Medics have discovered how increased brain volume affects health
In recent decades, the human brain has been increasing in volume. This may have a positive effect on health and on the risk of age-related dementia, scientists from the USA have admitted.
Brain volume changes both in a particular person while they are alive and in humans as a whole during evolution. The human brain has been getting bigger in recent decades, according to a large-scale study, and this has implications for long-term health.
Researchers from the University of California, Davis (USA) studied the results of magnetic resonance imaging scans that 3,226 people (53% women and 47% men) born between 1930 and 1970 underwent. At the time the study participants underwent MRI scans, they were between 45 and 70 years old. The scientists compared the performance of people from different generations and published the results in JAMA Neurology.
The authors of the scientific paper found that the younger the study participant was, the more noticeable was the increase in several brain structures. For example, intracranial volume steadily increased from decade to decade. It averaged 1,234 cubic centimeters for those born in the 1930s, and 1,321 cubic centimeters for those born in the 1970s, about 6.6 percent more.
The increase in cortical surface area was even more marked. In the study participants who were born in the 1970s, it was equal to 2104 square centimeters, while in the "generation" of the 1930s - 15% less, 2056 square centimeters. Similar changes were recorded for other brain structures: gray matter, white matter and hippocampus - an area that is involved in learning and memory.
According to the authors of the study, the increase in brain size can lead to the fact that a person will have more so-called brain reserve - the number of healthy brain areas that can take on at least part of the functions of the affected areas. As a consequence - people would have a lower overall risk of age-related dementias:
"Larger brain structures, such as those studied in our study, may reflect improved brain development and health. A larger brain structure represents greater brain reserve and may mitigate the effects of age-related brain diseases such as Alzheimer's disease and related dementias."
Speaking about the reasons that may have led to an enlarged brain, the researchers noted that it's not just about genetics. Scientists believe that social and cultural factors as well as education play an important role.
In general, over the past 20,000 years, the brain volume of humans has decreased significantly. Cro-Magnon of that era by brain volume on average by 5-10% exceeded modern man, and anthropologists have not yet come to a consensus on the reasons for this. One possibility is a decline in dietary quality. Humans 20,000 years ago relied heavily on meat. After the transition to agriculture, the share of meat decreased sharply, and crop failures steadily began to bring famine. The latter "stunted" the growth of children, which is why the average height of Paleolithic hunters until the second half of the 20th century was greater than the typical height of a European of the agricultural era. Perhaps similar effects of nutritional problems had not only on growth, but also on the brain. However, the final clarification of this question requires serious additional research.