The impact of age on cognitive functioning in HIV-1 infection

Date of Award




Degree Name

Doctor of Philosophy (Ph.D.)

First Committee Member

Gail Ironson - Committee Chair

Second Committee Member

Frances Wilkie - Committee Member


The present study examined the impact of HIV infection, age, and the combined effects of HIV infection and age on cognitive functioning. It further explored the contribution of cognitive deficits to impairment in functional and work status. A detailed neuropsychological test battery was administered to a cohort of 20 younger seronegatives (mean age = 33.4), 20 younger seropositives (mean age = 33.3), 20 older seronegatives (mean age = 55.2), and 20 older seropositives (mean age = 56.4).Comparisons of group means revealed that older adults performed significantly less well than younger adults on domains of executive functioning, information processing speed, memory, motor performance, and visuoconstructive/visuospatial performance. Using parametric analyses, no differences were observed between seropositive and seronegatives groups on any of the neuropsychological test domains. The predicted interactions between age group and serostatus also failed to reach significance for any of the domains.Subjects' neuropsychological test performance was further classified as impaired or non-impaired for each domain using the younger seronegatives as the reference group for the younger seropositives and the older seronegatives as the reference group for the older seropositives. Non-parametric analyses based on these impairment ratings revealed that seropositive adults were more likely to be classified as impaired on the memory, motor performance and visuoconstructive/visuospatial domains compared to suronegative adults.Neuropsychological impairment has been associated with lower viral loads and CD4 cell counts. However, this study did not end these two factors to be significantly related to cognitive functioning.Limited support was found for the hypothesis that neuropsychological impairment would predict impairment in aspects of daily functioning. Additionally, both neuropsychological impairment and serostatus predicted work status. However, neuropsychological impairment did not mediate the impact of serostatus on work status as was predicted.Findings from this study support the utility of neuropsychological impairment ratings for detection of subtle cognitive deficits in seropositive individuals. These impairment ratings may provide a more accurate estimate of the incidence of cognitive impairment in seropositive individuals than comparisons of group means. The potential contribution of a fairly large number of control variables was examined. Findings for each of the covariates are briefly summarized. Results from this study further highlight the importance of including appropriate controls.Taken together, these findings suggest that while cognitive impairment was relatively low in the seropositive group, even the presence of mild cognitive deficits may have an impact on some aspects of daily functioning. Practical implications of these findings are discussed.


Psychology, Developmental; Psychology, Clinical; Psychology, Cognitive

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