Nondependent stimulant users of cocaine and prescription amphetamines show verbal learning and memory deficits.
BACKGROUND
Stimulants are used increasingly to enhance social (cocaine) or cognitive performance (stimulants normally prescribed, prescription stimulants [e.g., methylphenidate, amphetamines]). Chronic use, by contrast, has been associated with significant verbal memory and learning deficits. This study sought to determine whether subtle learning and memory problems characterize individuals who exhibit occasional but not chronic use of stimulants.


METHODS
One hundred fifty-four young (age 18-25), occasional, nondependent stimulant users and 48 stimulant-naive comparison subjects performed the California Verbal Learning Test II. Lifetime uses of stimulants and co-use of marijuana were considered in correlation and median split analyses.


RESULTS
Compared with stimulant-naive subjects, occasional stimulant users showed significant performance deficits, most pronounced in the verbal recall and recognition domains. Lifetime uses of stimulants and marijuana did not affect California Verbal Learning Test II performance. The type of stimulant used, however, was of major relevance: users of cocaine only were less impaired, whereas cumulative use of prescription stimulants was associated with impaired verbal learning and memory capacities.


CONCLUSIONS
These results support the hypothesis of subtle and possibly pre-existing neurocognitive deficiencies in occasional users of stimulants, which might be related to the motivation for using these drugs. More importantly, despite beneficial short-term effects, cumulative use, particularly of prescription amphetamines and methylphenidate, intensifies these deficits.
Reske
Martina
M
Department of Psychiatry, University of California, San Diego, La Jolla, California 92037-0985, USA.
Eidt
Carolyn A
CA
Delis
Dean C
DC
Paulus
Martin P
MP
D000293:Adolescent; D000328:Adult; D000662:Amphetamines / Q000009:adverse effects*; D002188:Cannabis / Q000009:adverse effects; D000697:Central Nervous System Stimulants / Q000009:adverse effects*; D003042:Cocaine / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000139:chemically induced*; D055553:Prescription Drugs / Q000009:adverse effects*; D014706:Verbal Learning / Q000187:drug effects*
D000662:Amphetamines; D000697:Central Nervous System Stimulants; D055553:Prescription Drugs; D003042:Cocaine