A dissociation in attentional control: evidence from methamphetamine dependence.
BACKGROUND
Selective attention comprises multiple, dissociable component processes, including task shifting and selective inhibition. The goal of this study was to test whether task-shifting, selective inhibition, or both processes were impaired in long-term but currently abstinent methamphetamine-dependent individuals.


METHODS
Participants were 34 methamphetamine-dependent subjects and 20 nonsubstance abusing controls who were tested on an alternating-runs switch task with conflict sequences that required subjects to switch tasks on every second trial (AABBAABB).


RESULTS
Methamphetamine-dependent individuals committed more errors on trials that required inhibition of distracting information compared with controls (methamphetamine = 17%; controls = 13%; p = .02). By contrast, error rates did not differ between the groups on switch trials (methamphetamine = 7%; controls = 6%; p = .68).


CONCLUSIONS
These results indicate that selective inhibition, but not task switching, is selectively compromised by methamphetamine.
Salo
Ruth
R
Department of Psychiatry and Behavioral Sciences and the Imaging Research Center, University of California-Davis 95817, USA. resalo@ucdavis.edu
Nordahl
Thomas E
TE
Moore
Charles
C
Waters
Christy
C
Natsuaki
Yutaka
Y
Galloway
Gantt P
GP
Kile
Shawn
S
Sullivan
Edith V
EV
D000328:Adult; D000704:Analysis of Variance; D001288:Attention / Q000502:physiology*; D004193:Discrimination Learning / Q000502:physiology; D004213:Dissociative Disorders / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008694:Methamphetamine / Q000009:adverse effects*; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010775:Photic Stimulation / Q000379:methods; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D019966:Substance-Related Disorders / Q000503:physiopathology*; D013647:Task Performance and Analysis
D008694:Methamphetamine