Detrimental impact of remote methamphetamine dependence on neurocognitive and everyday functioning in older but not younger HIV+ adults: evidence for a legacy effect?

Prior studies examining the combined adverse effects of HIV and methamphetamine (MA) on the central nervous system (CNS) have focused on younger to middle-aged adults with recent MA use diagnoses. Aging, HIV, and MA all converge on prefrontal and temporolimbic neural systems and confer independent risk for neurocognitive and functional decline. Thus, this study sought to determine the residual impact of a remote history of MA dependence on neurocognitive and real-world outcomes in older people living with HIV (PLWH). Participants included 116 older (≥50 years) and 94 younger (<40 years) adults classified into one of six study groups based on HIV serostatus (HIV+/HIV-) and lifetime histories of MA dependence (MA+/MA-): older HIV-MA- (n = 36), older HIV+MA- (n = 49), older HIV+MA+ (n = 31), younger HIV-MA- (n = 27), younger HIV+MA- (n = 33), and younger HIV+MA+ (n = 34). No participant-met criteria for current MA use disorders and histories of MA dependence were remote in both the older (average of nearly 9 years prior to evaluation) and younger (average of over 2 years prior to evaluation) HIV+MA+ groups. Findings revealed that a remote history of MA dependence exerts a significant detrimental impact on specific aspects of neurocognitive performance (e.g., memory) and a broad range of real-world functioning outcomes (e.g., employment) among older, but not younger PLWH. These results suggest that MA-associated neurotoxicity may have significant "legacy" effects on both neurocognitive and functional outcomes to which older PLWH are particularly vulnerable.