The more a woman weighs, the worse her memory. No, I am not a chauvinist pig. This claim comes from actual research—by a woman, no less. Diana Kerwin and her colleagues at Northwestern University studied 8,745 women ages 65 to 79 and found that for every one-point increase in female body mass index, the score on a 100 point memory test dropped by one point.

The problem was greatest in women who had put the weight on around the hips, which is fairly typical for weight gain in women. Nobody knows why this is so. Fat deposits may increase the amount of cytokines, which are hormones that can cause inflammation. In a couple of earlier columns I explained how body inflammation, from sore joints or sore throat, for example, can trigger inflammation in the brain. I explained that brains can get inflamed too, irritated from the release of cytokines and other toxins from the brain’s immune cells in response to inflammation. In both genders, these toxins diminish mental capabilities, especially memory. Remember, everything the brain does affects memory (and everything affecting memory affects the brain).

Another obvious possibility is that excess weight often creates vascular problems, and everybody tends to have a problem with circulation in small arteries as they get older. Excess weight is a risk factor for stroke, as well as Alzheimer’s Disease.

This finding about memory loss is just one of many good reasons to lose weight. There are only two ways to lose weight: eat fewer calories and exercise more. Though exercise doesn’t do much to cause weight loss, it has many other benefits (improved circulation of blood to the brain) that can directly benefit memory and cognitive function.

It is not surprising then to learn of recent studies showing that losing weight can improve thinking and memory, in both men and women. John Gunstad, at Kent State University, compared attentiveness and memory test scores in 150 overweight subjects 109 of whom who had bariatric stomach by-pass surgery and 41 controls who did not. Those who lost weight because of gastric bypass surgery showed mental function improvements within 12 weeks after surgery. Those without hypertension improved more than the bariatric patients who had hypertension. Memory performance of the obese controls actually decreased over this period. Gunstad has a U tube video on his work at www.youtube.com/watch?v=gsFP2zAkStU.

Of course bariatric surgery is not without its problems. This surgery can lead to Wernicke's encephalopathy, a condition associated with thiamin or vitamin B1 deficiency. Symptoms of Wernicke's encephalopathy include loss of short-term memory, vision and muscle coordination. Presumably, vitamin supplements prevent this problem.

Most of us lose weight the old fashioned way: diet and exercise. Will weight loss help mental function, especially in people who are overweight but not to the point of obesity? What Gunstad hopes to test next is the possible mental benefit from losing weight through diet and exercise rather than surgery. I suspect he will see a benefit, but it could come from exercise as such rather than the weight loss. As I have reported in earlier columns, normal-weight people see a mental improvement from aerobic exercise.

But up to a point, you can just sit in your lounge chair and munch potato chips and still improve your memory—if you are learning from my book, Memory Power 101.

Sources:

Gunstad, J. et al. (2013). Improved memory function 12 weeks after bariatric surgery. Surgery for Obesity and Related Diseases. 7 (4): 465-472. http://www.soard.org/article/S1550-7289%2810%2900688-X/abstract

Kerwin, D. R. et al. 2010. The cross-sectional relationship between body mass index, waist–hip ratio, and cognitive performance in postmenopausal women enrolled in the Women's Health Initiative. Journal of the American Geriatrics Society. 58 (8): 1427–1432.

Neurologic Complications Associated with Novel Influenza A (H1N1) Virus Infection in Children. Center for Disease Control, July 24 2009

Snore a lot? Get up frequently at night to urinate? Wake up at 2 A.M. with bright ideas or worries? All these disruptions of sleep are common and more so as we get older. Does it matter? Well, of course such awakenings disrupt our sleep, and maybe it is just inconvenient. But disrupted sleep not only is more likely with age, it may promote deterioration in mental functioning. A recent study compared the effects of sleeping behavior in young adults and seniors. The study involved assessing the memory after sleeping of 18 young adults in their 20s and 15 older adults in their 70s. The subjects were tested on 120 word sets before they went to bed, and an EEG machine monitored their brain activity while they slept. Upon awakening, they were tested once again on the word pairs, but this time they took the tests while undergoing functional  magnetic resonance imaging (fMRI) scans.

The quality of deep sleep among the older adults was 75 percent lower than the younger ones, and their memory was significantly worse the next day−55 percent worse. The scans suggested deterioration of the frontal lobe. Shrunken brains can occur from aging and shrunken brains impair thinking and memory. But is it possible we have the cause and the effect backwards. Maybe what happens in the environment, such as impaired sleeping, causes both the shrunken brain and the impaired memory. Or in other words, what causes older brains to shrink?

Scientists consider a decrease of about 2% shrinkage every 10 years as normal. That may not be normal, just what most people experience because they are not taking care of their brains. There is abundant research that shows that exercises for both the brain and body help to reduce brain atrophy.

Of course, anything that damages neurons can reduce the number of their tree-like processes and the density of their contact points with other neurons. The list of such causes is long, including: alcohol abuse, brain inflammation, certain infections, concussion, impaired blood supply, lack of intellectual stimulus, vitamin B12 deficiency. It now appears that we should add fragmented sleep to the list.

Common natural causes of fragmented sleep in older humans are alcohol abuse and sleep apnea. Also, in males, enlarged prostate causes a need for frequent urination. As I have explained in my learning and memory blog posts (thankyoubrain.blogspot.com), learning events during the day are consolidated into lasting form during the sleep at night of the same day. We don’t know exactly how sleep helps, but obviously, you have far fewer mental distractions during sleep — unless, of course you keep waking up.

Alzheimer’s Disease also causes fragmented sleep. So, it is no surprise that the brain degeneration by the disease would cause memory problems. But maybe, just maybe, it is the fragmented sleep that accelerates onset of Alzheimer’s disease. Now, this seemingly ridiculous possibility has to be taken seriously in light of new research showing that sleep-disordered breathing, as in sleep apnea, seems to increase the risk of mental decline and even dementia in older women.

Disrupted sleep may also accelerate normal aging. This is certainly true when the cause is sleep apnea, which raises blood pressure and increases the cardiovascular damage that high blood pressure causes. Blood clotting is promoted, increasing the likelihood of strokes. Obesity and diabetes are often associated with sleep apnea, and it seems that sleep apnea not only results from obesity but can promote obesity and the diabetes that often accompanies obesity. Diabetes is toxic for nerve terminals. Similar neuropathy may also be occurring in their brain. Sleep apnea causes daytime sleepiness, and that it turn reduces attentiveness and mental activity, which when sustained over many years reduces the mental stimulus and promotes atrophy of neuronal processes.

Obviously, blood oxygen drops during sleep apnea. Normally, blood is 94% to 98% saturated with oxygen. But not breathing for 30 seconds or more during sleep causes oxygen level to drop to 80% or less. Any level below 90% oxygen level is dangerous, especially to the brain which demands nearly 20% of all the body’s oxygen supply. The adult brain can only survive about four minutes once oxygen is completely cut off.

So it is entirely possible that the slipping memory we see in so many elderly is a warning sign of something much more serious. But by the time the memory deficits show up, much of the damage has already been done. Prevention is the best hope.

Source:

Mander, B. A., Rao, V.,  Brandon, B. L., Saletin, J. M.,  et al. (2013). Prefrontal atrophy, disrupted NREM slow waves and impaired hippocampal-dependent memory in aging. Nature Neuroscience  doi:10.1038/nn.3324 

http://www.livestrong.com/article/161959-what-are-the-causes-of-brain-atrophy/

Yaffe, K., Laffan, A. M., Harrison, S. L. et al. (2011). Sleep-disordered breathing, hyupoxia, and risk of mild cognitive impairment and dementia in older women. JAMA. 306(6), 613-619. doi:10.1001/jama.2011.1115

For those who want to learn more about the brain, Dr. Klemm has just released the second edition of his e-book, “Core Ideas in Neuroscience.” See http://thankyoubrain.com/neurobook/index.htm