SCHIZOPHRENIA

Schizophrenia



Schizophrenia

Introduction

Schizophrenia is a clinical syndrome that involves cognition, emotion, perception, and other aspects of behavior. The expression of these manifestations varies across people with schizophrenia and over time, but the illness always has a profound impact upon the life of the affected individual.

Characteristics of schizophrenia typically include positive symptoms such as hallucinations or delusions, disorganized speech, and negative symptoms such as a flat affect or poverty of speech. A diagnosis of schizophrenia is based on the presence of such symptoms, coupled with social or occupational dysfunction for at least six months, in the absence of another diagnosis that would better account for the presentation. This topic discusses the epidemiology of schizophrenia. The clinical manifestations, diagnosis, and course of schizophrenia are discussed separately. Anxiety, depression, and substance abuse in schizophrenia are discussed separately. The treatment of schizophrenia and antipsychotic medications are discussed separately, as are other psychotic disorders. (Tsuang, 2000)

Epidemiology and Natural History

The lifetime risk of schizophrenia is estimated to be 0.2 to 0.7 percent, with an annual incidence of 11 per 100,000. Variation in the prevalence of the disorder across populations, ethnic groups, and geographic regions has been suggested. An apparent trend toward higher prevalence in lower socioeconomic groups has been attributed to downward drift (the tendency of individuals with the disorders to become socially disadvantaged). "Onset" is generally defined as the time at which psychotic symptoms are first identified and typically occurs in young adulthood. This is deceptive, however, because in many cases other symptom domains have been active long before the onset of delusions or hallucinations. (Hafner, 1991)

Several studies have found that cognitive symptoms are present from birth, with only slight, or no, progression after the onset of psychosis. Negative symptoms may also predate the onset of psychosis by months or years. Subtle signs of functional impairment may be present at an early age, including social ineptitude, poor school function, communication difficulties, and affective aberrances. Not all individuals with these symptoms go on to develop schizophrenia; therefore, the prodromal syndrome of declining function, negative symptoms, and cognitive impairment is not included in diagnostic classification systems, leaving the patient without definitive diagnosis until the onset of psychosis. (Malmberg, 1998)

The identification of prodromal symptoms with at least some predictive value for the development of schizophrenia has led to several proposals for study and intervention with prophylactic treatment. Two studies compared risperidone and olanzapine to placebo in individuals judged to be at high risk on the basis of family history and premorbid symptoms. In each case the active treatment group had a lower rate of onset of psychosis, with the relative risk 2.5 to 3.5 times higher in the placebo groups. The benefits became less dramatic with longer time, suggesting that the onset of illness was merely delayed, rather than prevented, and in each case the benefits were lost within one year of discontinuation of treatment.

Schizophrenia is more common in men than women, with a gender ratio of 1.4:1 male: female. Men typically exhibit symptoms at an earlier age, and have a worse ...