Grant: Master's Award: Canada Graduate Scholarships

The Canadian population is faced with a drastic demographic shift as our senior population is expected to more than double by 2050. With age, various neurological changes occur. Of particular interest to this study is the degeneration of white matter (WM) occurring within the frontal lobes and frontal neural networks. WM changes impair the brain's ability to send signals and communicate between cortical regions and decreased WM integrity is associated with poor executive functioning. Executive functions (EF) are high order cognitive processes which govern our behavior in accordance with our goals. Compromised executive functioning impairs daily functioning in numerous ways including cooking and dressing and is associated with longitudinal declines in functional status within elderly populations. In order to effectively address this age-related executive dysfunction to improve functional independence and late-life cognition, interventions should confront the problem on two tiers: preserving the neural substrates subserving EF and identifying cognitive strategies to enhance daily functioning. To assess the neural substrates, in this study we will be examining changes in WM connectivity using diffuse tensor imaging (DTI). In order to mitigate WM decline, we plan to use an aerobic intervention as aerobic activity has previously been found to improve WM integrity and cognitive status in elderly participants. To confront issues in daily functioning, we will be using an established cognitive intervention called Goal Management Training. In addition to furthering our understanding of the mechanisms underlying age-related executive dysfunction, we also aim to assess the efficacy of those two interventions on both a neural and behavioral level. Furthermore, we aim to assess whether exercise-induced neurological changes can be extended to facilitate the efficacy of the cognitive intervention. As such, our objectives are to: 1) examine changes in WM connectivity occurring through GMT; 2) examine changes in WM connectivity occurring after aerobic intervention; 3) to assess the efficacy of a combined intervention by comparison; and 4) to examine changes in regional cerebral blood flow (CBF), to evaluate the treatments' cerebrovascular outcomes. We hypothesize that the combined intervention will have the greatest changes in WM, EF and CBF scores. Participants will be seniors aged 65-80 and will be randomized into three groups: 1.GMT condition: which will have take-home assignments, participate in 4 educational sessions and complete in-class activities. 2. Aerobic condition: participants will keep an exercise log to record their aerobic activity and will be asked to briskly walk within their target heart rate daily beginning at 10 minutes and increasing up to 40 minutes at 5 minute increments/week. 3. Combined condition: an amalgamation of the two. This study represents a novel approach to the study of EF intervention in the elderly because, to our knowledge, no other research has yet evaluated the effects of these therapies on WM connectivity in the elderly. Further, since exercise is believed to achieve structural and functional changes by the upregulation of neurotrophic factors, we aim to assess whether such exercise-induced plasticity can be generalized. Specifically, by combining the two approaches we hypothesize that the increased plasticity induced by the aerobic intervention may facilitate the structural changes targeted in the cognitive intervention and thereby increase its efficacy. This study will examine the efficacy and neural basis of combined aerobic intervention and executive control training (GMT). These results could inform the design of future interventions for executive dysfunction arising from multiple etiologies.