Effects of Aerobic Dance Training on Cognitive Functions, Mood and Physical Functions in Community Elderly Persons With Cerebral Small Vessel Disease

Cerebral small vessel disease (SVD) is manifested as age-related white matter lesions (WML) and lacunar infarcts and on brain imaging. SVD is prevalent in the elderly population. In community dwelling persons ≥ 60 years of age, up to a quarter had lacunar infarcts and 96% had varying degree of WML. Significant SVD, namely early confluent or confluent WML and multiple lacunar infarcts, are found in up to 1 in every 5 elderly persons. In a previous study we found that Chinese are more prone to develop significant SVD than Caucasians. SVD is associated with a plethora of age-related disabilities such as dementia, falls, depression, impaired daily functioning and death Cognition - SVD is the most common cause of vascular cognitive impairment (VCI) and vascular dementia, which is the second most prevalent type of dementia. Community elderly persons with SVD had two-fold increased risk of developing dementia when compared to those without. SVD may direct damage neural structures, disrupt connectivity or cause atrophy in brain regions important for cognitive functioning. Depression - Disconnection of frontosubcortical pathways by SVD contributes to late-life depression, and increased comorbidity of depression and SVD has been observed in the older populations. Depression contributes to poor quality of life and death in older persons.

Physical impairment - increased severity of SVD is associated with poor physical functions including poor gait and balance. SVD is a strong risk factor for falls, a major contributing factor for disability and death in older persons. In summary, non-disabled older adults with SVD are at high risk of multiple disabilities.

As the elderly population in Hong Kong is projected to triple over the next 30 years, means to prevent age-related disabilities such as cognitive decline, depression and physical impairments in vulnerable individuals are of enormous importance to the patient, family and healthcare system. Existing preventive therapies mainly involve medications to control vascular risk factors associated with SVD. Primary prevention by means of lifestyle intervention is therefore of utmost importance.

Evidence on effects of physical activities upon cognition, mood and physical functions The health values of physical activities are well recognized. Physical activities can be performed by anybody at any time and place at minimal cost. Physical activities are shown to improve the clinical conditions associated with SVD. For cognition, physical activities are associated with reduced risk of cognitive decline in normal and cognitively impaired elderly persons. Aerobic and strength training improved executive functions, memory and general cognitive functions in community-dwelling adults with mild cognitive impairment. The investigators showed that in a large cohort (n=1,013) of stroke patients free of dementia before the stroke, participation in regular physical activities reduced 79% of risk of incident dementia after stroke. With regard to the mechanism, physical activities may improve endothelial functions and blood perfusion and neuroplasticity in brain regions mediating cognitive functions. Moreover, physical exercise may protect cognition by reducing incident strokes, which is particular relevant to people with SVD due to their increased risk of strokes. A randomized controlled trial (RCT) showed that a 24-week, 3 x 50-minute per week of moderate intensity exercise intervention significantly improved cognitive functions in patients at risk of AD, with outcome effect size superior to that reported for drug treatment in another study. Moreover, treatment benefits persisted at least one year after active intervention, suggesting that physical exercise is associated with enduring changes in the neurological substrate underpinning cognitive functioning. However, this study only recruited patients likely to have degenerative (Alzheimer's) pathology. For mood, physical activities may protect against depression in older adults. For physical functions, the investigators previously showed that physical exercise training improved balance, gait performance, exercise endurance and quality of life in local patients with Parkinson's Disease (PD). Taken together, there is good evidence that physical activities can improve many of the negative consequences of cerebral SVD.

Possible biological mechanism underlying physical exercise in SVD The development of SVD is hypothesized to be related to endothelial dysfunction that results from chronic hypertension impairs cerebral vasomotor reactivity (CVR), a marker of cerebral autoregulation. Changes in CVR may reflect impairment in the homeostasis of blood pressure in the brain, hence cerebral perfusion becomes more dependent on the systemic blood pressure. Ischemia occurs in response to drop of systemic blood pressure and lead to hypoperfusion and subsequently the development of SVD. Using Transcranial Doppler (TCD) ultrasonography, our group previously showed that decreased CVR is associated with SVD. Reduced CVR is linked to cognitive decline, depression and poor physical functions in elderly persons. Physical exercise may lead to significant improvement in CVR. These data suggest that physical exercise is likely to benefit cognition, mood and physical functions in persons with SVD due to its positive effects on CVR.