Define the effect of niacin deficiency on Nervous System?

Delirium is the most common -mental disturbance in acute pellagra. Dementia is more frequently seen in the chronic cases. Milder mental disturbances consisting of irritability, peripheral neuritis, paralysis, change in disposition, depression, inability to concentrate and poor memory are more common in the mild cases. The symptoms of postero-lateral tract degeneration, ataxia, spasticity and the, involvement of the bladder and rectal sphincters are seen in chronic cases.