Niacin deficiency in humans causes the disease pellagra, characterized, in part, by dementia. We hypothesized that niacin deficiency will affect learning through depletion of substrate (NAD+) required for synthesis of cADPr and NAADP. To explore this we (1) determined the effect of niacin deficiency and supplementation on NAD+ levels; (2) studied the effects of niacin deficiency and supplementation on Morris water maze (MWM) performance. Guinea pigs were fed 25%, 20%, 15%, 10% casein niacin deficient (ND) or pair fed (PF) (50 mg/kg) diets. Guinea pigs were resistant to ND with no differences in MWM. Rats were fed a 5% casein/8% gelatin or 6% casein/7% gelatin ND or PF diets (30mg/kg). The 5% casein/8% gelatin produced the best ND model with no differences in MWM. Niacin supplementation caused significantly higher NAD+ levels and differences in MWM. Supplementation of niacin in disease treatment supports further research on NAD+ status in learning.