Changes in neurocognition and adherence over six months in HIV-infected individuals with cocaine or heroin dependence

We sought to examine the course of adherence and cognition in HIV-infected individuals with either cocaine or heroin dependence and investigate independent predictors of cognition change. A prospective study over six months was undertaken in which adherence was measured by monthly electronic pill cap monitoring (Medication Event Monitoring System), while a comprehensive neuropsychological battery resulting in a composite score (NPZ8) was performed at baseline and six months. Multivariable regression models were performed in order to determine independent associations with change in cognition. There were 101 subjects at baseline, of whom 62% were male and 83% were non-Hispanic black. 46.6% of subjects at baseline had completed high school, 36.6% reported active cocaine use during the course of the study, and 0% reported active heroin use during the course of the study. 66 subjects completed the final cognitive assessment at six months. Subjects had markedly impaired cognitive function at baseline (NPZ8 -1.49) which persisted at six months (NPZ8 -1.47) in the group of study completers. There was an average monthly decrease in adherence of -2.91% overall (p = 0.008). In the multivariable model, each of the following variables: baseline cognition (R² change = 0.121, p = 0.006), cocaine use during the study (R² change = 0.059, p = 0.046), and monthly adherence change (R² change = 0.078, p = 0.018) independently contributed to NPZ8 change with an overall R² change = 0.219 (p = 0.001). This study shows an overall decrease in adherence over time in this population of subjects with a history of drug dependence. Active cocaine use, baseline cognition, and temporal adherence changes independently contributed to changes in cognition. Further study on enhancing adherence, cognition, and limiting drug abuse are warranted in this subgroup of HIV-infected individuals.