in the publication of DSM-III in 1980

Due to its use of specific, clear, and detailed criteria for mental disorders, the DSM-III was accepted, preferred, and used worldwide over the ICD-9

CONTROVERSIES Dimensional versus Categorical

Approaches Towards Classification At present the research community is not unified in its

opinion regarding the categorical–dimensional debate Personality disorder researchers favor replacing the

categorical system with a dimensional approach There has not been much discussion on extending the

dimensional approach to AXIS I disorders

PAUL MEEHL'S TAXOMETRIC ANALYSIS Taxometric analysis is a statistical method of examining

whether the interrelationships among the defining features of a disorder better fit a dimensional or categorical model

Nick Haslam reviewed studies applying taxometric analytic methods to different disorders

He suggested that some disorders are more categorical in nature whereas other disorders are dimensional

Absence of clear-cut superiority of a dimensional approach

The categorical system seems appropriate at this time

SEPARATE DISORDERS VERSUS SUBTYPES

Arthur C. Houts has criticised DSM of the increasing number of disorders listed in each successive edition

Disorders are being created that had previously not been recognized as pathology

This is indicative of a lack of scientific progress Wakefield concluded that the greater number of

diagnoses listed in successive DSMs represented greater specification rather than diagnostic discoveries

LUMPERS VS SPLITTERS

Debate within the field between the so-called “lumpers,” who favor broader categories, and the “splitters,” who favor sub-classification

Researchers are more likely to benefit from embracing the splitters approach

It is easier to publish findings demonstrating that a method of sub-classification is associated with statistically significant differences

Many research articles suggest the validity of diagnostic and (sub)classification distinctions

The principles guiding the incorporation of these distinctions into a classification of disorders are unwritten

Some resulting questions include:1. When is a syndrome sufficiently distinct from its near

neighbors to warrant being considered a separate disorder?

2. When is the heterogeneity among members of a disorder sufficient to warrant subdividing the group into more homogeneous subgroups (i.e., subtyping)?

CONTROVERSIES L. Wittgenstein commented that

the classifications in Psychiatry are as if one were to classify clouds by their shape

Clouds have fuzzy boundaries, tend to merge imperceptibly and drift by invisible air currents

Observation and measurement of their movement predict, within a margin of error, the weather, yet the inner physical and chemical structure of clouds is hidden to the naked eye

The conceptual outlines of syndromes and disease entities tend to change with successive revisions of their classification, relative to their utility for predicting course, outcome and likely response to available treatments, even if their inner biological and psychological structure is not fully understood

The quest for validity of our concepts continues

E. Kraepelin stated in one of his last articles, ‘Patterns of Mental Disorder’

“It is necessary to turn away from arranging illnesses in orderly well defined groups, and to set ourselves the undoubtedly higher and more satisfying goal of understanding their essential structure”

DISEASE VS DISORDER VS SYNDROME Psychiatric classifications classify disorders Status of concepts like “disease” and “disorder” remains

obscure Disease is an explanatory construct integrating

information about pathology and cause The typical progression of knowledge starts with the

identification of clinical manifestations (the syndrome) Understanding of the pathology and aetiology comes

much later There is no fixed point or agreed threshold beyond which

a syndrome can be said to be a disease The majority of the “disorders” in our current

classifications are syndromes

CONTROVERSIES Role of pharmaceutical companies in classification Consideration of functional brain imaging/

investigations as diagnostic criteria Considering Family History and Genetic Markers

as Diagnostic Criteria Financial Implications of Revising the Classification

QUESTIONS FACED BY PSYCHIATRIC NOSOLOGY

Recurrent questions about the nosological status of the brain and mind disorders that constitute the core of the discipline

Are we dealing with discrete entities or with graded continuous phenomena to which we can apply cut-off points to separate “pathology” from “normal variation”?

What is the relationship between the clinical manifestations of a disorder and the underlying brain dysfunction, pathological processes or predisposing genetic aberrations?

FUTURE OF CLASSIFICATION

NIMH-sponsored Research Domain Criteria (RDoC) project is intended to establish “a framework for creating research classifications that reflect functional dimensions stemming from translational research on genes, circuits, and behavior”

Represents a true paradigm shift in the classification of mental disorders, moving away from defining disorders

CONCLUSION

None of the many attempts to re-shape the nosology of the major psychiatric disorders has been entirely satisfactory

There can be no doubt that the classical nosological hypothesis was a major step forward, introducing order and parsimony in a field that had previously been chaotic or arbitrarily subdivided

CONCLUSION The nosological hypothesis helped to bring into

focus issues which critics could oppose or endorse This contributed to a diversity of viewpoints that was

fruitful in a developing discipline called psychiatry A more fundamental re-thinking of the nosological

theory will require the development of a conceptual framework that allows a better integration of clinical, neurobiological, genetic and behavioural data

SUMMARY DEFINITION OF CLASSIFICATION GOALS/ PURPOSE OF CLASSIFICATION

1. DENOMINATION2. QUALIFICATION3. PREDICTION

ADVANTAGES OF PSYCHAITRIC CLASSIFICATION1. Communicability2. Predictability

APPROACHES TO PSYCHIATRIC CLASSIFICATION:1. Etiological Versus Descriptive2. Syndrome Versus Symptom3. Categorical Versus Dimensional

SUMMARY VALIDITY OF PSYCHIATRIC CLASSIFICATION:

1. Content2. Criterion 3. Construct 4. Procedural

RELIABILITY OF PSYCHIATRIC CLASSIFICATION:1. First generation- 20th century to world war-I2. second generation- 2nd world war to DSM-III3. Third generation- DSM-III till Present

CONTROVERSIES IN PSYCHIATRIC CLASSIFICATION:1. Dimensional vs categorical approach2. Separate disorders vs subtypes( Lumpers vs splitters)3. Disease vs disorder4. Use of genetic studies and functional neuroimaging

REFERENCES

1. Psychiatry (Tasman) Psychiatry / edited by Allan Tasman, Jerald Kay, Jeffrey A. Lieberman, Michael B. First, Michelle B. Riba.–Fourth edition. ISBN 978-1-118-84547-9 (cloth)

2. Kaplan & Sadock's Comprehensive Textbook of Psychiatry, 9th Edition; Sadock, Benjamin J.; Sadock, Virginia A.; Ruiz, Pedro

3. The Reliability of Psychiatric Diagnosis Revisited: The Clinician’s Guide to Improve the Reliability of Psychiatric Diagnosis; by Ahmed Aboraya, Md, Drph; Eric Rankin, Phd; Cheryl France, Md; Ahmed El-missiry, Md, Mrcpsych; Collin John. Psychiatry 2006 [ J A N U A R Y ],Page 42

4. The validity of Psychiatric Diagnosis Revisited: The Clinician’s Guide to Improve the Reliability of Psychiatric Diagnosis; by Ahmed Aboraya, Md, Drph; Eric Rankin, Phd; Cheryl France, Md; Ahmed El-missiry, Md, Mrcpsych; Collin John. Psychiatry 2005 [ J A N U A R Y ],Page 42

5. Psychiatric classifications: validity and utility. Assen Jablensky. (World Psychiatry 2016;15:26–31)

6. Indian Psychiatry and classification of psychiatric disorders. K. S. Jacob. Indian J Psychiatry. 2010 Jan; 52(Suppl1): S104–S109.

Classification of psychiatric disorders

Health & Medicine