Schizophrenia - Assessment

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• Schizophrenia: Psychological tests
• Schizophrenia: Early detection
• Schizophrenia: Assessment isssues
• Schizophrenia: Evaluation protocols

Criteria (signs and symptoms)

Like many mental illnesses, the diagnosis of schizophrenia is based upon the behavior of the person being assessed. There is a list of criteria that must be met for someone 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 Organization’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; the full version is available here. (DSM cautionary statement)

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

• A) Characteristic 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; speaking in abstracts). See thought disorder.
  • grossly disorganized behavior (e.g. dressing inappropriately, crying frequently) 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 hallucinations consist of hearing one voice participating in a running commentary of the patient's actions or of hearing two or more voices conversing with each other.

• 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 or interpersonal relations 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 that meet Criterion A.

Additional criteria (D, E and F) are also given that exclude a diagnosis of schizophrenia if symptoms of mood disorder or pervasive developmental disorder are present. Additionally a diagnosis of schizophrenia is excluded if the symptoms are the direct result of a substance (e.g., abuse of a drug, medication) or a general medical condition.

Subtypes

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

• (295.2/F20.2) catatonic type (where marked absences or peculiarities of movement are present),
• (295.1/F20.1) disorganized type (where thought disorder and flat affect are present together),
• (295.3/F20.0) paranoid type (where delusions and vivid, often horrifying, hallucinations are present but thought disorder, disorganized behavior, and affective flattening is absent),
• (295.6/F20.5) residual type (where positive symptoms are present at a low intensity only) and
• (295.9/F20.3) undifferentiated type (psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types has not been met).

NB: Brackets indicate codes for DSM and ICD-10 diagnostic manuals, respectively. Some older classifications still use "Hebephrenic schizophrenia" instead of "Disorganized schizophrenia".

Presentation

Symptoms may also be described as 'positive symptoms' (those additional to normal experience and behavior) and negative symptoms (the lack or decline in normal experience or behavior). '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 'disorganization syndrome', is also given. This considers thought disorder and related disorganized behavior to be in a separate symptom cluster from delusions and hallucinations.

Some symptoms, such as social isolation, may be caused by a number of factors. One possible factor is impairment in social cognition, which is associated with schizophrenia, but isolation may also result from an individual reacting to psychotic symptoms (such as paranoia) or avoiding potentially stressful social situations which may exacerbate mental distress in some 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 that he thought were particularly useful in distinguishing between schizophrenia and other disorders that 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 questioned⁴, although they remain in use as diagnostic criteria in many countries.

Diagnostic issues and controversies

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.⁵

Of particular concern is that the decision as to whether a symptom is present is a subjective decision by the person making the diagnosis or relies on an incoherent definition (for example, see the entries on delusions and thought disorder for a discussion of this issue). More recently, it has been argued that psychotic symptoms are not a good basis for making a diagnosis of schizophrenia as "psychosis is the 'fever' of mental illness — a serious but nonspecific indicator".⁶

Perhaps because of these factors, studies examining the diagnosis of schizophrenia have typically shown relatively low or inconsistent levels of diagnostic reliability. Most famously, David Rosenhan's 1972 study, published as On being sane in insane places, demonstrated that the diagnosis of schizophrenia was (at least at the time) often subjective and unreliable. More recent studies have found agreement between any two psychiatrists when diagnosing schizophrenia tends to reach about 65% at best⁷. This, and the results of earlier studies of diagnostic reliability (which typically reported even lower levels of agreement) have led some critics to argue that the diagnosis of schizophrenia should be abandoned.⁸

Proponents have argued for a new approach that would use the presence of specific neurocognitive deficits to make a diagnosis. These often accompany schizophrenia and take the form of a reduction or impairment in basic psychological functions such as memory, attention, executive function and problem solving. It is these sorts of difficulties, rather than the psychotic symptoms (which can in many cases be controlled by antipsychotic medication), which seem to be the cause of most disability in schizophrenia. However, this argument is relatively new and it is unlikely that the method of diagnosing schizophrenia will change radically in the near future.

The diagnostic approach to schizophrenia has also been opposed by the anti-psychiatry movement, who argue that classifying specific thoughts and behaviors as an illness allows social control of people that society finds undesirable but who have committed no crime. They argue that this is a way of unjustly classifying a social problem as a medical one to allow the forcible detention and treatment of people displaying these behaviors, which is something which can be done under mental health legislation in most western countries.

An example of this can be seen in the Soviet Union, where an additional sub-classification of sluggishly progressing schizophrenia was created. Particularly in the RSFSR (Russian Soviet Federated Socialist Republic), this diagnosis was used for the purpose of silencing political dissidents or forcing them to recant their ideas by the use of forcible confinement and treatment. In 2000 similar concerns about the abuse of psychiatry to unjustly silence and detain practitioners of the Falun Gong movement by the Chinese government led the American Psychiatric Association's Committee on the Abuse of Psychiatry and Psychiatrists to pass a resolution to urge the World Psychiatric Association to investigate the situation in China.

Western psychiatric medicine tends to favor a definition of symptoms that depends on form rather than content (an innovation first argued for by psychiatrists Karl Jaspers and Kurt Schneider). Therefore, you should be able to believe anything, however unusual or socially unacceptable, without being diagnosed delusional, unless your belief is held in a particular way. In principle, this would stop people being forcibly detained or treated simply for what they believe. However, the distinction between form and content is not easy, or always possible, to make in practice (see delusion). This had led to accusations by anti-psychiatry, surrealist and mental health system survivor groups that psychiatric abuses exist to some extent in the West as well.