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Older age raises odds of amnestic mild cognitive impairment (but not HAND) with HIV - by 5% per year of aging
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9th International Workshop on HIV and Aging, September 13-14, 2018, New York
Mark Mascolini
Every additional year of age raised odds of amnestic mild cognitive impairment (aMCI) 5% in a study of 244 people with HIV infection [1]. But older age did not affect chances of HIV-associated neurocognitive disorder (HAND) in people without aMCI. Levels of two inflammatory markers--TNF-alpha and MCP-1--were higher in older people with aMCI.
Amnestic mild cognitive impairment (aMCI) is marked by memory loss but not more severe symptoms of Alzheimer's disease, such as personality changes [2]. People with aMCI may often lose things or forget appointments. ("Amnestic" refers to amnesia.) Cognitive and functional decline is characteristic of aMCI, while HAND is relatively stable.
Researchers from the University of California, San Diego (UCSD) and other centers conducted this study to assess the relationship between age and odds of aMCI versus HAND and to track markers of inflammation in people with aMCI.
The analysis involved 244 people in care for HIV infection in the United States. All had a viral load below 50 copies while taking antiretroviral therapy, and all completed comprehensive neurobehavioral and neuromedical evaluations. The analysis excluded people with current substance use disorder and those with low premorbid IQ. Researchers measured three inflammatory markers, TNF-alpha, MCP-1, and IL-6.
To determine which participants had aMCI, the investigators used an empirically based neuropsychological diagnostic approach adapted to distinguish HAND from aMCI by focusing on recognition memory impairment, a feature of aMCI but not HAND. They used standard Frascati criteria to classify people with HAND. This process created 3 groups: people with aMCI (aMCI+), people with HAND but without aMCI (HAND+/aMCI-), and people with neither condition (HAND-/aMCI-).
The research team used multivariable linear regression predicting inflammatory markers to examine relationships between cognitive group, age, and inflammation. Final analyses included age, sex, and comorbidities and demographic variables related to the outcome at P < 0.10.
The 244 HIV-positive participants ranged in age from 24 to 68, 86% were men, and 59% non-Hispanic white. The researchers classified 85 people (35%) as aMCI+ (78% with HAND), 66 (27%) as HAND+/aMCI-, and 93 (38%) as HAND-/aMCI-.
The group with aMCI had a higher proportion of non-Hispanic whites than the HAND+/aMCI- group (49% versus 30%, P = 0.06). Both the aMCI group and the HAND+/aMCI- group had a lower premorbid IQ than the HAND-/aMCI- group (P < 0.001). People with aMCI were slightly older than the HAND-/aMCI- group (average 50.7 versus 47.4, P = 0.06). Every additional year of age raised odds of being in the aMCI+ group 5% (odds ratio [OR] 1.05, 95% confidence interval [CI] 1.01 to 1.09, P < 0.01). The same association did not hold for HAND+/aMCI- (OR 1.02, 95% CI 0.83 to 105, P = 0.33).
Levels of the 3 inflammatory markers did not differ between the 3 cognitive groups. But a separate multivariate model assessing links between markers and cognitive group x age (under 50 or older) determined that aMCI+ people 50 or older had significantly higher TNF-alpha levels than younger aMCI+ people (beta = 0.05, P < 0.01). The same held true for MCP-1 but that association stopped short of statistical significance (P = 0.08). There was no association between age and inflammation when comparing the aMCI+ group with the HAND-/aMCI- group.
The researchers believe their findings "suggest that some inflammatory biomarkers are more strongly associated with older age in aMCI and may be a mechanism of aMCI particularly in the context of HIV." They called for longitudinal studies assessing these associations in people with versus without HIV.
References
1. Campbell L, Sundermann E, Letendre S, et al. The relationship between amnestic mild cognitive impairment and biomarkers of inflammation among adults living with HIV. 9th International Workshop on HIV and Aging, September 13-14, 2018, New York. Abstract 13.
2. National Institute on Aging. What is mild cognitive impairment? https://www.nia.nih.gov/health/what-mild-cognitive-impairment
What is Cognitive impairment ? - (09/11/18)
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