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Exercise and the brain

Larry H. Bernstein, MD, FCAP, Curator

LPBI

Importance of physical activity and aerobic exercise for healthy brain function

December 15, 2015   http://www.kurzweilai.net/importance-of-physical-activity-and-aerobic-exercise-for-healthy-brain-function

http://www.kurzweilai.net/images/fitness-vs.memory-accuracy.jpg

Results of exploratory whole-brain analysis. Parts (a) and (b) illustrate the results of an exploratory whole brain analysis, showing regions (red) where gray matter volume may be associated with fitness percentile or memory accuracy, respectively. Results are depicted within the group average brain. (credit: Andrew S. Whiteman et al./NeuroImage)

Young adults who have greater aerobic fitness also have greater volume of their entorhinal cortex, an area of the brain responsible for memory, Boston University School of medicine (BUSM) researchers have found.

While aerobic fitness is not directly associated with performance on a recognition memory task, the participants with a larger entorhinal cortex also performed better on a recognition memory task.

The entorhinal cortex is a brain area known to show early pathology in Alzheimer’s disease, which is characterized by profound memory impairment.

The researchers recruited healthy young adults (ages 18-35 years) who underwent a treadmill test to measure aerobic capacity. During this test, the amount of oxygen and carbon dioxide in the participants’ breath as they walked or ran on a treadmill was measured.

Participants then underwent magnetic resonance imaging and performed a recognition memory task. Entorhinal and hippocampal volume was determined using a method known as voxel-based morphometry and then regression analysis to examine whether recognition memory and aerobic fitness predicted brain volumes.

Effects of aerobic exercise

“Our results suggest that aerobic exercise may have a positive effect on the medial temporal lobe memory system (which includes the entorhinal cortex) in healthy young adults. This suggests that exercise training, when designed to increase aerobic fitness, might have a positive effect on the brain in healthy young adults,” explained corresponding author and principal investigator Karin Schon, PhD, BUSM assistant professor of anatomy and neurobiology.

Researchers said this work could support previous studies that suggest aerobic exercise may forestall cognitive decline in older individuals at risk of dementia, and extends the idea that exercise may be beneficial for brain health to younger adults. “This is critical given that obesity, which has recently been linked with cognitive deficits in young and middle-aged adults, and physical inactivity are on the rise in young adults,” Schon said.

These findings appear in the journal NeuroImage.

Abstract of Entorhinal volume, aerobic fitness, and recognition memory in healthy young adults: A voxel-based morphometry study

Converging evidence supports the hypothesis effects of aerobic exercise and environmental enrichment are beneficial for cognition, in particular for hippocampus-supported learning and memory. Recent work in humans suggests that exercise training induces changes in hippocampal volume, but it is not known if aerobic exercise and fitness also impact the entorhinal cortex. In animal models, aerobic exercise increases expression of growth factors, including brain derived neurotrophic factor (BDNF). This exercise-enhanced expression of growth hormones may boost synaptic plasticity, and neuronal survival and differentiation, potentially supporting function and structure in brain areas including but not limited to the hippocampus. Here, using voxel based morphometry and a standard graded treadmill test to determine cardio-respiratory fitness (Bruce protocol; VO₂ max), we examined if entorhinal and hippocampal volumes were associated with cardio-respiratory fitness in healthy young adults (N = 33). In addition, we examined if volumes were modulated by recognition memory performance and by serum BDNF, a putative marker of synaptic plasticity. Our results show a positive association between volume in right entorhinal cortex and cardio-respiratory fitness. In addition, average gray matter volume in the entorhinal cortex, bilaterally, was positively associated with memory performance. These data extend prior work on the cerebral effects of aerobic exercise and fitness to the entorhinal cortex in healthy young adults thus providing compelling evidence for a relationship between aerobic fitness and structure of the medial temporal lobe memory system.

references:

• Andrew S. Whiteman, Daniel E. Young, Andrew E. Budson, Chantal E. Stern, Karin Schon. Entorhinal volume, aerobic fitness, and recognition memory in healthy young adults: A voxel-based morphometry study. NeuroImage, 26 November 2015; DOI: 10.1016/j.neuroimage.2015.11.049

		Aurelian Udristioiu
Two comprehensive reviews found little evidence of an intensity threshold for changes in HDL cholesterol, LDL cholesterol, or triglycerides, although most studies did not control for exercise volume, frequency and/or duration, and were conducted using intensities ≥40% VO2max[17]. The American College of Sports Medicine (ACSM) recommends that most adults engage in moderate-intensity cardio-respiratory exercise for at least 30 min/day, at least 5 days per week, for a total of over 150 min of exercise per week. The levels of physical exercises are associated with lower total visceral fat, liver fat, and intramuscular body fat, with the active twin having on average 50% less visceral fat and 25% less subcutaneous abdominal fat than the inactive twin. [17] Edwar MA, Clark N, Macfadyen MA. Lactate and ventilatory thresholds reflect the training status of professional soccer players where maximum aerobic power is unchanged. JSSM 2003; 2: 23-29.