A three months study was performed on 150 aging patients with primary memory deficits in order to verify the effectiveness of CDP-Choline, administered in repeated cycles of four weeks, with an interval of one week between cycles, in improving patients' cognitive and behavioral efficiency and in stabilizing their cognitive decline. Objective measures of memory and attention, and a behavioral rating scale were used to assess treatment effects. CDP-Choline treatment demonstrated both symptomatic efficacy and a long lasting effect on cognition and behavior of these patients. Level of activation and attention responsiveness improved during treatment cycles and no further changes were identified of these variables in the follow-up period. Measures related to specific memory functioning showed, besides improvements during treatment, after-effects still active in the follow-up period, suggesting a long lasting change of the cognitive decline trend characteristic of these patients.