It’s a fact that obesity dulls the brain. A slew of research shows that when weight piles on around the middle, inflammation increases in the brain, shrinking key processing areas, and leading to reduced concentration and memory loss. Middle-age spread, the excuse that comes with advanced years, means those who add pounds with age are at an increased risk of dementia and Alzheimer’s — and if that doesn’t get you to the gym, nothing will.
A recent study in The Journal of Neuroscience detailed the “milkshake test”: Scientists scanned the brains of women who drank a milkshake, and saw the striatum — a subcortical part of the forebrain responsible for movement, motivation and reward — light up. Six months later, they repeated the test: The brains of women who had gained weight in the interim failed to respond to the milkshake this time, their brains had become dulled by fat. So, a little like an addict who needs more heroin or cocaine over time to get a high, people who consume a lot of sugar or carbs start consuming more in order to get that same dopamine high.
Of course, the middle-aged and the elderly are hardly the only two groups at risk. The impact of obesity on children has been a particular concern. In a recent study, reported by the American Academy of Child and Adolescent Psychiatry, the adjacent orbitofrontal cortex, which controls decision-making and impulsivity, was observed to be smaller in children who are overweight. With this part of the brain reduced, so too is the ability to turn away from a plate of cookies. Dr. Antonio Convit, of the New York University School of Medicine, says, “There is a vicious cycle, where obesity leads to inflammation, which damages certain parts of the brain, which in turn leads to more disinhibited eating and more obesity.”
This is echoed by research from the Institute of Metabolic Science at the University of Cambridge, in the United Kingdom, where researchers found genetic mutations in the hypothalamus of obese children, the area of the brain concerned with metabolism, body temperature, thirst, fatigue, sleep, and attachment in relationships. However, it may not always leave a permanent effect. The good news is that one of these mutations is dramatically curable if the patient receives a daily injection of a recombinant protein called leptin, which can then reverse it. Cambridge’s Department of Pharmacology is now studying hypothalamic anatomy and function to further explore the circuitry in our brains that may lead us to eat beyond what our metabolisms can process at a time. Another obesity disorder, known as melanocortin-4 receptor deficiency, is present in 5 to 6 percent of severely obese children and 0.5 to 1 percent of obese adults. Remarkably, the mutant receptor can predict spontaneous food intake behavior at a test meal in individuals who have this genetic defect. Further research at Cambridge has also implicated the brain’s neurotrophin system in the regulation of human appetite and body weight.
The importance of this research is considerable. Belly fat is associated with a decrease in total brain volume in middle-aged adults, especially menopausal women, according to a study published in the Annals of Neurology, and another one with similar findings in the Journal of the American Geriatric Society. This visceral fat releases hormones that increase inflammation, damaging the immune system and certain areas of the brain. The American Geriatric Society looked at memory test scores for 8,745 women aged 65 to 79, and found that a one-point increase in a woman’s body mass index correlated to a one-point decrease on memory tests.
Further, research at the University of California, Los Angeles, found that obese, elderly individuals had 8 percent lower brain mass than those of appropriate weight. People who were simply overweight had 4 percent less brain volume than their slimmer counterparts.
A number of studies have demonstrated that people with smaller brain volumes experience decreases in cognition and are at a higher risk for dementia. This seems connected to the ability of neural messages to travel rapidly through the brain’s white matter or myelin sheathing — obesity slows this transfer of information. Neurologist Stefan Knecht of the University of Munster, Germany, says that among the morbidly obese: “You can actually watch them getting worse from one three-month period to the next if you have sufficiently sensitive measures.” In obese individuals, this sheathing shows signs of damage. Using MRIs Knecht’s team linked C-reactive protein (CRP) — a blood marker of systemic inflammation — with white matter integrity in a group of 447 older adults. Both Type 2 diabetes and obesity chronically elevate CRP levels in the blood.
As CRP levels in blood increased, Knecht and his colleagues discovered, so did the likelihood that white matter’s insulation would be impaired, leading to poor cognitive functioning, memory loss, poor reasoning, and language impairment.
Losing weight, even with surgery, can reverse this memory loss — but not if it is done through starvation diets. A study in The Journal of Neuroscience found that after mice were put on a diet and lost 10 to 15 percent of their body weight, the mice that were exposed to stress ate more food than those who had never been on a diet.
Western and Eastern researchers insist that a balanced diet and exercise are the only way to reach acceptable weight levels, and maintain optimum physical and brain health. Chinese medicine specialist and author, Daverick Leggett, says that obesity diminishes the spleen, which is critical to cleaning blood: “Obesity will not be overcome by starvation diets (which further weaken the spleen), nor by the consumption of cold or purgative foods (which further weaken the Yang).” Warm, cooked foods flavored with herbs and spices, especially plenty of vegetables, soups and stews, whole grains, legumes and just a little meat and low-fat protein are his prescription.
In Boston, the Newton School of Acupuncture advocates broths made by simmering organic beef or chicken bones overnight to help nourish the body, which, over time, leads to weight loss. The old Jewish recipe of chicken soup healing may have a lot more brain-sense than we give it credit for. However, Chinese medicine also counsels against the use of microwave ovens to warm or heat, saying they destroy the goodness in food.
And we’ve heard it over and over, but you still probably don’t do it: Read the labels on foods, avoid foods sweetened with corn syrup or those genetically modified, increase the amount of gluten-free foods, buy organic, cook more, and grow more. If you can buy direct from a local organic farmer, that’s even better. “We are what we eat” is an adage passed down from our grandparents. It’s never been truer.
LOSING WEIGHT, BOOSTING THE BRAIN
- Get moving — even just a daily walk around the block is better than nothing.
- Every hour, get up from your desk and do brief stretching exercises or run on the spot.
- If you have an exercise routine, add something else — qigong, yoga, or pilates to increase challenges.
- Keep sugary foods and alcohol out of your home.
- Soup is better for your body than salad. Increase your warm food intake.
- Have a glass of hot water with lemon as your first drink of the day to increase alkalinity in your body and combat inflammation.