Dissociable executive functions in behavioral variant frontotemporal and Alzheimer dementias

Abstract

Objective: The objective of this study was to determine which aspects of executive functions are most affected in behavioral variant frontotemporal dementia (bvFTD) and best differentiate this syndrome from Alzheimer disease (AD). Methods:We compared executive functions in 22 patients diagnosed with bvFTD, 26 with AD, and 31 neurologically healthy controls using a conceptually driven and comprehensive battery of executive function tests, the NIH EXAMINER battery (http://examiner.ucsf.edu).Results: The bvFTD and the AD patients were similarly impaired compared with controls on tests of working memory, category fluency, and attention, but the patients with bvFTD showed significantly more severe impairments than the patients with AD on tests of letter fluency, antisaccade accuracy, social decision-making, and social behavior. Discriminant function analysis with jackknifed cross-validation classified the bvFTD and AD patient groups with 73% accuracy. Alzheimer disease (AD) and behavioral variant frontotemporal dementia (bvFTD) are neurodegenerative diseases that affect executive functions. Conclusions:1,2 Executive functions support goal-oriented behavior and include working memory, inhibition, mental flexibility, fluency, self-monitoring, and organizing appropriate social behavior. [3][4][5] It is unknown whether the executive impairments are the same in both disorders, or whether differences could assist with differential diagnosis.According to a recent meta-analysis of 94 studies, the frequently used executive function tests do not reliably differentiate FTD and AD. 6 Several of the studies included progressive aphasia patients with bvFTD, making the results difficult to interpret. Some studies have identified select measures of rule violation, poor planning, perseveration, letter fluency relative to category fluency, and organizing appropriate social behavior that are more impaired in bvFTD than AD. [7][8][9][10][11]

Understanding the cognitive underpinnings of functional impairments in early dementia: a review

“…In particular, a larger proportion of FTD patients performed poorly on ADLs than SD and AD patients, whilst similar proportions of FTD patients struggled with IADLs compared with SD and AD patients. One of the main areas of cognition that deteriorates early in FTD is executive function (Possin et al, 2013). These findings therefore suggest that executive function critically supports both IADL and ADL performance, but perhaps more the latter as, compared to FTD, mild AD (with relatively less executive impairment) shows a relative sparing of ADL performance.…”

Evaluating Behavior in Mouse Models of the Behavioral Variant of Frontotemporal Dementia: Which Test for Which Symptom?

“…Lack of concentration is common in bvFTD and is associated with a loss of selective attention and a susceptibility to interferences [76]. For instance, bvFTD patients show deficits in the Stroop test [68].…”

Apraxia profile differentiates behavioural variant frontotemporal from Alzheimer's dementia in mild disease stages

“…Yet, apraxia has not been evaluated in behavioural variant frontotemporal dementia (bvFTD), a neurodegenerative disease that is characterised by early and progressive atrophy of the medial frontal cortex 12. Alongside insidious changes in social conduct, patients with bvFTD display deficits in social perspective taking and mentalising abilities13 14 but also in planning and organisation of complex action due to frontal-executive dysfunction 15…”