THE CLINICAL CHARACTERISTICS OF MAJOR DEPRESSION AS INDEXES OF THE FAMILIAL RISK TO ILLNESS

Background. From both a clinical and an aetiological perspective, majo r depression (MD) is probably a heterogeneous condition. We attempt to relate these two domains. Method. We examined which of an extensive s eries of clinical characteristics in 646 female twins from a populatio n-based resister with a lifetime diagnosis of MD predicts the risk for MD in co-twins. MD was defined by DSM-III-R criteria. Results. Four v ariables uniquely predicted an increased risk for MD in the co-twin: n umber of episodes, degree of impairment and co-morbidity with panic di sorder or bulimia. One variable uniquely predicted decreased risk: co- morbidity with phobia. Variables that did not uniquely predict risk of MD in the co-twin included age at onset, number and kind of depressiv e symptoms, treatment seeking, duration of the longest episode and co- morbidity with generalised anxiety disorder and alcohol dependence. Co nclusions. Our results suggest that the clinical features of MD can be meaningfully related to the familial vulnerability to illness, partic ularly with respect to recurrence, impairment and patterns of co-morbi dity.