To the Editor: Now that there is direct evidence of a reduction in acetylcholine synthesis in Alzheimer#x0027; s disease1,2 as well as a clinical response to an acetylcholine precursor in some patients,3 it can be anticipated that the clinical testing of appropriate agonists will be intensified. However, a word of caution on such studies may be called for. We examined cerebral-biopsy and cerebrospinal-fluid (CSF) samples from seven patients 43 to 66 years old with progressive dementia. Histologic evidence of Alzheimer#x0027; s disease was evident in all but the two youngest patients (men 43 and 50 years old), in whom there was also. . .