October 18, 2008
Myelin And Finger Tapping Speed Peak At Age 39

Have you mentally peaked yet? If we could reverse the decay of neuron insulation in our brains we'd probably maintain fast coordination and better thinking ability for decades longer.

Reporting in the online version of the journal Neurobiology of Aging, Dr. George Bartzokis, professor of psychiatry at the UCLA Semel Institute for Neuroscience and Human Behavior at UCLA, and his colleagues compared how quickly a group of males ranging in age from 23 to 80 could perform a motor task and then correlated their performances to their brains' myelin integrity. The researchers found a striking correlation between the speed of the task and the integrity of myelination over the range of ages. Put another way, after middle age, we start to lose the battle to repair the myelin in our brain, and our motor and cognitive functions begin a long, slow downhill slide.

The myelination of brain circuits follows an inverted U-shaped trajectory, peaking in middle age. Bartzokis and others have long argued that brain aging may be primarily related to the process of myelin breakdown.

"Studies have shown us that as we age, myelin breakdown and repair is continually occurring over the brain's entire 'neural network,'" said Bartzokis, who is also a member of UCLA's Ahmanson–Lovelace Brain Mapping Center and the UCLA Laboratory of Neuro Imaging. "But in older age, we begin losing the repair battle. That means the average performance of the networks gradually declines with age at an accelerating rate."

As the years go by other things are going wrong in the brain as well. But just preventing demyelination would make a big difference.

Myelin is a phospholipid (fat) insulation layer around the axon sections of neurons. It speeds the transmission of electrical impulses down nerves.

Your finger tapping speed and myelin insulation both peak at about age 39. After that it is all downhill until the development of rejuvenation therapies that will remyelinate the brain.

In the study, each of the 72 participants had a magnetic resonance imaging (MRI) scan that measured the myelin integrity in the vulnerable wiring of their brain's frontal lobes. The maximum finger-tapping speed (the number of taps over a period of 10 seconds) was measured just before the MRI measure was obtained.

The results supported what the researcher had suspected, that finger-tapping speed and myelin integrity measurements were correlated and "had lifespan trajectories that were virtually indistinguishable," according to Bartzokis. And yes, they both peaked at 39 years of age and declined with an accelerating trajectory thereafter.

Bartzokis said these observations are consistent with the hypothesis that "maximum motor speeds depend upon high frequency AP bursts that, in turn, depend on the myelin integrity of the neural networks involved in the task."

"Beginning in middle age," he said, "the process of age-related myelin breakdown slowly erodes myelin's ability to support the very highest frequency AP bursts. That may well be why, besides achy joints and arthritis, even the fittest athletes retire and all older people move slower than they did when they were younger."

So what might a rejuvenating myelin repair therapy look like? In the brain we might need youthful oligodendrocyte glial cells that can replace old glial cells that can no longer do as much myelination. In the peripheral nervous system we'll need rejuvenated Schwann cells that serve a similar function.

Another approach might involve development of drugs or gene therapies that will regulate existing glial cells to turn on their myelination activity. Scientists are studying the genetic regulatory mechanisms of how myelination is controlled with research into genes like LINGO-1, connexin29 and connexin32, WAVE1, and the Quaking gene Qk1 among many others. The many scientists trying to figure out myelin formation and glial cell differentiation are doing valuable work that will help at least some of us avoid the cognitive decay characteristic of aging.

Several myelin-related degenerative disorders such as multiple sclerosis and leukodystrophy provide most of the impetus behind myelin research. In fact, myelination problems might underlie some childhood development disorders and addictive disorders. At this point the idea of manipulating glial cells to reverse general brain aging still seems too unorthodox in the mainstream. But fortunately the need to cure diseases that strike at younger ages provides a compelling rationale for developing therapies which will also help to reverse aging. However, if the desirability and attainability of the goal to reverse aging could become mainstream the amount of resources going into brain rejuvenation therapies would soar and we'd get useful treatments sooner.

Share |      Randall Parker, 2008 October 18 09:17 AM  Brain Aging


Comments
Nick G said at October 18, 2008 10:34 AM:

hmmm. Myelin has a large Essential Fatty Acid component. Turmeric is thought to reduce MS (Indians have low levels). Vitamin D is thought to help with MS as well.

I wonder if diet, such as additional EFA, Turmeric and Vitamin D help prevent this age-related myelin degeneration?

Randall Parker said at October 18, 2008 11:50 AM:

Nick G,

I was wondering while writing this post what will slow down myelin degeneration. I wonder if there's any research literature that addresses this question. Will, for example, more dietary omega 3 fatty acids help?

Vitamin D and MS: That's an auto-immune angle I think.

Fly said at October 18, 2008 5:55 PM:

Long term dietary supplementation with choline significantly increased rodent neuron membrane mass.

Nick G said at October 18, 2008 6:45 PM:

"Will, for example, more dietary omega 3 fatty acids help?"

That's what I had in mind when I was talking about EFA's. I believe DHA is the most important. Yes, I want to know about research.

HellKaiserRyo said at October 19, 2008 12:04 AM:

I do not imagine brain rejuvenation therapies being around 40 years. Maybe in 50? What are your timelines for brain rejuvenation?

I am more interested if these brain "rejuvenation" therapies can be used to enhance mental ability. If it can, I suppose many social problems would be solved.

Tj Green said at October 19, 2008 5:20 AM:

MS is very common in Scotland, and there is a lot of research trying to identify the genetic cause. For us the children must survive, for evolution the children must survive until they have reproduced. By stopping the aging process we could end a lot of evolutions obsolete survival strategies before they become destructive. Aging seems to be operating as a switch for many of these disorders like MS. Aging is partly responsible for much of the collateral damage we observe.

Lou Pagnucco said at October 19, 2008 10:21 AM:

My web search for treatments to remyelate aging/injured peripheral/central nervous systems came up with several speculative proposals.

As mentioned above, omega-3 oils may help (whose effects may be enhanced when included in a cocktail with choline and uridine.)

Neurosteroid therapies, particularly with progesterone, and also pregnenolone and testosterone are proposed - although, they may be detrimental for some conditions.

Certain flavonoids and the various forms of vitamin K may promote myelin formation also.

Randall Parker said at October 19, 2008 11:19 AM:

Lou,

Knowing how thorough you can be with digging up studies I appreciate your attempt.

The hormones: I would not expect we could maintain them without serious side-effects. Though perhaps this argues for testosterone supplementation as we age.

Flavonoids: Berries. I eat cranberries every day.

Vitamin K: Kale, collards, spinach, broccoli, asparagus, cabbage (go about half way down that page to see the table).

So this is just another reason to eat greens and berries.

Uridine: Really? This is news to me.

Lou Pagnucco said at October 19, 2008 3:50 PM:

Randall,

Good vitamin K chart. Hopefully, consuming kale, spinach, etc., is protective.

There are quite a few papers on the neurosteroids, especially progesterone.
Yes, there certainly are risks. Maybe they are outweighed by a good risk/benefit ratio?
When we are certain that our brains are deteriorating, even risky options may look good, like jumping from the third story of a burning building.

Regarding uridine - Here are a couple references:

Acylated uridine and cytidine for elevating tissue uridine and cytidine
http://www.freepatentsonline.com/5583117.html

Use of pyrimidine nucleotides for the treatment of affections of the peripheral nervous system
http://www.patentdebate.com/PATAPP/20050222078

The flavonoids that seem to most potently prevent macrophages from demyelinating nerves are luteolin, quercetin and fisetin. (I don't know how much macrophages are to blame for the demylination due to aging.) See:

Flavonoids Inhibit Myelin Phagocytosis
http://bromsams.wikidot.com/flavonoids-inhibit-myelin-phagocytosis

But, some flavonoids may worsen some autoimmune conditions

Oral flavonoids delay recovery from experimental autoimmune encephalomyelitis in SJL mice
http://lib.bioinfo.pl/pmid:15946653

beowulf said at October 19, 2008 11:48 PM:

Beyond fish oil and Vitamin D (I'm sure most everyone here is already taking both), I'd also suggest B12 as a myelin protector.

"Vitamin B12 helps maintain the myelin sheath by playing a crucial role in the metabolism of fatty acids essential for the maintenance of myelin."
http://ms.about.com/od/livingwellwithms/a/vitamin_b12.htm

Kane said at October 20, 2008 12:43 PM:

I came across similar info about uridine a little over a year ago while I was studying for the bar exam and looking for a mental edge. At the time, I was able to find only supplement formula that contained uridine; I purchased it, but did not continue after the bottle ran out. Maybe I should have.

Also, I have read that Evening Primrose Oil is myelin-protective.

Gargle said at November 3, 2008 9:24 AM:

You're so obsessed with living forever, while there are millions of people who can't even afford the most basic of health care, even in our own country. This state of affairs makes me sick, that people like you will be driving medical progress for the next century. You'll be living forever while many don't even get the chance to live even until adulthood.

Gargle-This said at November 3, 2008 5:59 PM:

Hey Gargle,
Indeed your confession of sickness is accurate. However, it is your mindset that is pathological. Having concern about one's own longevity is normal. Your over-developed sense of guilt places you numerous standard deviations away from the mean in the wrong direction. Perhaps self-loathing is a symptom of under-myelination?

Stephen said at March 11, 2012 5:05 PM:

Some will live and some will die. Self loathing is a sickness, get over yourself.

Geert said at June 6, 2013 2:23 PM:

Haha Gargle, you got so owned.

It's simple, in order to take care of others i have to take care of me first. Taking care of me does not exclude taking care of others. Both can go hand in hand.
The world is a crazy place gargle. Keep yourself and your tribe safe. You can't fend for all the world.

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