Dementia is a prevalent issue that is expected to almost triple in the next 30 years due to the growing and aging population as well as lifestyle factors, however, a recent study has discovered some positive news in the field of dementia. The study found that people’s brains have been increasing in size over the past 100 years, which could potentially reduce the risk of age-related dementias. Brain volume typically decreases as people age, but in individuals with dementia, many regions of the brain shrink due to nerve cell damage. The study from UC Davis Health revealed that individuals born in the 1970s had brains that were 6.6% larger on average than those born in the 1930s, indicating a potential link between brain size and a reduced risk of dementia.
Currently, dementia affects around 58 million individuals globally, with Alzheimer’s disease being the most common cause. Symptoms of dementia include memory problems, confusion, difficulty finding words, trouble with numbers, mood changes, and more. Brain shrinkage is a common occurrence in all types of dementia, particularly in Alzheimer’s disease and vascular dementia. The study looked at participants in the Framingham Heart Study, which has followed 15,000 individuals for over 75 years, and found that those born in the 1970s had greater brain volumes than those born in the 1930s, suggesting a potential protective effect of larger brain size against dementia.
Previous studies have suggested that larger brain volume can protect against the effects of dementia pathology, with the ‘brain reserve hypothesis’ proposing that a larger brain with more neurons and connections can provide a buffer against cognitive decline. However, experts note that factors such as genetics, environment, socioeconomic status, education, and lifestyle also play a role in brain health and resilience to cognitive decline. The increase in brain volumes seen over the four birth decades in the study could predict a lower risk of dementia in individuals born later in the Framingham Heart Study, though the study cohort was predominantly non-Hispanic White, healthy, and well-educated.
While the findings of the study suggest a potential association between brain size and reduced dementia risk, more research is needed to confirm these results in more diverse populations. The Alzheimer’s Association’s U.S. Study to Protect Brain Health Through Lifestyle Intervention to Reduce Risk (U.S. POINTER) aims to address this research gap by enrolling over 2,000 older adults at risk for cognitive decline and following them for two years. The study acknowledges the need for greater diversity in research populations to better understand changes in brain size over generations and their impact on cognition, resilience, and dementia risk. Future studies will hopefully provide more insights into the relationship between brain size, cognitive reserve, and dementia risk in a wider range of individuals.
