Abstract: A method for improving the cognitive function, memory, and orientation abilities of persons having senile or presenile dementia of the Alzheimer's type wherein the reduced form of nicotinamide-adenine-dinucleotide (NADH), or the reduced form of nicotinamide-adenine-dinucleotide phosphate (NADPH), or physiologically compatible salts of NADH and/or NADPH, are administered orally or parenterally. Patients so treated exhibit greatly improved cognitive abilities over time.