Classification of Mental Disorders: A Comprehensive Guide for Students - Prof. Dahiya, Thesis of Personality Psychology

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Indira Gandhi National Open University School of Social Sciences

MPC-

Mental Disorders

Classification of Mental Disorders

Block

CLASSIFICATION OF MENTAL DISORDERS

UNIT 1

Classification of Mental Disorders: Need, Historical

Perspective and the Modern System of Classification 5

UNIT 2

Schizophrenia and Other Psychotic Disorders 25

UNIT 3

Mood Disorders 43

UNIT 4

Neurotic Group of Disorders 66

UNIT 5

Other Disorders which do not Fall in above Categories of

Psychiatric Disorders 90

MPC- Mental Disorders Indira Gandhi National Open University School of Social Sciences

MPC-052 MENTAL DISORDERS The Course on “ Mental Disorders ” is the second course in the P.G. Diploma in Mental Health (PGDMH) programme of IGNOU. This course will orient you towards the various group of mental disorders and their epidemiology. It further deals with the clinical picture, course and outcome of the mental disorders. The identification and assessment of the mental disorders are also described in this course. As part of this course, you’ll have continuous evaluation through assignment and a term-end examination at the end of the year. The course has four theory Blocks as follows: The Blocks Block 1 is on “ Classification of Mental Disorders”. This Block focuses on the classification system of mental disorders. It provides you understanding about the different types of mental disorders such as the psychotic and neurotic group of disorders. It talks about their clinical features, course and outcome, identification and assessment, and treatment procedures. After studying this Block, you will be able to describe the classification systems for various mental disorders and point out their various aspects in terms of symptoms, clinical characteristics, diagnosis, causes and treatment. Block 2 is titled “ Epidemiology and Prevalence of Mental Disorders”. The Block talks about the epidemiological methods. You will also learn about the epidemiology of mental disorders in India. Further, you will understand the global burden of mental illness and the impact of mental disorders on the society. After going through this Block, you will be able to describe the epidemiology of mental disorders and the adverse effect of mental disorders on the society. Block 3 is on “Clinical Manifestations, Course and Outcome of Mental Disorders”. This Block will help you understand the clinical manifestations of the mental disorders in its cognitive, conative and affective aspects. Further, you will also learn about the course and outcome of the mental disorders. After studying this Block, you will be able to describe the mental disorders in terms of the disturbances in cognitive, affective and behavioural aspects; and depict their course and outcome. Block 4 is on “Identification and Assessment of Mental Disorders”. This Block delineates the process of identification and assessment of mental disorders through interview and case history taking. You will learn about the steps followed in the assessment and the role of physical investigation and psychological assessment in the diagnosis of mental disorders. After going through this Block, you will develop an understanding of the procedure for identification and assessment of mental disorders. How Will This Course Help You The course will provide you knowledge and understanding about the various mental disorders. It will help you develop awareness and understanding of the mental disorders in its various aspects such as classification, identification, assessment, clinical manifestations, course, aetiology and treatment.

BLOCK 1 CLASSIFICATION OF MENTAL DISORDERS In MPC-051 you have learned about the fundamentals of mental health, including the concept of mind, schools of psychology, concepts of normality and abnormality, and role of family and culture in mental health. In MPC-052, we will be discussing about the mental disorders, their classification, clinical manifestations and assessment of mental disorders. Here in Block 1 of MPC-052, we will be focusing on the classification of Mental Disorders. Unit 1 deals with the “Classification of Mental Disorders: Need, Historical Perspective and the Modern System of Classification”. It defines mental disorder and highlights the need and importance of having a classification system for mental disorders. The modern system of classification used are described in detail. Unit 2 deals with “Schizophrenia and other psychotic disorders”. Schizophrenia, a major mental disorder is described in this unit in terms of its clinical features and diagnosis. Further, the etiology and treatment for schizophrenia are also explained. A few other related mental disorders are also mentioned in this Unit. Unit 3 describes “Mood Disorders”, most commonly observed in the field of mental health. The clinical features of manic episode, depressive episode and mixed episode are explained. The Unit also describes the classification of mood disorders and the treatment of mood disorders. The Unit will help you be familiar with the common mood disorders. Unit 4 is “Neurotic Group of Disorders”. It describes the anxiety related disorders, stress related disorders found frequently in the population. The Unit also deals with somatoform disorders and dissociative disorders. In all these disorders, the clinical picture, symptoms and the treatment options are elaborated. Unit 5 is on “Other Disorders which do not fall in above categories of Psychiatric Disorders.” In this Unit, various other mental disorders are described such as sleep disorders, personality disorders, psychosexual disorders and eating disorders. The etiology, symptoms and the treatment options of these disorders are also described.

Disorders

1.1 OBJECTIVES

After studying this Unit, you will be able to :  define a mental disorder;  explain the need and purpose of classification of mental disorder;  describe the history of classification of mental disorders; and  explain the modern systems of classifications of mental disorders.

1.2 DEFINITION OF MENTAL DISORDER

Before we proceed further, it is important to define mental disorder and distinguish it from normal. Whether or not a problem is considered a disorder has implications in terms of deciding treatment, legal aspects, and also for medical insurance reimbursements. In comparison to most medical illnesses, mental disorders are manifested by a quantitative deviation in behaviour, ideation, and emotion from a normative concept. The debate remains which behaviours, ways of thinking, or emotional states could be considered abnormal or deviant to indicate mental disorder. The10th^ edition of the World Health Organisation’s International Classification of Diseases (ICD 10) does not define mental disorder, but refers to the term ‘disorder’, using it to imply the existence of a clinically recognisable set of symptoms or behaviours, associated with distress or interference with personal functions. It further mentions that social deviance or conflict alone, without personal dysfunction, does not constitute mental disorder (World Health Organisation, 1992). The Mental Health Act of India does not define mental disorder or illness, but defines a mentally ill person as a person who is in need of treatment by reason of any mental disorder other than mental retardation. American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders, 4th^ Edition (DSM IV), defines mental disorder as a “clinically significant behavioural or psychological syndrome or pattern that occurs in an individual and that is associated with present distress (e.g., a painful symptom) or disability (i.e., impairment in one or more important areas of functioning) or with a significantly increased risk of suffering, death, pain, disability, or an important loss of freedom.” The syndrome or pattern must not be merely an expected and culturally sanctioned response to a particular event, for example, the death of a loved one. Whatever be the original cause, the disturbance is considered a manifestation of a behavioural, psychological, or biological dysfunction in the individual. Neither deviant behaviour (e.g., political, religious, or sexual) nor conflicts that are primarily between an individual and the society are mental disorders unless the deviance or conflict is a symptom of a dysfunction in the individual, as described above (American Psychiatric association, 2000). Thus in simple words, mental disorder can be conceptualised as a disturbance in psychological functioning expressing itself in the form of psychological or behavioural disturbance, which is associated with significant distress to self or others or dysfunction in different areas of functioning. Self Assessment Questions 1 Note : i) Read the following questions carefully and answer in the space provided below. ii) Check your answer with that provided at the end of this unit.

1. Differentiate between mental disorder and mental illness. ..................................................................................................................... ..................................................................................................................... .....................................................................................................................
2. How do you define a mental disorder? ..................................................................................................................... ..................................................................................................................... ..................................................................................................................... .....................................................................................................................

1.3 NEED FOR CLASSIFICATION OF MENTAL

DISORDERS

There is a wide range of mental disorders with different kinds of manifestations. Hence it becomes important to arrange them into specific categories, based on some established criteria for different purposes. The classification serves this purpose and can be defined as the process by which the complexity of phenomena is reduced by grouping them into categories as per some defined criteria. The ultimate purpose of classification is to improve the treatment and prevention of illnesses. Ideally, a classification of any illness group should be based on its etiology or pathophysiology because this increases the likelihood of improving treatment and prevention. Since, exact etiology or pathophysiology of most of the mental disorders is not known; the disorders are grouped into various classes on the basis of some shared phenomenological characteristics. Classification of mental disorders serves the purpose of communication, control, and comprehension.  Communication refers to communicating information about the illness and the diagnosis. Thus when a clinician diagnoses a mental disorder as a specific category (e.g. generalised anxiety disorder) as per a particular classification system, and puts it on an outpatient prescription or the case records; another clinician would understand the clinical symptoms of the patient on seeing the diagnosis in the records. Thus it has served the purpose of communication.  Control refers to developing the strategies for modifying the course of illness with treatment and also planning preventive strategies. A definition of disorder as per some classification would make it easy to develop control methods.  Comprehension refers to understanding about the illness. Classification has a potential to improve understanding of an illness and hence also the causes and the processes involved in the development of illness and its maintenance. Self Assessment Questions 2 Note : i) Read the following questions carefully and answer in the space provided below. ii) Check your answer with that provided at the end of this unit. Disorders: Need, Historical Perspective and the Modern System of Classification

1.5 PRINCIPLES OF CLASSIFICATION OF

MENTAL DISORDERS

The development of classification system and their subsequent revisions reflect the contemporary understanding of the mental illness. The classification of psychiatric disorders has been primarily based on the clinical presentation of the illness and its course, since we are not aware of their exact etiology and pathophysiology. Clustering of different clinical symptoms in different areas of psychological functioning, their severity, and the course often form the basis of the categorisation, as also historically used by Kraepelin. At the simplest, the mental disorders are divided into organic and functional, and then into psychotic and neurotic disorders. This dichotomy, though still used sometimes, is not valid in the current classificatory systems. But for historical reasons and for understanding purpose, it is important to understand these terms. If in a psychiatric patient there is an evidence of a structural or functional disturbance in brain on taking history, clinical examination or investigations, the disorder is termed as ‘organic’. If there is no such evidence, the illness is called ‘functional’.The functional illnesses are further broadly categorised into psychoses (psychotic disorders) and neuroses (neurotic disorders). The term ‘psychoses’ refers to severe psychiatric disorders characterised by grossly disturbed behaviour, loss of contact with reality, lack of insight and inability to meet the general demands of life, whereas the ‘neuroses’ are psychiatric disorders of lesser severity, where anxiety is the predominant feature which may be experienced directly or on being altered into some other symptoms by mental defence mechanisms. The patient usually retains insight and contact with reality in neuroses. The traditional dichotomy between neuroses and psychoses is not followed in the current classificatory systems e.g. lCD 10 and DSM IV. In both, the disorders are arranged in groups according to major common themes or descriptive likenesses, making it more convenient to use. Self Assessment Questions 3 Note : i) Read the following questions carefully and answer in the space provided below. ii) Check your answer with that provided at the end of this unit.

1. What is Kraepelin’s contribution to classification of mental disorders? ..................................................................................................................... ..................................................................................................................... .....................................................................................................................
2. What is the principle used in classification of mental disorders? ..................................................................................................................... ..................................................................................................................... .....................................................................................................................
3. What are the differences between psychoses and neuroses? ..................................................................................................................... ..................................................................................................................... ..................................................................................................................... Disorders: Need, Historical Perspective and the Modern System of Classification

Disorders

1.6 MODERN SYSTEMS OF CLASSIFICATION OF

MENTAL DISORDERS

As introduced earlier, there are currently two official classification systems which are recognised internationally. Both have been in use now for more than 60 years. The two systems are the WHO’s International Classification of Diseases (ICD) and American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM). Both the systems have undergone a number of revisions and also expansions since their initial introduction. Though initially, there were many differences between the two systems, their latest editions (ICD 10 of 1992 and DSM IV of 1994) with revisions in their respective editions over the years, the two are now quite similar in basic principle. Both are recognised internationally. DSM IV is the official diagnostic system of USA and its latest version is of 2000, called DSM IV-TR (DSM IV- Text Revision).WHO’s ICD has got acceptance all over the world and is also the official diagnostic system in India. Both ICD 10 as well as DSM IV are in the process of a final revision to ICD 11 and DSM V, which are expected in another 2-3 years. Let us now discuss both DSM and ICD classification.

1.6.1 Diagnostic and Statistical Manual (DSM)

The DSM-IV (TR) recommends clinicians to assess an individual’s mental state across five factors or axes. Together the five axes provide a broad range of information about the individual’s functioning, not just a diagnosis. The system contains the following axes.

1. Axis I: Clinical Disorders and Other Conditions That May Be a Focus of Clinical Attention This axis incorporates a wide range of clinical syndromes, including anxiety disorders, mood disorders, schizophrenia and other psychotic disorders, adjustment disorders, and disorders usually first diagnosed during infancy, childhood, or adolescence (except for mental retardation, which is coded on Axis II). Axis I also includes relationship problems, academic or occupational problems, and bereavement, conditions that may be the focus of diagnosis and treatment but that do not in themselves constitute definable psychological disorders. Also coded on Axis I are psychological factors that affect medical conditions, such as anxiety that exacerbates an asthmatic condition or depressive symptoms that delay recovery from surgery. The Axis I clinical disorder categories are as follows:
2. Disorders usually first diagnosed in Infancy, Childhood, or Adolescence
3. Delirium, Dementia, and Amnestic and other Cognitive Disorders
4. Mental Disorders due to a General Medical Condition not elsewhere Classified
5. Substance Related Disorders
6. Schizophrenia and other Psychotic Disorders
7. Mood Disorders
8. Anxiety Disorders
9. Somatoform Disorders
10. Factitious Disorders
11. Dissociative Disorders
12. Sexual and Gender Identity Disorders
13. Eating Disorders

Disorders Table 1: Psychosocial and Environmental Problems Problem Categories Examples Problems with primary support group Death of family members; health problems of family members; marital disruption in the form of separation, divorce, or estrangement; sexual or physical abuse within the family; child neglect; birth of a sibling Problems related to the social environment Death or loss of a friend; social isolation or living alone; difficulties adjusting to a new culture (acculturation); discrimination; adjustment to transitions occurring during the life cycle, such as retirement Educational problems Illiteracy; academic difficulties; problems with teachers or classmates; inadequate or impoverished school environment Occupational problems Work-related problems including stressful workloads and problems with bosses or co- workers; changes in employment; job dissatisfaction; threat of loss of job; unemployment Housing problems Inadequate housing or homelessness; living in an unsafe neighbourhood; problems with neighbours or landlord Economic problems Financial hardships or extreme poverty; inadequate welfare support Problems with access to health care services Inadequate health care services or availability of health insurance; difficulties with transportation to health care facilities Problems related to interaction with the legal system/crime Arrest or imprisonment; becoming involved in a lawsuit or trial; being a victim of crime Other psychosocial problems Natural or human-made disasters; war or other hostilities; problems with caregivers outside the family, such as counselors, social workers, and physicians; lack of availability of social service agencies Source: Adapted from the DSM-IV-TR (APA, 2000)

5. Axis V: Global Assessment of Relational Functioning (GARF) The clinician rates the client’s current level of psychological, social, and occupational functioning using a 0-100 scale (see Table-2). The clinician may also indicate the highest level of functioning achieved for at least a few months during the preceding year. The level of current functioning indicates the current need for treatment or intensity of care. The level of highest functioning is suggestive of the level of functioning that might be restored. The GARF Scale can be used to indicate an overall judgment of the functioning of a family or other ongoing relationship on a hypothetical continuum ranging from competent, optimal relational functioning to a disrupted, dysfunctional relationship (APA. 2000).

Table 2: Global Assessment of Functioning (GAF) Scale Source: Adapted from the DSM-IV-TR (APA, 2000) Disorders: Need, Historical Perspective and the Modern System of Classification Code Severity of Symptoms Examples 91 - 100 Superior functioning across a wide variety of activities of daily life Lacks symptoms, handles life problems without them “getting out of hand” 81 - 90 Absent or minimal symptoms, no more than everyday problems or concerns Mild anxiety before exams, occasional argument with family members 71 - 80 Transient and predictable reactions to stressful events, or no more than slight impairment in functioning Difficulty concentrating after argument with family, temporarily falls behind in schoolwork 61 - 70 Some mild symptoms, or some difficulty in social, occupational, or school functioning, but functioning pretty well Feels down, mild insomnia, occasional truancy or theft within household 51 - 60 Moderate symptoms, or moderate difficulties in social, occupational, or school functioning Occasional panic attacks, few friends, conflicts with co-workers 41 - 50 Serious symptoms, or any serious impairment in social, occupational, or school functioning Suicidal thoughts, frequent shoplifting, unable to hold job, has no friends 31 - 40 Some impairment in reality testing or communication, or major impairment in several areas Speech illogical, depressed man or woman unable to work, neglects family, and avoids friends 21 - 30 Strong influence on behavior of delusions or hallucinations, or serious impairment in communication or judgment, or inability to function in almost all areas Grossly inappropriate behavior, speech sometimes incoherent, stays in bed all day, no job, home, or friends 11 - 20 Some danger of hurting self or others, or occasionally fails to maintain personal hygiene, or gross impairment in communication Suicidal gestures, frequently violent, smears feces Largely incoherent or mute 1 - 10 Persistent danger of severely hurting self or others, or persistent inability to maintain minimal personal hygiene, or seriously suicidal act with clear expectation of death Serious suicidal attempt, recurrent violence

1 5 Self Assessment Questions 4 Note : i) Read the following questions carefully and answer in the space provided below. ii) Check your answer with that provided at the end of this unit.

1. Discuss briefly the international classification systems of mental disorders currently in use. ..................................................................................................................... ..................................................................................................................... ..................................................................................................................... .....................................................................................................................

1.7 CATEGORIES OF MENTAL DISORDERS

This section gives salient features of various mental disorders, as these are described in ICD 10. The categories are broadly similar to those of DSM IV, though there are minor differences in diagnostic guidelines or in the precise grouping or sub grouping of the diagnostic categories. All the disorders as enumerated below are discussed in details in subsequent chapters. As mentioned earlier, the following mental disorders are included under ICD 10: — Organic, including symptomatic, mental disorders — Mental and behavioural disorders due to psychoactive substance use — Schizophrenia, schizotypal and delusional disorders — Mood [affective] disorders — Neurotic, stress-related and somatoform disorders — Behavioural syndromes associated with physiological disturbances and physical factors — Disorders of adult personality and behaviour — Mental retardation — Disorders of psychological development — Behavioural and emotional disorders with onset usually occurring in childhood and adolescence — Unspecified mental disorder Characteristics of some important illnesses in each category are briefly discussed.

1. Organic, including symptomatic, mental disorders Organic mental disorders, also known as organic brain disorders, are a group of disorders, characterised by a demonstrable etiology in the brain in form of a cerebral disease, brain injury or some other insult leading to cerebral dysfunction. The illness may be primary, where the pathology involves the brain directly or secondary, where the brain is affected as secondary consequence of another systemic disease, which has involved the brain as one of the multiple organs or systems. For example, the brain is the primary organ involved in Alzheimer’s disease, Parkinson’s disease, head injury or Disorders: Need, Historical Perspective and the Modern System of Classification

Disorders cerebrovascular accidents, and secondarily involved in diabetes mellitus (ketosis, hyperglycemia), hyperthyroidism, hypothyroidism, HIV infection, nutritional deficiencies, cerebral anoxia due to any systemic cause, etc. Common organic mental disorders include dementia, delirium, organic amnestic syndrome, organic delusional disorder, organic mood disorder, organic personality disorder, mild cognitive disorder, post encephalitic disorder, etc. Dementia is a syndrome resulting from disease of brain, usually of chronic or progressive nature, which is characterised by a global impairment of higher mental functions, such as memory, intelligence, comprehension, cognition, learning capacity, judgement, reasoning, language, orientation and personality, occurring as a result of degenerative changes in the brain. Consciousness is not affected. Alzheimer’s disease is the commonest type of dementia. Other types include vascular dementia, sub cortical dementia, dementia due to Parkinson’s disease. A large number of neurological and systemic illnesses can lead to dementia. Delirium is an organic mental disorder of acute onset, characterised by concurrent disturbances of consciousness and attention, perception, thinking, memory, psychomotor behaviour, emotion and sleep-wake cycle. It is usually transient and runs a fluctuating course. Delirium is a result of some disturbance in the cerebral functioning, which can be due to a large number of cerebral and non cerebral systemic causes. Organic amnestic disorder is characterised by an impairment of recent and remote memory. While immediate recall is preserved, ability to learn new material is markedly reduced, resulting in anterograde amnesia and disorientation in time. Any kind of psychiatric symptomatology characterised by psychotic symptoms, mood symptoms, personality disturbances or others can occur due to an organic cause and comes under the broad category of organic mental disorders.

2. Mental and behavioural disorders due to psychoactive substance abuse Abuse of various psychoactive substances like alcohol, opioids, stimulants or other such substances, can result in a wide variety of psychiatric conditions, such as acute intoxication, harmful use, dependence syndrome, withdrawal phenomena, amnestic syndrome and disorders resembling functional psychiatric conditions like schizophrenia, depression, mania, amnestic syndrome or others. Common substances that are abused include alcohol, opioids, cannabinoids, sedatives and hypnotics, hallucinogens, cocaine, stimulants, tobacco and volatile solvents. Acute intoxication is a transient disturbance which occurs following the administration of a psychoactive substance and is characterised by disturbances in consciousness, cognition, perception, affect or behaviour, or in other psychophysiological functions and responses. The condition is usually transient. Harmful use refers to a pattern of psychoactive substance abuse, which can cause damage to the physical or mental health of the person using the substance. Dependence syndrome is characterised by a cluster of physiological, behavioural and cognitive phenomena, in which, the use of a substance takes on a much higher priority for an individual than other behaviours, which have a greater value. There is a strong desire or an urge (craving) to take the psychoactive substance, appearance of withdrawal symptoms on reducing or stopping the substance, need to take increasing amounts of the substance to achieve the desired effect, and persisting with substance use despite

Disorders Sometimes, there occur mixed kind of episodes with a mixture of manic and depressive symptoms. Hypomania and dysthymia are relatively milder forms of manic and depressive episodes respectively. Cyclothymia is a condition, in which there occur alternating phases of hypomania and dysthymia.

5. Neurotic, stress related and somatoform disorders The group of neurotic, stress related and somatoform disorders includes a large number of conditions, which were earlier included under the broad group of neuroses, and stress related symptoms. Most such patients present with anxiety symptoms, or somatic symptoms without an organic basis. Stress related disorders like post traumatic stress disorder and dissociative disorders also grouped in this broad category. Neurotic disorders include phobic anxiety disorder, panic disorder, generalised anxiety disorder, obsessive compulsive disorder and dissociative disorders. The central feature in phobic anxiety disorder (earlier known as phobic neurosis) is phobia. Phobia is a persistent, unrealistic and intense fear of an object, activity or a situation, which is considered irrational by the person. Common types of phobia are agoraphobia, social phobia and specific phobias. Generalised anxiety disorder is characterised by the presence of generalised and persistent anxiety. The presenting symptoms include feelings of nervousness, muscular tension, sweating, light-headedness, palpitations, dizziness, epigastric discomfort and tremulousness. In panic disorder , there occur recurrent brief episodes of severe anxiety (panic). The episodes occur suddenly and spontaneously and are not restricted to any particular situation or set of circumstances (unlike phobias), and usually last for minutes, though may be longer in some cases. Obsessive compulsive disorder is characterised by obsessions and compulsions. An obsession is a persistent and recurrent idea, image or impulse, which enters the individual’s mind against one’s wish, is considered absurd by the person, is anxiety provoking and cannot be eliminated from the consciousness by any amount of reasoning or logic. It is recognised as one’s own thought or impulse. Compulsive acts or rituals are stereotyped behaviours that are repeated again and again. The individual often views them as preventing some objectively unlikely event or performs it in response to an obsession. Behaviour is considered purposeless by the person and person may feel compelled to perform it. Dissociative (conversion) disorders are characterised by the presence of psychological or physical symptoms, presumed to result from partial or complete loss of normal integration (dissociation) between memories of the past, awareness of identity and immediate sensations, and control of bodily movements. The term conversion refers to the mechanism by which an unpleasant affect, resulting from a conflict is transformed into the symptoms. Psychological presentations include amnesia, fugue states, stupor, possession states, multiple personality, etc. Physical presentations include disorders of movement and sensation, convulsions and dissociative anaesthesia or loss of sensation. The conversion disorder with presentation of physical symptoms is grouped under somatoform disorders in DSM IV. In somatoform disorders , the patient presents with physical symptoms suggesting a physical illness, though there is none. Even if a physical pathology is present, it is not

1 9 sufficient to explain the symptoms. The patient repetitively requests for medical investigations, in spite of repeated negative findings and reassurances from the doctors that the symptoms have no physical basis. Psychological factors are responsible or are presumed to be responsible for the symptoms. Even when the onset and continuation of the symptoms bear a close relationship with unpleasant life events or with difficulties or conflicts, the patient usually resists attempts to discuss the possibility of psychological causation. The category of somatoform disorders includes somatization disorder, hypochondriacal disorder, undifferentiated somatoform disorder, somatoform autonomic dysfunction and persistent somatoform pain disorder. In stress related disorders , the genesis of illness is related to stress. The illness may occur either immediately following the stress or with a delayed onset.These include acute stress reaction, post traumatic stress disorder and adjustment disorders. Acute stressre action is a transient disorder occurring in response to exceptional physical or mental stress, which usually subsides within hours or days. The clinical picture is often changing, starting with a daze and later characterised by depression, anxiety, anger, despair, overactivity or withdrawal. Stressor may be an overwhelming traumatic experience posing serious threat to the security or physical integrity of the person (e.g. a criminal assault, natural catastrophe, rape, accident, etc.) Post traumatic stress disorder (PTSD) is characterised by a delayed or protracted response to a stressful event or situation of an exceptionally threatening or catastrophic nature(e.g., natural or man-made disasters, serious accidents, wars, torture, terrorism) which is likely to cause pervasive distress in almost all the affected population. Symptoms include repeated reliving of the trauma in flashbacks or dreams, sense of numbness, detachment from other people, unresponsiveness to others,a state of hyper arousal with hyper vigilance and avoidance of activities and situations reminiscent of trauma. Adjustment disorders are characterised by subjective distress and emotional disturbance, occurring in the period of adaptation to a significant life change. Symptoms usually interfere with social functioning and performance, and include a range of depressive, anxiety or behavioural disturbances.

6. Behavioural syndromes associated with physiological disturbances and physical factors This group includes eating disorders, non organic sleep disorders, sexual dysfunctions, mental and behavioural disorders associated with puerperium (not classified elsewhere), psychological and behavioural factors associated with disorders and diseases classified elsewhere and abuse of non dependence producing substances. Eating disorders include anorexia nervosa, bulimia nervosa, overeating and others. Anorexia nervosa is characterised by deliberate weight loss, induced and/or sustained by the patient and is usually seen in adolescent girls and young women, and is associated with body image distortions and endocrine disturbances like amenorrhea. In bulimia nervosa, there occur repeated bouts of overeating and an excessive preoccupation with the control of body weight, leading to episodes of self induced vomiting, purgative abuse, diuretics or appetite suppressants. Non organic sleep disorders include non organic insomnia, non organic hypersomnia, disorder of sleep wake schedule, sleepwalking, sleep (night) terrors and nightmares. Sexual dysfunctions (not caused by organic disorder or disease) or psychosexual disorders include a range of dysfunctions like failure of genital response (erectile impotence in males), premature ejaculation, retarded ejaculation, excessive sexual drive, Disorders: Need, Historical Perspective and the Modern System of Classification