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Exercise Preserves Brain Function

People who exercise into later life are smarter than those who do not exercise. To prove that exercise preserves brain function, studies must show that the loss of brain function with aging is not just genetic. Identical twins have exactly the same genes, so a study on twins can yield stronger results to show which environmental factors help to prevent loss of brain function. A new study from King’s College in London showed that of 162 healthy pairs of twins, ages 43 to 73, the ones with the strongest legs were the smartest (Gerontology, Nov 10, 2015).

The researchers used leg strength because leg strength correlates well with how much a person exercises. Asking people to tell you how much they exercise often causes them to lie. People usually answer lifestyle questions based on what they think is the best answer, not on what they are really doing. The authors tested memory and other brain functions as well as leg strength at the start of their data collection and again ten years later. They controlled for factors known to damage your brain such as high blood sugar, high cholesterol, high blood pressure, a high-fat diet, overweight, smoking and alcohol, and found that:
• The more powerful twin was smarter and the difference had increased at the end of the ten-year study.
• MRIs showed that the smarter twin had a larger brain and the difference increased over ten years.

Why Aging Causes Brain Loss
An expected result of aging is loss of memory and other mental functions. Aging-associated loss of brain power is most likely caused by decreased ability of the brain to convert food to energy. All cells in your body get their energy from two main sources:
1) The Krebs cycle of consecutive reactions that convert food to energy is located inside the mitochondria in all cells except aging red blood cells.
2) Glycolysis, the conversion of sugar to energy, located inside cells, but outside the mitochondria.
With aging, mitochondria slowly lose their ability to power your cells. Anything that preserves mitochondria in cells should help to retain brain function.

How Exercise Makes you Smarter
Researchers at Johns Hopkins discovered that an enzyme called SIRT3 that is located inside mitochondria may protect mice brains from loss of their energy supply (Cell Metabolism, November 19, 2015). Normal mice who ran on a spinning wheel increased their levels of SIRT3 in nerve cells, maintained brain function with aging, and did not suffer brain damage from neurotoxins, poisons that damage brain cells. A special group of mice that were genetically engineered to be unable to produce SIRT3 gained no benefit from running on a spinning wheel and developed brain damage and seizures when exposed to neurotoxins. This implies that SIRT3 strengthens brains and that blocking SIRT3 prevents exercise from benefiting brain function. The authors believe that exercise increases SIRT3 levels in the mitochondria of brain cells and may help to prevent age-related loss of brain function.

People Who Compete In Sports in Later Life Are Smarter than Non-Exercisers
Another study showed that men and women who compete in sports in later life are smarter than people who do not compete (Exercise & Sport Sciences Reviews, October 2015;43(4):181–189). The authors found that regular exercise improves brain health and function with aging by improving blood flow to the brain, brain structure, and brain function. The greater the intensity of the exercise, the greater the protection of brain health.

Other studies show that as you age, exercise helps to preserve:
• Memory (Proc. Natl. Acad. Sci. U. S. A., 2011; 108(7): 3017–22)
• Brain size (Psychol. Sci, 2003; 14(2): 125–30; J. Gerontol. A Biol. Sci. Med. Sci, 2006; 61(11): 1166–70; Hum. Brain Mapp, 2013; 34(11): 2972–85)
• Blood flow to the brain (Stroke, 2013; 44(11): 3235–8; J. Hypertens, 2013; 31(12): 2400–9)
• Brain function in general (J. Magn. Reson. Imaging, 2013; 38(5): 1169–76)
• Brain function by preventing strokes (Stroke, 2003; 34(10): 2475–81)
• Brain function by preventing Alzheimer's disease (Lancet Neurol, 2014; 13(8): 788–94)

Lifestyle Changes to Reduce Dementia Risk
More than 30 percent of dementia cases may be related to modifiable risk factors such as physical inactivity and all heart attack risk factors (Lancet Neurol, 2014; 13(8): 788–94). Anything that damages arteries also damages brain cells. We can measure arterial brain damage by measuring artery health and brain volume. Master athletes have higher brain function and less arterial stiffness (Med. Sci. Sports Exerc, published online Nov. 2015), better blood flow to their brains and less damage to the inner linings of their blood vessels (J. Hypertens, 2013; 31(12): 2400–9).

My Recommendations
A visit to a retirement community should be a strong stimulus for you to immediately start a program to help prevent age-associated dementia. If you live in a retirement community as we do, you will see a very large proportion of older people who are losing, or have already lost, a considerable amount of their ability to reason, think, remember, function and solve problems. Many cannot take care of themselves and have to be cared for 24 hours a day by family members or in special care facilities.

Everything that helps to prevent heart attacks and diabetes also helps to reduce your chances of suffering dementia. To help reduce your chances of suffering from dementia:
• Do not smoke
• Severely restrict alcohol
• Avoid recreational drugs
• Avoid being overweight
• Try to exercise every day
• Protect your head from injuries
• Restrict red meat, sugared drinks, sugar-added foods and fried foods
• Eat lots of fruits and vegetables
• Keep blood levels of hydroxy vitamin D above 55 nmol/L
• If you are overweight, pre-diabetic or diabetic, restrict all refined carbohydrates such as bakery products and pasta.

Checked 7/1/17

November 29th, 2015
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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