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

December 5, 2007

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. The researchers linked the deterioration to a decrease in the integrity of the brain’s “white matter,” the tissue containing nerve cells that carry information. The researchers found that the disruption occurred even in the absence of pathology associated with Alzheimer’s disease (AD).

Randy Buckner and his colleagues reported their findings in the December 6, 2007, issue of the journal Neuron, published by Cell Press.

The 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.

The researchers reported a “dramatic reduction” in functional connections when they compared the younger and older groups.

The researchers 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.”

Source: Cell Press

Explore further: The diet that feeds your brain

Related Stories

The diet that feeds your brain

September 22, 2016

The Mediterranean diet—rich in vegetables, fish and olive oil and featuring moderate alcohol consumption—has been shown to reduce the risk of heart disease, certain cancers and diabetes.

'Sixth sense' may be more than just a feeling

September 22, 2016

With the help of two young patients with a unique neurological disorder, an initial study by scientists at the National Institutes of Health suggests that a gene called PIEZO2 controls specific aspects of human touch and ...

Automated screening for childhood communication disorders

September 22, 2016

For children with speech and language disorders, early-childhood intervention can make a great difference in their later academic and social success. But many such children—one study estimates 60 percent—go undiagnosed ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Cow embryos reveal new type of chromosome chimera

May 27, 2016

I've often wondered what happens between the time an egg is fertilized and the time the ball of cells that it becomes nestles into the uterine lining. It's a period that we know very little about, a black box of developmental ...

Shaving time to test antidotes for nerve agents

February 29, 2016

Imagine you wanted to know how much energy it took to bike up a mountain, but couldn't finish the ride to the peak yourself. So, to get the total energy required, you and a team of friends strap energy meters to your bikes ...

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.