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Cognitive Function in HIV-1-Infected Intravenous Drug Users

Gail Shor-Posner, Ph.D.
University of Miami School of Medicine

Lecture Outline

  1. HIV and the Brain
    1. Blood Brain Barrier
    2. CNS Effects

  2. Cognitive Impairment
    1. Evaluation
    2. Prevalence of Deficits
    3. Confounding Factors
    4. Onset of Alterations

  3. Treatment/Prevention of Cognitive Dysfunction
    1. Nutrition Cofactors
    2. Antiretrovirals

  4. Future Research
    1. Need for Further Studies
    2. Areas of Concern/Limited Information

Learning Objectives

  • Understand the controversy regarding the prevalence and onset of cognitive alterations in HIV-1-infected drug users.

  • Become familiar with possible strategies for prevention/treatment of HIV-1-associated cognitive dysfunction.


Loss of cognitive ability, the most common neuropsychological complication in HIV-1 disease, may affect compliance, functional capacity, and be a significant predictor of early mortality (1). Detectable deficits in cognitive/motor function among HIV-1+ drug users have been described (2-4) and are similar to those observed in predominantly homosexual groups. In other studies, the use of toxic substances appears to be more important than the effect of the virus (5,6) and age and education more powerful predictors of cognitive function (7). Determination of cognitive impairment presents substantial difficulties, as confounding factors including substance abuse can affect performance and contribute to impairment. Additional research is necessary to clarify the effect of specific drugs and HIV-1 aspects of neuropsychological performance.

There is also controversy regarding the onset of cognitive impairment. Similar to research in other HIV-1-seropositive cohorts, some studies report that neuropsychological alterations in HIV-1-infected drug users precede clinical evidence of AIDS, as opposed to investigations revealing no evidence of dysfunction in the asymptomatic stage (5,6,8), emphasizing the need for further research.

Some of the cognitive dysfunction, observed in HIV-1-infected non-drug-using cohorts, may be due to inadequate nutritional status. Whereas low levels of cobalamin (vitamin B12) appear to contribute to cognitive changes (9), an increase in cobalamin has been linked to improved performance (10), underscoring the importance of determining nutritional status in cognitive assessment. Further research will be required to determine whether cobalamin administration and/or supplementation with micronutrients, which prevent oxidative damage, can be of therapeutic value in preventing cognitive decline in HIV-1-infected drug users.


Wilkie FL, Goodkin K, Eisdorfer C et al., Mild cognitive impairment and risk of mortality in HIV-1 infection. J Neuropsychiatry and Clinical Neurosciences 1998;10:125-132.

Del Pesce M, Franciolini B, Censori B et al., Cognitive behavior in asymptomatic (CDC stage II and III) HIV-seropositive intravenous drug users (IVDUs). Ital J Neurol Sci. 1993;17:619-625.

Handelsman L, Aronson M, Roick H, Mauss S, Arendt G. HIV-specific changes in the motor performance of HIV-positive intravenous drug abusers. J Neurol 1994;242:20-25.

Silberstein CH, O'Dowd MA, Chartock et al., A prospective four-year follow-up of neuropsychological function in HIV seropositive and seronegative methadone-maintained patients. Gen Hosp Psychiatry 1993;15:351-359.

Egan VG, Crawford JR, Brettle RP, Goodwin GM. The Edinburgh cohort of HIV-positive drug users: current intellectual function is impaired, but not due to early AIDS dementia complex. AIDS 1990;4:651-656.

Grassi MP, Clerici F, Perin C et al., HIV infection and drug use: influence on cognitive function. AIDS 1995;9:165-170.

Concha M, Graham NMH, Munoz A et al., Effect of chronic substance abuse on the neuropsychological performance of intravenous drug users with a high prevalence of HIV-1 seropositivity. Am J Epidemiol 1992;136:1338-48.

Selnes, OA, Galai N, McArthur JC et al., HIV infection and cognition in intravenous drug users: Long-term follow-up. Neurology 1997;48:223-230.

Beach RS, Morgan R, Wilkie F et al., Plasma vitamin B12 level as a potential cofactor in studies of human immunodeficiency virus type 1-related cognitive changes. Arch Neurol 1992;49:501-506.

Shor-Posner G, Morgan R, Wilkie F, Eisdorfer C, Baum MK. Plasma cobalamin levels affect information processing speed in a longitudinal study of HIV-1 disease. Arch Neurol 1995;52:195-198.

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