Our brains are getting bigger. Scientists think this could help lower risks of dementia

Human brains are getting larger. That may be good news for dementia risk
Human brains are getting larger. That may be good news for dementia risk Copyright Canva
Copyright Canva
By Oceane Duboust
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Several brain structures increased in volume between people born in the 1930s and people born in the 1970s which may reduce dementia risk.


A new study has found that our brains are getting larger, which could be good news for reducing dementia risk.

Researchers from the University of California analysed data from a cohort in the Framingham Heart Study (FHS) which started in 1948 in the US and originally consisted of 5,209 men and women between the ages of 30 and 62.

The study has continued for 75 years, meaning that it now includes participants born during the 1930s through the 1970s.

Though it was originally designed to study cardiovascular diseases, the researchers focused on MRI results of more than 3,200 people.

Published in the journal JAMA Neurology, their findings showed significant increases in various cerebral measures over time.

A bigger brain could act as a ‘buffer’ against dementia

“The decade someone is born appears to impact brain size and potentially long-term brain health,” Charles DeCarli, first author of the study and professor of neurology at the University of California, said in a statement.

“Genetics plays a major role in determining brain size, but our findings indicate external influences - such as health, social, cultural and educational factors - may also play a role,” he added.

There was an increase in brain volume of about 6.6 per cent with an average volume of 1,234 millilitres for participants born in the 1930s compared to 1,321 millilitres for people born in the 1970s.

Researchers also found that the surface of the brain's outer layer - called the cortical surface area - increased by nearly 15 per cent between people born in the 1930s compared to people born in the 1970s.

There were also increases in white matter, grey matter, and hippocampus volumes between the older and younger participants.

“Larger brain structures like those observed in our study may reflect improved brain development and improved brain health,” DeCarli said.

“A larger brain structure represents a larger brain reserve and may buffer the late-life effects of age-related brain diseases like Alzheimer’s and related dementias,” he added.

Currently, more than 55 million people have dementia worldwide, according to the World Health Organization (WHO), with between 60 to 70 per cent of the cases being Alzheimer's disease.

In the US, while Alzheimer's disease cases are rising, the incidence of the condition, or the percentage of the population affected, is decreasing.

A previous study of participants from the same cohort found a 20 per cent reduction in the incidence of dementia per decade since the 1970s.

“We hypothesise that larger brain volumes indicate larger brain development and potentially greater ‘brain reserve’ that could explain the declining incidence of dementia as previously reported,” the researchers explain in the latest study.

However, brain size is just one piece of the puzzle.

The WHO states that people can reduce their risk of dementia with physical activity, and eating a healthy diet.


Researchers say further research is needed, particularly in more diverse cohorts as white participants make up the majority of the study group.

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