N-methylnicotinamide excretion and affective disorders

N-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 (1) that in PAD patients and their first-degree relatives the frequency of low N1-MN excretion was significantly higher (P less than 0-001) than in healthy controls and in patients with secondary affective disorders, and (2) 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.