Tag: brain volume

Categories : Ageing NeurologyTags :

Human Brains are Getting Larger, which may Protect against Dementia

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A new study by researchers at UC Davis Health found human brains are getting larger. Study participants born in the 1970s had 6.6% larger brain volumes and almost 15% larger brain surface area than those born in the 1930s. The researchers hypothesise that the increased brain size may lead to an increased brain reserve, potentially reducing the overall risk of age-related dementias.

The findings were published in JAMA Neurology.

“The decade someone is born appears to impact brain size and potentially long-term brain health,” said first author Charles DeCarli, a distinguished professor of neurology and director of the UC Davis Alzheimer’s Disease Research Center.

“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.”

75-year study reveals brain changes between generations

The researchers used brain magnetic resonance imaging (MRIs) from participants in the Framingham Heart Study (FHS). The community-based study was launched in 1948 in Framingham, Massachusetts, to analyse patterns of cardiovascular and other diseases.

The original cohort consisted of 5209 men and women between the ages of 30 and 62. The research has continued for 75 years and now includes second and third generations of participants.

The MRIs were conducted between 1999 and 2019 with FHS participants born during the 1930s through the 1970s.

The brain study consisted of 3226 participants (53% female, 47% male) with an average age of about 57 at the time of the MRI.

The research led by UC Davis compared the MRIs of people born in the 1930s to those born in the 1970s.

It found gradual but consistent increases in several brain structures.

For example, a measure that looked at brain volume (intracranial volume) showed steady increases decade by decade.

For participants born in the 1930s, the average volume was 1234mL, but for those born in the 1970s, the volume was 1321 mL, or about 6.6% greater volume.

Cortical surface area showed an even greater increase over the decades.

Participants born in the 1970s had an average surface area of 2104cm2 compared to 2056cm2 for participants born in the 1930s — almost a 15% increase in volume.

The researchers found brain structures such as white matter, gray matter and hippocampus (a brain region involved in learning and memory) also increased in size when comparing participants born in the 1930s to those born in the 1970s.

Larger brains may mean lower incidence of dementia

Although the numbers are rising with America’s aging population, the incidence of Alzheimer’s – the percentage of the population affected by the disease – is decreasing.

A previous study found a 20% reduction in the incidence of dementia per decade since the 1970s.

Improved brain health and size may be one reason why.

“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.”

One of the study’s strengths is the design of the FHS study, which allows the researchers to examine brain imaging of three generations of participants with birthdates spanning almost 80 years.

A limitation is that non-Hispanic white participants make up the majority of the FHS cohort, which is not representative of the U.S. population.

Source: University of California – Davis Health

Categories : Ageing NeurologyTags :

Social Isolation Linked to Reduced Brain Volume in Older People

On By ModernMedia
Photo by Kindel Media on Pexels

A study of nearly 9000 older people in Japan found that those who have little social contact with others may be more likely to have reduction of overall brain volume, and in areas of the brain affected by dementia, compared with those who have more frequent social contact. The study results were published in Neurology.

“Social isolation is a growing problem for older adults,” said study author Toshiharu Ninomiya, MD, PhD, of Kyushu University in Fukuoka, Japan. “These results suggest that providing support for people to help them start and maintain their connections to others may be beneficial for preventing brain atrophy and the development of dementia.”

The study involved 8896 people without dementia, average age 73. They had MRI brain scans and health exams, and were asked how often they were in contact with friends or relatives that did not live with them.

The people with the lowest amount of social contact had overall brain volume that was significantly lower than those with the most social contact. The total brain volume, or the sum of white and grey matter, as a percentage of the total intracranial volume, or the volume within the cranium, including the brain, meninges, and cerebrospinal fluid, was 67.3% in the lowest contact group compared to 67.8% in the highest contact group. They also had lower volumes in areas of the brain such as the hippocampus and amygdala that play a role in memory and are affected by dementia.

The researchers took into account other factors that could affect brain volume, such as age, diabetes, smoking and exercise.

The socially isolated people also had more small areas of damage in the brain, called white matter lesions, than the people with frequent social contact. The percentage of intracranial volume made up of white matter lesions was 0.30 for the socially isolated group, compared to 0.26 for the most socially connected group.

The researchers found that symptoms of depression partly explained the relationship between social isolation and brain volumes. However, symptoms of depression accounted for only 15% to 29% of the association.

“While this study is a snapshot in time and does not determine that social isolation causes brain atrophy, some studies have shown that exposing older people to socially stimulating groups stopped or even reversed declines in brain volume and improved thinking and memory skills, so it’s possible that interventions to improve people’s social isolation could prevent brain volume loss and the dementia that often follows,” Ninomiya said.

Since the study involved only older Japanese people, a limitation is that the findings may not be generalisable to people of other ethnicities and younger people.

Source: American Academy of Neurology