Although cognitive impairment (CI) is frequently reported in people with HIV (PWH), limited data exist on the dynamics of change in treated individuals meeting definitions of CI over time. A greater understanding of these dynamics would assist in targeting individuals at risk of cognitive decline.
Treated PWH with HIV RNA <50 copies/mL for ≥1 year and comparable controls underwent assessment of cognitive function (six domains) at baseline and after two years. Demographically-adjusted T-scores at baseline and follow-up were derived and the multivariate normative comparison (MNC) criterion was used to determine CI. Fisher’s exact test was used to assess differences in the number of people moving over time from CI to no CI (and vice versa) between PWH and controls. Individuals showing a significant change over time in their cognitive function, whilst accounting for practice effect, were identified by applying the MNC criteria to the differences between follow-up T-scores and those expected given baseline T-scores, socio-demographics and time between testing.
The 123 PWH and 77 controls were predominantly male (93% in both), with a median (IQR) age of 55 (50-61) and 56 (51-63) years, respectively. At baseline, the prevalence of CI was 20% in PWH and 4% in controls (p<0.001). Whilst none of the controls with CI at baseline improved to no CI at follow-up, 9/21 (43%) PWH moved from CI to no CI (p=0.50, Table). Moreover, 2% and 4% of PWH and controls without CI at baseline were classified as impaired at follow-up (p=0.70). Twelve (10%) PWH and 5 (6%) controls experienced a significant decline in cognitive function over two years (p=0.42): 6/12 (50%) PWH and 2/5 (40%) controls were classified with no CI at both baseline and follow-up; 1 (8%) PWH and 2 (40%) controls moved from not having CI to have CI.
We observed different dynamics of change in cognitive function within this cohort. A substantial proportion of PWH who were classified as having CI initially, did not meet criteria for CI after 2 years; only less than half of both PWH and controls who significantly declined, stably met the definition of CI. Linkage of these detailed cognitive phenotypes with biomarker and neuroimaging findings may assist in understanding the underlying pathogenic mechanisms and developing future targeted management approaches.