Our Brains Are Getting Bigger!

May 1, 2024

Brain size is increasing with successive generations, according to a new report. Researchers found that people born in the 1970s had, on average, brain volumes that were 6.6 percent larger than those born in the 1930s. During the same years, the surface area of brains increased by an average of almost 15 percent. The findings could bode well for dementia prevention, as a larger brain volume is associated with a lower risk of Alzheimer’s disease. 

The findings come from an analysis by researchers at the University of California, Davis, that spanned three generations over more than 75 years. The researchers used MRI brain scans from over 3000 participants in the Framingham Heart Study, a large and ongoing health study that began in 1948 with people who lived in Framingham, Massachusetts. The study has continued in the decades since, looking at offspring of the original participants. 

The research compared the MRIs of people born in the 1930s to those born in the 1970s. It found gradual but consistent increases in several brain measures, including intracranial brain volume and cortical surface area. There were also increases in the amount of white matter and gray matter, brain features tied to cognition, as well as the size of the hippocampus, a part of the brain tied to learning and memory and one of the first areas affected by Alzheimer’s. The findings were published in JAMA Neurology. 

“The decade someone is born appears to impact brain size and potentially long-term brain health,” said Dr. Charles DeCarli, the study’s first author and director of the UC Davis Alzheimer’s Research Center. “Genetics plays a major role in determining brain size, but our findings indicate external influences —such as health, social, cultural and educational factors —may also play a role.”

The findings underscore the importance of health and lifestyle factors that may influence brain health. Brain growth begins in the uterus, increases throughout childhood, and reaches a maximum size in early adulthood, the authors note. Nutritional factors, educational stimulation, social interaction and physical activity may all impact the growth of the brain and connections between brain cells during those years and beyond, research has shown.

A larger brain and more robust network of brain connections may lead to greater so-called cognitive reserve, which may help to protect the brain against the ravages of Alzheimer’s disease. As brain cells die because of Alzheimer’s and aging, according to the cognitive reserve theory, enough healthy cells and connections remain to keep brain function in check.

“Larger brain structures like those observed in our study may reflect improved brain development and improved brain health,” Dr. DeCarli said. “A larger brain structure represents a larger brain reserve and may buffer the late-life effects of age-related brain diseases like Alzheimer’s and related dementias.”

While you can’t change the year you were born, you can take steps to help maintain the health of your brain. So whatever you might be doing to help keep your brain healthy — whether it’s staying physically active, socializing, doing crossword puzzles, or eating a heart-healthy diet — keep doing it. It may help to maintain brain reserve throughout your life and could ward off or delay the worst effects of Alzheimer’s disease in old age.

By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.

Source: Charles DeCarli, MD; Pauline Maillard, PhD; Matthew P. Pase, PhD; et al: “Trends in Intracranial and Cerebral Volumes of Framingham Heart Study Participants Born 1930 to 1970.” JAMA Neurology, March 25, 2024


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