Cognitive efficiency in stimulant abusers with and without alcohol dependence.
BACKGROUND
Although previous studies have found stimulant (i.e., cocaine, methamphetamine) abusers and alcoholics to have neuropsychological deficits, research examining which cognitive abilities are most affected by concurrent exposure to these substances is lacking. To address this issue, detoxified men and women who met criteria for dependence of (a) alcohol only (ALC) (n = 15); (b) stimulants only (STIM) (n = 15); and (c) both alcohol and stimulants (A/STIM) (n = 15) were compared with age- and education-matched community controls (n = 15).


METHODS
Tasks that measured visual spatial skills, problem-solving and abstraction, short-term memory, cognitive flexibility, and gross motor speed were administered to participants. For each test, both speed and accuracy were assessed and an efficiency ratio (accuracy/time) was derived. Based on an average of these efficiency ratios, an overall performance index of cognitive efficiency was obtained.


RESULTS
Overall, controls performed more efficiently than all other groups. However, they were statistically significantly better only in relation to the A/STIM and STIM groups (p < 0.01). Individual comparisons revealed that the ALC group performed significantly better than the STIM group, although the ALC group did not differ from either the control or A/STIM groups (p </= 0.05). This pattern of results was relatively consistent across the individual subtests of problem-solving/abstraction, short-term memory, and cognitive flexibility.


CONCLUSIONS
As expected, substance abuse was associated with cognitive inefficiency. More importantly, these findings suggest that the cognitive effects of chronic stimulant abuse are not additive with those of alcohol abuse. That is, singly addicted stimulant abusers demonstrated similar or greater neurocognitive impairments than individuals who abuse alcohol and stimulants concurrently. The reason for this pattern is speculative but may be attributed to alcohol's opposing actions on cerebrovascular effects brought on by stimulant abuse.
Lawton-Craddock
Andrea
A
Center for Alcohol and Drug-Related Studies, Department of Psychiatry and Behavioral Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA. andrea-lawton@ouhsc.edu
Nixon
Sara Jo
SJ
Tivis
Rick
R
D000328:Adult; D000437:Alcoholism / Q000523:psychology*; D000704:Analysis of Variance; D000697:Central Nervous System Stimulants / Q000009:adverse effects; D016009:Chi-Square Distribution; D003071:Cognition; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000523:psychology; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000523:psychology*
D000697:Central Nervous System Stimulants