Archive for April, 2008
One of the earliest and most consistent findings in the extensive research base on risk factors of Alzheimer’s is the observation that those with higher education levels are less likely to be diagnosed with Alzheimer’s disease. Why would education protect against Alzheimer’s? If Alzheimer’s is a disease of the brain, why would people with more education be less likely to get it?
As it turns out, there are two major explanations, and both may be partly right.
The first and most common explanation is based on an idea called cognitive reserve. The idea behind this is that Alzheimer’s is diagnosed when someone has clearly developed memory problems as well as problems in some other areas of mental or personal functioning. People with higher levels of education probably function at somewhat higher levels in memory and other cognitive domains. The distance between where they start and the point at which they have recognizable decline is greater than for people whose baseline isn’t quite as high. When their functioning declines, it takes longer for them to reach the point where doctors will say they have Alzheimer’s.
The second explanation is, I think, more interesting because it gives us a direction to go in trying to prevent Alzheimer’s disease and maybe cognitive decline more generally. People with higher levels of education may also be more intellectually active as they get older. We know that what kinds of things people do on an everyday basis is related to how likely it is that they’ll get Alzheimer’s. People who have active social lives and spend time doing intellectually challenging things are less likely to get Alzheimer’s. And people with higher levels of education may do more of these things.
This raises the question of which comes first. Is that people with more education do things that make it less likely that they’ll get Alzheimer’s, or is that people who are less likely to get Alzheimer’s like to do intellectually stimulating activities. Since most of the research is done in a way that won’t less us decide which causes which, this question is still not answered completely. We do know, however, that certain kinds of mentally stimulating activities (as well as improved physical fitness) make changes in the brain. These changes in the brain are the kind of things that should improve people’s abilities, and decrease their chances for developing Alzheimer’s disease.
Does this mean that if you don’t have a high school diploma, a college degree, or a graduate education that you’re doomed to get Alzheimer’s? Nope. If you look closely at almost any of the risk factor studies, the actual change in risk for Alzheimer’s disease is fairly small, even if it’s statistically significant. It does mean that if you’re looking to do something to reduce your risk of Alzheimer’s, following a brain fitness program might be able to reduce your chances of getting memory or other cognitive problems.
No matter what you believe about computer-based cognitive training and what it can do for you (see previous post), it’s pretty clear that computer training isn’t the only answer to the question of how to keep your brain fit as you get older. Exercise and physical activity are pretty clearly related to cognitive function in people over 50. There are even some prospective studies that show that increasing physical activity can improve your mental abilities.
A recent update to a systematic review in the Cochrane Database of Systematic Reviews once again confirms this (Angevaren, M., et al., Physical activity and enhanced fitness to improve cognitive function in older people. The Cochrane Database of Systematic Reviews, 1, 2008). Animal studies have shown that exercise has multiple physical effects on basic biological processes that can improve memory and cognition. Improved aerobic fitness (being able to do things like walking, running, or swimming) increases blood flow to the brain as well as the body’s ability to get oxygen from the blood. Exercise also activates substances called growth factors in the body. These factors causes cells to grow, and may increase the number of blood vessels in the brain. Human research shows that similar mechanisms may be at work in older adults.
Several meta-analyses (special studies that look at the results of multiple studies all at once) have shown a relation of physical activity of mental abilities including memory. Although many of these studies are correlational (this means that they show us which factor causes the improvement), there are also some prospective studies of exercise in older adults. These have shown that people who improve their physical fitness also improve their mental fitness. Brain fitness is more than computer-based training.
I think that many of us who work in the field of aging and mental abilities sometimes may forget to explain some key terms and phrases to patients. One of the most general and frequently used is the phrase “cognitive aging.” What does it mean/
Cognitive Aging refers to how our mental capacities change over time. It may seem as though all of our abilities go downhill after age 30 or 40, but research shows that isn’t completely true. The truth is that some abilities decline over time, some stay about the same, and some actually improve as we get older. For example, psychomotor speed is an ability in which most people perform more poorly over time. The precise definition of psychomotor speed varies from study to study, but it’s often assessed by tests that ask you to do some kind of task that requires that you think and to something with your hands as quickly as you can. One task is called a pegboard. A piece of metal attached to a block of wood has rows of holes in it, a little like the kind of pegboard you might put up in your workshop to hold tools. The person being evaluated is asked to put small metal pegs in the board as quickly as he or she can. This is the sort of thing that younger persons in general do much better than older persons do.
Another ability that may decline over time is called working memory. This ability is usually assessed by asking someone to keep a couple of things in their minds and then do something with them. The person being evaluated might be given a series of numbers and then asked to repeat them backwards – he or she has to remember the numbers and then somehow mentally read them backwards. Being asked to do mental arithmetic problems also taps working memory. Here, the person being assessed might have to remember some elements of the problem that are given, might have to access some existing knowledge (like how many quarts are in a gallon), and then do a calculation.
What abilities may actually get better over time? Things that don’t require speed or working memory, but may benefit from life experience. The most common example is vocabulary. Many older adults score better than their younger counterparts on tests of how many words they know. Older adults probably have had more opportunities to learn words, and once a word is in long-term memory, older adults can recall it pretty well. Some people have also suggested that because of the benefits of experience, older adults are better able to discern patterns in events around them. Finally, some research has shown that older adults are better than younger persons at certain kinds of problem solving, especially when it involves social skills or awareness of social issues.
A lot has been written (and televised) lately about computer software for brain training. It seems to me there a couple of key issues to consider when we talk about brain training and its relation to your brain’s health.
- Neural plasticity: This phrase refers to the ability of the brain to change in response to experience. In the past, many believed that the number of brain cells was fixed early in life and only got smaller as we got older. There was also skepticism about how much the way the nerve cells were wired could change. That has changed. Several studies have shown that the human brain can make new nerve cells (called “neurogenesis”). One study showed that the hippocampus of London taxi drivers changed its size and shape in response to learning about London streets. Another study showed that some parts of the brain may increase in size after learning how to juggle.
- Preventing Alzheimer’s disease: Does computer training prevent Alzheimer’s disease? What we know is that people who engage in mental, physical, and social activity are less likely to develop Alzheimer’s disease. But it’s a chicken and egg questions, since most of the research just shows the relation but not whether one is cause and one is effect. Maybe people who are developing Alzheimer’s are less likely to engage in stimulating activities.
- Improving cognitive function: This is a “no brainer” (sorry for the pun). Few people today believe the adage that “You can’t teach an old dog new tricks.” People of any age can learn new things, whether it’s a teenager learning how to drive a car or an 80-year-old learning how to use a computer, as Dr. Sara Czaja has shown in studies at the Center on Aging at the University of Miami. The big question isn’t whether we can improve cognitive functioning. We can. The real question is whether computer training will transfer to other real-world situations. So far, there’s very little information about that
So if you’re looking for a cognitive training program, we think the best idea is to have diagnostic testing like we do in the Miami Brain Fitness Program. It can help to pinpoint your areas of strength and weakness, and help you to learn what you should focus on in any kind of cognitive training activity.
When you’re looking to do everything you can to maintain and improve your brain’s fitness, you should think about how you eat. Why? Because in a number of studies, diet has been shown to influence things like high blood pressure, cholesterol, and even your risk for developing Alzheimer’s disease.
While you may already have heard about keeping your salt intake low to keep your blood pressure low, too, many people don’t know about the DASH or Mediterranean diets and what they may be able to do for you.
DASH stands for “Dietary Approaches to Stop Hypertension.” An article published just this week in the Archives of Internal Medicine shows that women who were the most adherent to the DASH diet guidelines had a significantly reduced risk of coronary heart disease and stroke. Women who ate 4-5 servings of fruits and vegetables, lots of whole grains, and avoided red and processed meats and sugary beverages had a lower chance of developing heart disease or having a stroke. Since the evidence is increasing that heart disease is linked to poorer memory and developing Alzheimer’s disease, anyone interested in keeping their brain fitness level high should consider changing their diet.
Other studies have shown that the Mediterranean diet may reduce the chances of having Alzheimer’s disease. An article in 2006 in the journal Neurology showed that people who follow the Mediterranean diet have reduced chances of having Alzheimer’s disease (Scarmeas et al. Neurology, 2006, 63, 1709-1717; you need a subscription to see this paper). This same group of researchers followed a group of people with Alzheimer’s disease over several years. They found out that the patients with Alzheimer’s who followed the Mediterranean diet were less likely to die over an average follow-up time of 4.5 years (reported as an abstract at the 2007 meeting of the American Academy of Neurology).
You can find out more about the DASH diet in a publication from the NIH. You can download it here: http://www.nhlbi.nih.gov/health/public/heart/hbp/dash/new_dash.pdf.
This booklet is 979 Kb, and may take a long time to download if you don’t have a high-speed Internet connection. You’ll need the free Adobe Acrobat reader to read the booklet. You can get it by clicking here: http://www.adobe.com/products/acrobat/readstep2.html.
You can read the article about the DASH diet, for free, here: http://archinte.ama-assn.org/cgi/content/full/168/7/713.
You can find out more about the Mediterranean diet at the Mayo Clinic website: http://www.mayoclinic.com/health/mediterranean-diet/CL00011.
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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. (more…)
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.