Human immunodeficiency virus infection heightens concurrent risk of functional dependence in persons with long-term methamphetamine use.

Objectives: Disability among long-term methamphetamine (MA) users is multifactorial. This study examined the additive adverse impact of human immunodeficiency virus (HIV) infection, a common comorbidity in MA users, on functional dependence.

Methods: A large cohort of participants (N = 798) stratified by lifetime MA-dependence diagnoses (ie, MA+ or MA-) and HIV serostatus (ie, HIV+ or HIV-) underwent comprehensive baseline neuromedical, neuropsychiatric, and functional research evaluations, including assessment of neurocognitive symptoms in daily life, instrumental and basic activities of daily living, and employment status.

Results: Independent, additive effects of MA and HIV were observed across all measures of functional dependence, independent of other demographic, psychiatric, and substance-use factors. The prevalence of global functional dependence increased in the expected stepwise fashion across the cohort, with the lowest rates in the MA-/HIV- group (29%) and the highest rates in the MA+/HIV+ sample (69%). The impact of HIV on MA-associated functional dependence was moderated by nadir CD4 count, such that polysubstance use was associated with greater disability among those HIV-infected persons with higher but not lower nadir CD4 count. Within the MA+/HIV+ cohort, functional dependence was reliably associated with neurocognitive impairment, lower cognitive reserve, polysubstance use, and major depressive disorder.

Conclusions: HIV infection confers an increased concurrent risk of MA-associated disability, particularly among HIV-infected persons without histories of immune compromise. Directed referrals, earlier HIV treatment, and compensatory strategies aimed at counteracting the effects of low cognitive reserve, neurocognitive impairment, and psychiatric comorbidities on functional dependence in MA+/HIV+ individuals may be warranted.