title: Deficits in response inhibition associated with chronic methamphetamine abuse.
abstract: Chronic methamphetamine (MA) abuse is associated with cerebral deficits, involving frontal/basal-ganglia regions that are important for inhibitory control. We used the Stop-Signal Task to measure response inhibition in 11 MA abusers (5-7 days abstinent) and two groups of control subjects who did not use MA (14 tobacco smokers and 29 non-smokers). Stop-signal reaction time (SSRT), which indicates the latency to inhibit an initiated motor response, was significantly longer for MA abusers than for either control group (p's<.01). In contrast, the MA abusers did not differ from either group on Go trial reaction time (RT) or number of discrimination errors, which reflect motor speed and decision-processes, respectively. MA abuse in this study was therefore associated with a specific deficit in inhibiting a pre-potent response. Future research could examine whether SSRT is different for MA abusers who respond to treatment compared to those who do not. If such differences are established then response inhibition may serve as a marker for investigating MA abuse in basic science and clinical trials.
authors.affiliation: Department of Psychiatry and Biobehavioral Sciences, University of California Los Angeles, Los Angeles, CA 90024-1759, USA. jmont@ucla.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Monterosso
authors.forename: Adam R
authors.initials: AR
authors.lastname: Aron
authors.forename: Xochitl
authors.initials: X
authors.lastname: Cordova
authors.forename: Jiansong
authors.initials: J
authors.lastname: Xu
authors.forename: Edythe D
authors.initials: ED
authors.lastname: London
mesh_terms: D000328:Adult; D000697:Central Nervous System Stimulants / Q000009:adverse effects*; D016000:Cluster Analysis; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008694:Methamphetamine / Q000009:adverse effects* / Q000652:urine; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D017397:Prefrontal Cortex / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance / Q000187:drug effects / Q000502:physiology*; D011930:Reaction Time / Q000187:drug effects / Q000528:radiation effects*; D019966:Substance-Related Disorders / Q000652:urine
chemical_list: D000697:Central Nervous System Stimulants; D008694:Methamphetamine