IQ score could be detrimentally influenced by an individual’s HIV infection, both through neurons and the gut.
HIV infection could have a negative influence on an individual’s IQ score and gut microbiome based on differences in a patient’s neurons, according to a review published in Frontiers in Behavioral Neuroscience.
HIV infections, although efficiently suppressed through antiretroviral therapy (ART), are still spreading without a cure throughout the world. HIV is known to affect the brain, which could include cognitive, motor, and/or mood problems after being diagnosed. Given these neurological effects, this review aimed to assess how HIV could influence human intelligence interactions through measurements of IQ as well as how HIV could influence the gut microbiome.
The researchers of this review defined intelligence as the ability to learn from experience and to adapt to and mold different environments. Cognitive impairment has been linked with poor cortical development, which is delayed when an individual has HIV. HIV enters the central nervous system (CNS) soon after infection, which initiates a T-cell response that affects white matter and neurons and indirectly starts the destruction of gray matter in the brain. White matter, which includes myelin, can also be affected by HIV. Studies have found that individuals with HIV have seen a reduction of white matter, which could be associated with motor and cognitive impairment.
Although not many studies have gone over the relationship between HIV and IQ, the studies that do exist focused on children and adolescents. A study published in 2012 by Martinez et al. found children who had HIV had significantly lower IQ scores (84.6) compared with children who didn’t have HIV (91.7), which extended to the verbal sub test (81.2 vs 90.3 respectively). Children who had more advanced HIV also had worse IQ scores and measures of verbal performance.
A study conducted in 2014 by Kerr et al. found similar results, with no significant difference between uninfected children who were exposed to HIV compared with children who were not exposed and were uninfected; however, children who were exposed had lower overall scores (90.3 vs 94.5). Children who were infected with HIV perinatally were found to have significantly lower mean (SD) IQ compared with controls (81  vs 97 ) in a study published in 2019. Therefore, the researchers concluded that HIV may affect the brain in ways that have not yet been fully uncovered or understood.
The CNS and the gastrointestinal tract (GI) communicate both ways through the body, referred to as the gut-brain axis, which calls the relationship between the gut and IQ into question. Patients who have HIV have higher levels of HIV DNA in the gut rather than in the blood, according to 2 studies published in 2008 and 2013. Researchers also believe that the gut is the primary location for HIV replication. HIV infection, therefore, could modulate the gut microbiome. This can cause structural damage, impairment of immunological function, and long-term immune activation.
Microbial communities and metabolites are modified in patients with HIV compared with those without. This includes the reduction of beneficial bacteria, such as those that can produce serotonin, essential to brain development and functioning. Gut integrity is also compromised in patients with HIV, with the depletion of immune cells and reduction of beneficial bacteria. This can lead to gastrointestinal dysfunction.
The researchers concluded that recent evidence supported the idea that HIV infection could negatively influence an individual’s IQ score. This can be a result of both neurons and the gut microbiome can influence the development of the brain. The researchers recommend future studies in cognitive functioning in relation to HIV infection.
Zaongo SD, Harypursat V, Rashid F, Dahourou DL, Ouedraogo AS, Chen Y. Influence of HIV infection on cognition and overall intelligence in HIV-infected individuals: advances and perspectives. Front Behav Neurosci. Published online October 26, 2023. doi:10.3389/fnbeh.2023.1261784