Clinical Phenotypes in Behavioural Variant Frontotemporal Dementia and Primary Psychiatric Disorders

Abstract

Frontotemporal dementia is the second most common form of dementia under the age of 65 years, of which behavioural variant frontotemporal dementia (bvFTD) is a subtype. In clinical practice, much overlap exists between bvFTD and primary psychiatric disorders (PPD). 50% of bvFTD patients get a misdiagnosis of PPD at first and the average diagnostic delay is five to six years. The aim of the current study was to investigate which clinical phenotypes might be helpful in the diagnostic process to better differentiate between bvFTD and PPD patients. The study sample consisted of 268 patients, seen on the screening day of the Social Brain Project at the VUmc Amsterdam. In this cross-sectional study, 103 bvFTD patients were compared with 64 PPD patients on their baseline scores on several questionnaires, cognitive screeners and neuropsychological assessment. These were used to measure behaviour, neurocognition, social cognition and mental impact. Regarding behavioural questionnaires, PPD patients were more affected on the MADRS, measuring depressive symptoms. Within neurocognition, bvFTD patients were more affected on cognitive screeners, global cognition and language. Regarding social cognition, bvFTD patients were more affected on the Ekman 60 faces test, measuring emotion recognition. In conclusion, this study suggests that bvFTD patients might be differentiated from PPD patients by depressive symptoms, overall cognitive functioning, language and basic social cognitive functioning. These findings contribute to the literature and the clinical diagnostic process of differentiating between bvFTD and PPD patients.