Aerobic fitness is associated with hippocampal volume in elderly humans

Abstract

Deterioration of the hippocampus occurs in elderly individuals with and without dementia, yet individual variation exists in the degree and rate of hippocampal decay. Determining the factors that influence individual variation in the magnitude and rate of hippocampal decay may help promote lifestyle changes that prevent such deterioration from taking place. Aerobic fitness and exercise are effective at preventing cortical decay and cognitive impairment in older adults and epidemiological studies suggest that physical activity can reduce the risk for developing dementia. However, the relationship between aerobic fitness and hippocampal volume in elderly humans is unknown. In this study, we investigated whether individuals with higher levels of aerobic fitness displayed greater volume of the hippocampus and better spatial memory performance than individuals with lower fitness levels. Furthermore, in exploratory analyses, we assessed whether hippocampal volume mediated the relationship between fitness and spatial memory. Using a region-of-interest analysis on magnetic resonance images in 165 nondemented older adults, we found a triple association such that higher fitness levels were associated with larger left and right hippocampi after controlling for age, sex, and years of education, and larger hippocampi and higher fitness levels were correlated with better spatial memory performance. Furthermore, we demonstrated that hippocampal volume partially mediated the relationship between higher fitness levels and enhanced spatial memory. Our results clearly indicate that higher levels of aerobic fitness are associated with increased hippocampal volume in older humans, which translates to better memory function.

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

“…Erickson et al. (2009) observed significant positive associations between CRF and both left and right hippocampal volumes in cognitively healthy, sedentary older adults. Similar positive findings between CRF and hippocampal volume were reported for obese (BMI ≥ 30), cognitively healthy older adults (Bugg et al., 2012).…”

“…It is possible that hippocampal volume may mediate the relationship between CRF and memory performance (Erickson et al., 2009); enhanced CRF may cause an increase in hippocampal volume, which then leads to enhanced memory performance (Erickson et al., 2011). However, here too, the evidence is contradictory.…”

Home Based Exercise Effects on Cognition in the Semi-Independent Elderly

“…response to regular walking among the elderly 5) as well as jogging among young adults 6) . Additionally, hippocampal volume and spatial memory are positively correlated with aerobic fitness 7) , and aerobic exercise may increase the volume of prefrontal gray matter 8) . Although the mechanisms underlying the beneficial effect of physical activity on the brain are not well understood, brain-derived neurotrophic factor (BDNF) and dopamine may be involved.…”

Impoverished environment, cognition, aging and dementia

“…Correspondingly, a low level of physical activity during life is related to higher rates of dementia and might increase the risk of developing dementia (Hamer and Chida , 2009 ;Middleton et al , 2010 ;Radak et al , 2010 ). A mechanism underlying these fi ndings is that a low level of physical activity is related to a smaller volume of the hippocampus (Erickson et al , 2009 ), an area in the medial temporal lobe that is involved in long-term memory and spatial navigation (Lui et al , 2011 ). It is important to note that these studies only show a ' relationship ' between physical activity and cognition, not a ' causal ' relationship.…”