Nonencephalopathic Psychiatric Manifestations (NEPM) and Response to Niacin in Pellagra: A Scoping Review

Abstract

Psychiatric manifestations of pellagra could be subtle but important to recognize in clinical practice. These may vary from non-syndromic symptoms of anxiety, depression, and psychosis to pellagrous encephalopathy. The course and outcome of pellagra’s non-encephalopathic psychiatric manifestations (NEPM) are variable and have not received much attention. Therefore, a review in this regard is deemed necessary to understand the evolution of psychiatric symptoms and possible neurochemical changes produced in pellagra. A focused scoping review of the literature using Preferred Reporting Items for Systematic reviews and Meta-Analyses- extension for Scoping Reviews (PRISMA-ScR) guidelines was carried out to chart the results of studies to find out the characteristic nature of NEPM, role of niacin, and underlying etiopathogenesis. The review included 12 studies comprising 271 participants. Depressive and insomnia symptoms were the most frequent manifestations of NEPM followed by anxiety, thought disorder, psychomotor agitation, hallucinations, confusion, and disorientation. Alcohol use remains the most common cause of NEPM in pellagra, followed by nutritional deficiency. The alteration in the kynurenine pathway is a probable mechanism implicated in the NEPM of pellagra and future research should explore the role of niacin replacement in such patients. The findings of the review incite further discussion and research on biomarkers for patients with pellagra and subtype of patients with depression who share a common immune-inflammatory pathway.