Alterations of niacin skin sensitivity in recurrent unipolar depressive disorder

IntroductionSkin flushing after niacin (methylnicotinate, vitamin B3) stimulation is a biological marker of availability of polyunsaturated fatty acids (PUFA). Decreased PUFA levels have been reported in depressive disorder, while add-on supplementation of omega-3 PUFA has been suggested to improve depressive symptoms. This study aimed to clarify whether a disturbance of niacin skin flushing occurs also in depression, and to identify patient characteristics for those who might benefit from PUFA supplementation.MethodWe studied 30 patients with recurrent unipolar depressive disorder during a major depressive episode (treated with antidepressants), and 30 healthy volunteers matched for age and gender. Aqueous methylnicotinate was applied in three dilution steps (0.001 M, 0.01 M, and 0.1 M) onto the inner forearm skin. Skin flushing was assessed in three-minute intervals over 15 min using optical reflection spectroscopy.ResultsWhile there was no overall difference in skin flushing between patients and controls, niacin sensitivity was inversely correlated with severity of symptoms, and flush deficits were significantly associated with depressed mood, feelings of anxiety and somatic symptoms (loss of appetite and weight loss).ConclusionResults are suggestive of a subgroup of depressive patients characterised by a specific symptom cluster and disturbed niacin skin flushing.