The occurrence of secondary affective disorder in an in-patient population with severe and recurrent affective disorder.

One hundred and eighty nine consecutive in-patients with treatment-resistant affective disorder were administered the Renard Diagnostic Interview to determine whether the 45 with secondary affective disorder (SAD) differed from the 144 with primary affective disorder (PAD). The SAD group, including 15 subjects with bipolar disorder, had an earlier mean age of onset of depression and contained more unmarried individuals. The total secondary group could not usefully be differentiated by assessment of clinical symptoms or discriminating analysis of social and clinical variables. While the present study of a severely depressed population does not lend itself to generalisability, this combined sample does have characteristics of patients used in biological investigations. No significant inter-group discrimination was found to support a previous assumption that identification of a prior psychiatric disorder provides the most suitable mechanism for selecting a population for research in affective disorders.