Heterogeneity of major affective disorders. Biological and clinical evidence

In this paper we summarize the results of our recent and present research focused on analyzing the correlations between neurochemical, pharmacological and clinical parameters in patients with Major Depression. There is evidence that: a) pretreatment urinary MHPG is a useful predictor for clinical response to tricyclic antidepressants and to long-term lithium treatment; b) urinary MHPG is positively correlated to the age at onset of the disease; c) previous responses to tricyclics and age at onset of affective illness are supplementary tools for predicting the effectiveness of lithium and antidepressant drugs; d) platelet alpha-2-adrenoceptor density is inversely correlated with both urinary MHPG and age at onset; e) cerebral ventricular size is positively correlated with urinary MHPG and age at onset and may discriminate between patients with different outcomes on lithium prophylaxis; f) low MHPG excretors are more likely to have suffered from stressful life events in early childhood than normal-to-high excretors. Taken together, these results lend strong support to the hypothesis that Major Affective Disorder is a heterogeneous illness and that inherently different subgroups of affective patients can be recognized.