Brain Health and the Role of Exercise in Maintaining Late-Life Cognitive Reserve: A Narrative Review Providing the Neuroprotective Mechanisms of Exercise

Abstract

<h3>Introduction</h3> Inrecent years more focus has been placed on investigating the effects of exercise on cognitive and mental health in older adults. Depression and cognitive decline are highly prevalent in the aging populations and exercise can be a viable and accessible option in treatment and prevention. The annual cost of Alzheimer's and other dementias in 2021 will cost the United States $355 billion and is expected to increase to $1.1 trillion by 2050 unless there will be an efficient method for prevention of cognitive decline or slowing its progression. Postponing cognitive decline by 5 years yields huge economic savings and precious quality of life for the patients and their families. Exercise is a simple, accessible, and non-costly method of maintaining brain health. It also encounters the benefits of a non-pharmacological intervention which is of high importance in the aging population. Moreover, Exercise is of outmost importance in prevention of late-life cognitive decline and dementia, due to its positive metabolic and cerebrovascular impact on neuropathology. Data suggests that older adults who meet the physical activity guidelines have 20% risk reduction for cognitive decline and dementia. Nevertheless, existing exercise recommendation have not shown to increase the prevalence of a physically active lifestyle among elderly persons. Educating older adults and healthcare professionals on the benefits of exercise is an integral part of prevention and treatment strategies. The aim of this review is to bring depth into the healthcare recommendations by providing the scientific evidence for the neuroprotective mechanism of exercise in later life. <h3>Methods</h3> Our aim was to provide a narrative review and present the scientific evidence of exercise on brain health. We searched MEDLINE, MEDLINE RCTs, PsycINFO, and EMBASE from inception till date using key words including cognition, cognitive decline, dementia, exercise, physical activity, neuroplasticity, neuroanatomy, brain health, aging, late life, elderly. Studies that explore the impact of exercise on brain function, neuroanatomy, neurophysiology, neurovascular and cognitive functions in the aging population were reviewed and evaluated. Additionally, studies on the impact of exercise on the aging population and late-life mental health were explored. <h3>Results</h3> Over2,000 studies were found. We focused on clinical trials that explored the impact of exercise specifically on brain function, involving neuronal and cerebrovascular mechanisms. Exercise is shown to effect brain function and anatomy in various pathways. Scientific evidence from previous studies have successfully demonstrated that an increased heart rate directly increases cerebral blood flow and neuronal metabolism, which in turn increases oxygen extraction, and glucose utilization in the brain. This process initiates a cascade of events which promotes neuronal health, involving enhancement of neurotrophic factors such as Brain Derived Neurotrophic Factor (BDNF) and more which are of high importance in cognitive function and mood regulation. Moreover, exercise enhances secretion of neurotransmitters, including dopamine, norepinephrine, and serotonin all of which play a major role in attention and the management of anxiety and mood symptoms. There are also neurophysiological and neuro-anatomical changes, as shown by neuroimaging studies, such as increased metabolism and volume of the hippocampus, and improved connectivity and density of the white and grey matter. These changes are significantly important in the aging brain and cognitive reserve. Additional studies showed exercise effective in reducing cardiovascular risk factors, which reduced the risk of stroke and vascular cognitive decline which is the second common cause of dementia after Alzheimer's dementia. Clinical studies exploring exercise and cognitive functions have suggested exercise beneficial in maintenance of cognitive functions, especially of executive functions, and prevention of late-life cognitive decline. <h3>Conclusions</h3> Evidence suggests that exercise modifies and maintains brain function and promotes brain health. Brain health is vital in maintaining late life mental health and preventing cognitive decline. Delivering the scientific evidence and neuroprotective mechanisms of such major benefits from exercise is of vast importance. Providing this in-depth understanding is essential in promoting physical activity in the aging population, which is highly significant in prevention of late-life cognitive decline and depression. <h3>This research was funded by</h3> There was no funding of any kind and no financial support to this research project.