DEC 30, 2019 6:55 PM PST

Amyloid Plaques May Not Come First in Alzheimer's

WRITTEN BY: Annie Lennon

It’s commonly thought that excessive build-up of amyloid plaques, destroying the connections between nerve cells, is the first sign of Alzheimer’s disease. Now however, a new study challenges this theory. 

For the study, researchers examined 747 participants without dementia from the Alzheimer’s Disease Neuroimaging Initiative. With each participant having received amyloid PET scan and structural MRIs, 305 were classified as cognitively normal, 289 had mild cognitive impairment (MCI), and 153 had objectively defined, subtle cognitive difficulties (Obj-SCD). Their mean age at the beginning of data collection was 72, and approximately half were men. 

After adjusting for age, education, sex, APOE ε4 allele frequency and baseline amyloid levels, the researchers found that tha Obj-SCD group had acceleated amyloid accumulation over 4 years than those in the cognitively normal group. They also had faster entorhinal cortical thinning, something known to negatively affect perceptual and cognitive function, than those in the cognitively normal group. 

By comparison, those with MCI did not display faster accumulation of amyloid plaques than cognitively normal participants. However, like those in the Obj-SCD group, they also faced accelerated entorhinal cortical thinning. They also displayed faster hippocampal atrophy, known to increase memory loss, over the study period. 

Lead author of the study, Kelsey Thomas, said, “Our research was able to detect subtle thinking and memory differences in study participants and these participants had faster amyloid accumulation on brain scans over time, suggesting that amyloid may not necessarily come first in the Alzheimer's disease process.”

She added, “Much of the research exploring possible treatments for Alzheimer's disease has focused on targeting amyloid...But based on our findings, perhaps that focus needs to shift to other possible targets."

Despite these findings however, the researchers warn that their results do not necessarily refute the amyloid-first hypothesis. This comes as although baseline amyloid levels were numerically higher in the group with cognitive difficulties, they were not statistically higher, meaning that the start of fibrillar or soluble forms of beta-amyloid may have come before, if not coincided with, cognitive decline. Moreover, it remains unknown as to whether such cognitive issues are representative of longer-term, trait-like issues, or just more recent impairment. 

 

Sources: Medpage Today, Neurology and News Medical   

 

About the Author
  • Science writer with a keen interest in behavioral biology, consciousness medicine and technology. Her current focus is how the interplay of these fields can create meaningful interactions, products and environments.
You May Also Like
JAN 18, 2021
Chemistry & Physics
Watching the eletronic signals of a wandering mind
JAN 18, 2021
Watching the eletronic signals of a wandering mind
A study published recently in the Proceedings of the National Academy of Sciences contemplates the places our minds ...
JAN 24, 2021
Neuroscience
Is Parkinson's Disease Linked to Gut Fungi?
JAN 24, 2021
Is Parkinson's Disease Linked to Gut Fungi?
Studies show an association between the gut microbiome and Parkinson's disease. Up until now, though, no studies had ...
FEB 10, 2021
Neuroscience
Traumatic Childhood Affects Adult Brain Structure
FEB 10, 2021
Traumatic Childhood Affects Adult Brain Structure
For some time, trauma or maltreatment during childhood has been known to increase one’s risk of developing mental ...
MAR 24, 2021
Cardiology
Supplement Can Prevent Strokes in Patients with Rare Disease
MAR 24, 2021
Supplement Can Prevent Strokes in Patients with Rare Disease
Scientists have found that it may be possible for people with a rare genetic disorder to prevent fatal strokes by taking ...
APR 18, 2021
Genetics & Genomics
The Biology of Autism May Depend on Sex
APR 18, 2021
The Biology of Autism May Depend on Sex
It's been unclear whether boys are diagnosed with autism spectrum disorder more often because of detection issues, or if ...
APR 26, 2021
Health & Medicine
Brain Circuit Activity Can Predict Who Handles Stress Better
APR 26, 2021
Brain Circuit Activity Can Predict Who Handles Stress Better
    People often complain of stress in their daily lives, but what makes one person swear and fume at the begi ...
Loading Comments...