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Over 10% in Older HIV Group Fit Alzheimer's Biomarker Risk Profile
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20th Conference on Retroviruses and Opportunistic Infections, March 3-6, 2013, Atlanta
Mark Mascolini
Slightly more than 10% of older Australian patients with well-controlled HIV infection had cerebrospinal fluid (CSF) marker profiles consistent with Alzheimer's disease--a risk prevalence more than 10 times higher than in the general population at the same age.
Lucette Cysique and colleagues in Australia and the UK noted that neurologists have yet to devise a reliable way to assess Alzheimer's risk in people with HIV, partly because no one knows how much traditional risk factors (APOE genotypes and age) plus HIV-related variables contribute to Alzheimer's risk in HIV-positive people. In an attempt to begin defining an Alzheimer's risk profile, these investigators compared biomarker profiles in three groups: 44 HIV-positive people with undetectable plasma and CSF viral load, 5 HIV-negative people with Alzheimer's, and 3 older HIV-negative controls.
Age averaged 56.7 in the HIV group, 63 in the Alzheimer's group, and 64.3 in the control group. All but 2 HIV-positive people were men, and all 8 people in the comparison groups were men. One HIV-positive person was an Asian-Pacific islander, and everyone else in the study was Caucasian. HIV-positive people had been infected for 20 years (range 5 to 25).
Everyone had standard neuropsychological testing, APOE genotyping, and lumbar puncture to assess CSF Abeta1-42, h-tau, and p-tau. Researchers who analyzed the markers did not know which group a person belonged to. The investigators used published cutoffs to define Alzheimer's risk according to three profiles:
-- Profile 1: h-tau > 350 and Abeta1-42 < 530
-- Profile 2: p-tau > 60 and Abeta1-42 < 530
-- Profile 3: h-tau > 350 and Abeta1-42/p-tau < 6.5
Five of 44 HIV-positive participants (11.4%) fit one of the three Alzheimer's risk profiles: 4.5% had profile 1, 7.4% had profile 2, 6.8% had profile 3, and 1 person met all three profile cutoffs. Everyone in the Alzheimer's comparison group fit into at least one Alzheimer's profile, while no healthy elderly controls did.
Among people with HIV, five factors tended to predict having an Alzheimer's profile: (1) APOE genotype epsilon4/epsilon4, (2) lower current neurocognitive performance (P < 0.01), (3) history of HIV-associated dementia (P < 0.01), (4) lower nadir CD4 count (average 117 versus 181, not significant at P= 0.36), and (5) longer HIV duration (average 23 versus 19 years, not significant at P = 0.32).
The researchers noted that Alzheimer's profile prevalence in these HIV-positive people exceeds by more than 10 the rate in a general population the same age [2]. They cautioned, though, that "it is not clear whether these profiles have prognostic significance when used in the HIV-positive population."
References
1. Cysique L, Lamoury J, Hewitt T, et al. Prevalence of CSF AlzheimerÕs disease-like profile in chronic middle-aged HIV+ individuals. 20th Conference on Retroviruses and Opportunistic Infections. March 3-6, 2013. Atlanta. Abstract 442. http://www.retroconference.org/2013b/PDFs/442.pdf
2. Paternico D, Galluzzi S, Drago V, et al. Cerebrospinal fluid markers for Alzheimer's disease in a cognitively healthy cohort of young and old adults. Alzheimers Dement. 2012;8:520-527.
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