Cholinesterases in the cerebrospinal fluid, plasma, and erythrocytes of patients with Alzheimer's disease.

In patients with probable Alzheimer's disease and in controls, acetyl- and butyrylcholinesterase activities were studied in cerebrospinal fluid (CSF) and plasma, and acetylcholinesterase activity of erythrocytes was determined. In addition, the molecular forms of acetylcholinesterase were measured in CSF. Severely demented patients had significantly lower acetylcholinesterase (p less than 0.01) and butyrylcholinesterase (p less than 0.05) activities in CSF than the controls had, but the activities of these enzymes in plasma and erythrocytes were within the same range in both groups. Acetylcholinesterase and butyrylcholinesterase activities in the CSF of mildly demented patients did not differ from control values. The ratio of the intermediate molecular form of acetylcholinesterase to the light molecular form of the enzyme did not differ significantly between patients with Alzheimer's disease and controls. According to our results, AChE levels were lower in the CSF of severely demented patients, but both light and intermediate molecular forms were affected.