To the Editor: In a previous issue of the Journal of Frailty & Aging, Houles and colleagues (1) presented a review paper entitled “Frailty and cognition”. The association between frailty and cognitive impairment was proposed, and Authors discussed a large amount of evidence. However, a number of conceptual and methodological issues should be taken into account as potentially affecting the possibility to include cognition in the operational definition of frailty (as suggested by Authors). Frailty should be considered as a construct under development and several concepts are still intensely discussed (2). We think the paper fails to fully cover the vast amount of on-going debate in this field. In particular: