Altered deactivation in individuals with genetic risk for Alzheimer's disease.
Regions that show task-induced deactivations may be part of a default-mode network related to processes that are more engaged during passive than active task conditions. Alteration of task-induced deactivations with age and dementia is indicated by atypical engagement of default-mode network regions. Genetic studies show a relation between the apolipoprotein E4 (APOE4) allele and the common form of Alzheimer's disease (AD), and altered functional brain activation has been observed in non-demented APOE4 carriers compared to non-carriers. Here we investigate the hypothesis of altered default-mode network brain responses in individuals with genetic risk for AD. Functional MRI was used to assess task-induced deactivation in 60 subjects of which 30 carried at least one copy of the APOE4 allele, and 30 non-carriers. Subjects were scanned while performing a semantic categorization task shown to promote episodic memory encoding. The results show patterns of deactivation consistent with the default-mode network. We also found reduced deactivation in non-demented APOE4 carriers compared to non-carriers, suggesting alterations in the default-mode network in the absence of dementia. These results implicate possibilities for investigating altered properties of task-induced deactivations in individuals with genetic risk for AD, and may prove useful for pre-clinical identification of individuals susceptible to memory problems and AD.
Persson
J
J
Department of Psychology, Stockholm University, S-106 91 Stockholm, Sweden. jonas.persson@psychology.su.se
Lind
J
J
Larsson
A
A
Ingvar
M
M
Sleegers
K
K
Van Broeckhoven
C
C
Adolfsson
R
R
Nilsson
L-G
LG
Nyberg
L
L
D000368:Aged; D000544:Alzheimer Disease / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology*; D053327:Apolipoprotein E4; D001921:Brain / Q000098:blood supply / Q000473:pathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D010100:Oxygen / Q000097:blood; D012660:Semantics
D053327:Apolipoprotein E4; D010100:Oxygen