This study will measure brain structure through its mechanical properties, assessed with magnetic resonance elastography, and determine whether it improves with aerobic exercise in older adults with low memory abilities. Additionally, this study will determine if memory abilities improve with exercise and if they are related to brain structure. Overall, this project has the potential to identify how brain health is impacted by exercise in older adults.

Mechanical properties of the human brain, measured with magnetic resonance elastography (MRE), reflect the health of brain tissue. Our previous research has shown that these mechanical properties of the hippocampus are highly sensitive to memory function in young adults. Based on these findings, we believe that these mechanical properties may be strong indicators of memory health in older adults and populations experiencing decline in memory function (i.e. mild cognitive impairment, MCI). Further, our results indicate these properties and associated functions are positively impacted by fitness and exercise training, thus making them potentially ideal markers for brain health in assessing rehabilitation.

The objective of this research is to examine these properties in older adults with and without MCI. We will do the following: (1) determine if there are differences in mechanical properties of memory systems in older adults with and without MCI; (2) establish structure-function relationships between mechanical properties and memory performance in the older adult population; and (3) determine if both mechanical properties and memory performance are impacted by cardiovascular health, both through cross-sectional assessment of aerobic fitness and longitudinal response to exercise training.

Inclusion Criteria:

• Cognitive function scores consistent with amnestic mild cognitive impairment based on pre-screening evaluation
• age 60-90 years
• MMSE score >24 at time of initial consent

Exclusion Criteria:

• major psychiatric disorder (e.g. schizophrenia, bipolar disorder, major depression within past two years)
• neurological or autoimmune conditions affecting cognition (e.g. Parkinson's disease, epilepsy, multiple sclerosis, head trauma with loss of consciousness greater than 30 min, large vessel infarct)
• other systemic medical illnesses (e.g. cardiovascular disease, cancer, renal failure, diabetes, chronic obstructive pulmonary disease, liver diseases, hypertension)
• current medication use likely to affect CNS functions (e.g. long active benzodiazepines)
• failed outcome on the baseline graded exercise test
• hypertension (systolic 130+ mmHg OR diastolic 80+ mmHg) from baseline blood pressure measurement
• claustrophobia, metal implants, pacemaker or other factors affecting feasibility and/or safety of MRI scanning
• concussion within last 2 years and more than 3 lifetime concussions
• current smoking (including marijuana) within the past 3 months