“UCLA researchers recruited 35 people ages 45 to 75 and asked about their physical activity levels and the average number of hours per day they spent sitting over the previous week. Each person had a high-resolution MRI scan, which provides a detailed look at the medial temporal lobe, or MTL, a brain region involved in the formation of new memories.
The researchers found that sedentary behavior is a significant predictor of thinning of the MTL and that physical activity, even at high levels, is insufficient to offset the harmful effects of sitting for extended periods…The researchers next hope to follow a group of people for a longer duration to determine if sitting causes the thinning and what role gender, race, and weight might play in brain health related to sitting.
MTL thinning can be a precursor to cognitive decline and dementia in middle-aged and older adults. Reducing sedentary behavior may be a possible target for interventions designed to improve brain health in people at risk for Alzheimer’s disease, researchers said.”
Sedentary behavior associated with reduced medial temporal lobe thickness in middle-aged and older adults (PLOS One). From the abstract:
- (Background) Atrophy of the medial temporal lobe (MTL) occurs with aging, resulting in impaired episodic memory. Aerobic fitness is positively correlated with total hippocampal volume, a heavily studied memory-critical region within the MTL. However, research on associations between sedentary behavior and MTL subregion integrity is limited. Here we explore associations between thickness of the MTL and its subregions, physical activity, and sedentary behavior.
- (Methods) We assessed 35 non-demented middle-aged and older adults (25 women, 10 men; 45–75 years) using the International Physical Activity Questionnaire for older adults, which quantifies physical activity levels in MET-equivalent units and asks about the average number of hours spent sitting per day. All participants had high resolution MRI scans performed on a Siemens Allegra 3T MRI scanner, which allows for detailed investigation of the MTL.
- (Results) Controlling for age, total MTL thickness correlated inversely with hours of sitting/day (r = ‑0.37, p = 0.03). In MTL subregion analysis, parahippocampal (r = ‑0.45, p = 0.007), entorhinal (r = ‑0.33, p = 0.05) cortical and subiculum (r = ‑0.36, p = .04) thicknesses correlated inversely with hours of sitting/day. No significant correlations were observed between physical activity levels and MTL thickness. Though preliminary, our results suggest that more sedentary non-demented individuals have less MTL thickness. Future studies should include longitudinal analyses and explore mechanisms, as well as the efficacy of decreasing sedentary behaviors to reverse this association.