Chapter 2: Burden of Mental and Behavioural Disorders:
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Mental and behavioural disorders are identified and diagnosed using clinical methods that are similar to those used for physical disorders. These methods include a careful and detailed collection of historical information from the individual and others, including the family; a systematic clinical examination for mental status; and specialized tests and investigations, as needed. Advances have been made during recent decades in standardizing clinical assessment and improving the reliability of diagnosis. Structured interview schedules, uniform definitions of symptoms and signs, and standard diagnostic criteria have now made it possible to achieve a high degree of reliability and validity in the diagnosis of mental disorders. Structured interview schedules and diagnostic symptom/sign checklists allow mental health professionals to collect information using standard questions and pre-coded responses. The symptoms and signs have been defined in detail to allow for uniform application. Finally, diagnostic criteria for disorders have been standardized internationally. Mental disorders can now be diagnosed as reliably and accurately as most of the common physical disorders. Concordance between two experts in the diagnosis of mental disorders averages 0.7 to 0.9 (Wittchen et al. 1991; Wing et al.1974; WHO 1992; APA 1994; Andrews et al. 1995). These figures are in the same range as those for physical disorders such as diabetes mellitus, hypertension or coronary artery disease.
Since a reliable diagnosis is a prerequisite to appropriate intervention at the individual level as well as to accurate epidemiology and monitoring at the community level, advances in diagnostic methods have greatly facilitated the application of clinical and public health principles to the field of mental health.
Box 2.1 Mental and behavioural disorders classified in ICD-10
A complete list of all mental and behavioural disorders is given in The ICD-10 classification of mental and behavioural disorders: clinical descriptions and diagnostic guidelines.1 Additional diagnostic criteria for research are also available for a more precise definition of these disorders.2 These materials, which are applicable cross culturally, were developed from Chapter V(F) of the Tenth Revision of the International Classification of Diseases (ICD-10)3 on the basis of an international review of scientific literature, worldwide consultations and consensus. Chapter V of ICD-10 is exclusively devoted to mental and behavioural disorders. Besides giving the names of diseases and disorders, like the rest of the chapters, Chapter V has been further developed to give clinical descriptions and diagnostic guidelines as well as diagnostic criteria for research. The broad categories of mental and behavioural disorders covered in ICD-10 are as follows.
- Organic, including symptomatic, mental disorders e.g., dementia in Alzheimer's disease, delirium.
- Mental and behavioural disorders due to psychoactive substance use e.g., harmful use of alcohol, opioid dependence syndrome.
- Schizophrenia, schizotypal and delusional disorders e.g., paranoid schizophrenia, delusional disorders, acute and transient psychotic disorders.
- Mood [affective] disorders e.g., bipolar affective disorder, depressive episode.
- Neurotic, stress-related and somatoform disorders e.g., generalized anxiety disorders, obsessivecompulsive disorders.
- Behavioural syndromes associated with physiological disturbances and physical factors e.g., eating disorders, non-organic sleep disorders.
- Disorders of adult personality and behaviour e.g., paranoid personality disorder, transsexualism.
- Mental retardation e.g., mild mental retardation.
- Disorders of psychological development e.g., specific reading disorders, childhood autism.
- Behavioural and emotional disorders with onset usually occurring in childhood and adolescence e.g., hyperkinetic disorders, conduct disorders, tic disorders.
- Unspecified mental disorder.
This report focuses on a selection of disorders that usually cause severe disability when not treated adequately and which place a heavy burden on communities. These include: depressive disorders, substance use disorders, schizophrenia, epilepsy, Alzheimer's disease, mental retardation, and disorders of childhood and adolescence. The inclusion of epilepsy is explained later in this chapter.
Some of the mental, behavioural and neurological disorders are included under "neuropsychiatric disorders" in the statistical annex of this report. This group includes unipolar major depression, bipolar affective disorder, psychoses, epilepsy, alcohol dependence, Alzheimer's and other dementias, Parkinson disease, multiple sclerosis, drug dependence, post-traumatic stress disorder, obsessivecompulsive disorders, panic disorder, migraine and sleep disorders.
1 The ICD-10 classification of mental and behavioural disorders: clinical descriptions and diagnostic guidelines (1992b). Geneva, World Health Organization.
2 The ICD-10 classification of mental and behavioural disorders: diagnostic criteria for research (1993a). Geneva, World Health Organization.
3 International statistical classification of diseases and related health problems, Tenth revision 1992 (ICD-10). Vol.1: Tabular list. Vol.2: Instruction manual. Vol.3: Alphabetical index (1992a). Geneva, World Health Organization.
Chapter 2: Burden of Mental and Behavioural Disorders:
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