Neurocognition Affected More by Ethnicity Than HIV Factors

Daniel M. Keller, PhD

October 28, 2011

October 28, 2011 (Belgrade, Serbia) — In a large group of effectively treated patients infected with HIV, neurocognitive function test results were associated with ethnicity but not HIV disease-related factors.

The measured rates of impairment may partly be the result of limitations in the normative data on which the tests were based, Alan Winston, MD, consultant physician and senior lecturer in HIV and genitourinary medicine at the Imperial College Healthcare NHS Trust and Imperial College London, United Kingdom, reported here at the 13th European AIDS Conference (EACS).

As part of the large, multicenter, United Kingdom–based Protease Inhibitor monotherapy Versus Ongoing Triple-therapy in the long-term management of HIV infection (PIVOT) trial, investigators assessed neurocognitive function and associated factors in this cohort. The assessments comprised 5 domains: attention, executive function, verbal learning, verbal memory, and fine motor function. Raw scores for each test were transformed into z-scores as a measure of performance in terms of standard deviations (SDs) from a normative mean (age-matched for all tests and education-matched for the attention and executive function tests).

The cohort consisted of 560 evaluable patients (68% white, 28% black; 77% male; mean age, 44 years). Baseline CD4 cell counts were similar for the 2 ethnicities at 554 cells/μL for the cohort overall. Both had an undetectable viral load for 4 years and had an average of 15 years of education.

Dr. Winston said that by using standard normative data (derived mainly from people in the United States and Canada), one would expect 84% of a control population to be within or above the normal range and 16% to be more than 1 SD below the mean for neurocognitive function. Test results for the population of HIV-infected patients overall showed that 31% had neurocognitive function more than 1 SD below the mean (95% confidence interval [CI], -1.2 to 0.0). For whites, 17% scored more than 1 SD below the mean (95% CI, -0.7 to 0.1), but 66% of blacks performed at this level (95% CI, -2.0 to -0.8; P < .001 for whites vs blacks).

When neurocognitive function scores were calculated by using race-adjusted general population normative data, 55% of blacks scored at least 1 SD below the mean compared with 38% of whites.

Multivariate analysis revealed that black race was associated with a risk for low neurocognitive function scores (95% CI, -1.28 to 0.92; P < .001). "For future work in this area, it's essential that we have control data to accurately assess the cognitive function and the diverse European HIV-infected populations," Dr. Winston said.

The multivariate analysis showed that for whites, hepatitis C and a history of nevirapine use predicted low neurocognitive scores (P < .045 and P < .019, respectively). For blacks, smoking was associated with better neurocognitive function (P < .021).

Nadir CD4 cell count was not an independent predictor of neurocognitive impairment for either ethnicity, "which may have been related to the long length of antiretroviral therapy and [viral load] being undetectable," Dr. Winston surmised.

Except for nevirapine, Dr. Winston's findings showed that the specific antiretroviral therapy was not associated with neurocognitive performance. Marta Boffito, MD, PhD, consultant physician at Chelsea Westminster Hospital in London, who was not involved in the study, commented to Medscape Medical News, "We need more data about the normal population to understand what's happening in the HIV-infected population, especially because he showed that there was no impact of different antiretrovirals."

She said it is still early to make sense of this result, "[but] it's a very important finding, I believe...showing that it doesn't matter what antiretroviral you're taking, you may have or you may not have any neurocognitive impairment. Nevirapine was the only difference, but as Dr. Winston said during his presentation, nevirapine might have been chosen for a population with baseline depression or mild neurocognitive impairment already, so it might have been a selected population that took nevirapine."

The study received no commercial funding. Dr. Winston reported receiving honoraria or research grants or has been a consultant or investigator in clinical trials sponsored by Abbott, Boehringer Ingelheim, Bristol-Myers Squibb, Gilead Sciences, GlaxoSmithKline, Janssen Cilag, Roche, Pfizer, and ViiV Healthcare. Dr. Boffito has disclosed no relevant financial relationships.

13th European AIDS Conference (EACS); Abstract # PS2/4. Presented October 13, 2011.

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