A common marker of affect recognition dysfunction in the FTD spectrum of disorders

Background: Poor affect recognition is an early sign of frontotemporal dementia (FTD). Here, we applied the abbreviated version of the Comprehensive Affect Testing System (CATS-A) battery to Italian FTD cases and healthy controls (HC) to provide cut-offs of emotional dysfunction in the whole group and in different FTD clinical syndromes. Methods: One hundred thirty-nine FTD patients (60 behavioural variant [bvFTD],13 semantic behavioural variant of FTD [sbvFTD], 28 progressive supranuclear palsy [PSP], 21 semantic [svPPA] and 17 nonfluent [nfvPPA] variants of primary progressive aphasia) and 116 HC were administered the CATS-A, yielding an Affective Recognition Quotient (ARQ), which was used as outcome measure. Age- and education-adjusted, regression-based norms were derived in HC. In patients, the ARQ was assessed for its internal reliability, factorial validity and construct validity by testing its association with another social cognition paradigm, the Story-Based Empath Task (SET). The diagnostic accuracy of the ARQ in discriminating patients from HC, genetic cases from HC and patient groups among each other was tested via ROC analyses. Results: In the whole FTD cohort, CATS-A proved to be underpinned by a mono-component factor (51.1%) and was internally consistent (McDonald's ω = 0.76). Moreover, the ARQ converged with the SET (r(122) = 0.50; p < 0.001) and optimally discriminated HC from both the whole cohort (AUC = 0.89) and each clinical syndrome (AUC range: 0.83-0.92). Conversely, CATS-A subtests were able to distinguish patient groups. Conclusions: The ARQ score from the CATS-A distinguishes FTD clinical syndromes from HC with high accuracy, making it an excellent tool for immediate use in clinical practice.