https://www.britannica.com/science/mental-disorder
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Mental disorder, any illness with significant psychological or behavioral manifestations that is associated with either a painful or distressing symptom or an impairment in one or more important areas of functioning.
Mental disorders, in particular their consequences and their treatment, are of more concern and receive more attention now than in the past. Mental disorders have become a more prominent subject of attention for several reasons. They have always been common, but, with the eradication or successful treatment of many of the serious physical illnesses that formerly afflicted humans, mental illness has become a more noticeable cause of suffering and accounts for a higher proportion of those disabled by disease. Moreover, the public has come to expect the medical and mental health professions to help it obtain an improved quality of life in its mental as well as physical functioning. And indeed, there has been a proliferation of both pharmacological and psychotherapeutic treatments. The transfer of many psychiatric patients, some still showing conspicuous symptoms, from mental hospitals into the community has also increased the public’s awareness of the importance and prevalence of mental illness.
There is no simple definition of mental disorder that is universally satisfactory. This is partly because mental states or behaviour that are viewed as abnormal in one culture may be regarded as normal or acceptable in another, and in any case it is difficult to draw a line clearly demarcating healthy from abnormal mental functioning.
A narrow definition of mental illness would insist upon the presence of organic disease of the brain, either structural or biochemical. An overly broad definition would define mental illness as simply being the lack or absence of mental health—that is to say, a condition of mental well-being, balance, and resilience in which the individual can successfully work and function and in which the individual can both withstand and learn to cope with the conflicts and stresses encountered in life. A more generally useful definition ascribes mental disorder to psychological, social, biochemical, or genetic dysfunctions or disturbances in the individual.
A mental illness can have an effect on every aspect of a person’s life, including thinking, feeling, mood, and outlook and such areas of external activity as family and marital life, sexual activity, work, recreation, and management of material affairs. Most mental disorders negatively affect how individuals feel about themselves and impair their capacity for participating in mutually rewarding relationships.
Types and causes of mental disorders
Psychiatric classification attempts to bring order to the enormous diversity of mental symptoms, syndromes, and illnesses that are encountered in clinical practice. Epidemiology is the measurement of the prevalence, or frequency of occurrence, of these psychiatric disorders in different human populations.
Classification
Diagnosis is the process of identifying an illness by studying its signs and symptoms and by considering the patient’s history. Much of this information is gathered by the mental health practitioner (e.g., psychiatrist, psychotherapist, psychologist, social worker, or counselor) during initial interviews with the patient, who describes the main complaints and symptoms and any past ones and briefly gives a personal history and current situation. The practitioner may administer any of several psychological tests to the patient and may supplement these with a physical and a neurological examination. These data, along with the practitioner’s own observations of the patient and of the patient’s interaction with the practitioner, form the basis for a preliminary diagnostic assessment. For the practitioner, diagnosis involves finding the most prominent or significant symptoms, on the basis of which the patient’s disorder can be assigned to a category as a first stage toward treatment. Diagnosis is as important in mental health treatment as it is in medical treatment.
Classification systems in psychiatry aim to distinguish groups of patients who share the same or related clinical symptoms in order to provide an appropriate therapy and accurately predict the prospects of recovery for any individual member of that group. Thus, a diagnosis of depression, for example, would lead the practitioner to consider antidepressant drugs when preparing a course of treatment.
The diagnostic terms of psychiatry have been introduced at various stages of the discipline’s development and from very different theoretical standpoints. Sometimes two words with quite different derivations have come to mean almost the same thing—for example, dementia praecox and schizophrenia. Sometimes a word, such as hysteria, carries many different meanings depending on the psychiatrist’s theoretical orientation.
Psychiatry is hampered by the fact that the cause of many mental illnesses is unknown, and so convenient diagnostic distinctions cannot be made among such illnesses as they can, for instance, in infectious medicine, where infection with a specific type of bacterium is a reliable indicator for a diagnosis of tuberculosis. But the greatest difficulties presented by mental disorders as far as classification and diagnosis are concerned are that the same symptoms are often found in patients with different or unrelated disorders and a patient may show a mix of symptoms properly belonging to several different disorders. Thus, although the categories of mental illness are defined according to symptom patterns, course, and outcome, the illnesses of many patients constitute intermediate cases between such categories, and the categories themselves may not necessarily represent distinct disease entities and are often poorly defined.
The two most frequently used systems of psychiatric classification are the International Statistical Classification of Diseases and Related Health Problems (ICD), produced by the World Health Organization, and the Diagnostic and Statistical Manual of Mental Disorders (DSM), produced by the American Psychiatric Association. The 10th revision of the former, published in 1992, is widely used in western Europe and other parts of the world for epidemiological and administrative purposes. Its nomenclature is deliberately conservative in conception so that it can be used by clinicians and mental health care systems in different countries. The 11th revision (ICD-11) was slated for publication in 2018. The DSM, by contrast, has undergone five revisions since its introduction in 1952; the most recent version, DSM-5, was presented in 2013. The DSM differs from the ICD in its introduction of precisely described criteria for each diagnostic category; its categorizations are based upon the detailed description of symptoms.
The DSM is the standard resource in the United States, though it has been widely used worldwide. Its detailed descriptions of diagnostic criteria have been useful in eradicating the inconsistencies of earlier classifications. However, there are still some major problems in its everyday clinical use. Chief among them is the DSM’s innovative and controversial abandonment of the general categories of psychosis and neurosis in its classificatory scheme. These terms have been and still are widely used to distinguish between classes of mental disorders, though there are various mental illnesses, such as personality disorders, that cannot be classified as either psychoses or neuroses. Furthermore, its use of broad diagnostic criteria and its lack of inclusion of diagnostic criteria based on known biological factors have been sources of criticism.
Psychoses
Psychoses are major mental illnesses that are characterized by severe symptoms such as delusions, hallucinations, disturbances of the thinking process, and defects of judgment and insight. Persons with psychoses exhibit a disturbance or disorganization of thought, emotion, and behaviour so profound that they are often unable to function in everyday life and may be incapacitated or disabled. Such individuals are often unable to realize that their subjective perceptions and feelings do not correlate with objective reality, a phenomenon evinced by persons with psychoses who do not know or will not believe that they are ill despite the distress they feel and their obvious confusion concerning the outside world. Traditionally, the psychoses have been broadly divided into organic and functional psychoses. Organic psychoses were believed to result from a physical defect of or damage to the brain. Functional psychoses were believed to have no physical brain disease evident upon clinical examination. Much research suggests that this distinction between organic and functional is probably inaccurate. Most psychoses are now believed to result from some structural or biochemical change in the brain.
Neuroses
Neuroses, or psychoneuroses, are less-serious disorders in which people may experience negative feelings such as anxiety or depression. Their functioning may be significantly impaired, but personality remains relatively intact, the capacity to recognize and objectively evaluate reality is maintained, and they are basically able to function in everyday life. In contrast to people with psychoses, neurotic patients know or can be made to realize that they are ill, and they usually want to get well and return to a normal state. Their chances for recovery are better than those of persons with psychoses. The symptoms of neurosis may sometimes resemble the coping mechanisms used in everyday life by most people, but in neurotics these defensive reactions are inappropriately severe or prolonged in response to an external stress. Anxiety disorders, phobic disorder (exhibited as unrealistic fear or dread), conversion disorder (formerly known as hysteria), obsessive-compulsive disorder, and depressive disorders have been traditionally classified as neuroses.
