Dementia is a growing concern globally, with the number of cases expected to nearly triple over the next three decades. While the increase is largely attributed to the aging population, lifestyle factors can also contribute to the risk of developing dementia. However, a recent study has provided a glimmer of hope in the field of dementia research. Researchers found that people’s brains have been increasing in size over the past century, which may potentially reduce the risk of age-related dementias. As individuals age, the brain naturally decreases in size, but in those with dementia, brain cells are damaged and die, leading to shrinkage in various regions of the brain.
The study, published in JAMA Neurology, looked at individuals born between the 1930s and 1970s. The researchers found that individuals born in the later decade had larger brain volumes, with a 6.6% greater overall intracranial volume, 7.7% more white matter, 2.2% more cortical gray matter, 5.7% greater hippocampal volume, and a 14.9% larger cortical surface area. While cortical thickness was lower in those born in the 1970s, the differences remained significant even after adjusting for height variations. The study suggested that larger brain structures could potentially reflect improved brain development and health, providing a larger brain reserve that may protect against age-related brain diseases like Alzheimer’s.
Dementia encompasses a range of diseases, with Alzheimer’s disease being the most common cause. Symptoms of dementia can include memory problems, repetition of questions, difficulty with language, confusion, financial challenges, mood changes, and more. As brain cells deteriorate in dementia, brain shrinkage occurs, especially noticeable in Alzheimer’s and vascular dementia. The participants in the study came from the Framingham Heart Study, with scans measuring various brain structures. The findings suggested that the decade in which someone is born could impact brain size and long-term brain health.
Previous research has indicated that larger brain volume may offer protection against dementia pathology, proposing a ‘brain reserve hypothesis.’ This theory suggests that a larger brain with more neurons and connections could buffer against cognitive decline caused by brain atrophy. However, other factors like genetics, environment, socioeconomics, education, and lifestyle could also contribute to cognitive resilience. While the study cohort was mainly non-Hispanic White and well-educated, the researchers acknowledged the need for more diverse populations in future studies to draw conclusions about changes in brain size and their potential impact on dementia risk.
The Alzheimer’s Association’s U.S. POINTER study is working to address this research gap by including a more diverse group of participants. The study aims to follow over 2,000 older adults at risk for cognitive decline to better understand the influence of lifestyle interventions on reducing dementia risk. The hope is that by expanding research to include a broader range of individuals, more insight can be gained into how brain size changes over generations and its connection to cognitive function, resilience, and dementia risk. As the prevalence of dementia continues to rise, further research is essential to develop effective interventions and treatments to combat this growing public health issue.
