fMRI brain activation during a delay discounting task in HIV-positive adults with and without cocaine dependence

Abstract

Cocaine use is associated with poorer HIV clinical outcomes and may contribute to neurobiological impairments associated with impulsive decision making. This study examined the effect of cocaine dependence on brain activation during a delay discounting task involving choices between smaller immediate rewards and larger delayed ones. Participants were 39 HIV-positive adults on antiretroviral therapy who had current cocaine dependence ("active," n=15), past cocaine dependence ("recovered," n=13), or no lifetime substance dependence ("naïve," n=11). Based on responses on a traditional delay discounting task, three types of choices were individualized for presentation during fMRI scanning: hard (similarly valued), easy (disparately valued), and no (single option). Active participants had significantly smaller increases in activation than naïve participants during hard versus easy choices bilaterally in the precentral gyrus and anterior cingulate cortex and in the right frontal pole (including dorsolateral, ventrolateral, and orbitofrontal cortex). During hard and easy choices relative to no choices, active participants had smaller increases in activation compared to naïve participants in frontoparietal cortical regions. These deficits in the executive network during delay discounting choices may contribute to impulsive decision making among HIV-positive cocaine users, with implications for risk behaviors associated with disease transmission and progression.

Recent Translational Findings on Impulsivity in Relation to Drug Abuse

“…These studies typically compare patterns of brain activation when subjects opt for the delayed reward versus decisions for the immediate reward. Consistent with the behavioral studies reviewed above, all but one [86] of the fMRI studies reviewed here found that users discounted more steeply than non-users. As noted above, these group differences on task performance must be taken into account when interpreting the findings.…”

“…In smokers, greater activation was observed in the medial PFC and anterior insular cortex when choosing the delayed option relative to the immediate option for money and cigarettes [89]. Meade et al [86] found that among cocaine-using HIV patients, the increase in activity in fronto-parietal regions (including precentral gyrus, ACC, and right DLPFC, VLPFC, and OFC) was less than that in non-users when making hard decisions compared with easy decisions (although they did not differ in discounting rates). Finally, Camchong et al [90•] found that cocaine-dependent individuals discounted more steeply and had higher resting functional connectivity within a network comprising the perigenual ACC and frontal and temporal regions (i.e., DLPFC, middle temporal gyrus, and superior frontal gyrus) compared with controls.…”

Drug Induced Increases in CNS Dopamine Alter Monocyte, Macrophage and T Cell Functions: Implications for HAND

“…Some studies reported that drug abuse increased neurocognitive impairment with HIV infection (Meade et al 2011b; Meade et al 2011a), while others indicated that it had no effect on HAND (Byrd et al 2011; Basso and Bornstein 2003). …”

Past Stimulant Abuse is Associated with Reduced Basal Ganglia and Hippocampal Integrity in Older HIV+ Adults: A Diffusion Tensor Imaging Study

“…For easy choices, recovered users performed similarly to drug naïve participants, with greater increases in activation in the anterior cingulate cortex (ACC), orbitofrontal cortex (and the overlapping ventromedial prefrontal cortex (areas involved in decision making) compared to active cocaine users. In contrast, for hard choices, recovered users evidenced deficits similar to those observed in active cocaine users, suggesting that sustained remission from cocaine use may reverse some, but not all, of the impairments associated with active cocaine dependence [25].…”

“…It has been well-established that current drug abuse/dependence is associated with neurocognitive abnormalities. However, the neurocognitive effects of past drug use are less clear with some studies demonstrating no differences after even prolonged abstinence to [63,64] to those finding robust differences [25,65]. There are a number of reasons that may explain why neuropsychological findings may differ; many studies examining neuropsychological performance fail to account for premorbid factors such as cognitive reserve capacity [66] that can result in performance variation.…”