Alzheimer's Gene Alters Brain Function in Young Adults

September 10, 2009,

(PhysOrg.com) -- The gene most closely linked to an increased risk of developing Alzheimer's disease affects brain activity in young adults -- much earlier in life than previously reported -- according to researchers at Duke University Medical Center and The Pennsylvania State University.

Study participants in their mid-20s with a gene variant known as APOE4 demonstrated increased activity and altered connectivity in parts of the brain that are the first to show signs of Alzheimer's disease in older adults.

"While young people with and without the APOE4 gene had similar scores on a battery of memory tests, the brains of young people with the gene appear to be working harder or less efficiently to achieve the same results as people without the gene," said Jeffrey Browndyke, PhD, study co-author and director of the Functional Imaging Neurogenomics of Disease Lab at Duke.

While some researchers have theorized that APOE4 may enhance memory abilities in early life, the new findings suggest that the heightened activity may be the brain's way of compensating for a weakened ability to create memories.

In addition to the differences seen in an area of the brain known as the medial temporal lobes (MTL), researchers also found differences among people with the APOE4 gene in the MTL's communication with areas of the brain associated with memory processing.

"APOE4 gene carriers show increased activity in the MTL and increased communication between that region and other brain regions known to be effected by Alzheimer's disease, while those without the gene tend to show widespread cortical connectivity with the MTL," said Nancy A. Dennis, PhD, study co-author and assistant professor of Psychology at Penn State.

The study findings are published online in the journal Alzheimer's & Dementia, the official journal of the Alzheimer's Association.

Twenty-four healthy adults in their mid-twenties, twelve carriers and twelve non-carriers of the APOE4 gene, completed a memory test while undergoing functional magnetic resonance imaging (fMRI).

The were shown a series of images and asked to provide feedback about what they saw. The next day participants were brought back to the lab and presented with a surprise test to determine how well they remembered the images.

Brain activity for remembered versus forgotten items was compared between the study groups. The fMRI data provided the research team with information about the areas of the brain that became active when the individuals looked at pictures that were subsequently remembered a day after the brain scan.

The researchers said that the memory scores of the study participants and their brain structures were comparable in the two groups. People with and without the APOE4 gene variant were able to recall a similar amount of information and completed the tests with a similar level of accuracy and speed.

There were no differences in the volume of white matter, the communication channels of the brain, or grey matter, the information storage center of the brain.

"While all of the young adults performed similarly and their brains appeared the same, there are clear differences in brain activity and interconnection in people with the APOE4 gene that appear earlier in life than previously observed," Browndyke said.

"We need to further explore the gene's effect on brain development and early cognitive function to determine who ultimately is at risk for Alzheimer's disease."

The authors caution that the study findings need to be replicated in a larger population of with and without the APOE4 gene. They also said that the only confers an increased risk for , not a diagnostic certainty.


Join PhysOrg.com on Facebook!
Follow PhysOrg.com on Twitter!
Provided by Duke University (news : web)

Related Stories

Recommended for you

New software helps detect adaptive genetic mutations

February 20, 2018
Researchers from Brown University have developed a new method for sifting through genomic data in search of genetic variants that have helped populations adapt to their environments. The technique, dubbed SWIF(r), could be ...

15 new genes identified that shape human faces

February 20, 2018
Researchers from KU Leuven (Belgium) and the universities of Pittsburgh, Stanford, and Penn State have identified 15 genes that determine facial features. The findings were published in Nature Genetics.

New algorithm can pinpoint mutations favored by natural selection in large sections of the human genome

February 20, 2018
A team of scientists has developed an algorithm that can accurately pinpoint, in large regions of the human genome, mutations favored by natural selection. The finding provides deeper insight into how evolution works, and ...

Highly mutated protein in skin cancer plays central role in skin cell renewal

February 20, 2018
Approximately once a month, our skin completely renews itself. If this highly coordinated process goes awry, it can lead to a variety of skin diseases, ranging from skin cancer to psoriasis. Cells lining such organs as skin ...

Study of smoking and genetics illuminates complexities of blood pressure

February 15, 2018
Analyzing the genetics and smoking habits of more than half a million people has shed new light on the complexities of controlling blood pressure, according to a study led by researchers at Washington University School of ...

New mutation linked to ovarian cancer can be passed down through dad

February 15, 2018
A newly identified mutation, passed down through the X-chromosome, is linked to earlier onset of ovarian cancer in women and prostate cancer in father and sons. Kunle Odunsi, Kevin H. Eng and colleagues at Roswell Park Comprehensive ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.