A study has found evidence that brain changes associated with aging can be seen at a much younger age than would be expected, in the late 40s. However, this process may be prevented or reversed based on dietary changes that involve minimizing the consumption of simple carbohydrates.

It’s suggested that, as people get older, their brains start to lose the ability to metabolize glucose efficiently, causing neurons to slowly starve, and brain networks to destabilize.

The evidence came from two large-scale brain neuroimaging datasets involving nearly 1,000 individuals (age 18-88). This data revealed that functional communication between brain regions destabilizes with age, typically in the late 40's, and that destabilization correlates with poorer cognition and accelerates with Type 2 diabetes.

The researchers then selected an additional 42 adults under the age of 50, to test whether giving the brain a more efficient fuel source, in the form of ketones, either by following a low-carb diet or drinking ketone supplements, could provide the brain with greater energy. It was found that even in younger individuals, this added energy further stabilized brain networks.

Brain network stability was tested after participants had spent one week on a standard (unrestricted) vs. low carb diet (e.g., meat or fish with salad, but no sugar, grains, rice, starchy vegetables).

To pinpoint whether glucose vs. ketones was the crucial difference, another group was scanned before and after drinking a small dose of glucose on one day, and ketones on the other. The same result was found, confirming that the crucial difference between the diets was the type of fuel they provide to the brain.

A mouse study also found that a ketogenic diet significantly improved memory in aging mice.

Different groups of mice were given carefully designed diets that were matched in every way except fat and carbohydrate content: a normal high-carbohydrate diet, a zero-carbohydrate ketogenic diet, and a high-fat, low-carbohydrate diet that was not ketogenic. Mice were fed the ketogenic diet intermittently to prevent them from becoming obese, starting at one year old - middle age for mice.

Mice that had been eating a ketogenic diet performed at least as well on memory tests at old age as they did at middle age, while mice eating the normal diet showed an expected age-associated decline. Mice who ate the ketogenic diet also explored more, and their improved memory was confirmed with another test a few months later.

All the mice ate a normal diet during the actual memory testing, suggesting the effects of the ketogenic diet were lasting.

People shouldn’t get carried away with these findings. Ketogenic diets are used clinically for life-threatening conditions, and many experts say such a diet is dangerous. People should consult a health care professional before trying it on their own. A better way of getting the effects may be through exercise, which also creates ketone bodies.

A double-blind, placebo-controlled study involving 40 older adults (aged 51-84) who had mild memory complaints, found that those given 90 milligrams of curcumin twice daily for 18 months experienced significant improvements in their memory and attention abilities. Those taking curcumin also had mild improvements in mood, and brain scans showed significantly less amyloid and tau signals in the amygdala and hypothalamus, compared with those who took placebos.

Four people taking curcumin, and two taking placebos, experienced mild side effects such as abdominal pain and nausea.

Curcumin is derived from the Indian curry spice turmeric.

A mouse study found that high levels of alcohol over a long period of time were associated with high levels of a marker for inflammation, along with impaired cognition and motor skills.

However, those exposed to low levels of alcohol consumption, analogous to approximately 2 ½ drinks per day, actually showed less inflammation in the brain and their glymphatic system was more efficient in moving CSF through the brain and removing waste, compared to control mice who were not exposed to alcohol. Their cognitive performance also matched that of the controls.

The finding adds to a growing body of research that point to the health benefits of low doses of alcohol. While excessive consumption of alcohol is a well-documented health hazard, many studies have linked lower levels of drinking with a reduced risk of cardiovascular diseases as well as a number of cancers.

Research using human cell cultures and mice suggests that those with an uncommon variation of the aldehyde dehydrogenase 2 gene (ALDH2) may be more at risk of Alzheimer's if they consume alcohol. This gene variation is associated with facial redness following alcohol consumption, reflecting reduced activity of an enzyme that protects against a toxin produced by alcohol consumption (acetaldehyde). Flushing, and inflammation, is a response to the toxin.

The gene variant occurs in about 8% of the world’s population, but is particularly prevalent among people from East Asia, where nearly half the population carries it.

The research builds on previous epidemiological studies in East Asian populations that have previously suggested an association between the mutation in ALDH2 that causes facial flushing and Alzheimer’s disease. However, there have also been other studies that didn’t find an association.

Confirmation of these results requires large epidemiological studies of humans to see whether alcohol drinkers who have the mutation develop Alzheimer’s disease at a higher-than-average rate.

The gene variant is also associated with a higher risk of developing cancer in the esophagus.

An Australian study involving 102 older adults (60-90) has concluded that physical fitness and arterial stiffness account for a great deal of age-related memory decline.

The study that, while both physical fitness and aortic stiffness were associated with spatial working memory performance, the two factors affected cognition independently. More importantly, and surprisingly, statistical modelling found that, taking BMI and gender into account, fitness and aortic stiffness together explained a third (33%) of the individual differences in spatial working memory — with age no longer predicting any of the differences.

While physical fitness didn’t seem to affect central arterial stiffness, the researchers point out that only current fitness was assessed and long term fitness might be a better predictor of central arterial stiffness.

It's also worth noting that only one cognitive measure was used. However, this particular measure should be a good one for assessing cognition untainted by the benefits of experience — a purer measure of the ability to process information, as it were.

It would also be interesting to extend the comparison to younger adults. I hope future research will explore these aspects.

Nevertheless, the idea that age-related cognitive decline might be largely, or even entirely, accounted for by one's physical fitness and the state of one's arteries, is an immensely appealing one.

Fitness was assessed with the Six-Minute Walk test which involved participants walking back and forth between two markers placed 10 metres apart for six minutes. Only participants who completed the full six minutes were included in the analysis.

https://www.eurekalert.org/pub_releases/2018-06/ip-bpf061118.php