Presentation description

Aging is associated with substantial declines in cognitive and motor functioning. These declines may be attributed, in part, to age-related decreases in the levels of 𝛾-aminobutyric acid (GABA) – the brain’s primary inhibitory neurotransmitter – in task relevant brain regions. GABA plays an important role in the excitation/inhibition balance essential for optimal brain functioning, and as a result, age-associated decreases in GABA have been linked to known decrements in cognition, motor learning, and sensory processing. As exercise has shown promise to mitigate such aging-related decrements, one candidate mechanism suggests that it does so by increasing brain GABA levels. In this proof-of-concept study, we aim to investigate the extent to which an acute bout of high intensity aerobic exercise can modulate brain GABA levels in healthy older adults. We use magnetic resonance spectroscopy (MRS) to quantify GABA in the primary motor cortex (M1) and the hippocampus–two brain regions selected for their roles in motor and cognitive functioning, respectively. We hypothesize that high intensity aerobic exercise, as compared to a control (rest) intervention, will increase regional GABA concentrations in older adults, mitigating known age-related decreases in brain GABA levels. The exercise intervention consists of a high-intensity interval training (HIIT) regimen in which periods of high intensity exercise (85-95% of peak heart rate) are alternated with periods of active recovery (50-75% of peak heart rate). For the control intervention, participants sit quietly for a duration equivalent to the HIIT. The interventions are administered in a counterbalanced order one week apart, and MRS scans of GABA are completed immediately prior to and following each intervention. Preliminary data do not provide evidence that exercise increased GABA levels in the M1 nor the hippocampus, but more data are required to make definitive conclusions.