Study: Younger generation brains have more gray matter, which could increase memory and decrease dementia

In a finding that could aid the understanding and treatment of neurodegenerative diseases, a team of researchers has discovered that the size of the human brain is experiencing a gradual increase over time.

This study, led by neurologist Charles DeCarli of the University of California Davis, suggests that this trend could be associated with a reduced risk of developing dementia in younger generations.

The study, published in the prestigious journal JAMA Network, analyzed brain images of more than 3,000 American individuals from different generations. The results show that those born in the 1970s had an overall brain volume that was 6.6 percent larger than those born in the 1930s.

The findings also indicate that members of Generation X have a nearly 8 percent increase in white matter volume and a nearly 15 percent increase in surface gray matter volume compared to members of the Silent Generation, which could decrease the likelihood of dementia.

“In summary, our results indicate that ICV, white matter volume, and hippocampal volume as well as cortical surface area have increased over decades of birth ranging from 1930 to 1970. Differences were also found for a select, relatively age-matched subgroup born in the 1940s and 1950s,’ the report reads.

The hippocampal body of the brain is an area that consists largely of gray matter,” according to the U.S. National Institute of Health.

“These findings likely reflect both secular improvements in early life environmental influences through health, social-cultural, and educational factors, as well as secular improvements in modifiable dementia risk factors leading to better “brain health” and reserve,” the JAMA report explains.

One of the most significant discoveries was the increase in the size of the hippocampus, a key region of the brain associated with memory and learning. This area showed a 5.7 percent increase in volume across the generations studied, even after adjusting for factors such as height, age and sex.

According to DeCarli, the findings suggest that external influences, such as health, social, cultural and educational factors, can also have a significant impact on brain development.

The discovery takes on even greater relevance in the context of global dementia concerns, as researchers believe that the incidence of dementia in the United States and Europe has decreased by approximately 13 percent each decade over the past three decades.

“While these effects are likely to be small at the level of the individual, they are likely to be substantial at the population level, adding to growing literature that suggests optimized brain development and ideal health through modification of risk factors could substantially modify the effect of common neurodegenerative diseases such as stroke and Alzheimer disease on dementia incidence,” the JAMA Network study says.

“Moreover, taken together with increases in IQ throughout the 20th century, these secular trends in brain volume may contribute to greater cognitive resilience.”