Neuropsychological function and delay discounting in methamphetamine-dependent individuals
- 1.3k Downloads
Methamphetamine (MA) dependence accounts for substantial neuropsychiatric morbidity. Furthermore, there is evidence in the literature of psychiatric and cognitive impairment in chronic users.
This report compares the general psychiatric and cognitive functioning, including impulsive decision-making, of individuals dependent on MA and normal controls.
Materials and methods
Forty-one currently abstinent individuals in treatment for MA dependence and 41 controls participated. Controls were selected to minimize group differences in age and gender. MA users met DSM-IV criteria for MA dependence, had average daily use of 0.5 g/day (0.5–6 g/day), had been abstinent at least 2 weeks (2–24 weeks), and did not currently meet criteria for other Axis I psychiatric disorders. Psychiatric symptoms were rated on standardized scales. Cognitive function was assessed with a battery of standardized neuropsychological tests. Impulsivity was assessed using a delay discounting task, which measured preference for small, immediate, and large delayed rewards.
The MA group reported more psychiatric symptoms than controls, and was impaired relative to controls on the Babcock Story Recall-Delayed and the Rey Auditory Verbal Learning Test. MA-dependent subjects discounted delayed rewards more than controls, and this measure of impulsivity was correlated with memory impairment in the MA group but not in the controls.
MA-dependent individuals are more impulsive than controls, and this may be causally related to memory deficits but was unrelated to any other measure of psychiatric or cognitive impairment or any drug use history variable.
KeywordsMethamphetamine Impulsivity Delay discounting Memory
The authors wish to acknowledge Aaron Janowsky, who provided helpful comments on an earlier version of this manuscript, William G. Guethlein, who wrote the computer program used to measure delay discounting, and Vanessa B. Wilson for help with data analysis. Data in this paper was previously presented in an invited lecture at Dopamine 2002, Portland, OR, July 10–14, 2002. The investigations reported in this manuscript fully comply with the current laws of the USA and the State of Oregon. This work was supported by the Medical Research Foundation of Oregon (WFH), NIH grants AA11034, MH51372, AA13454; and the VA Merit Review Program (RJH), NIH grants AA00281 (BM) and DA015543 (SHM).
- American Psychiatric Association (1994) Diagnostic and statistical manual of mental disorders, 4th edn. Washington, DCGoogle Scholar
- Babcock H, Levy L (1940) The measurement of efficiency of mental functioning (revised examination). Test and manual of directions. C.H. Stoelting, Chicago, ILGoogle Scholar
- Cohen J, Cohen P (1983) Applied multiple regression/correlation analysis for the behavioral sciences, 2nd edn. Lawrence Erlbaum Associates, Hillsdale, NJGoogle Scholar
- Community Epidemiology Work Group (CEWG) (2005) Epidemiologic trends in drug abuse. U.S. Department of Health and Human Services, Public Health Service, Atlanta, GaGoogle Scholar
- Guy W (1976) ECDEU assessment manual for psychopharmacology (revised). US Department of Health, Education, and Welfare, USGPO, Washington, DCGoogle Scholar
- Hinson JM, Jameson TL, Whitney P (2003) Impulsive decision making and working memory. J Exp Anal Behav 29:298–306Google Scholar
- Kløve H (1963) Clinical neuropsychology. In: Forster FM (ed) The medical clinics of North America. Saunders, New YorkGoogle Scholar
- Osterrieth PA (1944) Le test de copie d’une figure complexe. Arch Psychol 30:206–356Google Scholar
- Rey A (1964) L’examen clinique en psychologie. Presses Universitaires de France, Paris, FranceGoogle Scholar
- Stevens J (1996) Applied multivariate statistics for the social sciences, 3rd edn. Lawrence Erlbaum Associates, Hillsdale, NJGoogle Scholar
- Volkow ND, Chang L, Wang GJ, Fowler JS, Ding YS, Sedler M, Logan J, Franceschi D, Gatley J, Hitzemann R, Gifford A, Wong C, Pappas N (2001a) Low level of brain dopamine D2 receptors in methamphetamine abusers: association with metabolism in the orbitofrontal cortex. Am J Psychiatry 158:2015–2021PubMedCrossRefGoogle Scholar
- Volkow ND, Chang L, Wang GJ, Fowler JS, Leonido-Yee M, Franceschi D, Sedler MJ, Gatley SJ, Hitzemann R, Ding YS, Logan J, Wong C, Miller EN (2001b) Association of dopamine transporter reduction with psychomotor impairment in methamphetamine abusers. Am J Psychiatry 158:377–382PubMedCrossRefGoogle Scholar
- Zachary RA (1986) Shipley institute of living scale. Revised manual. Western Psychological Services, Los AngelesGoogle Scholar