ABSTRACT.The clinical symptomatology, neuropathological characteristics, neurotransmitter deficiencies, and genetical aspects of Alzheimer's disease are briefly reviewed. In Alzheimer's disease, a diffuse cortical atrophy is present whereas the atrophy in Pick's disease is circumscript and restricted to the frontal and temporal lobes.Profound neurotransmitter deficits, especially in the cholinergic system has been demonstrated in Alzheimer's disease. Recent attempts to reverse the cholinergic deficit have been encouraging.The cerebral blood flow is decreased in both diseases but with different regional flow patterns. Generally, Alzheimer's disease is accompanied by slowly progressing diffuse EEG abnormalities. In Pick's disease, however, the EEG often appears to be normal on visual inspection, though computer analysis may reveal significant deviations from normality.