The famous Framingham Heart Study, spanning over 80 years from 1902 to 1985, looked at brain volumes across multiple generations of participants. The study analyzed MRI brain scans from 3,226 participants aged 45-74, born between the 1930s and 1970s. It found significant trends of larger brain volumes in several regions for individuals born in more recent decades:
– Intracranial volume, which represents the total brain size, was 6.6% greater in those born in the 1970s compared to the 1930s.
– Cerebral white matter volume, representing connections between brain cells, was 7.7% greater in the 1970s vs. 1930s cohort.
– Hippocampal volume, the area responsible for memory and other functions, was 5.7% larger in the 1970s compared to the 1930s.
– Cortical surface area, which correlates with the number of brain cells, was 14.9% greater in those born in the 1970s vs. 1930s.
The authors suggest these findings likely reflect improvements in early life factors over time, such as better nutrition, education, healthcare, and management of cardiovascular risk factors.
While the increase in brain size for any one individual is small, across entire populations, it can have a meaningful impact. Larger brain volumes are associated with higher cognitive abilities and resilience against degenerative neurological diseases like stroke, Parkinson’s, and Alzheimer’s.
So, the gradual increase in brain size over generations, even if subtle, may be contributing to higher average intelligence levels and lower rates of dementia in the population.
