Neuroscientists at Georgetown University Medical Center found cognitive differences in HIV positive adults over 50 when compared to HIV negative adults, according to a new study published in the journal AIDS Care.
The researchers were studying the prevalence of HIV-associated neurological disorder (HAND) among adults over age 50. Previous studies suggested that between 30 and 60 percent of HIV-positive individuals are affected by the disorder, according to lead author on the study neuroscientist Dr. Xiong Jiang.
According to Jiang, it is generally believed that HAND is caused by the virus though there is some controvery of whether HIV treatment could be a contributing factor.
The small pilot study of nine HIV positive and five HIV negative adults over 50 was intended to develop a hypothesis, and showed that all participants scored as "cognitively normal" in standard neuroscopy testing, but brain scans showed a different picture.
Functional MRI (fMRI) scans of the participants were taken while they were performing a task where they were cued to judge the gender of a face or the meaning of a word on face-word images. The cues were unpredictable in order to judge how quickly participants were able to switch between the tasks of judging faces and judging word meanings.
The HIV positive group, according to the researchers, was significantly slower at adjusting to switching tasks. The delayed reaction time correlated with a dysfunction in one of the brain's executive regions called the dorsal anterior cingulate cortex. Damage to this region has been linked to cognitive impairments, such as apathy and executive deficits.
Both of these impairments, says Jiang, are "highly prevalent in individuals with HIV-infection." This suggests the region is commonly affected by HIV could be a target of neural therapies in the future.
“These findings, although preliminary, could have a significant implication for public health,” said Jiang in a statement, “While there is no proven treatment that can effectively treat HAND other than control HIV replication, it is important for caregivers, families and the individuals themselves to know if they are affected.”
Jiang also stated that a larger study would be conducted on a population of 160 people with the backing of a $2 million grant from the National Institute for Mental Health.
In addition the larger study would be used to further develop the fMRI-based biomarkers for HAND that could be used to guide and evaluate targed therapies.