A Consumer’s Guide to Research: I. Observational Studies
I spend a lot of time teaching medical students, residents, fellows, and other health care professionals. Since I think it’s critical that we base our clinical practice on the best evidence available, I like to talk about what research evidence shows. This means that at least some of the time I have to explain a little bit about how research studies are done, what kind of evidence they produce, and why some studies are generally considered to give us better or stronger evidence than others.
One of the most important issues that comes up in discussions of research in the media and with patients and clinicians has to do with research design. Not all research is done in the same way, and we can draw certain kinds of conclusions from one research design but not others. We often want to decide whether something either causes disease (for example, smoking) or helps prevent it (for example, does vitamin C prevent colds?). Two basic kinds of research studies deal with these issues in different ways, and give us different kinds of information.
The most common type of study that gives us information about factors associated with disease is the observational study. These studies are very common, and usually involve collecting information from a group people at one point in time, and then collecting the information on other occasions. We might, for example, ask a group of people in the community about their memory, diet, exercise, and use of vitamin supplements. Later, we would ask them the same questions again. Perhaps some of the people would say that their memory had gotten worse. We could then find out if their diet, exercise, or use of vitamins was different from the people who said their memory was OK.
The good thing about this kind of study is it’s easy to do and therefore less expensive than many other kinds of research. The weakness is we can’t control all the things that might affect the study’s outcome.
Suppose we found that people who took vitamins were less likely to say their memory got worse. Would that mean that taking vitamin C is good for your memory? No. Although this kind of study is often interpreted this way, it’s not true. We don’t know whether something else is going on that is related to taking vitamin C but also affects memory.
A good example are the results of observational studies that ask people about taking drugs called non-steroidal anti-inflammatory drugs (NSAIDS). These are medications like ibuprofen; there are many brand names. Studies have shown that people who took NSAIDS for arthritis are less likely to develop Alzheimer’s disease. So far, so good. But when controlled clinical trials of NSAIDS in people with memory problems were done, they didn’t show any benefit.
Observational studies are really useful for helping us understand what may cause a disease, but they usually aren’t very good at nailing down exactly how to treat one.
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Mindfulness meditation as practiced over a long period by experts makes clear changes in someone’s brain function. But what about those of us who don’t have a few years to sit in a monastery in the Himalayas? A new study shows that even brief meditation practice can improve attention.
Researchers at Wake Forest University studied whether just four days of training (at just 20 minutes a day) could make a difference in participants’ mood, energy, and cognition. Undergraduate students (average age 22 years) either participated in the meditation sessions or spent a similar amount of time sitting quietly and listening to an audio book.
Participants in the meditation condition showed decreases in anxiety and improvements in several mental processing tasks compared to those in the audio book group. The meditators’ performance on one aspect of a working memory task (how many answers they got correct in a row) suggested that they may have improved their attention.
This is a small and very preliminary study that extends others’ work on meditation and the brain.It shows that even brief meditation practice can make a difference. you don’t have to be a Buddhist monk to learn to still your mind and pay better attention. Paying attention may be one of the most important things you can do to improve your brain’s functioning.
Reference:
Zeidan F et al.(in press) Mindfulness meditation improves cognition: Evidence of brief mental training. Consciousness and Cognition, doi:10.1016/j.concog.2010.03.014
I saw an interesting blog post yesterday evening on the site of the Huffington Post about the potential benefits of meditation – or at least about what one woman thinks might be the benefits. Priscilla Warner writes about the contrast between Tibetan monks’ apparent calm, evident even on brain scans, and her own anxiety disorder. Ms. Warner says that she suffers from panic disorder, a severe form of anxiety in which a person can have multiple anxiety attacks every day, even in the middle of the night. Her post is titled “I Want the Brain of a Monk” Although most people don’t suffer from anxiety this severe, many people have symptoms of anxiety. And research has consistently shown that higher levels of anxiety are related to more memory problems.
What’s the relation to brain fitness? In my brain fitness class, I often mention the usefulness of meditation in helping reduce stress and anxiety, both of which have negative effects on memory. You don’t have to go to Tibet to get the benefits of meditation. If you simply take 10 minutes several times a day to break in to the ongoing rush of getting things done, you’ve made a start. Use those 10 minutes to sit quietly, relax your muscles, and breathe deeply.
If you do that every day for two weeks, I think you’ll notice that you feel calmer and better able to focus. And if you’re better able to focus, you will be better able to pay attention and remember things.
Although many people are excited about the potential for using computers to train their brains, we shouldn’t forget that other techniques have been used to the train the brain for many centuries. I’m thinking about the large number of techniques for meditation. While free computer software still requires an investment in a computer, meditation only asks you to sit or lie quietly and focus your mind.
A recently-published study shows parts of the brain in long-term meditators are larger than the same parts of the brain in people who don’t meditate. The article by Eileen Luders and her colleagues appeared in a recent issue of the journal Neuroimage (Vol. 45, No. 3, pp. 672-678, April 15, 2009). The study showed that portions of the orbitofrontal cortex and the hippocampus were larger in persons who had been regular meditators for 5 or more years. The study is interesting because the parts of the brain that were larger are often thought to be important in helping people keep themselves emotionally balanced.
A number of strategies are likely to be helpful for meditators. There has been a great deal of interest over the last several years in mindfulness meditation. Researchers have studied how it can be used in reducing anxiety and depression. Mindfulness is based on Buddhist meditation (for a brief article, click here) but you don’t have to be a Buddhist to practice meditation. In fact, one of the most important persons who has promoted mindfulness is Jon Kabat-Zinn, a researcher at the University of Massachusetts. You can see a video presentation by him on YouTube by clicking here.
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