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Central Obesity Raises Neurocognitive Impairment Risk in US CHARTER Cohort
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19th Conference on Retroviruses and Opportunistic Infections, March 5-8, 2012, Seattle
Mark Mascolini
Central obesity--independently of higher body mass index (BMI) and other factors--raised the risk of neurocognitive impairment in a cross-sectional study of 130 HIV-positive people in the US CHARTER cohort [1]. The CHARTER group published these findings online shortly before the Conference on Retroviruses [2].
CHARTER, a prospective observational cohort study, aims to clarify rates of neurocognitive impairment and associated risk factors in US people with HIV. This cross-sectional analysis focused on 130 adults who gave fasting blood samples.
The investigators defined neurocognitive impairment as a global impairment rating at or above 5 on neuropsychological tests adjusted for age, education, gender, and race/ethnicity. They used two statistical models to analyze the impact of weight on neurocognition--a 90-person analysis that calculated the impact of BMI, and a 55-person analysis that figured the impact of central obesity (measured as waist circumference) and body mass index.
The study group averaged 46.2 years in age (+/- 8.9), 113 (87%) were men, and 74 (57%) were white. Most study participants (107, 82%) were currently taking antiretrovirals, and current median CD4 count stood at 501 (interquartile range 305 to 708). Fifty-two people (40%) met neurologic impairment criteria. Univariate analysis associated older age, longer HIV infection duration, obesity, and waist circumference, but not body mass index, with neurocognitive impairment.
The 90-person analysis with BMI as the only weight measure identified three factors that independently raised the risk of neurocognitive impairment: Each year of age raised the risk 6% (odds ratio [OR] 1.06, 95% confidence interval [CI] 1.01 to 1.12, P = 0.027). Each kg/m2 higher BMI raised the risk 12% (OR 1.12, 95% CI 1.01 to 1.24, P = 0.039), and self-reported diabetes made neurocognitive impairment 6 times more likely (OR 6.08, 95% CI 0.61 to 60.7, P = 0.12, not significant).
The 55-person analysis that simultaneously considered waist circumference and BMI determined that each kg/m2 of BMI lowered the risk of neurocognitive impairment about 30% (OR 0.69, 95% CI 0.49 to 0.98, P = 0.038). In this analysis each extra centimeter of waist circumference made neurocognitive impairment 34% more likely (OR 1.34, 95% CI 1.13 to 1.60, P = 0.001). Having a record of AIDS upped the risk almost 50 times (49.57, 95% CI 2.26 to 1089, P = 0.013), and self-reported diabetes tended to raise the risk (OR 17.6, 95% CI 0.76 to 409, P = 0.07, not significant). Higher triglycerides tended to lower the risk of neurocognitive impairment in this analysis (OR 0.32, 95% CI 0.09 to 1.21, P = 0.09).
The CHARTER team concluded that "of the 2 measures of obesity [BMI and waist circumference], only waist circumference, a measure of central obesity and a risk factor for insulin resistance and atherosclerosis, contributed to neurocognitive impairment."
They proposed that "the reversal of the effect of body mass index on neurocognitive impairment when waist circumference is accounted for suggests that central rather than generalized obesity conveys increased risk factor for neurocognitive impairment."
References
1. McCutchan A, Marquie-Beck J, FitzSimons C, et al. Role of central obesity, diabetes, and metabolic variables in HIV-associated neurocognitive disorder. 19th Conference on Retroviruses and Opportunistic Infections. March 5-8, 2012. Seattle. Abstract 490.
2. McCutchan JA, Marquie-Beck JA, FitzSimons CA, et al; for the CHARTER Group. Role of obesity, metabolic variables, and diabetes in HIV-associated neurocognitive disorder. Neurology 2012;78:485-492. http://www.natap.org/2012/HIV/Neurology2012McCutchan48592.pdf.
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