Research finds that many human brains tend to shrink with aging. Brain shrinkage has been linked to cognitive decline. But do our brains have to shrink? Can we slow the process of brain shrinkage? How about reversing what has already shrunk?
Brain shrinkage: Chimps versus humans
Back in 2011, a study compared brain scans of chimpanzees with humans. The research was published by the journal PSAS – the Proceedings of the National Academy of Sciences.
The researchers did magnetic resonance imaging (MRI) on 99 living chimpanzees’ brains. They compared these with 87 MRI scans of people. The humans ranged in age from 22 to 88 years old. The chimps’ were from 10 to 51 years old.
The age range of the chimps approximately corresponded to the ages of the humans, ‘in chimp years’ as they say. In the wild, chimps will generally live to about 45 years, but in captivity, they will survive up to about 60.
The odd thing this study found was that while the human brains shrank as the people aged, the chimp brains did not shrink.
On average, the human brains shrank up to 25 percent by the time they were 80 years old. Again, the chimps showed no brain shrinkage.
White versus gray matter
This study also found that among the humans, gray matter shrank gradually. This occurred between about 30 years old and 80 years old. The frontal lobe gray matter shrank 14 percent on average. The gray matter in the hippocampus shrank about 13 percent.
The white matter in the human brains shrank more abruptly. By age 70, the white matter in the frontal lobes of the human brains had shrunk an average of 6 percent at that point. But by age 80, their frontal lobe white matter had shrunk by 24 percent.
Other studies have focused on the locations of much of this brain shrinkage. A 2013 study from Wayne State University conducted MRI scans on 49 people. They found that shrinkage occurred mostly in the brain’s lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum. They didn’t see much shrinkage in the white matter regions of the prefrontal cortex, the orbital-frontal cortex and the cerebellum, however.
Shrinkage, cognition and Alzheimer’s
Several studies have found that brain shrinkage significantly relates to cognition.
A 2010 study from the University of Pittsburgh studied 299 people and found that shrinkage of gray matter volume was associated with cognitive decline. More gray matter shrinkage increased the rate of cognitive decline by two-fold.
Meanwhile, other research has found significant brain shrinkage among dementia and Alzheimer’s disease patients. A 2001 study from the UK’s University College London did MRIs of 20 people with Alzheimer’s disease along with 20 healthy people of similar ages. The researchers found that the Alzheimer’s patients had significantly more brain shrinkage than the healthy people.
Even those in early stage Alzheimer’s disease showed increased shrinkage. Brain regions found shrunk included the posterior cingulate and neocortical temporoparietal cortices. They also found shrunk regions in the medial temporal lobe.
A 2009 study from the University of California at San Diego found similar results. They did brain scans of 139 healthy people along with 175 people with mild cognitive impairment and 84 people with Alzheimer’s disease.
They found that those with mild cognitive impairment and Alzheimer’s disease had greater brain shrinkage. This included several brain regions, including frontal cortices, posterior parietal region and anterior cingulate cortex. Losses were seen in ventricular, temporal and posterior regions of the brain.
Can brain shrinkage be reversed or slowed? Yes. Let’s look at some research that has shown strategies that have been shown to reverse or slow brain shrinkage in the research.
Some research has shown that brain shrinkage can be reversed or slowed with brain training. For example, the Wayne State University study above found that cognitive training was able to significantly reduce brain shrinkage in the cerebellum. Other areas of brain shrinkage did not respond.
Another study, this from Germany’s Max Planck Institute for Human Development, tested young men along with older men. They focused upon the shrinkage of the hippocampus. The researchers split the men into two groups and half were given spatial navigation training. Spatial navigation training works with changes of focus and distance in a brain-training format.
After a four-month program, the research found that the spatial navigation training grew the hippocampus size among the brain training group. The control group continued to lose mass in the hippocampus.
Other studies have shown similar findings. For example, a 2010 study from Japan’s Tohoku University found that working memory training increased white matter in two brain regions.
Learning a new language can also increase brain size. A study from Germany’s University of Regensburg tested 16 healthy volunteers. They had them learn to decipher Morse code. After their training, they found that gray matter increased.
In 2011, researchers from the University of Pittsburgh studied 120 older adults. They measured the brain sizes of the people to determine their brain shrinkage. Then they divided the 120 people into two groups. For one year, 60 of them did stretching exercises for three days a week. The other 60 people did moderate-intensity aerobic exercise for three days a week.
The MRIs done at the end of the year found that the group that exercised over the one-year period had increased volume in the hippocampus. Their right-side hippocampus sizes increased by an average of 2.12 percent. The left side increased by an average of 1.97 percent.
Meanwhile, the stretching group’s hippocampus volumes shrunk by 1.4 percent on each side during the same period.
The brain size benefit of exercise lasts. The 2010 study from the University of Pittsburgh studied 299 older adults – also mentioned above. The study followed the subjects’ exercise and brain size over a period of nine years. The subjects had an average age of 78 years old.
The researchers compared brain sizes with the amount of walking done per week by each of the adults. Those who walked an average of 72 blocks or more per week had increased significantly gray matter through the nine-year period. They also had reduced incidence of cognitive decline after 13 years.
In 2006, a study from the University of Illinois tested people between 60 and 79 years old. Again one group stretched, while the other group did aerobic exercising. After six months, MRI scans showed that those who did the aerobic training had significant increases in brain size in both gray and white matter areas of the brain. Those who just did the stretching continued to show brain shrinkage.
Does exercise necessarily increase brain size in younger people? This study also studied 20 younger adults using the same process. They didn’t find any increase in brain size among the younger group. Certainly given the other results, exercising during younger years won’t be in vain, however.
Reducing blows to the head, regardless of our age, is a clear strategy to reduce brain shrinkage now and in the future.
Researchers from the Boston University of Medicine have found that repeated blows to the head tend to result in greater brain shrinkage over time. Sports they find are linked to brain shrinkage include football, hockey, soccer and professional wrestling. They also find that physical abuse can also result in shrinkage.
Multiple studies have linked alcohol consumption with greater brain shrinkage. This has been shown even in low-to-moderate drinking (1-3 glasses of alcohol per day). Researchers from The Netherlands’ Utrecht University illustrated this in their research of those over the age of 65 years old.
Researchers from the University of Barcelona studied 40 alcoholics who were otherwise healthy and well-nourished. They compared their MRI brain scans with 20 healthy non-drinkers. They found that the alcoholics’ brains had shrunk significantly. Furthermore, their brain shrinkage correlated with the amount of alcohol they drank and the number of years they had been drinking.
A U.S. study followed 16 alcoholics together with 28 control subjects of the same age for five years. The researchers found that the alcoholics had significant brain volume shrinkage over the five years, compared to the non-drinkers. Again, the shrinkage correlated with the extent of their drinking. They found significant brain shrinkage in the prefrontal cortex of the alcoholics.
In other words, the more we drink, and the longer we drink, the more brain shrinkage we will have. This is what is called a cumulative effect.
At Japan’s Kurihama Alcoholism Center, the MRIs of younger and older people were compared. The researchers found that alcoholics had increased cortical shrinkage. Regions of shrinkage due to alcoholism include the subcortical white matter, temporal lobes, thalamus, brainstem, cerebellum, corpus callosum, anterior cingulate and insula regions.
A study from the University of Sydney found the regions most affected by alcohol consumption were the cerebral cortex, hypothalamus, and the cerebellum.
This doesn’t mean that such alcoholic shrinkage can’t be reversed. The Japanese study above reported that abstinence significantly recovers brain size losses. The most recovery occurs after one month of sobriety. This recovery then continues, through at least eight months.
Diet and brain shrinkage
In late 2015, researchers from Columbia University, with support from National Institutes of Health published a brain shrinkage study in the American Academy of Neurology journal, Neurology. The research studied 674 people with an average age of 80 years. None suffered from dementia.
The researchers had each person complete extensive diet questionnaires. Seven months after their questionnaires, the volunteers were given MRI scans of their brains to determine their relative brain sizes.
The researchers analyzed their diets and compared their relative diets to their brain sizes. The researchers found those whose diets more closely adhered to a Mediterranean diet had significantly larger brain sizes than those who did not.
Those who followed a Mediterranean diet had total brain volumes that averaged more than 13 milliliters larger than those who didn’t follow the Mediterranean diet. Med diet followers had gray matter volumes that averaged five milliliters more, and their white matter volumes averaged 6.41 milliliters more.
A diet that more closely adheres to a Mediterranean diet means a greater proportion of fruits, vegetables and seafood, and significantly less red meat consumption.
The relative difference was calculated to be comparable to five years of aging. Lead researcher, Yian Gu, PhD, a professor at Columbia University confirmed the findings:
“These results are exciting, as they raise the possibility that people may potentially prevent brain shrinking and the effects of aging on the brain simply by following a healthy diet.”
Other studies have confirmed the link between nutrition and brain shrinkage. A 2011 study from Portland’s Oregon Health & Science University tested 104 people with an average age of 87 and no dementia. Of the group, 42 of the volunteers were given MRIs to measure their relative brain sizes. They were also given blood tests to determine their blood levels of nutrients.
The researchers found that the blood-nutrient markers of the volunteers correlated significantly with the brain volume of the participants. The researchers also found that those with diets high in trans fats had significantly greater brain shrinkage.
Diets high in trans fats included more refined and fried foods.
Another study found that high blood sugar levels were associated with brain shrinkage.
Several studies including the Oregon study above, have hinted that B vitamins might help delay brain shrinkage – or even increase brain size.
In 2013, researchers from the University of Oxford investigated this with 156 people who averaged 76 years old.
They split them into two groups – 76 and 80. For two years, 80 people took a daily supplement consisting of 800 micrograms of folic acid, 500 micrograms of B12, and 20 milligrams of B6. The other group of 76 people took a placebo for the two years.
The volunteers were given MRI brain scans before and after the supplementation period. The researchers found similar brain shrinkage in many areas of the brain between the two groups.
However, the researchers found that the vitamin B group had significantly less brain shrinkage compared to the placebo group in several regions of the brain – primarily the posterior regions. These included the bilateral hippocampus and parahippocampal gyrus, the retrosplenial precuneus, the lingual and fusiform gyrus, along with the cerebellum.
These regions mentioned also happen to be regions that are most seen with shrinkage among Alzheimer’s disease patients.
A 2008 study from the University of Illinois studied 32 people between 59 and 79 years old. This study also found increased gray matter in some brain regions with greater vitamin B6 and B12 supplementation.
Increased circulating levels of homocysteine – decreased with these B vitamins – has also been associated with brain shrinkage.
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Case Adams is a California Naturopath and a Board Certified Alternative Medicine Practitioner with a PhD in Natural Health Sciences, and diplomas in Homeopathy, Aromatherapy, Bach Flower Remedies, Blood Chemistry, Clinical Nutritional Counseling and Colon Hydrotherapy. He has authored 26 books on natural healing strategies.