Visual rating scales of atrophy to differentiate Frontotemporal dementia from Primary psychiatric disorder: results from DIPPA study

Abstract

AbstractBackgroundAdult‐onset behavioral changes and altered executive functioning are frequently caused by behavioural variant of Frontotemporal dementia (bvFTD) or primary psychiatric disorders (PPD) which overlap in terms of clinical presentations but differ in terms of treatment and prognosis. The multi‐centre study DIPPA‐FTD aims to develop diagnostic and prognostic algorithms to help distinguish sporadic bvFTD from late‐onset PPD. Although atrophy on neuroimaging seems to be an appropriate discriminator between neurodegenerative and non‐neurodegenerative conditions, the sensitivity of frontotemporal atrophy for bvFTD is relatively low, whereas decreased brain volumes may be found in conditions like schizophrenia. The aim of the study is to identify a discriminative pattern of brain atrophy between bvFTD and PPD in a clinically applicable way.MethodThe DIPPA FTD consortium retrospectively collected patients with late onset behavioral disturbances after the age of 45 years, across 5 centers (Milan, Amsterdam, Munich, Sydney, Montreal). The subjects had been classified either as bvFTD or PPD according to current clinical criteria and the majority had clinical follow‐up. Among the patients collected in the project, only those with T1 MRI available were selected. A protocol of 9 visual rating scales of atrophy (orbitofrontal, anterior cingulate, anterior temporal, fronto‐insula, medial temporal, parietal, medial ventricular and axial ventricular) was applied by a rater blind for clinical and demographic infomation. The rater was asked to classify the subjects as bvFTD or PPD. A composite score of frontal, temporal and ventricular rating scales was also calculated.ResultThe MRIs of 323 subjects (211 bvFTD and 112 PPD) were analysed. Groupwise bvFTD cases showed significantly higher scores of atrophy for all the scales used. The rater accurately predicted 72% of the cases (Sens 0.70, Spec 0.76) while the composite score reached an accuracy of 76% (Sens 0.77 Spec 0.74). ROC curve analysis showed that fronto‐insula was the single most useful scale in the differentiation between bvFTD and PPD (AUC 0.80).ConclusionBrain atrophy has a significant role in the discrimination between bvFTD and PPD. The use of visual rating scales, and in particular the fronto‐insula one, could increase the diagnostic accuracy in the clinical setting.