PSYCHOPATHOLOGICAL SYNDROMES AND FAMILIAL MORBID RISK OF PSYCHOSIS

Background Familiar liability in the functional psychoses had traditio nally been examined by comparing mutually exclusive diagnostic categor ies. This study examines overlapping psychopathological dimensions in relation to familial morbid risk of psychosis. Method We tested for as sociations between seven factor-analysis derived psychopathological di mensions and familial morbid risk of psychosis, in a sample of 150 pat ients with recent-onset function al psychosis and 548 of their first-d egree relatives. Results A syndrome characterised by affective bluntin g and insidious and early onset of illness, non-specifically predicted psychosis in the first-degree relatives, whereas a manic syndrome spe cifically predicted affective psychosis in the relatives. No other mai n effects were observed, but there were interactions with proband diag nosis: a syndrome characterised by bizarre behaviour, inappropriate af fect, catatonia and poor rapport predicted psychosis in relatives of s chizophrenic probands, and a syndrome of depressive symptoms predicted psychosis in relatives of schizoaffective probands. Positive symptoms were not associated with illness in the relatives. Conclusions Geneti c effects in the functional psychoses may comprise nonspecific compone nts that canalise a general, early-onset, affective blunting phenotype and several other, more specific, influences on phenotypic variation.