It is said that as healthy people age, the brain decreases in size. However, in people with dementia, as nerve cells get damaged and die, numerous regions within the brain shrink. This process is known as brain atrophy. Currently, researchers are finding the answer to the question, “Can a larger brain help reduce the risk of dementia in people? “.
A new study published in JAMA Neurology suggests this possibility. Researchers found that people born in the 1970s had brains that were, on average, 6.6% larger than those of people born in the 1930s. Thus, larger brain size is suggested to mean increased brain reserve, which may reduce the risk of age-related dementia.
Currently, 58 million people worldwide have dementia, and that number is supposed to reach 152.8 million by 2050. Even though memory loss is a natural part of aging, dementia is not. Dementia is a series of diseases ranging from Alzheimer’s vascular dementia to Lewy body dementia (which may be associated with Parkinson’s disease, frontotemporal dementia, and mixed dementia.
Symptoms of dementia are:
- memory problems
- asking the same question repeatedly
- difficulty finding or understanding words
- feeling confused in unfamiliar environments
- problems dealing with money and numbers
- anxiety and withdrawal
- difficulty planning and carrying out tasks
- mood, personality, and behavior changes
- sleep disturbances
- obsessive tendencies
One of the common occurrences in all types of dementia is that as brain cells are damaged and die, there is some degree of brain shrinkage, with this being particularly pronounced in Alzheimer’s disease and vascular dementia.
The current study analyzed participants in the Framingham Heart Study, where 15,000 individuals were followed for over 75 years. Three thousand two hundred twenty-six people had two MRI scans suitable for this study. Of them, 1,706 (53%) were women, and 1,520 (47%) were men. The scans measured intracranial volume (ICV), cortical gray matter, cerebral white matter, hippocampal volume, surface area, and thickness.
The participants were all born between 1930 and 1970, with the median decade of birth being the 1950s. On average, people born in the 1970s were 1.6 inches taller than those born in the 1930s, so the researchers adjusted for this when comparing brain measurements.
People born in the 1970s had more significant brain volumes than those born in the 1930s. They had a 6.6% greater ICV, 7.7% more white matter, 2.2% more cortical gray matter, 5.7% greater hippocampal volume, and 14.9% larger cortical surface area. The one measure that had decreased was cortical thickness, which was 20.9% lower. These differences remained significant when the researchers adjusted for height differences.
Genetics plays a significant role in determining brain size, but our findings indicate external influences such as health, social, cultural, and educational factors may also play a role. Thus, it can be concluded that larger brain volumes may be beneficial in maintaining resilience to cognitive decline and dementia. Still, many other factors can contribute to resilience, including genetics, environment, socioeconomic status, education, and active vs. sedentary lifestyle.
Journal Reference – Charles DeCarli, M. (2024). Intracranial and Cerebral Volumes in Framingham Heart Study Participants.
Retrieved from https://jamanetwork.com/journals/jamaneurology/fullarticle/2816798
