Monday, November 5, 2012

High BP may prematurely age the brain

Having even mildly elevated blood pressure at midlife prematurely ages the brain, a new study shows.

Researchers say the early changes seen with higher blood pressure may set the stage for problems with thinking, memory, and dementia down the road. “This is an important finding,” says Paul Rosenberg, MD, associate professor of psychiatry and behavioral sciences at Johns Hopkins University in Baltimore, Md.

“There’s a suggestion here that we should be treating blood pressure more aggressively in younger people,” says Rosenberg, who was not involved in the research. The study used magnetic resonance imaging (MRI) to take a snapshot of the brains of 579 healthy adults who were participating in the third generation of the long-running Framingham Heart Study. People in the study ranged in age from 19 to 63, but on average they were around 39. Doctors measured each person’s blood pressure twice and took the average of the numbers.

Those who had elevated blood pressures showed more signs of early changes on detailed brain scans than those with normal blood pressure. Normal is a systolic pressure (the top number) under 120 and a diastolic pressure (the bottom number) under 80. People who had prehypertension, meaning that their systolic pressure was between 120 and 139 or their diastolic blood pressure was between 80 and 89, had brains that looked about 3.3 years older than normal.Those with high blood pressure, meaning they had a systolic number over 140 or diastolic number over 90, had brains that looked about 7.2 years older. About 50 million Americans have elevated blood pressure. It’s estimated that less than 60% of people who know they have hypertension are treated for it. Only about a third of those people ever get it under control. “These changes are subtle,” says researcher Charles S. DeCarli, MD, director of the Alzheimer’s Disease Center at the University of California, Davis.

DeCarli says people who have them probably wouldn’t notice any problems with thinking or memory because of them, though those things were not measured for the study. But the changes they saw “are very consistent,” DeCarli says, and they look like the beginnings of the kind of damage that’s been seen in the brains of people with full-blown dementia and Alzheimer’s disease.

In particular, the white matter, which is sometimes called the wiring of the brain because it carries nerve signals between brain areas, was starting to look frayed. While the grey matter, which makes up the bulk of the brain’s lobes, was starting to shrink. “This is quite disconcerting because high blood pressure is so common,” DeCarli says. “I worry this can be harmful over time and cause late-life cognitive disability if not aggressively treated.” This study doesn’t prove that high blood pressure alone caused the brain changes. Other studies have shown that diets high in saturated fat and sugar, the same eating patterns that are thought to contribute to obesity and high blood pressure, play a role in changes in the brain that are thought to lead to Alzheimer’s disease.

The Game Theory of Brain Enhancement

A Hitachi engineer displays a portable optical...
,br /> A Hitachi engineer displays a portable optical topography device

Around two years ago I wrote about how brain enhancing technologies were inevitable from a game theoretic point of view. Here is how I put it:
Because nobody will be able to tell whether you’re using it, genius will be indistinguishable from brain mounted computer use. If nobody uses it you will have the advantages over your coworkers that perfect memory would give you today. If everybody but you uses it you will have all the disadvantages that someone with really terrible memory has today. When everyone else uses brain mounted computers, those without them will look forgetful and unknowledgeable. It will be a dominant strategy in the same way that optional genius would be today; only extreme individuals will choose to reject it.
Now in an interesting new article on how technology is increasingly allowing us to enhance our capabilities, David Duncan offers a glimpse of the game theory of brain enhancement in action:
Over the last couple of years during talks and lectures, I have asked thousands of people a hypothetical question that goes like this: “If I could offer you a pill that allowed your child to increase his or her memory by 25 percent, would you give it to them?”
The show of hands in this informal poll has been overwhelming, with 80 percent or more voting no.
Then I asked a follow-up question. “What if this pill was safe and increased your kid’s grades from a B average to an A average?” People tittered nervously, looked around to see how others were voting as nearly half said yes. (Many didn’t vote at all.)
“And what if all of the other kids are taking the pill?” I asked. The tittering stopped and nearly everyone voted yes.
There are a few interesting things to note here. Memory enhancement is not framed as providing a competitive advantage over peers, and few parents choose it. In contrast, “getting better grades” is purely competitive advantage and parents far more parents choose it.  In choosing whether to choose brain enhancements, competition with peers is a crucial determinant. Of course it’s quite easy to imagine that memory enhancement could raise grades by one letter on average, and so in reality parents will probably choose that enhancement in greater numbers than they are indicating here.

The important thing is that people are choosing their enhancements with a focus on strategic peer competition, as I predicted. This is in contrast to a focus on ability and intelligence for it’s own sake. This all suggests that enhancement technologies will be adopted much more frequently than considering our own preferences for enhancement would predict. In short: it doesn’t matter if you don’t want brain enhancement, because your competition will.

Brain May 'See' More Than Eyes

TEHRAN (FNA)- Vision may be less important to "seeing" than is the brain's ability to process points of light into complex images, according to a new study of the fruit fly visual system. 

The findings of the study has been released in the online journal Nature Communications.

University of Virginia researchers have found that the very simple eyes of fruit fly larvae, with only 24 total photoreceptors (the human eye contains more than 125 million), provide just enough light or visual input to allow the animal's relatively large brain to assemble that input into images.

"It blows open how we think about vision," said Barry Condron, a neurobiologist in U.Va.'s College of Arts & Sciences, who oversaw the study. "This tells us that visual input may not be as important to sight as the brain working behind it. In this case, the brain apparently is able to compensate for the minimal visual input."

Condron's graduate students, Elizabeth Daubert, Nick Macedonia and Catherine Hamilton, conducted a series of experiments to test the vision of fruit fly larvae after they noticed an interesting behavior of the animals during a different study of the nervous system. They found that when a larva was tethered to the bottom of a petri dish, other larvae were attracted to it as it wiggled attempting to free itself.

The animals apparently saw the writhing motion and were attracted to it, willingly traveling toward it. After several further experiments to understand how they sensed the motion, the researchers learned that the nearly blind animals likely were seeing the action, by wagging their heads side-to-side in a scanning motion to detect it, rather than by only hearing it or feeling vibration or by smelling the trapped larva. This was a surprise because of the very simple and limited vision of fruit fly larvae.

"The answer must be in the large, somewhat sophisticated brain of these animals," Condron said. "They are able to take just a couple dozen points of light and then process that into recognizable images; something like when an astronomer with a small telescope is able to use techniques to refine a limited image into useful information about a star." Condron believes the animals are able to assemble useful images by rapidly scanning their heads and, in so doing, gather up enough light points to allow the brain to compose a panoramic image clear enough to "see."

The researchers tested this by presenting larva with a video of a writhing larva (therefore no vibration, no sound and no smell) and found that the larvae still detected and sought out the struggling larva on the video. They also learned that if they slowed down or sped up the video, the larvae were less attracted or not attracted at all to the video larva. They also were not attracted to dead real larva, or to tethered larva of another species, and they also had difficulty finding tethered larva in near darkness. "Apparently they are -- to a very high degree -- visually sensitive to detail and rate of motion and can recognize their own species in this way," Condron said. "This provides us with a good model for trying to understand the role that the brain plays in helping organisms, including humans, to process images, such as recognizing faces."

He noted that the head scanning apparently plays an important role in helping the larvae to bring together multiple visual inputs into a unified whole for the brain to process, similar to collecting together multiple pixels to form a picture. Condron said people with severe vision loss also tend to use head scanning as a means for collecting a "picture" from very dim light sources. Likewise, visually impaired people who have received experimental retinal implants of just a small number of pixels also often scan their heads to take in enough light to form mental images.

"It's easy for lab biologists to view fruit flies as simple animals that just feed and reproduce, but we are beginning to realize that that may be in contradiction to the big brain," Condron said. "There's more to what they are able to do than previously thought, whether using that brain for behaviors or for constructing images from a limited visual system."

He said the fruit fly serves as an excellent model for studying neurons because the animal has only about 20,000 of them, whereas humans have about 100 billion. Yet there are many similarities to how fruit fly and human neurons work. According to Condron, researchers are within a year of mapping the entire nervous system of the fruit fly, which then will pave the way for greater understanding of how neurons work in a range of organisms, including humans.

Maths can hurt the brain

Not everyone enjoys solving maths problems. Picture Tim Hunter
maths lessons
STUDENTS have long argued it, teachers have long denied it. But at last science has confirmed what anyone who has ever attempted differential calculus suspected: maths problems can genuinely be physical torture. 
Researchers at the University of Chicago scanned the brains of 28 individuals as they were told they were about to be presented with a maths problem. Fourteen of them had been assessed as especially fearful of maths, having answered a questionnaire in which they were asked to rate their anxiety about different maths-related scenarios.

The questions ranged from the relatively benign “Receiving a math textbook” to the comparatively harrowing “Opening a math or statistics book and seeing a page full of problems”.

When those 14 were told that they were going to have to do some maths, their brain responded, the scientists said, in places also associated with “visceral threat detection, and often the experience of pain itself”.

While much of the public would be familiar with the idea of quadratic equations as visceral threats, the scientific acceptance of this result has been somewhat hampered until now by the fact that scientists are one of those rare groups that rather like quadratic equations.

But this paper, published in the journal PLoS One, could change all that. “Math can be difficult,” the authors say. “For some, even the mere prospect of doing math is harrowing. Those with high levels of mathematics anxiety report feelings of tension, apprehension, and fear of math.”

Interestingly though, it seems that calculus’ bark is worse than its bite. Once people begin to solve a problem, the unpleasant brain activity disappears.

The authors hypothesise that this could be because while people may be scared of maths as an abstract concept, simultaneous equations and, say, hyperdimensional geometry, were not themselves sufficiently common on the African savannah to have affected our evolution.

“Mathematics is a recent cultural invention, so it seems unlikely that pain responses specific to math have been evolutionarily selected for,” the authors said.

“This means that any observed relation between math anxiety and pain would likely be more dependent upon one’s feelings and worries about math (ie, their psychological interpretation or anticipation of the event) than something inherent in the math task itself.”