Research Spotlights June 2017

Research Spotlights June 2017

High-fat diet-induced cognitive deficits reversible by low-fat diet in Alzheimer’s mouse model

Obesity-induced declines in cognitive function, neuroinflammation, and glucose homeostasis appear to be partially reversed by a low-fat diet in mice with and without mutant copies of genes for Alzheimer’s disease.  This study, funded by NIDDK, NIA, and NIDCD, provides insights into the role of high-fat diets in Alzheimer’s disease pathogenesis and suggests that dietary modifications can improve neural health and cognition.

Transgenic APP/PSEN1 mice and wild-type littermates were fed either a high-fat or a low-fat diet for 7.5 months, after which a subset of high-fat diet-fed mice were switched to the low-fat diet.  Before and after the diet switch, mice were given a battery of behavioral tests, measuring locomotor activity, nest building, and performance on a two-trial Y-maze test which blocked access to one arm during the first trial, removed the blockade, then assessed exploration in all three maze arms. Mice without cognitive impairments typically spend more time in the previously blocked arm.

A high-fat diet reduced activity and exacerbated genetic impairments in nest building and Y-maze performance.  Switching to a low-fat diet led to weight loss, restored glucose tolerance, reduced inflammation, and reversed behavioral deficits, suggesting that dietary modification may be a viable strategy for combatting dementia.

Walker JM, Dixit S, Saulsberry AC, May JM, Harrison FE. 2017. Reversal of high fat diet-induced obesity improves glucose tolerance, inflammatory response, β-amyloid accumulation and cognitive decline in the APP/PSEN1 mouse model of Alzheimer's disease. Neurobiol Dis 100: 87-98.

Social support as a protective factor for HIV viral load suppression

Social support may have a protective effect on viral load suppression in sexually active HIV-positive men who have sex with men (MSM), according to a new study by grantees funded by NIAID, NCI, NIDA, NIMH, and NIDCD.

The study included over 700 sexually active HIV-positive MSM on antiretroviral therapy who were enrolled in the Multicenter AIDS Cohort Study (MACS) between 2002 and 2009.  MACS participants were invited to complete behavioral and medical questionnaires, blood draws, and physical examinations every six months.  Social support was measured by a one-item question which was found to have high reliability within the sample.  The study also included measures of viral load, antiretroviral adherence, and syndemic indicators (i.e., depression, polysubstance use, and unprotected intercourse).

Results revealed that MSM with medium or high social support had lower viral loads compared to MSM with low social support. Social support was lower in Black and Hispanic MSM and among those with greater syndemic indicators.  More importantly, social support was found to moderate the relationship between viral load and syndemic indicators.

These findings will be helpful for shaping future efforts to increase social support in HIV-positive MSM.  In particular, the authors indicate social support interventions may have the highest impact in men of color and those with higher psychosocial burden.

Friedman MR, Coulter RW, Silvestre AJ, Stall R, Teplin L, Shoptaw S, Surkan PJ, Plankey MW. 2017. Someone to count on: social support as an effect modifier of viral load suppression in a prospective cohort study. AIDS Care 29(4): 469-480.

Preference for oral fluid rapid HIV self-testing among social media-using high risk males

A new study, funded by NINR, revealed that despite availability and perceived advantages of oral fluid rapid HIV self-testing, previous use and future intention to use this test were low compared to other testing options in HIV-uninfected young men who have sex with men (MSM).

Researchers recruited 1975 young MSM from a variety of social media platforms including Facebook and Reddit.  Eligible participants completed an online survey about their opinions, willingness, and preferences for using oral fluid rapid HIV self-testing as well as five other HIV testing options.

The researchers found that young MSM viewed oral fluid rapid self-testing positively, with high proportions indicating that they believed the test offered the most privacy in testing and obtaining test results, caused the least HIV test anxiety, and was the least embarrassing test to obtain.  However, most participants preferred other HIV testing options, specifically medical facility-based testing, reporting greater trust in test results and lower cost compared to oral fluid rapid self-testing.

The study’s findings provide insights into HIV testing preferences in a high risk population of young MSM.  The authors suggest that positive aspects of oral fluid rapid HIV self-testing could be leveraged in interventions to increase use in this population.

Merchant RC, Clark MA, Liu T, Rosenberger JG, Romanoff J, Bauermeister J, Mayer KH. 2017. Preferences for oral fluid rapid HIV self-testing among social media-using young black, Hispanic, and white men-who-have-sex-with-men (YMSM): implications for future interventions. Public Health 145:7-19.

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