Neurocognitive impairment

Milder neurocognitive impairment has been detected in a number of studies of HIV-positive people receiving antiretroviral therapy.

The CHARTER study examined neurological status in 1555 people with HIV in the United States from 2002, and found that 10% had moderate impairment of neurocognitive function, manifesting at the level of lack of concentration, mild memory loss and difficulties in carrying out complex tasks. Brain impairment was strongly correlated with nadir CD4 count and current viral load.1

A second US study, ALLRT, looked at neurological status in 1160 HIV-positive adults who had received an average of 20 weeks of antiretroviral treatment. This stidy found that 39% exhibited mild impairment at baseline, but after 48 weeks 44% of those who had previously shown impairment had normal function. On the other hand 21% of those who had normal function at baseline displayed signs of impairment after 48 weeks.2

One interpretation of this finding is that brain impairment is mildly progressive, even in people receiving HAART. An alternative interpretation is that brain function is prone to fluctuate, and that much longer studies are needed in order to chart changes in people with HIV accurately.

Performance in the tests used in these studies may also be affected by hepatitis C infection, depression, alcohol and substance abuse, stress and sleep disorders, all highly prevalent in people living with HIV.

There is also evidence from several studies that HIV-negative gay men are more likely to display neurocognitive impairment than the general population.3 4 A recent UK study, for example, found that even among HIV-negative men with no history of hepatitis, alcohol abuse, recreational drug use or sigificant psychological problems, the rate of neurocognitive impairment was three times the level expected in men of their age. Although the study showed a trend towards more frequent impairment in HIV-positive men compared to HIV-negative men, this trend did not reach significance.5 

References

  1. Heaton R et al. HIV-associated neurocognitive impairment remains prevalent in the era of combination ART: the CHARTER study. 16th Conference on Retroviruses and Opportunistic Infections, Montreal, abstract 154, 2009
  2. Robertson KR et al. The prevalence and incidence of neurocognitive impairment in the HAART era. AIDS 21(14): 1915-1921, 2007
  3. Grant I et al. Evidence for early central nervous system involvement in the acquired immunodeficiency syndrome (AIDS) and other human immunodeficiency virus (HIV) infections. Studies with neuropsychologic testing and magnetic resonance imaging. Ann Intern Med. 107(6):828-36, 1987
  4. Heaton RK et al. The HNRC 500-neuropsychology of HIV infection at different disease stages. HIV Neurobehavioral Research Center. J Int Neuropsychol Soc 1(3):231-51, 1995
  5. Towgood K et al. Cognitive function and brain grey matter change in HIV-1 younger and older positive 'men who have sex with men' in the post-HAART era. Fifteenth BHIVA Conference, Liverpool, oral presentation O27, 2009