A recent study suggests that brain size is gradually increasing for individuals born after the 1930s.
The human brain appears to be increasing in volume according to recent research conducted by researchers at the
University of California Davis Health. The study indicates that individuals born in the 1970s had a brain volume 6.6% larger and a brain surface area nearly 15% greater than those born in the 1930s.
Researchers hypothesize that this increase in brain size could lead to a better brain reserve, potentially reducing the overall risk of age-related dementia. The findings were published in
JAMA Neurology.
"The decade of birth seems to influence brain size and potentially long-term brain health," said Charles DeCarli, lead author of the study. Charles DeCarli is a distinguished professor of neurology and director of the Alzheimer's Disease Research Center at University of California Davis Health. "Genetics plays a major role in determining brain size, but our results indicate that external influences - such as health, social, cultural, and educational factors - might also play a role."
The researchers utilized brain MRI imaging from participants in the
Framingham Heart Study (FHS). Launched in 1948 in Framingham to examine patterns of cardiovascular diseases initially, the study began with an initial cohort of 5,209 men and women aged 30 to 62 years. The research has continued for 75 years and now includes participants from the second and third generations.
The MRIs were conducted between 1999 and 2019 with FHS participants born in the 1930s to 1970s. The brain study included 3,226 participants (53% female, 47% male) with an average age of about 57 years at the time of the MRI.
Study findings
UC Davis researchers compared MRIs of people born in the 1930s to those born in the 1970s. They observed progressive but consistent increases in several brain structures. For example, a measure of brain volume (intracranial volume) showed consistent increases decade by decade. For participants born in the 1930s, the average volume was 1,234 milliliters, but for those born in the 1970s, the volume was 1,321 milliliters, representing about a 6.6% increase in volume.
The cortical surface area, a measure of the brain's surface, showed an even more significant increase: participants 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, which translates to almost a 15% increase in volume.
The researchers also noted that brain structures such as white matter, gray matter, and the hippocampus (a brain region involved in learning and memory) were also increasing in size when comparing participants born in the 1930s with those born in the 1970s.
A lower incidence of dementia with a bigger brain
Each year, 140,000 new cases of dementia (including at least 100,000 cases of Alzheimer's disease) are reported. A previous study found a 20% reduction in the incidence of dementia per decade since the 1970s. Improved brain health and size could be one of the reasons for this trend.
"Larger brain structures like the ones observed in our study may reflect better brain development and healthier brain states," said Charles DeCarli. "A larger brain structure represents a larger brain reserve and could buffer the late effects of age-related brain diseases like Alzheimer's disease and related dementias."
Article Author: Cédric DEPOND