Classification of patients with affective disorders using platelet monoamine oxidase activity, serum melatonin and post-dexamethasone cortisol.

Platelet monoamine oxidase activity (MAO), melatonin and cortisol post-dexamethasone suppression test (DST) were examined in 28 patients with major affective disorder and in 20 controls. MAO activity was lower and cortisol post-dexamethasone was higher in depressed patients. Platelet MAO activity and cortisol in depressed and controls yielded high sensitivity (90%) and specificity (89%). The patients were re-examined after 10 years and categorized into affective psychosis or neurotic depression (ICD-9). Multidimensional analysis identified one subgroup coinciding in 92% with affective psychosis and another subgroup coinciding in 87% with neurotic depression. Combination of MAO, melatonin and post-DST cortisol may be useful in the diagnosis of subgroups of depressed patients and in choice of therapy.