Regression analysis adjusted for demographics linked more cognitive activity to better cognitive performance in 176 older people with HIV infection. Further analysis determined that the association remained statistically significant only for blacks.
Aging people with and without HIV face a growing risk of impaired cognition. Research suggests that lifestyle factors such as cognitive activity (engaging in mentally stimulating tasks) can be modified to lower this risk. Identifying such factors is a priority for aging HIV populations. Because studies of cognitive activity in aging people with HIV have been limited by small size, a focus on a single cognitive activity and indirect or brief measures of cognitive activity, researchers in Chicago conducted this study.
The analysis involved 176 HIV-positive men and women at least 50 years old. Participants had no neurologic disorders and no history of substance use in the past three months. All were taking antiretroviral therapy. Participants completed a nine-item questionnaire that assessed frequency of cognitive activity including reading, visiting museums and attending concerts or plays. Researchers assessed neurocognitive function with a battery of 19 standardized neurocognitive tests measuring five domains. To examine the relationship between cognitive activity and neurocognitive test scores, they used multiple linear regression adjusted for age, sex, race and education; then they added clinical variables to the model one at a time.
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The analysis included 123 blacks and 53 whites, 24% of them women and 71% with an annual income below $25,000. Age averaged 58.7 years, education 13.2 years, medical conditions 2.9 and CD4 count 621 cells/mm3; 95% had an undetectable viral load. Blacks reported less cognitive activity than whites in three of nine areas: reading, visiting a museum and attending concerts. General health and HIV disease status were similar for blacks and whites.
More years of formal education were associated with better global cognition (estimate 0.06, P < .001), but age and sex were not. Compared with whites, blacks had significantly lower global neurocognitive scores (estimate -0.37, P < .001). In the model adjusted for age, sex, race and education, more cognitive activity was associated with better global cognition and better performance in two of five domains: semantic memory and perceptual speed. These associations remained largely unchanged after adjustment for employment, common medical conditions, vascular risk score, hepatitis status, CD4-cell nadir and average number of lifetime drugs. But adjusting for more depressive symptoms reduced the association to a nonsignificant trend (estimate 0.10, P = .060).
In subsequent models, the interaction between race and cognitive activity was significant, suggesting that the association between cognitive activity and global neurocognitive function applied only to blacks (estimate for interaction 0.38, P < .001). The interaction between race and cognitive activity was also significant for three of five domains: episodic memory (estimate 0.39, P = .006), working memory (estimate 0.54, P = .005) and perceptual speed (estimate 0.41, P = .02).
The authors believe their results suggest the link between cognitive activity and neurocognitive function may be stronger in older HIV-positive blacks than whites, but they caution that "the significance of this finding is unclear." The researchers think their findings "suggest that improved access to cognitive activity interventions, in particular among middle to older aged Blacks, could be an important target to reduce late-life disparities in brain health and neurocognitive function."