There may be an association between lower brain volume in the hippocampus and thalamus and decreased white blood cell count in patients with HIV who receive antiretroviral therapy, according to study results published in JAMA Network Open.

This cross-sectional study examined data on 1203 adult patients with HIV (mean age, 45.7 years) from 13 studies across Africa, Asia, Australia, Europe, and North America. A team of researchers extracted regional and whole brain segmentations from data sets as studies joined the HIV Working Group within the Enhancing Neuro Imaging Genetics through Meta Analysis (ENIGMA) consortium on a rolling basis. They conducted extractions between 2014 and 2019.

Specifically, the study researchers extracted volume estimates for 8 subcortical brain regions from T1-weighted magnetic resonance images to evaluate associations with blood plasma markers indicative of immunosuppression or detectable plasma viral load (dVL).

Results indicated a significant association between lower current CD4+ cell counts and smaller hippocampal volume (mean β=16.66mm3 per 100 cells/mm3; P <.001) and thalamic (mean β=32.24 mm3 per 100 cells/mm3; P <.001) volumes. In addition, lower current CD4+ cell counts were associated with larger ventricles (mean β=-391.50 mm3 per 100 cells/mm3; P =.001).

Lower current CD4+ cell counts in patients not taking combination antiretroviral therapy (cART) were associated with significantly smaller putamen volumes (mean β=57.34 mm3 per 100 cells/mm3; P =.003). Also, the study researchers noticed that dVL correlated with smaller hippocampal volumes (P =.005). Among patients taking cART, dVL correlated with smaller amygdala volumes (P =.004).

Limitations of this study were the inclusion of only patients positive for HIV infection and the lack of seronegative controls.

Study researchers added that further investigation into the neurologic signatures of HIV infection could improve understanding of “the neurobiological changes that may contribute to neuropsychiatric and cognitive outcomes in HIV-positive individuals.” Ultimately, this understanding will be “critical for identifying individuals at risk for neurologic symptoms, driving novel treatments that may protect the CNS, and monitoring treatment response.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

Reference

Nir TM, Fouche JP, Ananworanich J, et al. Association of immunosuppression and viral load with subcortical brain volume in an international sample of people living with HIV. JAMA Netw Open. Published online January 15, 2021. doi:10.1001/jamanetworkopen.2020.31190



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