Preliminary evidence of reduced cognitive inhibition in methamphetamine-dependent individuals

Salo, Ruth; Nordahl, Thomas E; Possin, Kate; Leamon, Martin; Gibson, David R; Galloway, Gantt P; Flynn, Neil M; Henik, Avishai; Pfefferbaum, Adolf; Sullivan, Edith V

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Volume 111, Issue 1 , Pages 65-74, 5 August 2002

Preliminary evidence of reduced cognitive inhibition in methamphetamine-dependent individuals

Ruth Salo
- Department of Psychiatry, UC Davis Medical Center, 2230 Stockton Blvd, Sacramento, CA 95817, USA
- UCD Center for Neuroscience, 1544 Newton Court, Davis, CA 95616, USA
- Corresponding author. Department of Psychiatry, UC Davis Medical Center, 2230 Stockton Blvd., Sacramento, CA 95817, USA. Tel.: +1-530-757-8800; fax: +1-530-757-8827
Thomas E Nordahl
- Department of Psychiatry, UC Davis Medical Center, 2230 Stockton Blvd, Sacramento, CA 95817, USA
Kate Possin
- Neuroscience Program, Center for Health Science (BN166), SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025, USA
Martin Leamon
- Department of Psychiatry, UC Davis Medical Center, 2230 Stockton Blvd, Sacramento, CA 95817, USA
David R Gibson
- Department of Internal Medicine, UC Davis Medical Center, 2230 Stockton Blvd., Sacramento, CA 95817, USA
Gantt P Galloway
- Haight-Ashbury Free Clinics, San Francisco, CA, USA
Neil M Flynn
- Department of Internal Medicine, UC Davis Medical Center, 2230 Stockton Blvd., Sacramento, CA 95817, USA
Avishai Henik
- Department of Behavioral Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
Adolf Pfefferbaum
- Neuroscience Program, Center for Health Science (BN166), SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025, USA
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305-5723, USA
Edith V Sullivan
- Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Road, Stanford, CA 94305-5723, USA

Received 8 October 2001; received in revised form 15 April 2002; accepted 29 April 2002.

Abstract

Chronic methamphetamine abuse is associated with disruption of frontostriatal function involving serotonin and dopamine circuitry. Clinically, methamphetamine-dependent (MD) individuals are highly distractible and have difficulty focussing. Here, we used a computerized single-trial version of the Stroop Test to examine selective attention and priming in MD. Subject groups comprised eight MD men (31.7±7.2 years of age), who had used methamphetamine for 15.75±8.4 years but were currently abstinent for 2–4 months, and 12 controls (35.7+9.7 years of age). Compared with the control group, the MD group exhibited significantly greater interference (P<0.05) despite intact priming. Error rates did not differ between the groups. This preliminary finding of reduced cognitive inhibition in MD individuals is consistent with the distractibility they show clinically. Furthermore, the dissociation between explicit attentional performance and priming effects suggests that some attentional functions are not as affected by long-term methamphetamine use as others.

Keywords: Methamphetamine, Cognition, Attention, Stroop