ABC Schizophrenia study: an overview of results since 1996.

PURPOSE: The ABC Schizophrenia study, led by a single research team, investigated a schizophrenia sample systematically over quarter of a century. This paper summarises results from 1996 onwards. The initial goals were to explain the considerably higher age at first admission in women, and to obtain precise information on the onset and early course of schizophrenia as a prerequisite for early intervention.
METHOD: The study was hypothesis-driven. People with schizophrenia were compared in the prodrome and at first admission to those with unipolar depression and to healthy controls. We analysed the medium-term (5-year) and the long-term (12-year) course of schizophrenia, its symptom dimensions, social parameters and predictors. SAMPLES: (1) 276 population-based first admissions (232 first episodes) of schizophrenia (age range 12-59 years); (2) a subsample of 130 first admissions for schizophrenia; (3) 130 first admissions for unipolar depression; (4) 130 healthy population controls and (5) 1,109 consecutive first admissions for schizophrenia spectrum disorder without an age limit.
RESULTS: The prodromal stages of schizophrenia and depression were very similar until positive symptoms appeared. The most frequent symptom in schizophrenia was depressed mood. The course of psychosis from prodrome to 12 years following first admission was very variable. From 5 to 12 years after first admission the course was characterised by irregular exacerbations of the main symptom dimensions, with no overall deterioration or improvement.
CONCLUSIONS: Schizophrenic psychosis and severe affective disorder, rather than representing discrete illnesses, probably mark different stages in the manifestation of psychopathology produced by various degrees of brain dysfunction.