This week, we take a look at the possible effect of exercise on the brain. A recent study examining this issue in twins only added to the discussion that has been taking place about the benefits of exercise across specialties -- from primary care to neurology and cardiology.

We contacted both neurology and cardiology experts and asked:

Do you agree that exercise has a measurable effect on brain function?

If so, does the exercise conversation with patients go beyond weight control and heart health into a discussion of possible "brain benefit?"

The participants this week are:

Patrick D. Lyden, MD, chair, department of neurology at Cedars-Sinai Medical Center in Los Angeles

Marian Evatt, MD, associate professor, neurology at Emory University School of Medicine in Atlanta

Brendan Kelley, MD, a neurologist at the Ohio State University Wexner Medical Center in Columbus

Thomas Thesen, PhD, assistant professor, departments of neurology and radiology at NYU Langone Medical Center in New York City

Carl "Chip" Lavie, MD, FACC, medical director, cardiac rehabilitation, and prevention at the John Ochsner Heart and Vascular Institute in New Orleans

Paul D. Thompson, MD, FACC, medical director, cardiology and The Athlete's Heart Program at Hartford Hospital in Connecticut

Benefits Across Specialties

Patrick Lyden, MD: "Exercise is definitely good for brain function. In fact, of all the strategies offered to prevent dementia, physical exercise has the best data to support it. For many years, older patients and those with memory issues were often encouraged to play brain games. Some popular 'neuroscience' games are quite sophisticated, but they do not work. But in study after study, physical activity is found to consistently and powerfully protect the human brain from deterioration. If we are to help our patients protect their brains, we must urge them to get up and move. When we work out, our brains get busy, and we make our own stem cells that populate the brain, enhancing memory and preventing dementia."

Brendan Kelley, MD: "Regular physical exercise has many health benefits that include decreasing the risk of diabetes, hypertension, stroke, and heart disease. Many large observational studies have demonstrated a reduced risk of incident dementia and reduced progression of cognitive decline among older adults who regularly exercise. The mechanisms that mediate this effect on cognitive function have not been well-defined. Hypothesized effects on cerebral blood flow, inflammation, stimulation of growth factors, and reduced risk of systemic diseases that have a deleterious effect of cognitive performance."

Marian Evatt, MD: "Absolutely -- I have that conversation virtually every clinic visit with Parkinson's disease patients unless exercise is impossible for them (due to certain medical conditions). It's clear that evidence is piling up that exercise is therapeutic -- insurance companies might save lots of money if exercise was 'prescribed' first before drugs."

Thomas Thesen, PhD: "Extensive research in mice has shown that prolonged aerobic exercise changes not only the brain's physiology and anatomy, but also can lead to improvements in memory and cognition. More and more evidence is now becoming available that exercise has profound changes on the brain of humans as well. The logical conclusion will be that physicians will start counseling patients about the cognitive benefits of exercise, especially patients who are at risk for dementia and other cognitive and mood disorders."

What the New Study Adds -- Or Doesn't

Carl Lavie, MD: "This is a very small study, and obviously measuring brain volume is not as powerful as measuring cognitive function, long-term development of dementia, or even important psychological endpoints such as depression, anxiety, and hostility and various measures of quality of life, as my colleagues and I have studied for the past 2 decades. In fact, we showed that exercise training and higher fitness are associated with marked, usually greater than 50%, reductions in all of these measures of psychological stress and, more importantly, the increases in fitness are associated with marked reductions in the stress-induced increased mortality risks. Therefore, this paper supports other data showing that higher physical activity, exercise training, and higher cardiorespiratory fitness not only benefit cardiovascular risk factors, insulin sensitivity, and body composition, but also have potentially profound benefits on brain health."

Paul Thompson, MD: "I think that exercise can affect brain function, such as coordination and motor control, but it may also affect hippocampal size, and one would think that since the hippocampus affects the memory that it may have something to do with reducing memory loss. There are other studies, including our own, that suggest there are changes in the hippocampus, and the hippocampus has a lot to do with memory. For example, we took a small group of people and we looked at their brain function as well as their exercise performance -- we exercise-trained them -- and those people who increased their oxygen uptake the most or increased their exercise performance the most had the biggest change in hippocampal size."

Kelley: "This recent study demonstrated a difference in cerebral volumes as measured using MRI between identical twins discordant for physical exercise. Although intriguing, this is not the same as demonstrating a difference in brain function or a measurable effect on cerebral metabolism. The reported difference in nondominant striatal and prefrontal cortex volume could reflect osmolar differences related to the reported differences in glucose metabolism and insulin sensitivity or could reflect the impact from other factors common to the group that more regularly engaged in physical exercise."

Potential Impact on Patients

Lyden: "Brain health is a newcomer to the conversation about physical fitness and exercise. For decades, doctors have preached the benefits of exercise for the heart and circulation, but we're only now getting the word out that increasing blood flow to the brain is just as important. We need to help our patients understand that moving around stimulates the brain and its stem cells. If they can stick to a low-fat, low-calorie diet like the Mediterranean diet and lose weight and get exercise, they will greatly improve their brain health. Even if they cannot achieve their ideal body weight, vigorous walking, swimming, jogging -- anything that gets their heart rate up -- will keep their brain in shape and help prevent dementia."

Thompson: "I think it's probably a little too early to go ahead with the discussion of brain benefits very formally, but I think it could probably be inserted that 'I want you to exercise because it will prevent the onset of diabetes, it will help you keep your weight down, and it may even help keep you smarter as you get older.' I think that's probably the way I would put it."