Age-related changes in memory and their pharmacologic modulation.

A passive avoidance procedure was used to measure the ability to learn and remember to avoid a noxious stimulus in 13-month-old mice and to test the effects that treatment with cytidine(5')-diphosphocholine (CDP-choline) had on these processes. Half of the mice received 500 mg/kg per day CDP-choline orally for 4 months, and the two groups were compared with a third group of younger animals (4-month-old mice). The older mice showed marked impairment in the execution of these tests; however, those treated with CDP-choline had significant improvement in their performance 24 hours after learning the task.