The earliest description of pellagra was that of the Spanish physician Don Gaspar Casal in 1763.Casal recorded all the clinical characteristics and ascribed the disease to the unbalanced diets, based on maize, of poor peasants in the Asturia region of Spain. The next description of the disease came from Italy in 1771 when pellagra was given its name, meaning "rough skin".
Pellagra mostly found in parts of India, China, and Africa where corn or maize as a staple food. The characteristic manifestations appear as dermatitis, diarrhea and dementia ("the three Ds") and can lead to death (the fourth D).
Causes of pellagra can be divided into primary and secondary. Primary pellagra is due to dietary deficiency. High leucine content in corn/maize prevents conversion of tryptophan to niacin, leading to deficiency of niacin. Secondary pellagra is due to defective absorption or metabolism of niacin/tryptophan.
Early neurological symptoms associated with pellagra include anxiety, depression, and fatigue; later symptoms include apathy, headache, dizziness, irritability and tremors. In early cases the manifestations are psychoneurotic; later, lesions affect the nerves. As the disease advances, patients become confused, disoriented, and delirious, then comatose and stuporous, and finally die.
Mental aberrations may pass to dementia: about 4-10 % of chronic pellagra patients developmental symptoms.
In the western world, it is almost eradicated due to fortification of flour with niacin.
Lack of niacin can cause pellagra 
