The efficacy and tolerability of memantine (1-amino-3,5-dimethyl-adamantane hydrochloride, Akatinol Memantine; CAS 41100-52-1) was investigated in a double-blind, randomized clinical study versus placebo in 66 patients aged between 65 and 80 years predominantly suffering from mild to moderate vascular dementia. The target variables assessed were the baseline differences of the Sandoz Clinical Assessment Geriatric scale (SCAG) and Syndrom-Kurz-Test (SKT) total scores and the total time required in the subtests of Activity of Daily Living tests (ADL). Additional parameters assessed were the physician's global impression, the Mini Mental State Evaluation (MMSE), the Tapping and Trace tests for fine motor rating and the quality in performing the ADL tests. Adverse drug effects were recorded by DOTES/TWIS. 59 of the 66 patients included in the study terminated the trial (29 in the placebo and 30 in the memantine group). For the baseline differences of the SCAG total score a statistically significant improvement was observed already after 14 days of memantine treatment as compared to placebo. After 42 days this difference was still more pronounced and highly significant. Significant improvements after 14 and 42 days of memantine treatment could also be demonstrated for the SCAG subscales cognitive disturbances, lack of drive, emotional disturbances, social behaviour and somatic disturbances. Additionally, the efficacy of the drug could be confirmed by the SKT and ADL tests. Particularly striking in the ADL tests was the considerable improvement achieved in the quality of performing the tasks under memantine treatment.(ABSTRACT TRUNCATED AT 250 WORDS)