The Relationship Between Cognitive Performance Assessments and the Mental Capacity Functional Test: A Systematic Review

Aim: Investigating the relationship between neurocognitive performance and the 2005 Mental Capacity Act (MCA) functional test in adults with a neurological diagnosis. Methods: Cochrane Library, MEDLINE, PubMed, CINAHL, PsycINFO, EMBASE, Scopus and Web of Science were searched in April 2021. Included studies reported cognitive test outcomes in adults with neurological diagnoses in relation to one or more of the four pillars of the MCA functional test (‘understanding’, ‘retention’, ‘using and weighing-up information’, ‘communication’). A narrative synthesis was structured in accordance with each pillar of the functional test. The NIH observational studies tool enabled quality assessment. Results: Of the 3,996 studies screened, 34 were included. Significant relationships between cognitive scores and capacity outcomes were identified in all but one study. The most consistent finding related to tests of information processing, executive functioning, and attention/working memory correlating strongly with ‘understanding’ in different samples. The relationships between other pillars and cognitive outcomes were seldom reported, with inconsistent findings. Conclusions: The pillars of the functional test are seldom referred to separately. Further research which clearly operationalises the pillars of capacity assessed is required to elucidate both the utility and limits of cognitive measures in supporting complex functional assessments in line with the MCA.