What Did the NIH Report on Lifestyle Modification/Alzheimer's Really Say?
My inbox flooded with links to the report released by NIH (and evangelized by TIME) stating that lifestyle interventions (diet, physical activity, mental exercises, etc.) may not be that effective in preventing Alzheimer's Disease. Before I mount my full counterattack, I need to carefully read through the studies the meta-analysis cites. Still, a quick glance at the exclusion criteria of the meta-analysis reveals the authors limited their review to studies using patients over the age of fifty. So really, these results imply that lifestyle modifications may not prevent, delay, or treat Alzheimer's Disease if you start these changes later in life.
My inbox flooded with links to the report released by NIH (and evangelized by TIME) stating that lifestyle interventions (diet, physical activity, mental exercises, etc.) may not be that effective in preventing Alzheimer's Disease. Before I mount my full counterattack, I need to carefully read through the studies the meta-analysis cites. Still, a quick glance at the exclusion criteria of the meta-analysis reveals the authors limited their review to studies using patients over the age of fifty. So really, these results imply that lifestyle modifications may not prevent, delay, or treat Alzheimer's Disease if you start these changes later in life.
My second point is that all lifestyle modifications are not created equal. Scientific evidence in animal studies suggests that of all interventions, aerobic exercise is our best chance of staving off cognitive decline. In fact, this meta-analysis also found some correlation between exercise and preserving or improving cognitive ability.
There's a good article in The Economist that discusses the failures of the drug industry to find a solution to treating Alzheimer's Disease. One particular quote resonates with my feelings on the NIH report:
Another fundamental problem is that, whatever is causing the damage, treatment is starting too late. By the time someone presents behavioural symptoms, such as forgetfulness, his brain is already in a significant state of disrepair. Even a “cure” is unlikely to restore lost function.
Why Behavior Change Is (Still) Better Medicine Than Drugs
While attending the Institute for the Future's Health Horizons Fall Conference on Monday, one thing became eminently clear. The 21st century will be the era of brain, the last great scientific frontier. Due to societal shifts, environmental changes, and the fact that we are just living longer, we are poised to see a sharp rise in cases of diseases such as Alzheimer's, Parkinson's, autism, and post-traumatic stress disorder. The only thing worse than the increasing prevalence of brain disease is the sobering fact that few viable treatments currently exist.
While attending the Institute for the Future's Health Horizons Fall Conference on Monday, one thing became eminently clear. The 21st century will be the era of brain, the last great scientific frontier. Due to societal shifts, environmental changes, and the fact that we are just living longer, we are poised to see a sharp rise in cases of diseases such as Alzheimer's, Parkinson's, autism, and post-traumatic stress disorder. The only thing worse than the increasing prevalence of brain disease is the sobering fact that few viable treatments currently exist.
For years, we've heard the mantra of behavior change and health. Exercise more and you'll cut your risk for heart disease and stroke. Eat more fruits and vegetables and you can decrease your risk for colon cancer (or possibly prostate cancer, as discussed in a previous Decision Tree post, "Why Behavior Change is Better Medicine than Drugs"). Could behavior change serve our brain health as well as it did other organs of the body?
On Monday, the neurotechnology community drew a definitive line in the sand with regard to treating the brain. On one side were panelists that believed that society is not being medicated enough for mental disorders, including ADHD in children. On the other side, proponents of behavioral training argued that brain plasticity, the innate ability of the brain to rewire itself continuously throughout life, is our best bet to combat brain disease.
Consider the use of ADHD drugs in children, or cognitive-enhancing drugs, such as modafinil, by professionals (including a large group of scientists) in the workplace. Proponents of medication say that the cognitive enhancers are not doing anything unnatural. Rather, they are taking someone who's a mediocre performer in terms of concentration, and simply moving them to the upper 90th percentile. Then, according to the same logic, I guess these panelists would also support legalizing steroids in major league baseball. After all, the steroids are not making the athletes super-human. Rather, they're taking the middle-of-the-road performers and nudging them to the upper echelon of the sport. Hmmm....
My former postdoc advisor, Dr. Michael Merzenich of the University of California San Francisco, led the charge for behavioral training as a better alternative to drugs for diseases of the brain. Mike's lifelong work focused on the neuroscience of learning, and how brain plasticity occurs at various stages of development. He believes that many ailments of the brain, including ADHD, occur because we are using our brains "incorrectly", but specific behavioral training can reverse and improve these deficits.
The wonders of behavioral training and brain plasticity are not limited to sparse findings in a dark lab. In fact, Mike's most promising research has been translated into several commercial computer software applications, which have enhanced the reading capabilities of dyslexic children, as well as improved the speech processing and memory of senior citizens.
Whether you are sold on behavioral training as a feasible alternative to drug therapy in brain illness or not, one point remains solid: the cost of conducting clinical trials for behavioral training regiments is a mere fraction of the cost of drug trials. Given that it's terribly expensive to run drug trials, and that only a small fraction of drugs in a pharma company's pipeline succeeds in the clinic, we clearly can't afford to ignore behavioral training as a new way to treat the brain.
Cheeseburgers on the Mind
Making a choice that leads to better health is not always easy. Otherwise, we would have many more ex-smokers and far fewer holiday pounds to shed. We would have no need for nicotine gum and patches, or Weight Watcher's meetings. So if it's that difficult, why bother? For years, physicians have told the American public that reducing your calorie intake, eating a diet low in salt/sugar/saturated fat, and exercising 3-5 days per week will reduce your risk for heart disease and diabetes. Now, new information has shown that the benefits of a healthy lifestyle are even more far reaching than initially thought -- diet and exercise can affect our minds. About 5-8% of people over the age of 65, and nearly 50% of people in their 80's, show signs of dementia. As the baby-boomer generation increases the population of the 55-64 age group in the U.S. from 29 to 40 million by 2014 , and their life expectancy continues to rise, the number of people affected by dementia is poised to increase as well. Recent studies have shown that regular exercise may prove to be a potent mediator of dementia and Alzheimer's Disease. In one study, those who exercised 3 or more days per week had a 32% risk reduction in developing dementia compared to those who exercised less. Exercise has also been linked in similar studies to moderate cognitive improvements in adults who are at risk for Alzheimer's Disease, as well as a lower occurrence of vascular dementia.
Making a choice that leads to better health is not always easy. Otherwise, we would have many more ex-smokers and far fewer holiday pounds to shed. We would have no need for nicotine gum and patches, or Weight Watcher's meetings. So if it's that difficult, why bother? For years, physicians have told the American public that reducing your calorie intake, eating a diet low in salt/sugar/saturated fat, and exercising 3-5 days per week will reduce your risk for heart disease and diabetes. Now, new information has shown that the benefits of a healthy lifestyle are even more far reaching than initially thought -- diet and exercise can affect our minds. About 5-8% of people over the age of 65, and nearly 50% of people in their 80's, show signs of dementia. As the baby-boomer generation increases the population of the 55-64 age group in the U.S. from 29 to 40 million by 2014 , and their life expectancy continues to rise, the number of people affected by dementia is poised to increase as well. Recent studies have shown that regular exercise may prove to be a potent mediator of dementia and Alzheimer's Disease. In one study, those who exercised 3 or more days per week had a 32% risk reduction in developing dementia compared to those who exercised less. Exercise has also been linked in similar studies to moderate cognitive improvements in adults who are at risk for Alzheimer's Disease, as well as a lower occurrence of vascular dementia.
Recent pre-clinical results have shown that diet is also tied to brain health. A 2002 study revealed that rats fed a diet high in saturated fat and refined sugar for 2 years exhibited changes in both gene expression in the brain, as well as performance on a memory task (finding its way through a water maze). This fast-food type diet decreased the levels of brain-derived neurotrophic factor (BDNF), which is a versatile molecule that mediates brain cell formation, function, and survival. Both BDNF gene expression (mRNA) and BDNF protein production in the hippocampus, an area crucial for short-term memory, were significantly reduced in the animals fed the high-fat and refined sugar diet, compared to those on a low-fat, complex carbohydrate diet. Although the experiment lasted for 2 years, and the greatest effects were seen at the end of the experiment, changes in gene expression were seen in as little as 6 months after the rats began downing cheeseburgers. Even more striking, the rats had a significant deficit in the water maze memory task after only 3 months on the high fat/sugar diet, which shows that the "McDiet" led to a change in behavior in the mice.
Nevertheless, the research presented here had limitations. The studies that looked at the effects of exercise on dementia were conducted in relatively small, non-diverse human populations and were not completely controlled against other "good health" factors that tend to occur when people exercise. For example, exercisers are much more likely to do other healthy things, such as eating right, quitting smoking, getting quality sleep, or maintaining target weight. The fast-food diet study was well controlled to show that decreased BDNF was not related to hypertension, atherosclerosis, obesity, and changes in activity level -- but the results must be taken at face value since it was conducted in rodents, not humans.
So what does all of this mean? The idea of eating right and getting more exercise is nothing new. We've known for years that changing our health behaviors can stave off heart disease, and potentially let us live longer. The studies mentioned here really highlight the positive-feedback nature of our actions -- behavior changes (diet and exercise) cause physiological and molecular changes in the body, which in turn alter another behavior (memory). This relationship tells us that our behavior choices no longer only determine life or death, but they also can impact our quality of life. It's true that the results don't make a direct link between diet/exercise and brain health, but rather, a loose correlation between the two that requires further study. But in my mind, it doesn't really matter what keeps the brain healthy -- my point isn't that diet and exercise are the end-all cure for disease, but rather, that they are an extremely important part of an overall healthy lifestyle that will allow us to make the most of our golden years.