Can nicotine improve cognitive function and inflammation in people with HIV?

By Priyanjana Pramanik, MSc.Reviewed by Lily Ramsey, LLMJan 3 2025

Nicotine's paradox: Study uncovers potential cognitive benefits of smoking for HIV-positive individuals amid neuroinflammatory challenges.

​​​​​​​Study: Cigarette smoking is associated with reduced neuroinflammation and better cognitive control in people living with HIV. Image Credit: Danijela Maksimovic/Shutterstock.com

In a recent article published in Neuropsychopharmacology, researchers investigated the combined impacts of smoking cigarettes and having human immunovirus (HIV) infection on cognitive control and neuroinflammation.

Their findings indicate that HIV-positive individuals who smoke may demonstrate improved cognitive control and show lower inflammation levels than those who do not, highlighting the potential of nicotine to enhance neurocognitive outcomes in this population.

Background

Advances in antiretroviral therapy (ART) have transformed HIV from a fatal disease to a manageable chronic condition. However, people living with HIV (PLWH) often face complications like chronic brain inflammation and cognitive issues, such as difficulty focusing or managing goals.

These challenges are linked to poor cognitive control and neuroinflammation. Smoking rates are significantly higher among PLWH, and nicotine, the main ingredient in tobacco has been found to reduce inflammation and improve cognitive performance.

Previous evidence shows that PLWH individuals generally have higher neuroinflammation levels, which correlate with poorer cognitive performance. Interestingly, smoking has been shown to reduce neuroinflammation in non-HIV individuals and improve attention in both humans and animals.

About the study

This study built on previous research by focusing on PLWH smokers who smoked just before testing, minimizing withdrawal effects. Their findings could provide insight into how nicotine impacts neuroinflammation and cognitive function, highlighting potential avenues for treatments targeting brain-related complications in PLWH.

Researchers investigated how smoking impacts brain inflammation and cognitive control in PLWH individuals, hypothesizing that PLWH who smoke would show lower levels of neuroinflammation across the brain and better cognitive control, assessed using the 5-choice continuous performance test (5C-CPT), compared to PLWH who do not smoke.

Additionally, the study explored whether these effects of smoking on neuroinflammation were consistent across individuals without HIV. The hypothesized order for brain inflammation levels and cognitive control performance, from lowest to highest and best to worst, respectively, was as follows: individuals without HIV who smoke, individuals without HIV who do not smoke, PLWH who smoke, and PLWH who do not smoke.

The sample comprised 59 adults, of whom 16 did not have HIV and did not smoke, 14 who did not have HIV and smoked, 18 PLWH who did not smoke, and 11 PLWH who smoked. Cognitive testing included the measurement of reaction times and accuracy during tasks that required participants to identify and respond to visual stimuli.

The neuroinflammation assessment included measuring the uptake of a protein marker for neuroinflammation called the translocator protein (TSPO) throughout the brain, along with structural brain scans to localize which areas of the brain would be included in additional analysis.

Participants also provided information about their nicotine dependence, smoking history, and mood. Their medical history included details related to HIV, including immune system health and viral load. Researchers confirmed smoking status through urinary and breath cotinine assessments.

The study used statistical tests to compare neuroinflammation and cognitive control metrics across the four groups. Analyses examined both whole-brain and specific brain regions to identify potential differences. Additional tests explored relationships between smoking intensity, HIV-related factors, and brain outcomes.

Findings

At the beginning of the study, the four groups were similar across health and demographic characteristics, including TSPO, education, sex, and age.

Smoking behavior, measured by dependence on nicotine and the number of cigarettes smoked daily, was comparable between PLWH and those without HIV. Among PLWH, the smoking and non-smoking groups differed only in HIV duration, which was adjusted for in the analysis.

Researchers found that smoking significantly reduced brain inflammation, while HIV showed a trend toward increasing it. However, no significant differences were observed between HIV smokers and non-smokers.

Smoking was also associated with better cognitive performance in PLWH, with those who smoked performing better on measures of task accuracy than those who did not. Improved performance in smokers was linked to better target detection (hit rate), with no effect on response inhibition (false alarms).

Lower brain inflammation in PLWH individuals who smoked was correlated with better cognitive performance, indicating the role of reduced neuroinflammation in improved cognition.

Conclusions

This study explored the relationship between cigarette smoking, neuroinflammation, and cognitive control in PLWH individuals. Findings revealed that PLWH who smoke exhibited lower levels of neuroinflammation and better cognitive control compared to non-smoking PLWH.

These results align with prior research suggesting that chronic HIV-related neuroinflammation contributes to cognitive impairment. Smoking appears to enhance cognitive control by improving target detection during challenging tasks, potentially through nicotine’s anti-inflammatory effects.

However, the harmful effects of smoking far outweigh any potential benefits, and the results should not be interpreted as a justification for smoking. The study also found an association between severe HIV infection and higher neuroinflammation.

Despite limitations such as sample size and the use of a cross-sectional design, the findings suggest that nicotine's effects on neuroinflammation may offer therapeutic potential for cognitive impairments in PLWH, warranting further investigation.