Inter-Individual Differences in Exercise Responses in Alzheimer’s Disease

Abstract Aerobic exercise is widely supported as a disease-modifying treatment for Alzheimer’s disease (AD) in animal models; however, its effects on cognition have been mixed in human studies, which may be attributable to inter-individual differences in aerobic fitness and cognitive responses to aerobic exercise. This study evaluated inter-individual differences in aerobic fitness and cognitive responses to 6-month aerobic exercise in participants with AD dementia by secondarily analyzing the FIT-AD Trial data. Aerobic fitness with the shuttle walk test (SWT), 6-minute walk test (6MWT), and maximal oxygen consumption (VO2max) from cycle-ergometer exercise test, and cognition with the AD Assessment Scale–Cognition (ADAS-Cog). Inter-individual differences were calculated as the differences in the standard deviation of 6-month change (SDR) in outcomes between the intervention and control groups. The sample size was 78 (77.4±6.3 years old, 15.7±2.8 years of education, 41% women). VO2max was available in 26 participants (77.7±7.1 years old, 14.8±2.6 years of education, 35% women). The results show that the SDR was 37.0, 121.1, 1.7, and 2.3 for SWT, 6MWT, VO2max, and ADAS-Cog, respectively, but there were no statistically significant differences between the intervention and control groups in these measures over six months. Our results indicate that inter-individual differences exist in aerobic fitness and cognitive responses to aerobic exercise in AD, which contributed to the favorable, but not statistically significant between-group differences in aerobic fitness and cognition. To conclude, our study is the first to demonstrate inter-individual differences in the responses to aerobic exercise in AD dementia using SDR.

exercise-related activities from a self-reported PA questionnaire.Group one expended less than 3,000 calories per week and group two spent more than 3,000 calories per week performing PA.The selected measures of functional fitness were a 4-m gait speed (GS), 30-s chair stand test (CS-30), 2-min step test (ST), and the 8-foot up and go test (GUG).Data were analyzed using a one-way ANOVA.There was a statistically significant difference between the groups on GS (F1, 24 = 9.29, p < .01)and 24 = 4.37,p = .05).The results yielded a trend for the GUG (p =.06).However, there was not a difference between the groups on the ST (p = .11).These results suggest older adults expending more than 3,000 calories per week performing PA walk faster and have greater lower-body strength.Aerobic exercise is widely supported as a diseasemodifying treatment for Alzheimer's disease (AD) in animal models; however, its effects on cognition have been mixed in human studies, which may be attributable to inter-individual differences in aerobic fitness and cognitive responses to aerobic exercise.This study evaluated inter-individual differences in aerobic fitness and cognitive responses to 6-month aerobic exercise in participants with AD dementia by secondarily analyzing the FIT-AD Trial data.Aerobic fitness with the shuttle walk test (SWT), 6-minute walk test (6MWT), and maximal oxygen consumption (VO2max) from cycle-ergometer exercise test, and cognition with the AD Assessment Scale-Cognition (ADAS-Cog).Interindividual differences were calculated as the differences in the standard deviation of 6-month change (SDR) in outcomes between the intervention and control groups.The sample size was 78 (77.4±6.3 years old, 15.7±2.8 years of education, 41% women).VO2max was available in 26 participants (77.7±7.1 years old, 14.8±2.6 years of education, 35% women).The results show that the SDR was 37.0, 121.1, 1.7, and 2.3 for SWT, 6MWT, VO2max, and ADAS-Cog, respectively, but there were no statistically significant differences between the intervention and control groups in these measures over six months.Our results indicate that inter-individual differences exist in aerobic fitness and cognitive responses to aerobic exercise in AD, which contributed to the favorable, but not statistically significant between-group differences in aerobic fitness and cognition.To conclude, our study is the first to demonstrate inter-individual differences in the responses to aerobic exercise in AD dementia using SDR.

IS HANDGRIP STRENGTH A VALID AND RELIABLE MEASURE IN OLDER ADULTS?
Jefferson Spicher, Amy Silva-Smith, and Melissa Benton,

University of Colorado Colorado Springs, Colorado Springs, Colorado, United States
Handgrip strength is related to mortality, disability, functional independence, and quality of life in older adults, and cut points for diagnosis of sarcopenia have been proposed.
However, there is no standardized procedure or device, so measurement may not be accurate.To assess validity and reliability we compared hydraulic (HD) versus digital (DD) handgrip dynamometers.Sixty-seven older (76.2 ± 0.9 years) men (n=34) and women (n=33) completed two measurements on sequential days (T1, T2) using both devices in random order.Participants sat in a chair with the device held in their dominant hand, their arm supported on a table or other stable surface, their wrist in a neutral position, and their elbow bent at a 90° angle.To avoid muscle fatigue that has been attributed to multiple attempts, participants squeezed the device one time as hard as possible for 3 seconds.Strong (p<0.001) intraclass correlations were observed for both devices (HD=0.98;SS=0.96) indicating good reliability.However, there were significant differences between devices and between measurements.Strength measured with HD was greater than DD at T1 (27.4 ± 1.4 vs. 23.4 ± 1.1 kg, p<0.001) and T2 (25.3 ± 1.4 vs. 21.8 ± 1.2 kg, p<0.001).Day-to-day measurements were also significantly different.Between T1 and T2 strength decreased 8% with HD (p<0.001) and decreased 7% with DD (p=0.001).In this group of older adults, significant differences in handgrip strength were observed between devices and timepoints indicating poor validity.As a diagnostic tool, standardization is needed for handgrip measurement procedures to improve accuracy.

MINDFULNESS MEDITATION AND TAI CHI CHUAN ON SLEEP DISTURBANCE IN CHINESE OLDER PEOPLE: A RANDOMIZED CONTROLLED TRIAL
Sunny Chan, 1 Wai Chi Chan, 2 Siu Man Ng, 2 and Chong Ho Alex Yu, 3 1.The Hong Kong Polytechnic University, Hong Kong, China, 2. The University of Hong Kong,Hong Kong,China,3. Azusa Pacific University,Azusa,California,United States Sleep disturbances are common during the aging process and can result in a reduced quality of life.Many older people who experience sleep disturbances would consider turning to complementary and alternative medicine (CAM) due to the limitations of traditional pharmaceutical or psychological and behavioural treatments.Mindfulness Meditation (MM) and Tai Chi Chuan (TCC) are two common forms of mindbody based CAM.The former focuses more on mind-based practices whereas the latter emphasizes predominantly on body or movement-based practices.An etiological model of sleep disturbance (Shallcross et al., 2019) can lay the groundwork for a better understanding of the mechanisms of MM and TCC in relation to sleep disturbances.This study aims at comparing the effects of MM and TCC with Sleep Hygiene Education (SHE) control group.A three-armed randomized controlled pilot trial was conducted involving 45 communitydwelling older adults aged 65 to 82 with symptoms of sleep disturbance.Moderate effect sizes (Cohen's d = 0.7 and 0.56) were found for the primary outcome of insomnia severity at post-intervention as comparing MM and TCC groups with SHE control group, respectively.More specific, participants in the MM group showed more amelioration on mental health status, introspective awareness, and objective measure of EEG-based brain arousal level; whereas participants in the TCC group showed better improvement on physical health status and subjective measure of hyperarousal.Findings