title: Executive deficits are related to the inferior frontal junction in early dementia.
abstract: Executive functions describe a wide variety of higher order cognitive processes that allow the flexible modification of thought and behaviour in response to changing cognitive or environmental contexts. Their impairment is common in neurodegenerative disorders. Executive deficits negatively affect everyday activities and hamper the ability to cope with other deficits, such as memory impairment in Alzheimer's disease or behavioural disorders in frontotemporal lobar degeneration. Our study aimed to characterize the neural correlates of executive functions by relating respective deficits to regional hypometabolism in early dementia. Executive functions were assessed with two classical tests, the Stroop and semantic fluency test and various subtests of the behavioural assessment of the dysexecutive syndrome test battery capturing essential aspects of executive abilities relevant to daily living. Impairments in executive functions were correlated with reductions in brain glucose utilization as measured by [(18)F]fluorodeoxyglucose positron emission tomography and analysed voxelwise using statistical parametric mapping in 54 subjects with early dementia, mainly Alzheimer's disease and frontotemporal lobar degeneration, and its prodromal stages: subjective and mild cognitive impairment. Although the analysis revealed task-specific frontoparietal networks, it consistently showed that hypometabolism in one region in the left lateral prefrontal cortex-the inferior frontal junction area-was related to performance in the various neuropsychological tests. This brain region has recently been related to the three component processes of cognitive control-working memory, task switching and inhibitory control. Group comparisons additionally showed hypometabolism in this area in Alzheimer's disease and frontotemporal lobar degeneration. Our study underlines the importance of the inferior frontal junction area for cognitive control in general and for executive deficits in early dementia.
authors.affiliation: Max Planck Institute for Human Cognitive and Brain Sciences, Stephanstr. 1A, 04103 Leipzig, Germany. schroet@cbs.mpg.de
authors.forename: Matthias L
authors.initials: ML
authors.lastname: Schroeter
authors.forename: Barbara
authors.initials: B
authors.lastname: Vogt
authors.forename: Stefan
authors.initials: S
authors.lastname: Frisch
authors.forename: Georg
authors.initials: G
authors.lastname: Becker
authors.forename: Henryk
authors.initials: H
authors.lastname: Barthel
authors.forename: Karsten
authors.initials: K
authors.lastname: Mueller
authors.forename: Arno
authors.initials: A
authors.lastname: Villringer
authors.forename: Osama
authors.initials: O
authors.lastname: Sabri
mesh_terms: D000368:Aged; D060825:Cognitive Dysfunction / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology; D003704:Dementia / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology; D056344:Executive Function / Q000502:physiology*; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011877:Radionuclide Imaging