Enhancing Cognition and Functional Independence in Senior Women With Mild Cognitive Impairment: A Randomized Trial of Aerobic vs. Resistance Training

Alzheimer's disease (AD) is a major health issue in Canada; it affects over 8% of the population aged over 65 years. Persons with AD have a reduced quality of life as they become dependent on others for activities of daily living (ADLs). This problem of loss of independence - functional dependence - is one focus of this grant application. It is projected that by 2020, Canada will have well over 10 million seniors with moderate to severe functional dependence. Functional dependence was the most significant contributor to an annual cost of dementia that had already reached $4 billion in the 1990s.

Mild cognitive impairment (MCI) is a well-recognized risk factor for both AD and functional dependence. Within the broader assessment of cognitive function, the literature suggests that executive functioning - the ability to concentrate, to attend selectively, to plan and strategize - is a robust cognitive predictor of functional status in seniors. Specifically, Royall and colleagues demonstrated executive functioning independently explained 43% of the functional status in community-dwelling seniors dementia. The researchers will investigate executive functioning in seniors with MCI.

Randomized trials of various exercise interventions have proven that exercise has many systemic benefits. Data are emerging that physical activity may improve cognition - specifically executive function - in healthy adults. The researchers' own pilot data suggest that resistance training in seniors may improve executive functioning as assessed by neuropsychological tests and neuro-imaging. However, at present the Cochrane Database of Systematic Reviews indicates there are insufficient published data to guide exercise prescription to prevent AD. In persons with MCI, no published studies have reported on whether physical activity can improve executive function, or delay its decline and thus, prevent or delay the onset of functional dependence (and later, dementia).

Therefore, among seniors with MCI, the researchers will investigate whether or not specific exercise prescription can: 1) provide absolute or relative improvement in cognitive function, particularly executive function; and 2) help maintain functional independence. This will facilitate the development of effective exercise-based strategies for the prevention of both cognitive and functional decline in the large population of seniors with MCI - people at greatly increased risk for AD.

The researchers' proposed research aims to ascertain whether a six-month, twice-weekly aerobic training (AT) program and a six-month, twice-weekly resistance training (RT) program, compared with a six-month, twice-weekly stretch & relax (S & R; control) program, will significantly improve cognition and functional status in community-dwelling women with MCI aged 70 years and older.

Primary Hypothesis:

At the end of six-month randomized trial, compared with the S & R program, both the AT and RT programs will significantly improve cognitive performance, as assessed by neuropsychological testing.

Secondary Hypotheses:

At the end of the six-month randomized trial, compared with the S & R program, participants of the AT and RT programs will:

1. Demonstrate evidence of cortical plasticity by fMRI, such as increased activation in cortical regions responsible for item and relational memory; and
2. Will significantly improve their everyday problem solving ability.