Cognitive frailty: what is still missing?

In recent years, the complex relationship between frailty and cognitive functioning has been increasingly investigated. Accordingly, the concept of "cognitive frailty" was recently proposed to describe a clinical condition characterized by the simultaneous occurrence of both physical frailty and cognitive impairment, in absence of overt dementia diagnosis or underlying neurological conditions. This novel construct has several elements of novelty and may delineate a promising target for preventive and therapeutic actions against age-related conditions. In the present paper we discuss the main issues that are still limiting the clinical and research implementation of the cognitive frailty construct. In particular, a) how to operationalize its definition; b) the supporting epidemiological data; and c) the underlying clinical and biological characteristics constitute points that need to be addressed and clarified.