Effects of Cocaine Use on Verbal Memory and Prefrontal Cortex Function in Women Infected with HIV
thesisposted on 28.06.2013, 00:00 by Vanessa J. Meyer
Objective: HIV infection and illicit drug use are each associated with diminished cognitive performance. This study included both epidemiological and functional neuroimaging components to investigate the impact of illicit drug use, particularly crack cocaine use, on cognitive function in women with HIV. Methods: The large-scale epidemiological study analyzed data from 952 HIV-infected and 443 uninfected women (mean age=43 years, 64% African-American) from the multicenter Women’s Interagency HIV Study. Outcome measures included standardized tests of verbal memory and executive function. We compared 3 groups: recent (past 6 months), former (lifetime use but not past 6 months), and nonusers of crack cocaine, powder cocaine, and/or heroin. In the neuroimaging study, a sample of 30 HIV-infected women underwent functional MRI during a novel verbal memory task. The analysis focused on recent, former, and nonusers of crack cocaine. Results: HIV infection and recent illicit drug use were each associated with worse verbal learning and memory. Importantly, there was an interaction between HIV serostatus and recent illicit drug use such that recent illicit drug use (compared to non-use) negatively impacted verbal learning and memory only in HIV-infected women. The functional neuroimaging study found that both recent and former crack cocaine users showed less activation of their left dorsal medial prefrontal cortex during encoding of words than women who had never used crack cocaine. Similarly, both recent and former crack cocaine users showed less activation of their bilateral prefrontal cortex during recognition of words than women who had never used crack cocaine. Importantly, activation in these areas was related to performance on the verbal memory task. Conclusions: The interaction between HIV serostatus and recent illicit drug use on verbal learning and memory suggests a potential synergistic neurotoxicity that may affect the neural circuitry underlying performance of verbal learning and memory. The finding of less activation in the prefrontal cortex, which correlated with behavioral measures, suggests crack cocaine may be negatively impacting prefrontally-mediated executive control of memory.