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Human brains are getting larger each decade. That's the conclusion of researchers conducting the large Framingham Heart study which has now gone on for 75 years.

Between 1999 and 2019 the researchers conducted MRIs on participants born from the 1930s to the 1970s, with participants having an average age of 57. They found that each decade the brain volume steadily increased, with the brains of people born in the 1970s having 6.6% more volume than those born in the 1930s. Brain surface area increased about 15% in that time.

Brain structures such as white matter, gray matter, and hippocampus (a brain region involved in learning and memory) also increased in size over time. This increase in brain volume clearly shows that environmental factors (e.g., nutrition, education, social), and not just genetic factors, influence brain size.

The researchers thought that a larger brain volume, which signifies brain health,  might be protective against Alzheimer's disease. And that this could explain why the percentage of people (the incidence) of Alzheimer's disease and dementia has gone down over time.

From Medical Xpress: Human brains are getting larger: That may be good news for dementia risk

A new study by researchers at UC Davis Health found human brains are getting larger. Study participants born in the 1970s had 6.6% larger brain volumes and almost 15% larger brain surface area than those born in the 1930s. ...continue reading "Human Brains Are Getting Larger Over Time"

Another study finds health benefits to eating a Mediterranean based diet (here combined with the DASH diet) - the MIND diet. The researchers found that the older adults who followed the diet best were about 7.5 years younger cognitively than those who followed it least, thus suggesting that it may slow the cognitive decline of aging. Earlier research had suggested that it may reduce a person's risk in developing Alzheimer's disease. Foods to eat: fruits, vegetables, berries, whole grains, legumes (beans), nuts, fish, a little wine, and some chicken. Foods to limit on this diet: butter, red meat, margarine, sweets and pastries, whole fat cheese, and fried or fast food. From Medical Xpress:

Eating away at cognitive decline: MIND diet may slow brain from aging by 7.5 years

While cognitive abilities naturally diminish as part of the normal aging process, it may be possible to take a bite out of this expected decline. Eating a group of specific foods known as the MIND diet may slow cognitive decline among aging adults, even when the person is not at risk of developing Alzheimer's disease, according to researchers at Rush University Medical Center. This finding is in addition to a previous study by the research team that found that the MIND diet may reduce a person's risk in developing Alzheimer's disease.

The recent study shows that older adults who followed the MIND diet more rigorously showed an equivalent of being 7.5 years younger cognitively than those who followed the diet least. The results of the study recently were published online in the journal Alzheimer's & Dementia: The Journal of the Alzheimer's Association.

The National Institute of Aging funded study evaluated cognitive change over a period of 4.7 years among 960 older adults who were free of dementia on enrollment. Averaging 81.4 years in age....residents of more than 40 retirement communities and senior public housing units in the Chicago area. .... Martha Clare Morris, ScD, a nutritional epidemiologist, and colleagues developed the diet, whose full name is the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay. As the name suggests, the MIND diet is a hybrid of the Mediterranean and DASH (Dietary Approaches to Stop Hypertension) diets. Both diets have been found to reduce the risk of cardiovascular conditions, like hypertension, heart attack and stroke.

"Everyone experiences decline with aging; and Alzheimer's disease is now the sixth leading cause of death in the U.S., which accounts for 60 to 80 percent of dementia cases. Therefore, prevention of cognitive decline, the defining feature of dementia, is now more important than ever," Morris says.

The MIND diet has 15 dietary components, including 10 "brain-healthy food groups" and five unhealthy groups - red meat, butter and stick margarine, cheese, pastries and sweets, and fried or fast food. To adhere to and benefit from the MIND diet, a person would need to eat at least three servings of whole grains, a green leafy vegetable and one other vegetable every day—along with a glass of wine—snack most days on nuts, have beans every other day or so, eat poultry and berries at least twice a week and fish at least once a week. In addition, the study found that to have a real shot at avoiding the devastating effects of cognitive decline, he or she must limit intake of the designated unhealthy foods, especially butter (less than 1 tablespoon a day), sweets and pastries, whole fat cheese, and fried or fast food (less than a serving a week for any of the three).

Berries are the only fruit specifically to be included in the MIND diet. "Blueberries are one of the more potent foods in terms of protecting the brain," Morris says, and strawberries also have performed well in past studies of the effect of food on cognitive function.

Much has been written in the past few months on how to keep your brain sharp and avoid cognitive and memory declines due to aging, and especially how to lower the risk of dementia.

Many studies have shown the following to be beneficial to brain health: exercise (any exercise, including walking, is good), having friends and social networks to interact with, eating a lot of healthy foods (fruits, vegetables, whole grains, legumes (beans), seeds, nuts, and fish), having a purpose in life, using the computer, playing video games (action puzzle games such as Portal 2 and NeuroRacer, but according to one study - not Lumosity), participating in arts or crafts, and learning new skills - that is, try out and learn new things (a musical instrument, a new language, take a class, a new craft, etc), or even visit new places.

Many of these can be summarized as: feed your brain and body, and keep your brain and body active. Here is one recent study of aging, from Medical Xpress:

Civic engagement may stave off brain atrophy, improve memory

Instead of shrinking as expected, as part of the normal aging process, the memory center in the brains of seniors maintained their size and, in men, grew modestly after two years in a program that engaged them in meaningful and social activities, new Johns Hopkins Bloomberg School of Public Health-led research suggests. At the same time, those with larger increases in the brain's volume over two years also saw the greatest improvements on memory tests, showing a direct correlation between brain volume and the reversal of a type of cognitive decline linked to increased risk for Alzheimer's disease.

The research, published online in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, studied participants in the Baltimore Experience Corps, a program that brings retired people into public schools to serve as mentors to young children, working with teachers to help them learn to read in understaffed school libraries."By helping others, participants are helping themselves in ways beyond just feeding their souls. They are helping their brains. The brain shrinks as part of aging, but with this program we appear to have stopped that shrinkage and are reversing part of the aging process."

For the study, Carlson and her colleagues randomized 111 men and women to either participate in the Experience Corps (58) or not (53).... The control arm of the study, those not involved in Experience Corps, exhibited age-related shrinkage in brain volumes. Typically, annual rates of atrophy in adults over age 65 range from .8 percent to two percent. The men who were enrolled in Experience Corps, however, showed a .7 percent to 1.6 percent increase in brain volumes over the course of two years.