A recent study conducted by researchers at UC Davis Health has found that human brains are increasing in size over generations. The study compared brain volumes and surface areas of participants born in the 1930s to those born in the 1970s. The researchers found that individuals born in the 1970s had brains that were 6.6% larger in volume and almost 15% larger in surface area compared to those born in the 1930s. This increase in brain size may lead to a larger brain reserve, potentially reducing the risk of age-related dementias.
The findings of the study were published in JAMA Neurology and suggest that the decade in which someone is born can impact brain size and long-term brain health. While genetics play a significant role in determining brain size, external factors such as health, social, cultural, and educational influences may also play a role. The research, led by Charles DeCarli, a distinguished professor of neurology and director of the UC Davis Alzheimer’s Disease Research Center, utilized brain magnetic resonance imaging (MRIs) from participants in the Framingham Heart Study (FHS) to analyze changes in brain structure over time.
The FHS is a community-based study that began in 1948 in Framingham, Massachusetts, to investigate patterns of cardiovascular and other diseases. The study initially included 5,209 men and women between the ages of 30 and 62 and has continued for 75 years, now encompassing multiple generations of participants. The MRI analysis included 3,226 participants born between the 1930s and 1970s, with an average age of around 57 at the time of the MRI. The research compared brain structures such as white matter, gray matter, and the hippocampus in individuals born in different decades.
The results showed consistent increases in brain structures across generations, with participants born in the 1970s exhibiting larger brain volumes and surface areas compared to those born in the 1930s. This suggests that brain development and overall brain health may have improved over time, leading to larger brain reserves that could potentially buffer the effects of age-related brain diseases like Alzheimer’s and related dementias. The incidence of Alzheimer’s disease is expected to rise in the coming years due to the aging population, but the percentage of the population affected by the disease is decreasing, possibly due to improved brain health and size.
The study’s strengths include the long-term design of the FHS study, which allows for the examination of three generations of participants with birthdates spanning almost 80 years. However, a limitation is that the majority of the FHS cohort consists of non-Hispanic white participants and may not be representative of the U.S. population as a whole. The research team included authors from various institutions, including UC Davis, Monash University, Boston University, and UT Health San Antonio. These findings open up new possibilities for understanding how changes in brain structure over generations may impact overall brain health and the risk of age-related dementias.
