In an article published online on January 31st in the Proceedings of the National Academy of Sciences, researchers show again that regular walking can make a difference in cognition. This study is new because the researchers also looked at the volume of the hippocampus with imaging techniques and looked at BDNF levels.

Exercise and BDNF levels may also be related to the way that antidepressants work to reduce depression, and we know that for many individuals exercise improves mood. While we think of the hippocampus most often because of its role in memory, it also has important effects in regulating emotion.

You can find the abstract here. The full article is available to subscribers only.

They argue that prevention of Alzheimer’s disease hasn’t worked because, as they point out, Ronald Regan got Alzheimer’s even though he was both mentally and physically active. They also argue what we really need is a massive increase in research funding to find drug treatments for Alzheimer’s disease. Click here to see the opinion piece.

Is it possible to agree with someone’s conclusion but think that their reasoning is wrong? I think the answer for me has to be yes.

Their argument reflects a basic misconception about prevention. It’s as though we were saying because Jim Fixx (a famous runner) died of a heart attack we should give up on exercise and only focus on drug and surgical treatments for heart disease. It as thought we are saying, Let’s give up being healthy, because even people who exercise and eat right still get heart disease.

O’Connor and her colleagues argue that a major increase in funding for Alzheimer disease drug development might lead more rapidly to effective treatments, and cite the effort made in the 1980s to develop treatment for HIV infection. A similar effort, they argue, would lead to similar progress in Alzheimer’s.

We don’t know that, but there’s only one way to find out. Even though there have been important advances in understanding the basic pathology of Alzheimer’s, it’s still not clear how well treatments based on those advances will work. Recent drug trials have not panned out. A major advance could happen tomorrow, or not for many years.

An alternative model for understanding potential advances in treating Alzheimer’s might be efforts to treat cancer. While major advances in treatment have occurred since the time of the Nixon administration, reductions in cancer rates for things such as lung cancer are also heavily influenced by public health efforts to reduce smoking.

Maybe what we really need is a targeted effort to evaluate both preventive as well as drug treatment strategies in Alzheimer’s. The op-ed piece neglects promising developments such as Carl Cotman’s work on reducing amyloid load in animals that I wrote about several weeks ago. He showed that diet and exercise actually reduced amyloid (a substance believed to be central in Alzheimer’s disease) in aging dogs. That work can lead to preventive efforts but may also lead to drug therapies for cognitive decline and perhaps Alzheimer’s. (See my earlier post here.)

So give up on brain health? I think that’s a really bad idea. We know that people who are healthy as well as physically, socially, and mentally active are less likely to have cognitive decline. Will brain health prevent all Alzheimer’s? Probably not. But should we give up and throw all of our efforts into drug development? Until we have better treatments for cognitive decline, a brain healthy lifestyle is probably the best strategy for staying mentally sharp.

The mice who ran performed much better on several tasks that required that they tell the difference between two visual patterns.The effect of running was very clear in adult mice. In mice who were very old, though, running didn’t make much difference, and they didn’t get much boost from the exercise.

John Grohol at PsychCentral also posted about the article, noting that some newspaper accounts barely mentioned the fact that the study was done with mice. He even points out that it was done with a specific variety of mice, and suggests that the relevance of the study may be limited. It’s true that it is very hard to know whether studies about mice really mean much for humans, since findings in animals often don’t generalize to humans.

As Grohol notes, the research is pretty clear that exercise can improve cognitive functioning in people as well as animals.But I’m not as concerned as he is that the results of this study will only apply to one strain of mice. Animal research has its problems when we apply it to human research, but in this case studies in humans have consistently shown similar results to those in animals. It may still be true that the reasons for changes in cognitive function in humans and animals may be different, but that means we would have to come up with two separate mechanisms for change. That’s actually making the situation more, rather than less, complex.

Dr Grohol makes an excellent point about human and animal research. Too often, we jump from preliminary findings to the real world. In areas in which animal and human studies generally agree,though, animals studies can extend and help find new directions for research at considerably less cost than similar studies in humans.

Reference:

Creer DJ et al. Running enhances spatial pattern separation in mice. Proceedings of the National Academy of Sciences, published online first January 19,2010 doi:10.1073/pnas.0911725107

The authors studied a  group of 2,841 men (yes, men only) who were born between 1920 and 1924 in the area around Uppsala, Sweden. They were followed up on several occasions, the most recent in 2006. At the end of the study, 20% more of the men in the most active group were still alive compared to men in the least active group. Again, this was after controlling for a number of variables that might have also been different in the two groups.

Most interesting to me was how activity levels were defined. The researchers asked participants only four questions. The first asked whether the man spent most of his time reading, watching TV, or engaged in sedentary activities. Persons who answered yes were placed in the lowest activity group. The second question asked whether the man walked or bicycled freqently for pleasure. Persons answering yes to this question were in the middle group. The last two questions asked whether the men participated regularly in sports or other active recreational sport, and whether they engaged regularly in hard physical training. People who answered yes to either of these questions were placed in the high activity group.

People in the lowest activity had the highest chances of dying in the followup period, while those in the middle activity group had an intermediate risk of death. Those in the highest activity level group had the lowest risk of death.

Based on this study, almost any increase in physical activity is probably beneficial. Many other studies have shown that increasing physical activity helps you lose weight, makes it more likely that you’ll quit smoking, and means that you’ll feel better about your health. This study is new in showing that the health benefits of exercise may have effects that last a lifetime.

This article is freely available on the Web at the BMJ site:  Click here to view the abstract. You can read the entire article by clicking on the words “Full Text” at the upper left of the page.

Here’s a link to the article on the Times’ web site:

Click Here