Neural correlates of behavioural symptoms in behavioural variant frontotemporal dementia and Alzheimer's disease: Employment of a visual MRI rating scale

Frontotemporal dementia (FTD) patients often present with severe behavioural disturbances and concomitant lack of insight. The underlying neural correlates of these disturbances are mostly attributed to prefrontal cortex dysfunction, but are still poorly understood. Objectives: The current study explores whether a simple visual magnetic resonance imaging (MRI) rating scale in combination with the Frontal System Behaviour Scale (FrSBe) can be used to identify the prefrontal correlates of behavioural symptoms in behavioural variant frontotemporal dementia (bvFTD) and Alzheimer's disease (AD). Methods: Forty-eight patients with a clinical diagnosis of bvFTD and AD participated in the study. Their behavioural profiles were assessed using the Frontal System Behaviour Scale (FrSBe) and cross-correlated to the atrophy of the sub-regions in the prefrontal cortex using a 5-point visual rating scale of MRI scans. Results: Patients with bvFTD showed higher incidence of behavioural disturbances than AD with apathy being the most significant. BvFTD patients also showed the highest incidence of atrophy in the orbital frontal cortex and this atrophy was correlated with the apathetic features. Conclusions: Employment of a simple visual MRI rating scale can be used in combination with a behavioural screening test to identify reliably the behavioural symptoms in bvFTD and AD. These findings will inform the diagnostic accuracy of the neural correlates of behavioural dysfunction in bvFTD in the future.