A multicentre study was planned and executed to evaluate the effect of psychopharmacological treatment in cognitive decline, while also monitoring the influence of pivotal variables. Using 42 health centres, whose comparability of methodology was ensured through a training seminar and an instructional booklet on the psychometric battery of tests employed, 469 Ss (60 years and over older) were enrolled using strict selection criteria. The treatment was run in four phases over 150 days. The first and the last phases consisted of 30-days placebo treatment, whereas the second and third consisted of 45-days treatment with 1,500 mg of acetyl-L-carnitine. A psychometric evaluation followed each phase. Using this plan it was possible to evaluate the placebo effects, make cross-study comparisons and isolate the effects of the drug treatment.