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Schizophrenia

Schizophrenia is a psychiatric diagnosis denoting a persistent, often chronic, mental illness variously affecting behavior, thinking, and emotion. The status of schizophrenia is controversial, largely due to the lack of objective criteria for diagnosis and the subsequent difficulty in adequately researching an inadequately defined condition. Research has suggested however, that both genetic and social influences are important contributing factors. Schizophrenia is commonly, but usually incorrectly, assumed to involve a 'split personality'.

Schizophrenia is most commonly characterized by both 'positive symptoms' (those additional to normal experience and behaviour) and 'negative symptoms' (the lack or decline in normal experience or behaviour). Positive symptoms are grouped under the umbrella term psychosis and typically include delusions, hallucinations, and thought disorder. Negative symptoms may include inappropriate emotional displays or flat emotional affect, poverty of speech, and lack of motivation. Some models of schizophrenia include thought disorder and planning problems in a third grouping, the 'disorganization syndrome'. Additionally, neurocognitive deficits may be present. These take the form of reduction or impairment in basic psychological functions such as memory, attention, problem solving, executive function and social cognition. The onset is typically in late adolescence and early adulthood, with males tending to show symptoms earlier than females.

The diagnostic approach to schizophrenia has been opposed, most notably by the anti-psychiatry movement, who argue that classifying specific thoughts and behaviours as illness allows social control of people that society finds undesirable but who have committed no crime.

More recently, it has been argued that schizophrenia is just one end of a spectrum of experience and behaviour, and everybody in society may have some such experiences in their life. This is known as the 'continuum model of psychosis' or the 'dimensional approach' and is most notably argued for by psychologist Richard Bentall and psychiatrist Jim van Os.

Although no definite causes of schizophrenia have been identified, most researchers and clinicians currently believe that schizophrenia is primarily a disorder of the brain. It is thought that schizophrenia may result from a mixture of genetic disposition (genetic studies using various techniques have shown relatives of people with schizophrenia are more likely to show signs of schizophrenia themselves) and environmental stress (research suggests that stressful life events may precede a schizophrenic episode).

It is also thought that processes in early neurodevelopment are important, particularly those that occur during pregnancy. In adult life, particular importance has been placed upon the function (or malfunction) of dopamine in the mesolimbic pathway in the brain. This theory, known as the dopamine hypothesis of schizophrenia largely resulted from the accidental finding that a drug group which blocks dopamine function, known as the phenothiazines, reduced psychotic symptoms. These drugs have now been developed further and antipsychotic medication is commonly used as a first line treatment. However, this theory is now thought to be overly simplistic as a complete explanation.

Differences in brain structure have been found between people with schizophrenia and those without. However, these tend only to be reliable on the group level and, due to the significant variability between individuals, may not be reliably present in any particular individual.

signs and symptoms - schizophrenia

Like many mental illnesses, the symptoms of schizophrenia are based upon the behaviour of the person being assessed. There is a list of diagnostic criteria which must be met for a person to be so diagnosed. These depend on both the presence and duration of certain signs and symptoms. The most commonly-used criteria for diagnosing schizophrenia are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM) and the World Health Organisation's International Statistical Classification of Diseases and Related Health Problems (ICD). The most recent versions are ICD-10 and DSM-IV-TR.

Below is an abbreviated version of the diagnostic criteria from the DSM-IV-TR.

To be diagnosed as having schizophrenia, a person must display:

  • A) Characteristic schizophrenia symptoms: Two or more of the following, each present for a significant portion of time during a one-month period (or less, if successfully treated)
  • delusions
  • hallucinations
  • disorganized speech (e.g., frequent derailment or incoherence). See thought disorder.
  • grossly disorganized or catatonic behavior
  • negative symptoms, i.e., affective flattening (lack or decline in emotional response), alogia (lack or decline in speech), or avolition (lack or decline in motivation).

Note: Only one Criterion A symptom is required if delusions are bizarre or hallucinations consist of hearing voices.

  • B) Social/occupational dysfunction: For a significant portion of the time since the onset of the disturbance, one or more major areas of functioning such as work, interpersonal relations, or self-care, are markedly below the level achieved prior to the onset.
  • C) Duration: Continuous signs of the disturbance persist for at least six months. This six-month period must include at least one month of symptoms (or less, if successfully treated) that meet Criterion A.

Historically, schizophrenia in the West was classified into simple, catatonic, hebephrenic, and paranoid. The DSM now contains five sub-classifications of schizophrenia. These are:

  • catatonic type (where marked absences or peculiarities of movement are present),
  • disorganized type (where thought disorder and flat or inappropriate affect are present together),
  • paranoid type (where delusions and hallucinations are present but thought disorder, disorganized behaviour, and affective flattening is absent),
  • residual type (where positive symptoms are present at a low intensity only) and
  • undifferentiated type (psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types has not been met).

Some symptoms of schizophrnia may also be described as 'positive symptoms' (those additional to normal experience and behaviour) and negative symptoms (the lack or decline in normal experience or behaviour). 'Positive symptoms' describe psychosis and typically include delusions, hallucinations and thought disorder. 'Negative symptoms' describe inappropriate or nonpresent emotion, poverty of speech, and lack of motivation. In three-factor models of schizophrenia, a third symptom grouping, the so called 'disorganisation syndrome' is also given. This considers thought disorder and related disorganized behaviour to be in a separate symptom cluster from delusions and hallucinations.

Some schizophrnia symptoms, such as social isolation, may be caused or appear to be caused by a reaction of the individual to avoid psychosis or other more severe symptoms that are inconvenient or unbearable. The person may place limits on his environment or on his own behaviour intended to avoid or limit whatever he experiences as causes for these symptoms. These limits or the resulting behaviour may appear strange or inappropriate to other people.

It is worth noting that many of the positive or psychotic symptoms may occur in a variety of disorders and not only in schizophrenia. The psychiatrist Kurt Schneider tried to list the particular forms of psychotic symptoms which he thought were particularly useful in distinguishing between schizophrenia and other disorders which could produce psychosis. These are called first rank symptoms or Schneiderian first rank symptoms and include delusions of being controlled by an external force, the belief that thoughts are being inserted or withdrawn from your conscious mind, the belief that your thoughts are being broadcast to other people and hearing hallucinated voices which comment on your thoughts or actions, or may have a conversation with other hallucinated voices. As with other diagnostic methods, the reliability of 'first rank symptoms' has been questioned, although they remain in use as diagnostic criteria in many countries.

how to diagnose schizophrnia?

It has been argued that the diagnostic approach to schizophrenia is flawed, as it relies on an assumption of a clear dividing line between what is considered to be mental illness (fulfilling the diagnostic criteria) and mental health (not fulfilling the criteria). Recently it has been argued, notably by psychiatrist Jim van Os and psychologist Richard Bentall, that this makes little sense, as studies have shown that psychotic symptoms are present in many people who never become 'ill' in the sense of feeling distressed, becoming disabled in some way or needing medical assistance.

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