The authors conducted placebo-controlled double-blind studies of physostigmine, choline, and deanol in 12 patients with tardive dyskinesia. Physostigmine and choline both had a positive therapeutic effect on tardive dyskinesia, but the authors note that interpretation of these results is not entirely clear because they found that the sedation effect of physostigmine may nonspecifically reduce the intensity of tardive dyskinesia symptoms. Deanol was not found to be effective in this group of patients; the authors suggest that this drug should not be assumed to be generally effective unless effectiveness is verified by a large placebo-controlled double-blind study.