Sunday, February 27, 2011

Enlarge your brain in only 8 weeks!

Having a big brain seems like a very desirable thing right now (it certainly wasn't "trendy" when I was in high school, though). Games like "Big Brain Academy" measure your success by the size of your virtual brain. In the real world, scientific studies right, left and center extol the virtues of anything ranging from exercise to learning a new language as ways of expanding your gray matter. It turns out that learning to manage your stress might also do the trick, as I found out from a recent article pointed out to me by my friend Fawn.

The article looks at mindfulness mediation, a practice that involves becoming aware of experiences in the present moment without judging oneself. Many studies have already shown that mindfulness-based stress reduction programs can ease symptoms of anxiety and depression and can improve sleep and attention. But how does it work? To answer this question, researchers studied what mindfulness meditation does to your brain (to learn about what mindfulness mediation does to your pain, see this post).

The study looked at a handful of participants enrolled in an 8-week Mindfulness-Based Stress Reduction course. This course entails one meeting per week, one full day of training in week 6, and daily homework to do at home (meditation exercises). The experiment was very simple: researchers took a picture of each participant's brain using magnetic resonance imaging (MRI) at two time points: before the course started, and once it was over (8 weeks later). They also took pictures of the brains of control subjects who didn't take the course (also about 8 weeks apart).

By now I'm sure you've guessed the results: yup, the participants who meditated had significantly bigger brains. One area of the brain in particular was bigger: the hippocampus, a region known for its role in memory, but also involved in emotions. The researchers hypothesized that the increase in gray matter in the brain of people who mediate may explain the improvement they experience in dealing with their emotions. This hypothesis is supported by the fact that people who suffer from certain emotion-related diseases and disorders like depression and post-traumatic stress disorder often have a smaller hippocampus.

While I'm a big believer in meditation (this blog is so biased!), there are two limitations of this study worth mentioning. First, the researchers only looked at about 14 participants in each group. That's a pretty small sample, so it will be interesting to see what later experiments looking at more subjects come up with. Second, the mindfulness-based stress reduction program is not only about meditating: it also involves social interaction at the weekly meetings, stress education, and gentle stretching, which the control participants didn't get. So it's quite possible that the effect described here (bigger brains) are not the result of meditation per se. At this point we can't tease it out.

Regardless of these limitations, though, the study drives home an important message: the adult brain can change in response to training. I for one find some comfort in that.

Reference: Mindfulness practice leads to increases in regional brain gray matter density. (2011) Holzel BK et al. Psychiatry Research: Neuroimaging, 191:36-43.

Wednesday, February 16, 2011

A picture better be worth a thousand words

My friend Michael (a.k.a. this crazy guy – would you please send him to New Zealand?) recently blogged about undergoing what he perceived as an unnecessary medical imaging procedure. He was concerned that this exposure to radiation might impact his fertility. A recent study suggests that Michael should add cancer to his list of concerns.

We’ve known for a long time that radiation is bad news. Scientists studied atomic bomb survivors and found that those who were closest to the blast had a higher incidence of cancer than survivors who were farther from the blast. While the evidence is conclusive, the atomic bomb delivered a much higher dose of radiation than medical imaging procedures. To tease out whether low-dose radiation from medical imaging procedures also increase one’s risk of developing cancer, a team of researchers from McGill University analyzed a group of over 80,000 patients who were admitted to the hospital for a heart attack. They perused the medical records of these patients and noted who received medical procedures involving radiation and who didn’t, and then followed-up by finding out who got cancer later on.

The researchers found that over 10,000 patients developed cancer later on. Interestingly, two-thirds of those cases of cancer were located in the abdomen, pelvis or thorax (presumably the areas that would be subject to medical imaging procedures aimed at the heart). After looking at each patient’s history of procedures, the researchers were able to determine that the more radiation one is exposed to, the higher the risk of developing cancer.

While the study looks at a large number of patients and shows a significant link between radiation exposure and cancer risk, the researchers were limited in that they only had the information available in the medical records. This means that while they controlled for variables like age and sex, they didn’t know everything about the patients: what they ate, how much exercise they did, what kind of environment they worked in. There may be a confounding variable that we don’t know about. As well, the researchers did not assess mortality as an end-point, and even write, “These patients most likely will die of cardiac-related causes”. So it’s important to remember that the scenario is not 1) patient has heart attack, 2) patient undergoes medical procedures, 3) patient gets all better heart-wise but develops cancer because of the procedures, 4) patient dies of cancer. It’s likely much, much more complicated than that.

That said, any medical procedure is all about risks and benefits. We need to weigh the risks of cumulative exposure to radiation (you’ll be glad to know that exposure to radiation from a single test does not substantially increase your risk of cancer) against the value of the information that the medical imaging procedure will provide. Not always an easy task. In Michael’s case, the physician was clear: she was running the test to appease his wife. Now what is that worth to you?

Reference: Cancer risk related to low-dose ionizing radiation from cardiac imaging in patients after acute myocardial infarction. (2011) Eisenberg MJ et al. Canadian Medical Association Journal. [Epub ahead of print].

Sunday, February 6, 2011

The Super Bowl: Inspiring traumatic brain injury since 1966!

It’s Super Bowl Sunday. Most of us spend the day eating nachos and wings, drinking beer, and acting rowdy in front of the television. For those of us who don’t have a television or snack foods in the vicinity (gasp!), we may chose to spend the day looking up scientific articles with a mention of football and writing blogs. I’m going to let you guess what I did.

High school can be a dangerous place: many will go through those few years carefully balancing social life, self-esteem, some sort of learning and the inevitable characterization of every single person into a specific group (you might be surprised to find out that I fit in the “jock” category). For the athletes, high school can also be dangerous for something very precious: their brains.

In a recent study, researchers looked at the incidence of concussions in high school sports over eleven years (1997 to 2008). They wanted to know whether certain sports had higher rates of concussions, and whether the incidence of concussions varied by gender, and over time. So they followed 25 high schools in a large public school district and recorded every instance of concussions for twelve sports: football, lacrosse, wrestling, soccer, basketball and baseball for boys, and field hockey, lacrosse, soccer, basketball, cheerleading and softball for girls.

The researchers reported a few interesting findings. They recorded nearly eleven million instances of a student playing a given sport, and out of those, identified 2651 instances of concussions. While boys accounted for just over half of the instances of students playing a sport, they accounted for three quarters of all concussions. Perhaps not surprisingly, football accounted for more than half of all instances of concussions. Baseball was the boy’s sport with the lowest incidence of concussions. For girls, soccer took the lead with the highest incidence of concussions, while cheerleading had the lowest incidence. Unfortunately for all my Canadian readers, the researchers left out our national sport, so I’m not sure how hockey would compare. But hey, we can talk about hockey when the Stanley Cup rolls around.

What surprised me the most in this study is that the overall rate of concussions increased significantly over time (a 4-fold increase between 1997 and 2008). Football showed the greatest increase in concussion rates over time, but it’s important to note that all twelve sports showed an increased concussion rate over time.

As for sex differences, the researchers found that for sports that are the same for girls and boys (like soccer and basketball), girls had a higher rate of concussions. However, in lacrosse, where the girl’s game has different rules, protective equipment and nature of play when compared with the boy’s game, girls had a lower concussion rate than boys.

There are several factors that could explain some of these results: an increase in concussion rates over time could be explained by a greater awareness of this medical phenomenon, and thus an increase in the reporting of concussions. Girls could be showing higher concussion rates for the sports they share with the boys because evidence shows that girls tend to be more willing to report injuries. However, even when all these factors are considered, the study highlights a need to prevent, detect and treat concussions across all sports, not just football. Concussions can be a serious brain injury, especially if complications develop, and repeated concussions are particularly dangerous, as they can lead to dementia.

In the heat of the Super Bowl, I don’t want to be a complete downer, though: being active during your teenage years can have numerous benefits, and can lead to habits that will last a lifetime and play an important role in preventing a whole load of diseases. So play away, but just make sure to protect that noggin’ (and parents: chose that extracurricular activity wisely)!

Reference: Trend in concussion incidence in high school sports: a prospective 11-year study. (2011) Lincoln AE and al. Am J Sports Med [Epub ahead of print].

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