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Additive effects of aging and HIV infection on category verbal fluency: an analysis of component processes
Iudicello, Jennifer E
Advances in the management of HIV infection have resulted in a growing population of older adults living with HIV. Both aging and HIV infection have been independently associated with central nervous system changes and corresponding declines in neurocognitive functioning. Poorer semantic verbal fluency output is also common in both HIV infection and healthy older adults, although, the possible additive effects of these risk factors are unknown. The present study aimed to examine the combined effects of aging and HIV on semantic verbal fluency and its component processes (i.e., clustering and switching), the neurocognitive correlates of clustering and switching in older HIV-infected adults, and the associations between clustering and switching and everyday functioning. Participants included 257 individuals across 4 demographically matched groups: Younger (i.e., <40 years) Healthy (n=93), Younger HIV-infected (n=50), Older (i.e., ≥50 years) Healthy (n=51), and Older HIV-infected (n=63) individuals. Participants were administered a standard semantic fluency protocol scored according to established clustering and switching guidelines (Troyer et al., 1997) and a self-reported assessment of everyday functioning as part of a comprehensive neuropsychological, medical, and psychological evaluation. Jonckheere-Terpstra tests revealed a significant stepwise additive effect between the groups for overall semantic fluency output (p = 0.004) and a trend for declining switching performance (p = 0.056), but not cluster size (p = 0.826), with greatest deficits evident in the Older HIV-infected participants. Results were not better explained by confounding psychiatric, medical, or HIV disease characteristics. Within the older HIV-infected adults, poorer switching was associated with deficits in learning and executive functioning and self-reported declines in everyday functioning. Results suggest that HIV infection and aging may confer adverse additive effects on the executive components of semantic fluency (i.e., switching), which was associated with poorer everyday functioning outcomes and may be driven by the combined frontostriatal neuropathological burden of these two conditions. This research provides preliminary insight into the cognitive architecture of HIV-associated neurocognitive disorders among older adults, and may ultimately guide rehabilitation efforts aimed at improving overall quality of life for the growing population of older adults living with HIV infection.
Doctor of Philosophy (Ph.D.) University of California, San Diego and San Diego State University, 2011
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