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The Human Brain Rewires Itself in Middle Age

After we hit forty, our brains integrate more and compartmentalize less

It seems designed to get the best of human longevity:

In a systematic review recently published in the journal Psychophysiology, researchers from Monash University in Australia swept through the scientific literature, seeking to summarize how the connectivity of the human brain changes over our lifetimes. The gathered evidence suggests that in the fifth decade of life (that is, after a person turns 40), the brain starts to undergo a radical “rewiring” that results in diverse networks becoming more integrated and connected over the ensuing decades, with accompanying effects on cognition.

Ross Pomeroy, “The brain undergoes a great “rewiring” after age 40” at Big Think (September 24, 2022)

According to the researchers, when we are young, our brains are modular, suited to learning specific tasks. However,

Around our mid-40s, however, that starts to change. Instead, the brain begins becoming less connected within those separate networks and more connected globally across networks. By the time we reach our 80s, the brain tends to be less regionally specialized and instead broadly connected and integrated.

Ross Pomeroy, “The brain undergoes a great “rewiring” after age 40” at Big Think (September 24, 2022) The paper is open access.

In other recent neuroscience news on aging, we learn at Smithsonian Magazine that elders with sharper memories have larger neurons in the brain’s “recall” centers:

In a new study published Friday in The Journal of Neuroscience, researchers imaged the brains of six super-agers who had, during their lives, taken part in ongoing research into their abilities. The super-agers sampled died at an average of 91 years old. The researchers compared those brains to those of seven cognitively average elderly people who had died after 80; six younger people who died at 49, on average; and five people who had early Alzheimer’s.

Margaret Osborne, “‘Super-Agers’ Might Have Super Neurons” at Smithsonian Magazine (October 4, 2022) The paper requires a fee or subscription.

Some of them had cells of the entorhinal cortex (a memory area) that were larger than those of people twenty to thirty years younger.

The entorhinal cortex can be seen at the bottom./
Hagmann P, Cammoun L, Gigandet X, Meuli R, Honey CJ, et al.

Not surprisingly, these “super-agers” also did not accumulate as much of the “tau” protein in their neurons, considered a characteristic of Alzheimer syndrome.

Some of this may be heredity, some an accident, or environment or lifestyle. But another recent large study points to the role of exercise in helping seniors in general retain their memories:

Conducting a meta-analysis of 3,000 patients over 36 studies (carefully vetted from more than 1,200 studies in all), psychologists were able to find that specific exercise helps episodic memory — 3 times a week for 4 months, with greater improvements among those who are age 55 to 68 years…

“Everyone always asks, ‘How much should I be exercising? What’s the bare minimum to see improvement?’ ” said lead author Sarah Aghjayan, a Clinical and Biological Health Psychology PhD student in the Kenneth P. Dietrich School of Arts and Sciences. “From our study, it seems like exercising about three times a week for at least four months is how much you need to reap the benefits in episodic memory.”

Episodic memory is the kind that deals with events that happened to you in the past. It’s also one of the first to decline with age.

University of Pittsburgh, “Exercise can help older adults retain their memories” at ScienceDaily (February 17, 2022) The paper is open access.

But then, maybe not …

You may also wish to read: Ever wish you had total recall? Ask people who do… Recall of every detail of one’s past works out better for some people than for others. Just why some people can recall almost everything that happened to them is a mystery in neuroscience, in part because they are few in number.


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The Human Brain Rewires Itself in Middle Age