Diagnosis and Classification in Psychiatry


Classification is a process by which phenomena are organized into categories so as to bring together those phenomena that most resemble each other and to separate those that differ.

Ways to classify psychiatric disorders

Any classification of psychiatric disorders, like that of medical illnesses, should ideally be based on aetiology. For a large majority of psychiatric disorders, no distinct aetiology is known at present, although there are many attractive probabilities for several of them.  Therefore, one of the most rational ways to classify psychiatric disorders at present is probably syndromal.


A syndrome is defined as a group of symptoms and signs that often occur together, and delineate a recognisable clinical condition. The syndromal approach of classifying psychiatric disorders, on the basis of their clinical signs and symptoms, is very similar to the historical approach of classification of medical illnesses, when aetiology of a majority of medical illnesses was still obscure.

Purposes of classification

There are three major purposes of classification of psychiatric disorders:

  1. To enable communication regarding the diagnosis of disorders,
  2. To facilitate comprehension of the underlying causes of these disorders, and
  3. To aid prediction of the prognosis of psychiatric disorders.

This syndromal approach of classification, in the absence  of  clearly known aetiologies, fulfils these purposes reasonably well.

Before proceeding to look at current classifications of psychiatric disorders,it is important to distinguish Normal Mental Health and Psychiatric Disorders.


According to the World Health Organization (WHO): Health is a state of complete physical, mental and social well being, and not merely absence of disease or infirmity. Normal mental health, much like normal health, is a rather difficult concept to define. There are several models available for understanding what may constitute ‘normality’

Some Models of Normality in Mental Health

Medical Model

(Normality as Health)

Normal mental health is conceptualized as the absence of any psychiatric disorder (‘disease’) or psychopathology.

Statistical Model

(Normality as an Average)

Statistically normal mental health falls within two standard deviations (SDs) of the normal distribution curve for the population.

Utopian Model

(Normality as Utopia)

In this model, the focus in defining normality is on ‘optimal functioning ‘.

Subjective Model:

According to this model, normality is viewed as an absence of distress, disability, or any help-seeking behaviour resulting thereof. This definition is similar in many ways to the medical model.

Social Model:

A normal person, according to this definition, is expected to behave in a socially ‘acceptable’ behaviour.

Process Model

(Normality as a Process)

This model views normality as a dynamic and changing process, rather than as a static concept. This model can be combined with any other model mentioned here.

Continuum Model

(Normality as a Continuum)

Normality and mental disorder are considered by this model as falling at the two ends of a continuum, rather than being disparate entities. According to this model, it is the severity (scores above the ‘cut-off’) that determines whether a particular person’s experience constitutes a symptom of a disorder or falls on the healthy side of the continuum.

Although, normality is not an easy concept to define, some of the following traits are more commonly found in ‘normal’ individuals.

  1. Reality orientation.
  2. Self-awareness and self-knowledge.
  3. Self-esteem and self-acceptance.
  4. Ability to exercise voluntary control over their behaviour.
  5. Ability to form affectionate relationships.
  6. Pursuance of productive and goal-directive activities.



The simplest way to conceptualize a psychiatric disorder is a disturbance of Cognition (i.e. Thought), Conation (i.e. Action), or Affect (i.e. Feeling), or any disequilibrium between  the three domains. However, this simple definition is not very useful in routine clinical practice.

Another way to define a psychiatric disorder or mental disorder is as a clinically significant psychological or behavioural syndrome that causes significant (subjective) distress, (objective) disability, or loss of freedom;  and which is not merely a socially deviant behaviour or an expected  response to a stressful life event (e.g. loss of a loved one). Conflicts between the society and the individual are not considered psychiatric disorders. A psychiatric disorder should be a manifestation of behavioural, psychological, and/or biological dysfunction in that person (Definition modified after DSM-IV-TR, APA). Although slightly lengthy, this definition defines a psychiatric disorder more accurately.


Like any growing branch of Medicine, Psychiatry has seen rapid changes in classification to keep up with a conglomeration of growing research data dealing with epidemiology, symptomatology, prognostic factors, treatment methods and new theories for the causation of psychiatric disorders.

Although first attempts to classify psychiatric disorders can be traced back to Ayurveda, Plato (4th century BC) and Asclepiades (1st century BC), classification in Psychiatry has certainly evolved ever since.

At present, there are two major classifications in Psychiatry, namely

  1. ICD-10(1992) and
  2. DSM-IV-TR (2000).


ICD-10 (International Classification of Diseases, 10th Revision, 1992) is World Health Organisation’s classification for all diseases and related health problems (and not only psychiatric disorders).

Chapter ‘F’ classifies psychiatric disorders as Mental and Behavioural Disorders (MBDs) and codes them on an alphanumeric system from F00 to F99. ICD-10 is now available in several versions, the most important of which are listed below.

Mental and Behavioural  Disorders  in ICD-10

  1. F00-F09 Organic, Including Symptomatic, Mental Disorders, such  as delirium,  dementia,  organic  amnestic syndrome,  and other organic mental disorders.
  2. F10-F19 Mental and  Behavioural  Disorders due  to Psychoactive Substance  Use, such  as acute intoxication, harmful use, dependence symdrome,  withdrawal state, amnestic  syndrome,   and psychotic  disorders due to psychoactive  substance  use.
  3. F20-F29 Schizophrenia, Schizotypal and Delusional Disorders, such  as  schizophrenia, schizotypal  disorder, persistent delusional disorders, acute and transient psychotic disorders. induced delusional disorder, and schizo-affective disorders.
  4. F31-F39 Mood (Affective) Disorders, such as manic episode, depressive episode, bipolar affective disorder, recurrent depressive disorder, and persistent mood disorder.
  5. F40-F48 Neurotic, Stress-related and Somatoform Disorders (There is no category with code number F49), such as anxiety disorders, phobic anxiety disorders, obsessive-compulsive disorder, dissocia­tive (conversion) disorders, somatoform disorders, reaction to stress,  and adjustment disorders, and other neurotic  disorders.
  6. F50-F59 Behavioural Syndromes Associated with Physiological Disturbances and Physical Factors, such as eating disorders, non-organic  sleep disorders, sexual dysfunctions  (not caused  by organic disorder or disease), mental and behavioural disorders associated with puerperium, and abuse of non-dependence-producing substances.
  7. F60-F69 Disorders of Adult Personality  and  Behav­iour,  such as specific personality disorders,  enduring personality changes, habit and impulse disorders, gender-identity disorders, disorders of sexual pre­ference, and psychological and behavioural disorders associated with sexual development  and orientation.
  8. F70-F79 Mental Retardation, including mild, moderate, severe, and profound mental retardation.
  9. F80-F89 Disorders of Psychological Development, such as specific developmental disorders of speech and language, specific developmental disorders of scholastic skills, specific developmental disorders of motor function, mixed specific developmental disorders, and pervasive  developmental disorders.
  10. F90-F98 Behavioural and Emotional Disorders with Onset Usually Occurring in Childhood  and Adolescence, such as hyperkinetic disorders, conduct disorders, mixed disorders  of conduct  and emotions, tic disorders,  and  other disorders.
  11. F99 Unspecified Mental Disorder

Some Versions  of ICD-10

There are several versions of ICD-10; some are listed below

  1. Clinical Descriptions and Diagnostic Guidelines (CDDG)
  2. Diagnostic Criteria for Research (DCR)
  3. Multi-axial Classification  Version
  4. Primary Care Version


DSM -IV-TR (Diagnostic and Statistical Manual of Mental Disorders, IV Edition, Text Revision, 2000) is the American Psychiatric Association (APA)’s classification of mental disorders. DSM-IV-TR is a text revision of the DSM-IV which was  originally published  in 1994 and listed more than 250 mental disorders.


The  process  of making  a correct  diagnosis is a very useful clinical   exercise  as  evidence-based manage­ment can be dependent  on making  a correct  diagnosis. However, sometimes making  a clinical  diagnosis  can lead  to labelling   of patient  and  can  be stigmatizing. This can also degrade the patient to “just another case” and does not direct attention  to the whole  individual.

In the last few decades,  there has been an upsurge of  interest   in  multi-axial    systems   for  achieving    a more  comprehensive    description   of  an  individual’s clinical  problems   and needs.  The pattern adopted by DSM-IV-TR   is a very  good  example  of this attempt.

In this system,  an individual  patient  is diagnosed   on five separate  axes, ensuring  a more through  evaluation of needs as below.

The Five Axes of DSM-IV-TR

AXIS I:      Clinical Psychiatric Diagnosis

AXIS II:    Personality Disorders and Mental Retardation

AXIS III:   General Medical Conditions

AXIS IV:   Psychosocial and Environmental Problems

AXIS V:    Global Assessment of Functioning: Current and in past one year

(Rated on a scale)


This  method   helps   in  making   a more  holistic, biopsychosocial    assessment   of an individual  patient. Recently,  ICD-10 has also brought  out its own multi­ axial  classification   version  (see Some Versions  of ICD-10).

The next editions of ICD (ICD-11) and DSM (DSM- V)  are  likely  to  be  available   in the  years 2012-14.

In this website(www.homoeopathic.in), it is intended to follow the ICD-10 classification. ICD-10 is easy to follow, has been tested extensively  all over the world (51 countries; 195 clinical centres), and has been found to be generally  applicable  across the globe. At some places in the website, DSM -IV-TR diagnostic criteria are also discussed, wherever appropriate.

Earlier classifications in psychiatry were based on hierarchies of diagnoses with presence of a diagnosis higher in the hierarchy usually ruling out a diagnosis lower in the hierarchy. This was felt to be in keeping with the teaching  of Medicine  at large at the time, where there was emphasis on making  a single diagnosis of one disease rather than explaining  different symptoms by different disease entities.

The presence of a diagnostic hierarchy  implied that the conditions higher up in the hierarchy needed to be considered  first, before  making  a diagnosis  of those lower down in the hierarchy. For example, it was felt that a current diagnosis of organic mental disorder such as delirium would exclude a diagnosis of anxiety disorder in presence of agitation; and alcohol and drug induced disorders would take precedence over a diagnosis of primary mood disorder.

The current classifications however encourage recording of multiple diagnoses in a given patient (as co-morbidity) regardless of any hierarchy. Although a diagnostic hierarchy  makes  much  clinical  sense, consideration and recording  of co-morbidity  can be helpful  in identifying more of patient’s needs; for example,  a diagnosis of co-morbid  anxiety  disorder in a patient with bipolar disorder helps identify and treat the anxiety component  adequately.

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