Protective Effects of Physical Exercise in Alzheimer's Disease and Parkinson's Disease: A Narrative Review

Abstract

Alzheimer's disease (AD) and Parkinson's disease (PD) are devastating, frequent, and still incurable neurodegenerative diseases that manifest as cognitive and motor disorders. Epidemiological data support an inverse relationship between the amount of physical activity (PA) undertaken and the risk of developing these two diseases. Beyond this preventive role, exercise may also slow down their progression. Several mechanisms have been suggested for explaining the benefits of PA in the prevention of AD. Aerobic physical exercise (PE) activates the release of neurotrophic factors and promotes angiogenesis, thereby facilitating neurogenesis and synaptogenesis, which in turn improve memory and cognitive functions. Research has shown that the neuroprotective mechanisms induced by PE are linked to an increased production of superoxide dismutase, endothelial nitric oxide synthase, brain-derived neurotrophic factor, nerve growth factor, insulin-like growth factor, and vascular endothelial growth factor, and a reduction in the production of free radicals in brain areas such as the hippocampus, which is particularly involved in memory. Other mechanisms have also been reported in the prevention of PD. Exercise limits the alteration in dopaminergic neurons in the substantia nigra and contributes to optimal functioning of the basal ganglia involved in motor commands and control by adaptive mechanisms involving dopamine and glutamate neurotransmission. AD and PD are expansive throughout our ageing society, and so even a small impact of nonpharmacological interventions, such as PA and exercise, may have a major impact on public health.

Altered neurogenesis in mouse models of Alzheimer disease

“…7 This has been mainly attributed to an elevated release of neurotrophic factors and boosted angiogenesis, both facilitating increased neuro-and synaptogenesis (reviewed in ref. 8). Transgenic AD mouse models have been extensively studied with respect to exercise-mediated effects on deposition of amyloid-b (Ab) peptides and the impact on hippocampal neurogenesis and cognitive function has been repeatedly described (reviewed in ref.…”

The Effects of Different Exercise Modalities in Alzheimer’s Disease

“…The growth factors then improve memory and cognitive functions via the stimulation of neurogenesis, synaptogenesis, neuroplasticity, and angiogenesis (7,20,21). Moreover, aerobic exercise increases cerebral blood flow and the levels of endothelial nitric oxide synthase and additionally decreases the levels of reactive oxygen species (ROS) in brain tissues, particularly in the hippocampus (7,9,21). Exercise-induced elevations in hippocampal cerebral blood volume were found to be associated with enhanced neurogenesis (22).…”

“…Different mechanisms are known to mediate its beneficial effects (Figure 3). Aerobic exercise initially contributes to an increase in the levels of growth factors such as vascular endothelial growth factor, brain-derived neurotroph- Isometrics ic factor (BDNF), IGF-1, glial-derived neurotrophic factor, neuronal growth factor (NGF), and neurotrophin-3, all of which act in a synergistic manner to induce neuroplasticity and neurogenesis (7,(17)(18)(19). The growth factors then improve memory and cognitive functions via the stimulation of neurogenesis, synaptogenesis, neuroplasticity, and angiogenesis (7,20,21).…”

“…Aerobic exercise initially contributes to an increase in the levels of growth factors such as vascular endothelial growth factor, brain-derived neurotroph- Isometrics ic factor (BDNF), IGF-1, glial-derived neurotrophic factor, neuronal growth factor (NGF), and neurotrophin-3, all of which act in a synergistic manner to induce neuroplasticity and neurogenesis (7,(17)(18)(19). The growth factors then improve memory and cognitive functions via the stimulation of neurogenesis, synaptogenesis, neuroplasticity, and angiogenesis (7,20,21). Moreover, aerobic exercise increases cerebral blood flow and the levels of endothelial nitric oxide synthase and additionally decreases the levels of reactive oxygen species (ROS) in brain tissues, particularly in the hippocampus (7,9,21).…”

“…Exercise is a non-pharmacological form of treatment for the prevention of AD and for slowing the progression of its symptoms (5)(6)(7)(8)(9). Recent studies have shown the beneficial effects of physical exercise on behavioral and psychological symptoms such as depressed mood and agitation, which are prevalent in AD.…”