N1 methylnicotinamide excretion and affective disorders

N¹ Methylnicotinamide urinary output is examined in 38 healthy volunteers, 52 patients with secondary affective disorders (SAD), 55 patients with primary affective disorders (PAD) and 46 healthy first degree relatives of PAD patients. The results indicate that in PAD patients and their first degree relatives the frequency of low N¹ MN excretion was significantly higher than in healthy controls and in patients with secondary affective disorders, and that PAD patients have a consistently low N¹ MN output, at all times constant and independent of the clinical phases of the disease. These findings provide evidence that the low N¹ MN levels may represent an index of a biological background linked to a high morbidity risk for primary affective disorders. The theoretical implications deriving from these data are briefly discussed.