Monday, June 28, 2010

The little-known benefits of pumping iron

At the risk of sounding like a broken record, exercise is good for you and your brain. That being said, most studies looking at exercise and cognitive function evaluate aerobic exercise (the kind that gets your heartbeat going). The other kind of exercise, resistance training (strength training with weights), has not been of much interest, perhaps due to the old stereotype that has been plaguing bodybuilders forever: big biceps, small IQ (although big biceps never stopped anyone from becoming governor of California). Switch the young lads for older women, though, and a recent study from a team of researchers at the University of British Columbia (represent!) suggests that gaining muscle can translate into a better brain.

The study looked at 135 women between the ages of 65 and 75 over the course of a year. The women were assigned one of three groups: group one took a one-hour resistance training class once a week, group two took a one-hour resistance training class twice a week, and group three, the control group, took a one-hour balance and stretching class twice a week. The women were all evaluated for a range of cognitive functions at the start of the study, at the six-month point, and at the end of the study (at the 12-month point).

The bad news is that strength training for six months, whether once or twice a week, didn’t lead to any changes. The good news is that if you stick to it for a year, you only need to train once a week to see an effect. After 12 months, the researchers found that all the women who underwent strength training showed a significant improvement in attention. The researchers evaluated attention using the well-established Stroop test (see image below), where the names of colors are written in an ink of a different color (for example, the word blue is written in red ink). To assess attention, the participants were asked to name the color of the ink (and not the word) as fast as they could (try it!). The once-a-week and the twice-a-week resistance training groups significantly improved on this task, while the performance of the balance and stretching group slightly deteriorated.

This improvement in cognitive function didn’t come without a price. The women in the once-a-week resistance training group complained of joint and muscle pains more than the women in the two other groups. It seems that the sweet spot for both an improvement in cognition and a lower risk of pain is to train twice a week (at least). This makes sense to me: the more frequently I exercise, the more my body gets used to the motions. It is also worth noting that the researchers tested other cognitive tasks such as memory and these didn’t show any change with resistance training.

Overall, though, I think this study is great news. I know that many older adults shy away from rigorous aerobic exercise (even young adults… *cough cough*), so this could be an easier alternative to help with brain health. And even if the “brain benefits” of resistance training could be a little more impressive (like by curing Alzheimer’s disease, while we’re at it), on the plus side, strength training also improves gait speed (your natural walking speed), and an improved gait speed is associated with a significant reduction in mortality. So if you don’t exercise for your brain, do it for your lifespan.
Reference: Resistance training and executive function: A 12-month randomized control trial. (2010) Liu-Ambrose T. et al. Arch Intern Med 170(2):170-8.

Tuesday, June 15, 2010

If I only had a (better) brain

Scarecrow, from the Wizard of Oz, desperately wanted a brain. Given the financial success of the brain training industry, it seems he’s not the only one hoping for cognitive enhancement. “Brain training” refers to the improvement of cognitive function by the regular use of computer exercises. Recently, it’s popped up everywhere, targeting kids through video games like “Big Brain Academy” to older adults through iPhone apps like “Lumosity”. While brain training companies are stuffing their pockets, the question remains: does it work?

A team of researchers from the UK set out to test how well brain training works. They teamed up with a popular science show on television and recruited over 11,000 healthy participants. The participants completed a general initial assessment of cognitive function (the “benchmarking” assessment), then started a regimen of 10-minute training session three times a week for six weeks. The online training sessions tested a broad range of cognitive functions: short-term memory, attention, math skills, and so on. These tests were designed to be similar to those found in commercial brain training programs. The researchers followed the progress of the participants over the six weeks of training and concluded the study with a final general benchmarking test similar to the initial one.

The good news is that the researchers saw a significant improvement on the specific tasks the participants trained on. The bad news is that this improvement did not extend to general cognitive function. These results mean that while you can improve at, say, a specific memory game that involves remembering the items in a scene, this won’t necessarily translate to better memory in your everyday life (where did I put my keys again?).

As can be expected, the study was criticized, especially by individuals with a commercial interest in brain training. Some suggested that the participants didn’t train long enough or often enough to see an improvement in general cognition. Others said that it’s not because these researchers didn’t observe an improvement that it’s impossible to achieve cognitive enhancement through computer games. However, it’s important to keep in mind that the study also scores some good points: the researchers looked at a very, very large number of participants, and the games used for brain training mimicked those that are commercially available.

Personally, the last thing I need is a reason to spend more time in front of the computer, and I like to think that fresh air is a terrific cognitive enhancer. What do you use to maximize your brain power? Coffee? Naps? Share in the comments!

Reference: Putting brain training to the test. (2010) Owen, AM et al. Nature 465:775-8.

Thursday, June 3, 2010

Light at night

At the end of June, I will once more ride my bike from Vancouver to Seattle as part of the Ride to Conquer Cancer. In the weeks leading to this event, I log many, many kilometers on the saddle and inevitably my thoughts wander to cancer biology (and sometimes to the excruciating pain emanating from my behind). What triggers cancer? How can cancer be prevented? Why are some cancers like breast cancer more prevalent in industrialized countries? While researching the question, I came across a most unsuspected potential risk factor. I’m especially excited about this piece of relevant science because for once I won’t be writing about how eating healthy and sleeping more can cure all your ailments.

In the study, researchers took groups of female rats and exposed each group to different intensities of white light during the dark phase of their daily cycle (typical lab rats live in a programmed 12-hour light/12-hour dark cycle). After two weeks of this night cycle disruption, the researchers implanted a tumor (derived from human breast cancer tumors) in the female rats, and continued on with the night cycle disruption for many weeks. By the end of the experiment, the rats that had been exposed to the strongest intensity of light showed a marked increase in tumor growth rates. The brighter the light at night, the bigger the tumor.

Ok, light at night makes tumors grow faster, but can too much light be the cause for cancer? To answer this question, it’s best to turn to studies in humans. There is convincing evidence that women who work night shifts have a significantly higher risk of breast cancer. As well, women with the brightest bedrooms also have a higher risk of breast cancer. Scientists believe the reason for these correlations is a molecule called melatonin. At night, in the dark, your body produces melatonin, which is a very effective anti-cancer molecule. Several studies have looked at this link in more detail and have shown that melatonin can block the development and the growth of tumors in non-human models of breast cancer.

The light-cancer link is gaining interest, and researchers even started sprucing things up by using a catchy acronym, LAN (for light-at-night), so it’s something to keep in mind. Based on this research, I’ve decided to break my habit of flicking on the lights for my midnight nature calls. Would this habit necessarily give me cancer? No. But flicking on the lights does interrupt my production of melatonin, and on top of being an anti-cancer molecule, it’s also a powerful antioxidant. So I’m just trying to put all the chances on my side. That being said, I’m running into a different problem, which is waking up everyone in the building when I stub my big toe on the door frame. Nobody said staying healthy was easy…

Training for the ride, thinking about cancer

Reference: Circadian stage-dependent inhibition of human breast cancer metabolism and growth by the nocturnal melatonin signal: consequences of its disruption by light at night in rats and women. (2010) Blask D.E. et al. Integrative Cancer Therapies, 8(4):347-353

Wednesday, June 2, 2010

Another quality science headline

My friend David just alerted me to a quality headline for an article based on the diet and Alzheimer's disease study:

"Salad dressing good for the brain, new study shows"

Wow. Excellent interpretation of the take-home message of the study! Forget orange juice: doctors now recommend a cup of creamy ranch dressing to kick-start your morning. It's good for your brain!

Seriously, headlines like this make me cringe.

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