Cognitive frailty: A conceptual systematic review and an operational proposal for future research

•There are significant but modest associations between cognitive frailty and physical frailty.•Screening instruments have often been used to determine objective cognitive decline.•Lifespan trajectories should be taken into account in understanding cognitive frailty.•A strong operational definition of cognitive frailty is necessary.•Interventional studies are needed to establish the role of preventive strategies.