By Dr. Mercola
Obesity is associated with cognitive decline, at least in part because it results in an inflammatory state in your body.1 Obesity increases levels of inflammatory chemicals known as cytokines, which are strongly damaging to brain function.
In fact, elevated cytokines are seen in such devastating conditions as Alzheimer's disease, Parkinson's disease, multiple sclerosis, and even autism.
Writing in The Journal of Neuroscience,2 researchers have suggested that your body may regard excess fat as an invader, which causes levels of cytokines to stay elevated, posing risks to your health. They also revealed a remarkably simple way to lower levels of inflammatory cytokines and thereby protect your brain function from damage.
Exercise Reverses Cognitive Decline in Obese Mice
When obese mice ran three to six miles a week for three months, they not only lost weight but also had reduced levels of interleukin-1 beta, an inflammatory cytokine. If left unchecked, interleukin-1 beta triggers a process that "eats up" neuronal synapses that are crucial for brain cells to communicate.
As the levels of interleukin-1 beta dropped, the synaptic function in the mice was repaired, thereby reversing cognitive decline.3 The same results were gained by surgically removing 15-20 percent of the mice's body weight – although if you're thinking of trying this option, it's probably not a good choice.
The researchers pointed out that the mice had "significantly more" belly fat removed than even a liposuction procedure would accomplish, and stressed that exercise is the best option.
In short, obesity (along with its increased risk of type 2 diabetes) will likely speed up the rate at which your brain function declines. If you want to keep your brain cells communicating effectively as you age, losing weight via exercise is the answer.
Exercise Helps You Grow New Brain Cells
Size does matter when it comes to our brain function. Declines in thinking and memory have been linked to actual brain shrinkage (atrophy). However, a study published in the journal Neurology found that physical exercise protects against age-related brain changes. People who engaged in the most physical exercise showed the least amount of brain shrinkage.
In fact, exercise actually causes your brain to grow. For example, Kirk I. Erickson, PhD of the University of Pittsburgh found that adults aged 60 to 80 walking moderately (just 30 to 45 minutes, three days per week for one year) showed a two percent increase in the volume of their hippocampus.4 The hippocampus is a region of your brain important for memory.
The growth correlated with changes in the participants' blood levels of brain-derived neurotrophic factor (BDNF). BDNF is part of a cascade of proteins produced in your brain that promote neuron growth and prevent neuron death. Erickson also found higher fitness levels associated with a larger prefrontal cortex. He called exercise "one of the most promising nonpharmaceutical treatments to improve brain health."
Interestingly enough, BDNF also expresses itself in the neuro-muscular system where it protects neuromotors from degradation. (The neuromotor is the most critical element in your muscle. Without the neuromotor, your muscle is like an engine without ignition. Neuromotor degradation is part of the process that explains age-related muscle atrophy.)
So BDNF is actively involved in both your muscles and your brain, and this cross-connection, if you will, appears to be a major part of the explanation for why a physical workout can have such a beneficial impact on your brain tissue. It, quite literally, helps prevent, and even reverse, brain decay as much as it prevents and reverses age-related muscle decay.
We're Only Beginning to Uncover the Many Roles Exercise Plays in Your Brain Health
Exercise boosts your brain health through multiple pathways, including improving your hormone levels, increasing blood flow to your brain, reducing stress, and many others likely yet to be discovered. For instance, it's known that exercise:
- Jump-starts neurogenesis — the creation of new brain cells. Neurogenesis is thought to be especially prevalent in your hippocampus. As you age, the stem cells in your brain tend to become less active and you produce fewer new cells, which may slow your brain function.5
- Encourages new brain cells to join the existing neural network, instead of "rattling around aimlessly in the brain before dying." Exercise helps the new brain cells learn how to "multitask."
- Upregulates production of brain chemicals and growth factors, like BDNF, which is key in maintaining memory, skilled task performance, and overall cognitive function.
- Lifts your mood and helps neutralize the harmful effects of stress by boosting neurotransmitters, such as serotonin, dopamine, and norepinephrine, and may even protect your brain cells against the effects of stress hormones.
- Increases insulin sensitivity and may even help you make better food choices.
Additionally, according to John J. Ratey, a psychiatrist who wrote the book Spark: The Revolutionary New Science of Exercise and the Brain, there's overwhelming evidence that exercise produces large cognitive gains and helps fight dementia. In addition to the benefits above, exercise also protects your brain by:
- Increasing production of nerve-protecting compounds
- Improving and increasing blood flow to your brain
- Improving development and survival of neurons
- Altering the way damaging proteins reside inside your brain, which appears to slow the development of Alzheimer's disease. In animal studies, significantly fewer damaging plaques and fewer bits of beta-amyloid peptides, associated with Alzheimer's, were found in mice that exercised
Your Brain Craves Regular Activity
If you work out religiously for three months, then suddenly stop for an extended period, your muscle tone will definitely suffer – but so, too, will your brain. Two studies presented at the 2012 annual meeting of the Society for Neuroscience revealed just how quickly the brain benefits of exercise fade if your exercise program stops.6
In the first study, active rats that had a week of inactivity were pitted against completely inactive rats while performing memory tests. The previously active rats completed the tests much faster and had at least twice as many new neurons in the hippocampus region of their brains. But remember, this was after just one week of inactivity. At three weeks of inactivity, their new neurons began to decrease, as did their performance on the memory test.
After six weeks of no activity, the neurons declined even more, as did their memory test scores, leading the study authors to suggest the "exercise-induced benefits may be transient." In the second study, rats that were active for 10 weeks, followed by three weeks of inactivity, had brains that were nearly identical to those of rats that had been completely inactive. The bottom line is that your brain needs regular, ongoing physical activity, not just a brief stint here and there. The good news is that while the benefits may fade fast, they're felt rather quickly too, providing ample motivation to keep going.
What Does a Brain-Boosting Exercise Regimen Entail?
The type of exercise program that will benefit your brain is one and the same as the one that will benefit the rest of your body. Ideally, to get the most benefits from your exercise, you need to incorporate workouts that push your body hard enough for a challenge while allowing adequate time for recovery and repair to take place. One of the best ways to accomplish this is with HIIT, or high-intensity interval training, which consists of short bursts of high-intensity exercise, as opposed to extended episodes of vigorous or moderate exertion. This is a core part of my Peak Fitness program.
HIIT maximizes your secretion of human growth hormone (HGH), optimizes your metabolism, and helps regulate your insulin and blood sugar. And nothing beats it in terms of efficiency. You can complete an entire Peak Fitness workout in 20 minutes or less. For detailed instructions and a demonstration, please see my previous article, "High Intensity Interval Training 101." In addition to HIIT, I also recommend incorporating the following:
- Stand Up Every 15 Minutes. While not intuitively obvious, emerging evidence clearly shows that even highly fit people who exceed the expert exercise recommendations are headed for premature death if they sit for long periods of time. My interview with NASA scientist Dr. Joan Vernikos goes into great detail why this is so, and what you can do about it.
- Strength Training: Rounding out your exercise program with a one-set strength training routine will ensure that you're really optimizing the possible health benefits of a regular exercise program. You can also "up" the intensity by slowing it down. For more information about using super slow weight training as a form of high-intensity interval exercise, please see my interview with Dr. Doug McGuff.
- Core Exercises: Your body has 29 core muscles located mostly in your back, abdomen, and pelvis. This group of muscles provides the foundation for movement throughout your entire body, and strengthening them can help protect and support your back, make your spine and body less prone to injury, and help you gain greater balance and stability.
Foundation Training, created by Dr. Eric Goodman, is an integral first step of a larger program he calls "Modern Moveology," which consists of a catalog of exercises. Postural exercises such as those taught in Foundation Training are critical not just for properly supporting your frame during daily activities; they also retrain your body so you can safely perform high-intensity exercises without risking injury. Exercise programs like Pilates and yoga, as well as bodyweight exercises, are also great for strengthening your core muscles, as are specific exercises you can learn from a personal trainer.
- Stretching: My favorite type of stretching is active isolated stretches. With Active Isolated Stretching, you hold each stretch for only two seconds, which works with your body's natural physiological makeup to improve circulation and increase the elasticity of muscle joints. This technique also allows your body to repair itself and prepare for daily activity. You can also use devices like the Power Plate to help you stretch.
A Secret Weapon for Your Brain: Intermittent Fasting and Exercise
Growing evidence indicates that fasting and exercise trigger similar genes and growth factors that recycle and rejuvenate both your brain and muscle tissues. These growth factors include BDNF, as previously mentioned, as well as muscle regulatory factors, or MRFs. These growth factors signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells respectively.
Even better, exercise while fasting can help keep your brain, neuromotors, and muscle fibers biologically young. For more information on how to incorporate intermittent fasting into your exercise routine for maximum benefits, please see this previous article.