The relevance of pellagra to psychiatry is that it also can present with psychosis, obsessions, mania, depression and confusion. It involves the main organs of the brain, the gut and the skin – many referred to the 4 Ds: dementia, diarrhoea, dermatitis and death. Pellagra (meaning rough skin) was first described in 1735. At the time, the cause was unknown but it was associated with poverty. Although linked to the poor person’s diet (often consisting mainly of corn products), the going wisdom at that time was that it was contagious (Pellagrans, as they were called, tended to live in close proximity) and was perhaps hereditary (sound familiar?).