Brain Activity Study Offers Potential Insight into Alzheimer’s Disease

Summary: A new study may provide key insights into the risk of developing Alzheimer’s disease. Researchers report people with higher levels of amyloid beta showed less activity in brain areas associated with working memory when engaged in cognitively demanding tasks.

Source: UT Dallas.

Slightly elevated beta-amyloid levels in the brain are associated with increased activity in certain brain regions, according to a new study from the Center for Vital Longevity (CVL) at The University of Texas at Dallas.

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Both hyper- and hypo-activation to cognitive challenge are associated with increased beta-amyloid deposition in healthy aging: A nonlinear effect

Beta-amyloid (Aβ) positive individuals hyper-activate brain regions compared to those not at-risk; however, hyperactivation is then thought to diminish as Alzheimer’s disease symptomatology begins, evidencing eventual hypoactivation. It remains unclear when in the disease staging this transition occurs. We hypothesized that differential levels of amyloid burden would be associated with both increased and decreased activation (i.e., a quadratic trajectory) in cognitively-normal adults. Participants (N = 62; aged 51–94) underwent an fMRI spatial distance-judgment task and Amyvid-PET scanning. Voxelwise regression modeled age, linear-Aβ, and quadratic-Aβ as predictors of BOLD activation to difficult spatial distance-judgments. A significant quadratic-Aβ effect on BOLD response explained differential activation in bilateral angular/temporal and medial prefrontal cortices, such that individuals with slightly elevated Aβ burden exhibited hyperactivation whereas even higher Aβ burden was then associated with hypoactivation. Importantly, in high-Aβ individuals, Aβ load moderated the effect of BOLD activation on behavioral task performance, where in lower-elevation, greater deactivation was associated with better accuracy, but in higher-elevation, greater deactivation was associated with poorer accuracy during the task. This study reveals a dose-response, quadratic relationship between increasing Aβ burden and alterations in BOLD activation to cognitive challenge in cognitively-normal individuals that suggests 1) the shift from hyper-to hypo-activation may begin early in disease staging, 2) depends, in part, on degree of Aβ burden, and 3) tracks cognitive performance.

Source: Alex Lyda – UT Dallas Publisher: Organized by Image Source: image is adapted from the UT Dallas news release. Original Research: Abstract for “Both hyper- and hypo-activation to cognitive challenge are associated with increased beta-amyloid deposition in healthy aging: A nonlinear effect” by Chris M. Foster, Kristen M. Kennedy,Marci M. Horn, David A. Hoagey, and Karen M. Rodrigue in NeuroImage. Published April 2018. doi:10.1016/j.neuroimage.2017.10.068