Low‐intensity daily walking activity is associated with hippocampal volume in older adults

Abstract

Hippocampal atrophy is associated with memory impairment and dementia and serves as a key biomarker in the preclinical stages of Alzheimer's disease. Physical activity, one of the most promising behavioral interventions to prevent or delay cognitive decline, has been shown to be associated with hippocampal volume; specifically increased aerobic activity and fitness may have a positive effect on the size of the hippocampus. The majority of older adults, however, are sedentary and have difficulty initiating and maintaining exercise programs. A modestly more active lifestyle may nonetheless be beneficial. This study explored whether greater objectively measured daily walking activity was associated with larger hippocampal volume. We additionally explored whether greater low-intensity walking activity, which may be related to leisure-time physical, functional, and social activities, was associated with larger hippocampal volume independent of exercise and higher-intensity walking activity. Segmentation of hippocampal volumes was performed using FMRIB's Software Library (FSL) and daily walking activity was assessed using a step activity monitor (SAM) on 92, non-demented, older adult participants. After controlling for age, education, body mass index (BMI), cardiovascular disease risk factors, and the Mini Mental State Exam (MMSE), we found that a greater amount, duration, and frequency of total daily walking activity were each associated with larger hippocampal volume among older women, but not men. These relationships were specific to hippocampal volume, compared to the thalamus, used as a control brain region, and remained significant for low-intensity walking activity, independent of moderate- to vigorous-intensity activity and self-reported exercise. This is the first study, to our knowledge, to explore the relationship between objectively measured daily walking activity and hippocampal volume in an older adult sample. Findings suggest the importance of better understanding whether increasing non-exercise, lifestyle physical activities may produce measurable cognitive benefits and effect hippocampal volume through molecular pathways unique to those related to moderate-intensity exercise.

Relationships between cardiorespiratory fitness, hippocampal volume, and episodic memory in a population at risk for Alzheimer's disease

“…This finding is consistent with a recent study that reported positive associations between steps per day (i.e., physical activity) and hippocampal volume in women but not men (Varma et al., 2015). Other randomized control trials have also found evidence for gender‐specific effects (van Uffelen, Chinapaw, van Mechelen, & Hopman‐Rock,2008; Vaughan, Morris, Shum, O'Dwyer, & Polit, 2012), with data suggesting the superior cognitive response in women may be the result of gender differences in exercise‐induced hormonal glucometabolic and hypothalamic–pituitary–adrenal axis responses (Baker et al., 2010).…”

“…In older adults, large‐scale cross‐sectional studies have reported contradictory associations. Positive associations between CRF/physical activity and RAVLT performance have been reported (Boots et al., 2014; Pizzie et al., 2014; Zhu et al., 2014) while others studies did not observe such associations (Maass et al., 2015; Varma et al., 2015). Randomized controlled trials provide evidence that aerobic exercise (Klusmann et al., 2010) and resistance exercise (Cassilhas et al., 2007) training can improve episodic memory in cognitively healthy older adults.…”

“…However, here too, the evidence is contradictory. Varma, Chuang, Harris, Tan, and Carlson, (2015) reported a positive association between physical activity and hippocampal volume, but no significant association between physical activity and episodic memory. ten Brinke et al.…”

“…The purpose of this study was to determine the relationship between objectively measured CRF, hippocampal volume, and episodic memory in a cohort of cognitively healthy men and women with familial and/or genetic risk for AD. Based on data suggesting gender differences between exercise and both hippocampal volume (Varma et al, 2015) and cognition (Colcombe & Kramer, 2003; Middleton, Kirkland, & Rockwood, 2008) that may be explained by altered metabolic effects of exercise (Baker et al., 2010), we also explored potential gender differences within our sample. We hypothesized that CRF would be positively associated with both hippocampal volume and episodic memory.…”

Impact of different physical activities on executive functioning

“…Evidence of greater brain volume in temporal brain regions in physical active older adults in comparison with less active older adults can be found as well [8]. Increasing amount of research suggests increase of volume in hippocampus and reduced brain atrophy due to physical exercise [7,9].…”