Over 50s with HIV at increased risk of cognitive impairment, even with HAART

Preliminary data from an ongoing study into the impact of aging on cognitive function in older HAART-treated HIV-positive individuals suggests that patients aged over 50 are more likely to have abnormal cognitive function than those under 40. The study is published, along with several others, in the journal AIDS, in a special supplement devoted to HIV and aging.

Figures from the US government suggest that approximately 10% of HIV-positive patients in the USA are over 50 years of age. Large populations of older HIV-positive patients are present in Florida and Hawaii, where in 2001 20% of all AIDS diagnoses involved individuals aged over 50.

Two distinct forms of cognitive impairment can be associated with HIV infection: minor cognitive motor disorder, and HIV-associated dementia. Before the advent of HAART, approximately 15% of individuals with AIDS had HIV-associated dementia and a further 5% experienced minor cognitive motor disorder. Although the incidence of both these disorders declined with the advent of HAART, there have been reports that, as HIV-positive individuals live longer, the overall prevalence of the disorders has increased. Indeed, during post-mortem examinations, HIV encephalopathy has been found in a quarter of all HIV-positive patients dying and undergoing autopsy.

Data from the US Centers for Disease Control suggest that the incidence of HIV-associated dementia increases with age and is present in a little under 20% of all HIV-positive patients aged over 75.

To gather definitive data on the incidence and prevalence of cognitive disorders in older HIV-positive individuals, a prospective cohort was established in 2001 in a collaboration between the University of Hawaii and John Hopkins University.

The specific aim of the cohort is to characterise cognitive function in HIV-positive patients aged over 50 compared to younger HIV patients (aged 20 – 40).

Preliminary data, gathered from the first 47 older and 32 younger patients enrolled to the cohort, indicates that older patients are statistically less likely than younger individuals to have normal cognitive function. The investigators found that although 88% of HIV-positive patients aged under 40 had normal or equivocal cognitive function, only 56% of HIV-positive individuals over 50 met this criteria (p=0.006).

The investigators believe that the increased prevalence of cognitive problems in older HIV-positive patients could be attributed to a number of causes, including a synergistic relationship between HIV-associated dementia and other dementias, vascular disease, which can be a complication of anti-HIV therapy, immune dysfunction in older age, and changes in neural response that can be associated with both aging and HIV infection.

A synergistic relationship between HIV infection and aging is stressed by the investigators, who note that "whereas immune function probably plays a pivotal role in the pathogenesis of neurocognitive dysfunction, other factors, including co-morbid neurodegenerative disorders, vascular pathology and astrocytic function, may also contribute…one might expect the aging brain to be at increased risk of injury [from] HIV."

Several other studies, published in the same supplement, report similar findings.

Investigators from the University of Pittsburgh found an increased risk of cognitive impairment in HIV-positive individuals aged over 50. Dementia was present in 22% of HIV-positive patients over 50 at study baseline and 9% of HIV-positive individuals under 50 at the same study point (p=0.036).

A history of alcohol or drug abuse/dependence significantly increased the risk of dementia (risk ratio 5.81).

The annual incidence of dementia was 7% in the over-50s and 4% in the under-50s. This difference was not statistically significant, but the investigators did find that individuals developing brain impairment had higher baseline HIV viral loads (p=0.035).

Despite having lower HIV viral loads in plasma and cerebrospinal fluid, HIV-positive patients aged 50 and above had a higher burden of neuropsychological impairment, in a study conducted by the University of California, San Diego.

This cross-sectional observational study recruited 67 HIV-positive patients aged over 50, and 52 HIV-positive patients aged under 35. Both groups of patients underwent neuropsychological assessment and had CD4 cell counts and their plasma and CSF viral loads measured. HIV treatment histories were also obtained.

Mean CD4 cell counts were comparable (280 cells/mm3 for the over 50s versus 265 cells/mm³ under 35s), but mean plasma viral load (3.40 log versus 4.17 log) and CSF viral load (2.04 log versus 2.60 log) was lower in the older patients, who were more likely to be taking HAART (60% versus 52%). However, 64% of older patients were assessed as impaired against 54% of the under 35s.

Multivariate analysis revealed that both viral load and age were significant predictors of impairment, and that there was a considerable interaction between viral load and age (p

Data from over 1,000 HIV-positive US veterans revealed that older individuals (again, aged 50 and above) had a higher incidence of depression and drug or alcohol problems than did age-matched HIV-negative controls. Indeed, the investigators from the US Department of Veterans’ Affairs found that whereas the incidence of depression and alcohol and drug problems declined in older HIV-negative individuals (p>0.05), it increased in those infected with HIV (p

Further information on this website

HIV associated dementia - overview

Dementia - factsheet

AIDS patients surviving longer with dementia since HAART in Australia, but prevalence up - news story