Study Finds That Human Brain Is Bigger Compared To 75 Years Ago, With A ‘Reserve’ Against Dementia


In a fascinating study comparing the brains of individuals today with those of World War II veterans, researchers have discovered a remarkable increase in brain size.

According to the findings, the average human brain today is 6.6% larger than those of individuals from 75 years ago, with a corresponding 15% increase in surface area.

These findings, published in the journal JAMA Neurology, indicate that modern humans may have an advantage in staving off neurodegenerative diseases such as dementia, which are often associated with brain shrinkage.

Director of the UC Davis Alzheimer’s Disease Research Center, Dr. Charles DeCarli, said, “Larger brain structures like those observed in our study may reflect improved brain development and improved brain health.”

“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.”

The study has conducted by a team at UC Davis, who analyzed brain magnetic resonance imaging (MRIs) data from participants in the Framingham Heart Study, spanning from 1999 to 2019.

The Framingham Heart Study, initiated in 1948 in Massachusetts, was aimed at understanding patterns of cardiovascular and other diseases. Its original cohort of 5,209 individuals, aged 30 to 62, has since expanded to include subsequent generations, born from the 1930s to the 1970s.

“The decade someone is born appears to impact brain size and potentially long-term brain health,” Dr. DeCarli, added.

Lead researcher Dr. DeCarli pointed out that various life and lifestyle factors, such as health, social activity, cultural behavior, and educational attainment, may contribute to changes in brain size over time. The study included 3,226 participants, with an average age of about 57 at the time of MRI scanning, of which 54% were female.

The results revealed a consistent increase in several brain structures across generations. For individuals born in the 1930s, the average brain volume was 1,234 milliliters, whereas those born in the 1970s had an average volume of 1,321 milliliters, representing a significant 6.6% increase.

Even more striking was the increase in cortical surface area, which saw a nearly 15% rise over the same period. Individuals born in the 1970s had an average surface area of 2,104 square centimeters, compared to 2,056 square centimeters for those born in the 1930s.

Despite the increasing numbers of elderly individuals in the United States, the incidence of Alzheimer’s disease, as a percentage of the population affected, is decreasing.

Previous has shown a 20% reduction in the incidence of dementia per decade since the 1970s. This decline may be attributed, at least in part, to improved brain health and size among the population.