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Diagnosis of Schizophrenia
Diagnosis is based on the self-reported experiences of the person as well as abnormalities in behavior reported by family members, friends or co-workers, followed by secondary signs observed by a psychiatrist, social worker, clinical psychologist or other clinician in a clinical assessment. 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.
An initial assessment includes a comprehensive history and physical examination by a physician. Although there are no biological tests which confirm schizophrenia, tests are carried out to exclude medical illnesses which may rarely present with psychotic schizophrenia-like symptoms. These include blood tests measuring TSH to exclude hypo- or hyperthyroidism, and serum calcium to rule out a metabolic disturbance, Complete blood count including Erythrocyte sedimentation rate|ESR to rule out a systemic infection or chronic disease, and serology to exclude syphilis or HIV infection; two commonly ordered investigations are EEG to exclude epilepsy, and a CT scan of the head to exclude brain lesions. It is important to rule out a delirium which can be distinguished by visual hallucinations, acute onset and fluctuating level of consciousness and indicates an underlying medical illness. There are several psychiatric illnesses which may present with psychotic symptoms other than schizophrenia. These include bipolar disorder, borderline personality disorder, drug intoxication, brief drug-induced psychosis, and schizophreniform disorder.
Investigations are not generally repeated for relapse unless there is a specific medical indication. These may include serum BSL if olanzapine has previously been prescribed, liver function tests if chlorpromazine or CPK to exclude neuroleptic malignant syndrome. Assessment and treatment are usually done on an outpatient basis; admission to an inpatient facility is considered if there is a risk to self or others.
The most widely used criteria for diagnosing schizophrenia are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, the current version being DSM-IV-TR, and the World Health Organization's International Statistical Classification of Diseases and Related Health Problems, currently the ICD-10. The latter criteria are typically used in European countries while the DSM criteria are used in the USA or the rest of the world, as well as prevailing in research studies. The ICD-10 criteria put more emphasis on Schneiderian first rank symptoms although, in practice, agreement between the two systems is high. The WHO has developed the tool SCAN (Schedules for Clinical Assessment in Neuropsychiatry) which can be used for diagnosing a number of psychiatric conditions, including schizophrenia.
DSM IV-TR Criteria
To be diagnosed with schizophrenia, a person must display:
- 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)
- 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 of these symptoms is required if delusions are bizarre or 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.
- 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.
- 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).
Additional criteria are also given that exclude the diagnosis; thus schizophrenia cannot be diagnosed if symptoms of mood disorder or pervasive developmental disorder are present, or the symptoms are the direct result of a substance (e.g., abuse of a drug, medication) or a general medical condition.
- Paranoid type: where delusions and hallucinations are present but thought disorder, disorganized behavior, and affective flattening are absent (DSM code 295.3/ICD code F20.0)
- Disorganized type: named 'hebephrenic schizophrenia' in the ICD. Where thought disorder and flat affect are present together (DSM code 295.1/ICD code F20.1)
- Catatonic type: prominent psychomotor disturbances are evident. Symptoms can include catatonic stupor and waxy flexibility (DSM code 295.2/ICD code F20.2)
- Undifferentiated type: psychotic symptoms are present but the criteria for paranoid, disorganized, or catatonic types have not been met (DSM code 295.9/ICD code F20.3)
- residual type: where positive symptoms are present at a low intensity only (DSM code 295.6/ICD code F20.5)
The ICD-10 recognises a further two subtypes:
- post-schizophrenic depression: a depressive episode arising in the aftermath of a schizophrenic illness where some low-level schizophrenic symptoms may still be present (ICD code F20.4)
- simple schizophrenia: insidious but progressive development of prominent negative symptoms with no history of psychotic episodes (ICD code F20.6)
Diagnostic issues and controversies
Schizophrenia as a diagnostic entity has been criticised as lacking in scientific validity or reliability, part of a larger criticism of the validity of psychiatric diagnoses in general. One alternative suggests that the issues with the diagnosis would be better addressed as individual dimensions along which everyone varies, such that there is a spectrum or continuum rather than a cut-off between normal and ill. This approach appears consistent with research on schizotypy and of a relatively high prevalence of psychotic experiences and often non-distressing delusional beliefs amongst the general public.
Another criticism is that the definitions used for criteria lack consistency; this is particularly relevant to the evaluation of delusions and thought disorder. 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".
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 best. 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.
In 2004 in Japan, Japanese term of schizophrenia was changed from Seishin-Bunretsu-Byo (mind-split-disease) to Tōgō-shitchō-shō (integration disorder). In 2006, campaigners in the UK, under the banner of Campaign for Abolition of the Schizophrenia Label, argued for a similar rejection of the diagnosis of schizophrenia and a different approach to the treatment and understanding of the symptoms currently associated with it.
Alternatively, other proponents have put forward using the presence of specific neurocognitive deficits to make a diagnosis. These 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 diagnosis of schizophrenia has been used for political rather than therapeutic purposes; in the Soviet Union 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 there were similar concerns regarding detention and 'treatment' of practitioners of the Falun Gong movement by the Chinese government. This 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.
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