Diagnosis of Schizophrenia

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Dr. Vidyadhar Watve, MD, D PM FIRS

The term psychosis is used when a patient has delusions (false beliefs not shared by others), hallucinations (perceptions in absence of stimuli), disorganized speech, disorganized or catatonic behaviour (maintaining posture or sudden severe excitement).
Schizophrenia is one type of psychosis; but every psychosis is not schizophrenia.

Diagnosis

Schizophrenia has four groups of symptoms.

  1. Positive symptoms, which consist of delusions, hallucinations and disorganized behaviour.
  2. Negative symptoms, which consist of emotional blunting, poor initiative, and poor communication.
  3. Cognitive symptoms, which consist of poor attention, memory impairment, and poor planning.
  4. Affective or emotional symptoms, which consist of anger, hostility, aggression, and depressive symptoms including suicidal ideation.

Schizophrenia consists of the presence of characteristic positive or negative symptoms of at least one month duration; deterioration in work, interpersonal relations, or self-care. These symptoms should not be due to general medical conditions, like brain tumor, encephalitis, malignancy or metabolic disorder.

Similarly, the above-mentioned clinical picture should not be due to substance dependence. Chronic alcohol dependence or cannabis dependence can produce a schizophrenia-like picture but such a case is diagnosed as substance-induced psychosis rather than schizophrenia.

If an illness otherwise meets the criteria but has a duration of at least one month but less than six months, it is termed as schizophreniform disorder. If it has lasted less than four weeks, it may be classified as brief psychotic disorder.

Schizophrenia can be diagnosed at any age if the criteria are met. Therefore the age-at-onset criterion is deleted from older classification of mental disorders.

Differential diagnosis

Schizophrenia remains a clinical diagnosis that is based on history and mental status examination (MSE). There are no pathological laboratory tests to diagnose schizophrenia.

After taking careful history from the relative, a compete physical examination is done to exclude psychoses with known medical causes. Similarly, substance-abuse as a cause of psychosis is also ruled out.

Psychotic symptoms have been found to result from substance - abuse (e.g. alcohol, cocaine, amphetamines, hallucinogens); intoxication due to commonly prescribed medications (e.g. steroids, anticholinergics, levodopa); infectious, metabolic and endocrine disorders; tumors and mass lesions; and temporal lobe epilepsy. Acute onset, clouding of the sensorium, or onset occurring after the age of 30 years requires careful investigation.

Routine lab tests are useful to rule out medical causes. They include CBC, urinalysis, L.FTs, BUN, TFT and serological tests for syphilis and HIV. In selected patients FEG, CT or MRI of brain will be useful.

The major task in differential diagnosis involves separating schizophrenia from schizoaffective disorder, mood disorder with psychotic features (mania or depression with psychotic features), delusional disorder, or a personality disorder. To rule out schizoaffective disorder and psychotic mood disorders, depressive or manic episodes should have been absent during the active phase and the mood episode should have been relatively brief as compared to the total duration of the psychotic episode. Delusional disorder has non-bizarre delusion which can be a delusion of infidelity or paranoid delusion or somatic delusion. The functioning in other areas is normal in delusional disorder. Schizophrenia is characterized by bizarre delusions and hallucinations.

Patients with personality disorders, particularly those in the eccentric' cluster (e.g. Schizoid, schizotypal and paranoid personality), may be indifferent to sociail relationship, may have bizarre ideation and odd speech, or may be suspicious; but they do not have delusions, hallucinations, or grossly disorganized behaviour.

Patients with schizophrenia may develop other symptoms like thought disorders, behavioural disturbances and personality deterioration. These symptoms are uncharacteristic of the mood disorders, delusional disorder or the personality disorders.

Sometimes panic disorder is accompanied by feelings of unreality but insight is well preserved and there are no delusions or hallucinations. The rituals of behaviour occurring in a patient with obsessive-compulsive disorder may result in bizarre behaviour, but they are performed to relieve anxiety and not in response to delusional beliefs.

Thus diagnosis of schizophrenia needs careful history-taking, detailed clinical evaluation, and routine investigations to rule out other medical and psychiatric disorders which can mimic clinical picture of schizophrenia.