Cholinergic enzymes in neocortex, hippocampus and basal forebrain of non-neurological and senile dementia of Alzheimer-type patients.

Choline acetyltransferase (ChAT) activity and acetylcholinesterase (AChE) staining were examined in different cortical regions, hippocampal formation and basal forebrain of non-neurological controls and of patients afflicted with senile dementia of Alzheimer type (SDAT). Both enzymes showed a clear topographical distribution in the various regions studied. In SDAT cases, ChAT activity was reduced by 0-60% in the neocortex and by up to 97% in the hippocampus depending on the area and layer examined. In the nucleus of the diagonal band of Broca (NDB) and the medial septal nucleus (MSN), the activity was decreased by 65% and 55%, respectively; no significant change was found in the lateral septal nucleus (LSN), nucleus basalis of Meynert (NBM), substantia innominata (SI) and globus pallidus (GP). Comparable changes were seen in AChE staining. The results indicate that degeneration or dysfunction of cholinergic neurons in the medial septal area and possibly neocortex is an important characteristic of SDAT.