We sought to determine the changes in the cholinergic pathways, which project from the nucleus basalis of Meynert (nBM) and travel in the subinsular region, in vascular dementia of the Binswanger type (VDBT) and Alzheimer's disease (AD). The subinsular regions were examined in 6 autopsied brains with VDBT, 5 brains with AD and 4 control brains without any neurologic diseases. The cholinergic pathway was labeled either by histochemistry for acetylcholine esterase (AChE), a degradatory enzyme of ACh, or by immunohistochemistry for choline acetyltransferase, its synthetic enzyme. The numerical density of nBM neurons did not differ significantly between these groups (163 +/- 49 in the VDBT, 105 +/- 82 in the AD and 198 +/- 76 in the control groups), but with a tendency towards a decrease in the AD group. The subinsular cholinergic fibers were impaired, with relative preservation of the nBM neurons in VDBT, whereas both the subinsular cholinergic fibers and the nBM neurons were degraded in AD. These results indicate that the cholinergic pathway is damaged not only in AD, but also in VDBT, and may further provide a pharmacological basis for treatment with AChE inhibitors in VDBT.