- Category: Neurocognitive Problems
- Published on Wednesday, 21 August 2013 00:00
- Written by Liz Highleyman
HIV positive people who recently engaged in physical exercise were about half as likely to show signs of neurocognitive impairment -- including impaired working memory and slower information processing -- as those who did not, according to a study published in the August 10, 2013, advance edition of the Journal of Neurovirology.
While effective antiretroviral therapy (ART) has dramatically reduced the risk of AIDS dementia, less severe neurocognitive impairment remains common, affecting approximately half of all people with HIV. A growing body of evidence suggests that ongoing immune activation, inflammation, and metabolic changes associated with persistent HIV infection and its treatment contribute to this an a host of other chronic non-AIDS conditions in an aging population.
Catherine Dufourand David Moore from the University of California at San Diego and colleagues investigated the link between physical exercise and neurocognitive tests results in a study of 335 "community-dwelling" (not in a hospital or other institutional facility) people with HIV.
Randomized trials have shown that exercise is associated with improved neurocognitive performance in HIV negative people, but this has not been studied extensively in people with HIV, the authors noted as background.
Participants were divided into 2 groups based on whether they self-reported engaging in any physical activity that increased their heart rate within the past 72 hours. They completed a comprehensive battery of tests designed to measure both global neurocognitive impairment and impairment in 7 specific domains (verbal fluency, working memory, information processing speed, learning, recall, executive function, and motor function).
The researchers also looked at potential confounding factors including demographics, HIV disease status, CD4 cell count, substance use, education, psychiatric comorbidities such as depression, and physical functioning.
- 83 participants reported recent exercise, while 252 did not.
- The exercise group had a significantly lower rate of global neurocognitive impairment compared with the no exercise group (15.7% vs 31.0%, respectively).
- In a multivariable analysis controlling for potential confounders, exercise remained significantly associated with less global neurocognitive impairment (odds ratio 2.63).
- Exercise was also associated with significantly less impairment in specific domains including working memory and information processing speed.
Based on these results, the study authors concluded, "The present findings suggest that HIV-infected adults who exercise are approximately half as likely to show [neurocognitive impairment] as compared to those who do not."
"Future longitudinal studies might be best suited to address causality, and intervention trials in HIV-infected individuals will determine whether exercise can prevent or ameliorate [neurocognitive impairment] in this population," they added. "[A]dditional research is needed to determine the intensity and frequency of exercise needed to achieve the best neurocognitive outcomes."
"The major benefit of exercise to the brain may be reduced neurocognitive risk factors, such as high blood pressure and hyperlipidemia," they explained in their discussion. "Metabolic syndrome associated with ART use is also associated with increased risk for developing diabetes, hypertension, obesity, and dyslipidemia...[O]ur findings are consistent with the notion of cerebrovascular disease as a possible mechanism underlying the association between exercise and neurocognition...Studies have also shown that exercise reduces oxidative stress and inflammatory markers, and increases neurogenesis, angiogenesis, and synaptogenesis [formation of neurons, supportive blood supply, and synapses] in the brain."
As a caveat, they noted that their results show a correlation but not the direction of causality: an alterative interpretation could be that poorer neurocognitive functioning is a barrier to exercise, or the relationship may be bi-directional.
"Exercise as a modifiable lifestyle behavior may reduce or potentially prevent neurocognitive impairment in HIV-infected persons," Moore said in a press release issued by journal publisher Springer. "Physical exercise, together with other modifiable lifestyle factors such as education, social engagement, cognitive stimulation and diet could be fruitful interventions to support people living with HIV."
CA Dufour, MJ Marquine, PL Fazeli, DJ Moore, et al. Physical exercise is associated with less neurocognitive impairment among HIV-infected adults. Journal of Neurovirology. August 10, 2013 (Epub ahead of print).
Springer. Exercise Helps with Better Brain Functioning in HIV-infected Adults. Press release. August 13, 2013.