There have been quite a few studies with vinpocetine.
Researchers at the University of Surrey in Guildford, England administered vinpocetine to patients suffering from mild to moderate dementia (Hindmarch 1991). Two hundred and three patients included in a placebo-controlled, randomized double-blind trial received every day for sixteen weeks either 10 mg doses of vinpocetine three times a day, 20 mg doses of vinpocetine three times a day, or placebo three times a day. There were no clinically relevant side effects reported. Statistically significant cognitive improvements were found in favor of active treatment groups compared to placebo. The patients on 10 mg performed slightly better than those on 20 mg.
Chronic Cerebral Dysfunction
In a double blind clinical trial, vinpocetine was shown to offer significant improvement in elderly patients with chronic cerebral dysfunction. Forty-two patients received 10 mg vinpocetine three times a day for thirty days, then 5 mg three times a day for sixty days. Matching placebo tablets were given to another forty patients for the ninety-day trial period. Patients on vinpocetine scored consistently better in all cognitive evaluations. No serious side effects were reported.
Twelve healthy female volunteers received pre-treatments with vinpocetine 40 mg three times a day or placebo for two days according to a randomized, double-blind crossover design. On the third day of treatment and one hour following morning dosage, subjects completed a battery of psychological tests. Memory was significantly improved following treatment with vinpocetine when compared to placebo.