• Posted March 27, 2024

Human Brains Are Getting Larger With Each Generation

Youngsters might have good cause to think they're brainier than their parents or grandparents, a new study finds.

It turns out that human brains are getting larger with each generation, potentially adding more brain reserve and reducing the overall risk of dementia, researchers report March 25 in the journal JAMA Neurology.

People born in the 1970s have nearly 7% larger brain volume and almost 15% larger brain surface area than folks born in the 1930s, according to the results of the 75-year study.

“The decade someone is born appears to impact brain size and potentially long-term brain health,” said lead researcher Dr. Charles DeCarli, director of the University of California, Davis Alzheimer's Disease Research Center. 

For the study, researchers analyzed brain scans of participants in the Framingham Heart Study, a multi-generational project launched in 1948 to analyze disease patterns among people in the town of Framingham, Mass.

The study has continued for 75 years and now includes second- and third-generation participants, researchers said. MRIs of the participants' brains were conducted between 1999 and 2019.

Researchers found gradual but consistent increases in several brain structures when they compared participants born in the 1930s to those born in the 1970s.

White matter, gray matter and the hippocampus -- a region involved in language and memory -- were all larger in people born in the 1970s, results show.

This could jibe with Alzheimer's disease trends in the United States, researchers said.

About 7 million Americans currently live with Alzheimer's, and that number is expected to rise above 11 million by 2040.

However, the percentage of the total population affected by Alzheimer's is actually decreasing, with about a 20% reduction in the dementia rate every decade since the 1970s, researchers said.

This increase in brain size might be one reason why the rate of Alzheimer's is declining, DeCarli said.

“Larger brain structures like those observed in our study may reflect improved brain development and improved brain health,” DeCarli said in a university news release. “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.”

More information

The Alzheimer's Association has more about dementia.

SOURCE: University of California, Davis, news release, March 25, 2024