Dementia is a growing global concern, with predictions indicating a significant increase in cases over the next three decades, largely attributed to aging populations. However, a recent study suggests a potential positive development in the fight against dementia: human brains have been growing larger over the past century. This increase in brain size, particularly observed in those born in the 1970s compared to earlier decades, may indicate a greater brain reserve that could potentially lower the risk of age-related dementias. The study, conducted by UC Davis Health and published in JAMA Neurology, analyzed brain measurements from participants in the Framingham Heart Study. It found that individuals born in later decades had greater brain volumes, including more cortical gray matter, white matter, and hippocampal volume.
While genetics play a significant role in determining brain size, external factors such as health, education, and environment may also contribute. The “brain reserve hypothesis” suggests that a larger brain volume may provide protection against cognitive decline, although cognitive reserve may ultimately be more crucial. This study offers hope for the future, indicating that increased brain size could potentially mitigate the risk of dementia in later life.