Cholinergic system and constructional praxis: a further study of physostigmine in Alzheimer's disease.

Subcutaneous or intravenous administration of physostigmine improved the copying of geometric figures in three out of six patients with presumed Alzheimer's disease who showed a remarkable constructional disturbance. This improvement reached its maximum 30 to 60 minutes after the physostigmine administration. These results not only provide further evidence supporting the hypothesis that central cholinergic potentiation ameliorates some of the impairments of Alzheimer's disease, but implicate a possible important role of the cholinergic system in the integration of constructional praxis.