Numerous studies show that exercise benefits memory and some show that acute exercise prior to encoding has larger benefits than exercise after encoding. This study was designed to investigate the effects of acute exercise on memory in middle-aged and older adults (Mage = 64.71 years) and to explore the influence of the timing of the exercise on these effects. Using a within-subjects design, moderate-intensity exercise (20 min) was either not performed (control), performed before the task (exercise prior), or performed after the task (exercise post). Memory was assessed using the Rey Auditory Learning Verbal Test. For short- and long-term memory and learning, significantly more words were remembered in the exercise-prior condition than the others. For 24-hr recall, participants remembered significantly more words in the exercise-prior condition than exercise post, which was better than control. Exercise benefits memory for healthy middle-aged and older adults, with the greatest benefits when performed prior to encoding.
BackgroundThinning of the posterior cingulate cortex (PCC) is implicated in Alzheimer’s disease (AD). Though some evidence suggests ApolipoproteinE (APOE) ε4 carriers (ε4+) have thinner PCCs than non‐carriers (ε4‐), the evidence is conflicting and lacks association with learning outcomes relevant to AD.MethodA subset from an ongoing clinical trial (NIH/NIA: R01AG058919) was used for analyses and included 26 ε4+ (73% female, Agemean=55.81±5.53) and 42 ε4‐ (88% female, Agemean= 57.54±5.10), who were all cognitively normal, sedentary, and had a family history of AD. Genetic sampling was completed via passive drool. Structural MRI was completed to assess PCC cortical thickness, and the Rey Auditory Verbal Learning Task (AVLT) was used to assess learning. Brain segmentation was completed with Freesurfer’s automated pipeline, and left and right PCC cortical thickness was extracted for analysis. A learning over trials (LOT) composite score from the AVLT was calculated to represent learning. An analysis of covariance was completed to assess the effect of carrier status on left/right PCC thickness, controlling for age and sex. Linear regressions were completed to assess main effects and interaction of carrier status and left/right PCC thickness in predicting LOT when controlling for age and sex.Resultε4+ had less cortical thickness in the left PCC (F(1,64)=5.07, p=.03), but not the right PCC (p=.33), relative to ε4‐. Carrier status predicted LOT (Left: F(1,62)=10.37, p<.01; Right: F(1,62)=10.66, p<.01), however this was superseded by significant interactions between carrier status and PCC thickness predicting LOT (Left: F(1,62)=10.72, p<.01; Right: F(1, 62)=11.10, p<.01), with post‐hoc analyses demonstrating PCC thickness predicts LOT for ε4+ (Left:β=‐21.07, p=.04; Right:β=‐24.33, p<.01), but not ε4‐ (p’s>.09).ConclusionIn cognitively normal sedentary adults with a family history of AD, carrying the APOE ε4 allele was associated with a thinner left PCC. Further, thinner bilateral PCCs in ε4+ were associated with greater learning during the AVLT task. This suggests that ε4+ may have compensatory neural pathways to account for losses in the PCC, which temporarily bolster learning to delay the onset of AD. However, additional research is needed to continue understanding the neural mechanisms affected by carrying the APOE ε4 allele.
BackgroundThe Apolipoprotein E (APOE) ε4 allele has been identified as a critical genetic risk factor for developing Alzheimer’s disease. Heart rate variability (HRV) metrics are non‐invasive indicators of autonomic nervous system function associated with cognitive performance in patients with dementia and mild cognitive impairment. Some evidence suggests reduced HRV complexity in elderly adults carrying the ε4 allele beyond the effects of aging. However, no study has evaluated whether cognitively normal middle‐aged adults differ in their HRV based on their APOE carrier status.MethodThe present cross‐sectional analysis was based on the larger Physical Activity and Alzheimer’s Disease 2 clinical trial (NIH: R01AG058919). Eighty‐six cognitively normal middle‐aged adults (sex: 85.9% female; age: 57.5±5.9 years; height: 166.5±8.8 cm; mass: 78.3±18.8 kg) had height, mass, and resting blood pressure assessed and completed a series of surveys. Participants provided a saliva sample via passive drool to determine APOE ε4 carrier status and also completed a 5‐minute seated electrocardiogram assessment. R‐waves were identified, and the RR interval time series were filtered prior to HRV analysis. HRV metrics of the standard deviation of the normal‐to‐normal interval, root mean square of successive differences, high and low‐frequency power, and sample entropy were calculated. Differences in HRV metrics between ε4 carriers (n = 32) and non‐carriers (n = 54) were tested via general linear models. Differences were also tested after controlling for sex, age, education, ethnicity, body mass index, moderate to vigorous physical activity, and mean arterial pressure.ResultNo differences in any HRV metric were observed between APOE ε4 carriers and non‐carriers (all p’s > 0.05), including after controlling for all and sets of covariates.ConclusionThe absence of significant associations between carrier status and HRV in cognitively normal adults suggests that HRV is not predictive of Alzheimer’s disease risk in the same manner as genetic factors. Rather, HRV may be concurrently altered with cognitive decline and thus serve as a non‐invasive biomarker that could be monitored to indicate when more intensive cognitive testing is required. Future research should test the similarity in HRV and cognition trajectories in APOE ε4 carriers and non‐carriers.
Little is known about whether physical activity and fitness could enhance cognition in adolescents and young adults living with HIV. The purpose of this study was to examine this relationship in a group of 250 HIV+ (n = 88) and HIV negative (n = 162) participants from Botswana, aged 12–23 years (Mean = 17.87, SD = 2.24). Fitness was operationalized as muscular strength (push-ups) and aerobic endurance (PACER). PA was assessed using items from the Youth Risk Behavior Surveillance Survey. Cognition was measured using the Corsi Test, Berg Card Sorting Task (BCST), and Stroop Color Word Task (Stroop). Multiple regression analyses indicated that the HIV x push-ups interaction was a significant predictor of Corsi performance, and HIV status was a significant predictor of BCST performance (p < 0.05). For the Stroop portions, HIV status and HIV x push-ups were significant predictors (p < 0.01). HIV status is predictive of cognition and interacts with muscular fitness to predict cognition.
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