Schizoaffective Disorder - Diagnosis

Diagnosis

Diagnosis is based on the observed behavior of an individual while ill by a mental health professional, the self-reported experiences of the individual as well as abnormalities in behavior reported by family members, friends or co-workers to a psychiatrist, psychiatric nurse, social worker, psychologist or mental health counselor 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.

As discussed above, there are several psychiatric illnesses which may present with a similar range of psychotic symptoms; these include bipolar disorder with psychotic features, major depression with psychotic features, schizophrenia, drug intoxication, brief drug-induced psychosis, and schizophreniform disorder. These disorders need to be ruled out before a firm diagnosis of schizoaffective disorder can be made.

An initial assessment includes a comprehensive history and physical examination by a physician. Although there are no biological tests which confirm schizoaffective disorder, tests should be carried out to exclude medical illnesses which rarely may be associated with psychotic symptoms. These include blood tests measuring TSH to exclude hypo- or hyperthyroidism, basic electrolytes and serum calcium to rule out a metabolic disturbance, full blood count including 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.

Further blood tests are not generally repeated for relapse unless there is a specific medical indication. These may include serum BSL if olanzapine has previously been prescribed, thyroid function if lithium has previously been taken to rule out hypothyroidism, liver function tests if chlorpromazine has been prescribed, and CPK levels 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 schizoaffective disorder are from the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, the current version being DSM-IV-TR.