THE ABC SCHIZOPHRENIA STUDY - A PRELIMINARY OVERVIEW OF THE RESULTS

The ABC Schizophrenia Study, a large-scale epidemiological and neurobi ological research project commenced in 1987, initially pursued two aim s: (1) to elucidate the possible causes of the sex difference in age a t first admission for schizophrenia and (2) to analyse the early cours e of the disorder from onset until first contact and its implications for further course and outcome. First, transnational case-register dat a (for Denmark and Germany) were compared, second, a population-based sample of first-episode cases of schizophrenia (n = 232) were selected and third, the results obtained were compared with data from the WHO Determinants of Outcome Study by using a systematic methodology. A con sistent result was a 3-4 years higher age of onset for women by any de finition of onset, which was not explainable by social variables, such as differences in the male-female societal roles. A sensitivity-reduc ing effect of oestrogen on central D2 receptors was identified as the underlying neurobiological mechanism in animal experiments. Applicabil ity to humans with schizophrenia was established in a con trolled clin ical study, A comparison of familial and sporadic cases showed that in cases with a high genetic load, the sex difference in age of onset di sappeared due to a clearly reduced age of onset in women, whereas in s poradic cases it increased. To analyse early course retrospectively, a semistructured interview, IRAOS, was developed. The early stages of t he disorder were reconstructed in comparison with age- and sea-matched controls from the same population of origin. The initial signs consis ted mainly of negative and affective symptoms, which accumulated expon entially until the first episode, as did the later emerging positive s ymptoms. Social disability appeared 2-4 years before first admission o n average. In early-onset cases, social course and outcome, studied pr ospectively over 5 years, was determined by the level of social develo pment at onset through social stagnation. In late-onset cases, decline from initially high social statuses occurred. Socially negative illne ss behaviour contributed to the poor social outcome of young men. Symp tomatology and other proxy variables of the disorder showed stable cou rses and no sex differences. Further aspects tested were the sequence of onset and the influence of substance abuse on the course of schizop hrenia, primary and secondary negative symptoms, structural models and symptom clusters from onset until 5 years after first admission.