1 School of Graduate Studies, Concordia University, 1550 de Maisonneuve Blvd W, Montreal, H3G 1N1, Canada; PERFORM Centre, Concordia University, 7200 rue Sherbrooke O, Montreal, H4B 1R6, Canada; Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Queen Mary Rd, Montréal, H3W 1W6, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, 5055 Rue Saint-Zotique E, Montréal, H1T 1N6, Canada. Electronic address: brittany.intzandt@mail.concordia.ca.
2 Centre de Recherche de l'Institut Universitaire de Gériatrie de Montréal, 4545 Queen Mary Rd, Montréal, H3W 1W6, Canada; Centre de Recherche de l'Institut de Cardiologie de Montréal, 5055 Rue Saint-Zotique E, Montréal, H1T 1N6, Canada; Département de Médecine, Université de Montréal, 2900 Edouard Montpetit Blvd, Montréal, H3T 1J4, Canada. Electronic address: vrinceanu.tudor@gmail.com.
3 PERFORM Centre, Concordia University, 7200 rue Sherbrooke O, Montreal, H4B 1R6, Cana

Aging is associated with cognitive decline. Importantly cognition and cerebral health is enhanced with interventions like cognitive (CT) and exercise training (ET). However, effects of CT and ET interventions on brain magnetic resonance imaging outcomes have never been compared systematically. Here, the primary objective was to critically and systematically compare CT to ET in healthy older adults on brain MRI outcomes. A total of 38 studies were included in the final review. Although results were mixed, patterns were identified: CT showed improvements in white matter microstructure, while ET demonstrated macrostructural enhancements, and both demonstrated changes to task-based BOLD signal changes. Importantly, beneficial effects for cognitive and cerebral outcomes were observed by almost all, regardless of intervention type. Overall, it is suggested that future work include more than one MRI outcome, and report all results including null. To better understand the MRI changes associated with CT or ET, more studies explicitly comparing interventions within the same domain (i.e. resistance vs. aerobic) and between domains (i.e. CT vs. ET) are needed.