The researchers had hypothesized that the so-called predetermined network of the brain, which participates in memory and social cognition, would probably experience changes related to loneliness.
“What surprised us was that, overwhelmingly, it was the biggest effect of the data,” said study lead author Nathan Spreng, an associate professor of neurology at McGill University in Montreal.
The ties between these areas had been strengthened and the volume of gray matter was greater than in those who were not alone.
The results converged on the default network, as most affected by perceived isolation and loneliness.
A lot of data
Participants in this study, aged between 40 and 69 years, completed assessments that included questions about whether or not they felt alone.
The researchers then compared the MRI scans of lonely people who identified with those who did not feel lonely on a regular basis.
The large size of the data sample is a rarity in this area of science, Spreng said, and was the result of the biobank dramatically increasing its available brain images last February.
“We started working on it right away when they came out and it was very exciting,” Spreng said.
Prior to that, most of his work in neuroscience had focused on cohorts with only hundreds of participants, a significant number in itself. But now, with tens of thousands of subject data to pull off, there was so much more to learn.
“There’s an old, old saying about neurology that we always use. And that’s ‘use it or lose it,'” Heilman said.
While parts of the brain prepared for creativity and thinking about oneself can grow during loneliness, this could mean that other social parts of the brain are atrophied by inactivity.
“The big question arises: are you starting to lose other parts of the brain that are important to interactions?” Heilman asked. “If you don’t use them, will this eventually lead to a more insane disorder?”
Information on Alzheimer’s
A key way for this study to benefit medicine more broadly is to help scientists better understand how social isolation (an even more crucial issue during an isolating pandemic) can change brain structure and put people with Alzheimer’s as they age.
“There are still many other factors that need to be examined, such as how loneliness interacts with the APOE-4 genotype,” Spreng said.
And because older people at risk for dementia tend to be more isolated when living alone or in shared living facilities, more research could reveal how loneliness could exacerbate an already present genetic predisposition.
“This first study was really important in terms of identifying which parts of the brain are affected by loneliness,” he said. “We are using this information and following a large sample of older adults. We are seeing how their brain ages for several years and how their experience of loneliness can accelerate atrophy patterns.”
And the study is of greater importance after a year of pandemic in which social isolation is more frequent.
“Feeling socially connected is extremely important,” Spreng said. “Getting out of Covid-related isolation will probably be a lot easier for some people, especially young adults. Older adults may need more help.”