Cognitive "fog" of normal aging linked to brain system disruption

December 7, 2007
Cognitive
Researchers concentrated on large-scale connections between frontal and posterior brain regions that are associated with high-level cognitive functions such as learning and remembering.

Comparisons of the brains of young and old people have revealed that normal aging may cause cognitive decline due to deterioration of the connections among large-scale brain systems, including a decrease in the integrity of the brain's "white matter," the tissue containing nerve cells that carry information, according to a new study co-authored by several researchers from Washington University in St. Louis.

The study, which finds that the disruption occurs even in the absence of pathology associated with Alzheimer's disease (AD), is published by Cell Press in the Dec. 6, 2007, issue of the journal Neuron.

WUSTL co-authors include Denise Head, Ph.D., assistant professor of psychology and of African and African American Studies in Arts & Sciences and research assistant professor of radiology in the School of Medicine; Abraham Z. Snyder, Ph.D., M.D., research scientist with the Mallinckrodt Institute of Radiology and research associate professor of radiology in the School of Medicine; and Marcus E. Raichle, M.D., professor of neurology, of radiology and of anatomy and neurobiology in the School of Medicine.

Researchers assessed brain function in a sample of adults ranging in age from 18 to 93 and comprising 38 young adults and 55 older adults. They did so using functional magnetic resonance imaging (fMRI), which uses harmless radio waves and magnetic fields to measure blood flow in brain regions, which in turn reflects activity.

To assess the integrity of functional connections between brain areas, the researchers used fMRI to measure spontaneous low-frequency fluctuations known to reflect the activity of such connections. The researchers concentrated on large-scale connections between frontal and posterior brain regions that are associated with high-level cognitive functions such as learning and remembering.

Researchers reported a "dramatic reduction" in functional connections when they compared the younger and older groups.

The team also used an MRI technique called "diffusion tensor imaging" to measure the integrity of white matter in the brains of the subjects. This technique reveals details of the structure of brain tissue. Their analysis revealed that the reduced functional connection they detected in brain areas of the older subjects was correlated with decreased white matter integrity.

When the researchers tested the subjects' cognitive function, they found that "Those individuals exhibiting the lowest functional correlation also exhibited the poorest cognitive test scores."

The researchers concluded that "our observations suggest that within the context of globally intact brain systems, subtle changes accumulate over time in advanced aging that disrupt the coordination of large-scale brain systems."

They also said that, although AD is known to produce similar deterioration due to pathological deposits of amyloid protein, "Our present results, in particular the analysis of individuals without amyloid deposition, show that normal aging is associated with a form of system disruption that is distinct from that associated with AD."

The research team also included investigators from the Howard Hughes Medical Institute, Harvard University, University of Michigan and Massachusetts General Hospital.

Source: Washington University in St. Louis

Explore further: Investigators compare effects of nicotine with and without menthol on brain and behavior

Related Stories

Investigators compare effects of nicotine with and without menthol on brain and behavior

November 16, 2017
A new study from UMass Medical School researchers at the Center for Comparative Neuroimaging explores the link between mentholated tobacco and nicotine addiction. They found that menthol administered with nicotine alters ...

Next-generation optogenetic molecules control single neurons

November 13, 2017
Researchers at MIT and Paris Descartes University have developed a new optogenetic technique that sculpts light to target individual cells bearing engineered light-sensitive molecules, so that individual neurons can be precisely ...

Researchers find pathological signs of Alzheimer's in dolphins, whose brains are much like humans'

November 14, 2017
A team of scientists in the United Kingdom and the U.S. recently reported the discovery of pathological signs of Alzheimer's disease in dolphins, animals whose brains are similar in many ways to those of humans.

New theory of how the brain transforms sensations into mental objects

November 15, 2017
Inputs to the brain from the eyes, ears, and skin are continually changing as we move. Yet our brain perceives objects in the world as stable. How the brain learns the structure of the world from rapidly changing inputs is ...

Music training strengthens children's brains, decision-making network

November 14, 2017
If the brain is a muscle, then learning to play an instrument and read music is the ultimate exercise.

Cognitive training enhanced innovative thinking and brain networks in older adults

November 14, 2017
Researchers at the Center for BrainHealth at UT Dallas have demonstrated in a pilot study that cognitive training improves innovative thinking, along with corresponding positive brain changes, in healthy adults over the age ...

Recommended for you

Hibernating ground squirrels provide clues to new stroke treatments

November 17, 2017
In the fight against brain damage caused by stroke, researchers have turned to an unlikely source of inspiration: hibernating ground squirrels.

Age and gut bacteria contribute to multiple sclerosis disease progression

November 17, 2017
Researchers at Rutgers Robert Wood Johnson Medical School published a study suggesting that gut bacteria at young age can contribute to multiple sclerosis (MS) disease onset and progression.

Molecular guardian defends cells, organs against excess cholesterol

November 16, 2017
A team of researchers at the Harvard T. H. Chan School of Public Health has illuminated a critical player in cholesterol metabolism that acts as a molecular guardian in cells to help maintain cholesterol levels within a safe, ...

Prototype ear plug sensor could improve monitoring of vital signs

November 16, 2017
Scientists have developed a sensor that fits in the ear, with the aim of monitoring the heart, brain and lungs functions for health and fitness.

Ancient enzyme could boost power of liquid biopsies to detect and profile cancers

November 16, 2017
Scientists are developing a set of medical tests called liquid biopsies that can rapidly detect the presence of cancers, infectious diseases and other conditions from only a small blood sample. Researchers at The University ...

FDA to crack down on risky stem cell offerings

November 16, 2017
U.S. health authorities announced plans Thursday to crack down on doctors pushing stem cell procedures that pose the gravest risks to patients amid an effort to police a burgeoning medical field that previously has received ...

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.