Operationalizing Cognitive Frailty: A Systematic Review of Definitions, Tools, and Measurement Inconsistencies.

Abstract

Cognitive frailty (CF), the co-occurrence of physical frailty and cognitive impairment without dementia, is a potentially reversible condition associated with adverse outcomes in older adults. However, heterogeneity in operational definitions and measurement approaches limits comparability and clinical translation. This review examined how CF has been defined and operationalized, including adaptations to established criteria. PubMed, Web of Science, and PsycINFO were searched for English-language studies published from 2013 through 2025. Eligible studies explicitly referred to CF in adults aged 50 years or older. Risk of bias was assessed using Joanna Briggs Institute tools. Definitions, assessment tools, thresholds, and operational criteria were synthesized descriptively. Fried Phenotype (FP) implementation was examined using an adaptation-equivalence typology classifying domain-level measurement and threshold deviations. Among 257 studies, 13 frailty and 26 cognitive assessment tools were identified. The FP was predominantly utilized (n = 164/257; 64%), although 68% (n = 112/164) modified the measurement method, threshold, or both in at least one domain. The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) thresholds used to define cognitive impairment varied substantially, whereas all studies using the Clinical Dementia Rating (CDR) used a threshold of 0.5. Dementia was not explicitly excluded in 50 studies, despite its exclusion being a defining criterion of CF. CF remains operationally heterogeneous. Updated international consensus and minimum reporting standards are needed to clarify core criteria and acceptable adaptations. FP-based studies should explicitly report domain-level modifications to improve comparability, reproducibility, and evidence synthesis.