Metabolic correlates of neuropsychological assessment in behavioral variant frontotemporal dementia

Abstract

AbstractBackgroundNeuropsychological assessment is an essential tool in the diagnosis and monitoring of patients with neurodegenerative disorders. Cognitive functions underlying neuropsychological tests are complex, and accordingly interpretation is often challenging. In behavioral variant frontotemporal dementia (bvFTD), neural correlates of cognitive testing are largely unknown, and they could be different to other settings such as Alzheimer’s disease (AD). In this study, we aimed to analyze the metabolic underpinnings of neuropsychological test results in a series of patients with bvFTD.MethodSeventy‐two patients with bv‐FTD according to the consensus criteria were included. Patients were examined with a comprehensive neuropsychological protocol and 18F‐FDG‐PET. Voxel‐based analysis was used to study the correlation between regional brain metabolism and cognitive performance of the following tests: Boston Naming Test (BNT), Trail Making Test (TMT), Rey‐Osterrieth Complex Figure, verbal fluency (semantic and phonological), Free and Cued Selective Reminding Test (FCSRT), Stroop Color Word Interference test, Tower of London, and Visual Object and Space Perception Battery (VOSP). Age, sex, and years of education were introduced as nuisance covariates. A healthy control and Alzheimer’s disease groups were also examined with the same protocol for comparison. Neuroimaging analyses were conducted using SPM12.ResultMean age in the bvFTD group was 71.33+/‐7.75 years, and 43 (59.7%) were men. In bvFTD, BNT was positively correlated with the left anterior temporal lobe; FCSRT was correlated with the left frontal cortex; Phonological fluency with left frontal lobe and right superior frontal; semantic fluency with left frontal, temporal and thalamus; TMT‐B was negatively correlated with bilateral medial frontal lobes, especially with the right side; VOSP was correlated with the right frontal lobe.ConclusionWe showed the brain regions associated to the performance of different standardized neuropsychological tests in bvFTD. The differences observed between bvFTD and AD suggests that neural underpinnings underlying these tests are different according to each disease, confirming the multiple cognitive processes involved during performance of each particular test. Overall, our study provides useful information to achieve a better understanding of neuropsychological examination in patients with bvFTD. In addition, these findings could be useful to detect cognitive subtypes within the syndrome of bvFTD.