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Dean Pomerleau posted a topic in CR PracticeWe've known for quite some time that exercise (and CR!) can help stave off the cognitive decline that is often associated with aging. Scientists are now beginning to understand the mechanism underlying this effect. Here is a popular press description: http://www.kurzweilai.net/long-term-aerobic-exercise-prevents-age-related-brain-deterioration of a new paper  that helps elucidate the physiological mechanism of brain health preservation via exercise. The authors experimented with mice. They found that with age the support cells in the brain (microglia, astrocytes, etc.) are lost or become dysfunctional, reducing blood flow to neurons, increasing inflammation, etc. This age-related decline and damage was prevented in the mice that exercised (~2 miles per day on a running wheel). But exercise didn't have any positive effect in mice that were completely APOE-deficient. It is interesting that the APOE gene is involved in the beneficial cognitive benefits of exercise, since variants in this gene (i.e. APOE4) are well known to be associated with increased risk of Alzheimer's disease. Exactly what this means for people with APOE gene variants like APOE4 isn't clear, at least to me. Would exercise be somewhat of a waste of time for these people, unable to preserve cognitive health, like in the APOE-deficient mice? Or would exercise be more important for APOE4 carriers, to get the most from their relatively-impaired APOE activity on the brain? --Dean -----------  PLOS Biology, October 29, 2015; DOI: 10.1371/journal.pbio.1002279 (open access) APOE Stabilization by Exercise Prevents Aging Neurovascular Dysfunction and Complement Induction. Ileana Soto, Leah C. Graham, Hannah J. Richter, Stephen N. Simeone, Jake E. Radell, Weronika Grabowska, W. Keith Funkhouser, Megan C. Howell, Gareth R. Howell. Abstract Aging is the major risk factor for neurodegenerative diseases such as Alzheimer's disease, but little is known about the processes that lead to age-related decline of brain structures and function. Here we use RNA-seq in combination with high resolution histological analyses to show that aging leads to a significant deterioration of neurovascular structures including basement membrane reduction, pericyte loss, and astrocyte dysfunction. Neurovascular decline was sufficient to cause vascular leakage and correlated strongly with an increase in neuroinflammation including up-regulation of complement component C1QA in microglia/monocytes. Importantly, long-term aerobic exercise from midlife to old age prevented this age-related neurovascular decline, reduced C1QA+ microglia/monocytes, and increased synaptic plasticity and overall behavioral capabilities of aged mice. Concomitant with age-related neurovascular decline and complement activation, astrocytic Apoe dramatically decreased in aged mice, a decrease that was prevented by exercise. Given the role of APOE in maintaining the neurovascular unit and as an anti-inflammatory molecule, this suggests a possible link between astrocytic Apoe, age-related neurovascular dysfunction and microglia/monocyte activation. To test this, Apoe-deficient mice were exercised from midlife to old age and in contrast to wild-type (Apoe-sufficient) mice, exercise had little to no effect on age-related neurovascular decline or microglia/monocyte activation in the absence of APOE. Collectively, our data shows that neurovascular structures decline with age, a process that we propose to be intimately linked to complement activation in microglia/monocytes. Exercise prevents these changes, but not in the absence of APOE, opening up new avenues for understanding the complex interactions between neurovascular and neuroinflammatory responses in aging and neurodegenerative diseases such as Alzheimer’s disease. Author Summary Aging is frequently accompanied with frailty and cognitive decline. In recent years, increasing evidence has linked physical inactivity with the development of dementias such as Alzheimer’s disease. In fact, it is recognized that exercise combats frailty and cognitive decline in older adults, but the biological mechanisms involved are not completely known. Understanding the biological changes that trigger cognitive deterioration during aging and the mechanisms by which exercise improves health and brain function is key to ensuring the quality of life of the elderly population and to reducing risk of dementias such as Alzheimer’s disease. Here, we show that the cerebrovascular system in mice significantly deteriorates with age, and the structure and function of the blood brain barrier is progressively compromised. These age-related neurovascular changes are accompanied by neuroinflammation and deficits in common and spontaneous behaviors in mice. We found, however, that exercise from middle to older age preserves the cerebrovascular health, prevents behavioral deficits and reduces the age-related neuroinflammation in the cortex and hippocampus in aged mice. Mice deficient in Apoe, a gene associated with longevity and Alzheimer’s disease, are resistant to the beneficial effects of exercise, suggesting a possible mediating role for APOE in the maintenance and function of the neurovascular system during aging.