Reassurance that patients with good CD4 cell counts not at risk of HIV-related brain impairment

HIV-positive patients with a good CD4 cell count do not have an increased risk of developing neurocognitive impairment, a study published in the online edition of the Journal of Acquired Immune Deficiency Syndromes suggests. All the patients in the study had a CD4 cell count above 350 cells/mm³ and the majority had been infected with HIV for over five years. The only characteristic that was associated with an increased risk of impairment was older age.

“Our patients do not have a higher risk of HIV-associated dementia”, emphasise the investigators, who were from three HIV treatment centres in Buenos Aires.

Cognitive impairment is common in patients with HIV, with the range of disorders associated with it ranging from the asymptomatic to HIV-associated dementia.

Earlier research has identified that 20% of patients with early HIV infection had asymptomatic impairment, with the prevalence increasing to approximately 80% in older patients with AIDS.

Cognitive impairment can be associated with worse outcomes in HIV-positive patients, therefore its diagnosis in patients in the early stages of HIV infection is important. Furthermore, research has suggested that although the prevalence of HIV-associated dementia has fallen dramatically since effective HIV treatment became available, a small number of patients still develop the condition and the CD4 cell count at which the disease is diagnosed is increasing.

Patients with HIV-associated brain impairment can be easily and accurately diagnosed using the International HIV Dementia Scale. This test has several advantages as it does not need any special equipment, can be performed by doctors in outpatient clinics, and only takes a few minutes to complete. A score below ten is suggestive of dementia.

Investigators in Buenos Aires hypothesised that HIV-positive patients with a reasonably intact immune system could still be at risk of developing cognitive impairment, especially if they were not taking HIV treatment as ongoing HIV replication in the brain may be damaging.

They therefore undertook a study involving 260 patients with a CD4 cell count above 350 cells/mm³. These individuals had their cognitive function assessed using the International HIV Dementia Scale.

Two-thirds of the patients had been diagnosed with HIV for over five years.

The mean age of the patients was 38 years (range, 21 to 73 years), and 158 were taking antiretroviral therapy. Median viral load was below 50 copies/ml in the patients receiving antiretroviral therapy and 21,000 copies/ml in the treatment-naïve individuals.

Overall, the mean International HIV Dementia Scale score was 10.9. The investigators examined the connection between age, sex, education, duration of HIV infection, current CD4 cell count, nadir CD4 cell count, and current viral load.

Only age was found to be associated with performance in the tests. Patients aged under 44 years had significantly higher mean score than those aged over this age (11.1 vs. 10.2, p < 0.001).

A total of 83 patients were taking efavirenz (Sustiva, also in the combination pill Atripla). This drug has been associated with neuropsychiatric side-effects, but the investigators found that these patients had comparable scores to patients taking other anti-HIV drugs.

Furthermore, International HIV Dementia Scale scores were comparable in the patients taking HIV treatment and those who were treatment naïve (11 vs. 10.8).

Lowest ever CD4 cell count was approximately 250 cells/mm³ amongst the patients taking HIV treatment and 500 cells/mm³ in the treatment-naïve individuals. No relationship was found between nadir CD4 cell count and test scores.

Finally, the investigators undertook statistical analysis to identify risk factors significantly associated with an International HIV Dementia Scale score below ten. The only factor they identified was age above 45 years (odds ratio, 3.5; 95% CI: 1.36-8.99. p < 0.01).

“Patients with preserved immune status do not seem to be at a high risk of developing clinically significant neurocognite impairment measured by [the] International HIV Dementia Scale”, conclude the researchers.