Early morning awakening in unipolar depressives with higher levels of platelet MAO activity.

Platelet monoamine oxidase (MAO) activity was analyzed in 51 patients with Major Depressive Disorder. The enzyme activity was correlated univariately and multivariately using split-half techniques with affective subdiagnosis, sex, body measures, and a great many depressive symptoms. The results indicate that unipolarly depressed patients with higher levels of platelet MAO activity woke up earlier in the morning than they had before becoming depressed. Waking up early appeared to be one least common denominator behind higher MAO activities and a unipolar subdiagnosis. Earlier reports on univariately significant differences in MAO activity between affective subdiagnoses or between the sexes were not replicated. Positive trend correlations were found between homovanillic acid and 5-hydroxyindoleacetic acid in cerebrospinal fluid and platelet MAO activity. Urinary free cortisol correlated significantly with platelet MAO activity, but only in unipolars.