What does a lonely person’s brain look like? Scientists make surprising discovery

MONTREAL, Quebec — There’s no question the coronavirus pandemic has left millions of people stuck indoors and feeling very lonely this year. For older adults, social isolation can have an even more devastating impact on their mental state. Now, a new study is looking at how the months-long quarantine physically changes the brain of lonely individuals. Researchers from McGill University say they were shocked to find that lonely people actually have more active brains with more gray matter vital to memory and other cognitive functions.

The Canadian team examined MRI scans, genetic information, and psychological surveys from about 40,000 middle-age and older adults to compare the differences between people saying they feel lonely and those who don’t. The results reveal several surprising differences in how lonely people are wired mentally.

Researchers say the key variations take place in the brain’s default network. This is a set of brain regions which control inner thoughts and activities like reminiscing, planning for the future, imagining, and thinking about others. The study finds the regions of the default network in lonely people are more strongly wired together. They also have higher volumes of grey matter in these regions than people not suffering from loneliness.

Grey matter consists mostly on neuronal cells and axons, which extend out from these cells and carry signals between them. Grey matter also has a strong connection to cognitive function. Those who suffer from Alzheimer’s disease often see this material in their brains shrink over time.

Researchers also spotted differences in the fornix, a bundle of nerve fibers which carry neural signals between the hippocampus and the default network. In lonely patients, this bundle is actually more well-preserved than in others.

Lonely people think more about what they’re missing

Study authors say humans use the default network to remember the past, envision their future, an imagine hypothetical situations in the present. The team suspects that these brain regions are positively affected by loneliness because lonely people are more likely to use the default network as they think of other things besides their isolation.

“In the absence of desired social experiences, lonely individuals may be biased towards internally-directed thoughts such as reminiscing or imagining social experiences. We know these cognitive abilities are mediated by the default network brain regions,” says Nathan Spreng from McGill’s The Neuro (Montreal Neurological Institute-Hospital) in a university release. “So this heightened focus on self-reflection, and possibly imagined social experiences, would naturally engage the memory-based functions of the default network.”

Study authors say loneliness is becoming a much more recognized symptom connected to both mental health disorders and cognitive conditions. Previous studies reveal that older adults who experience loneliness are at high risk of developing dementia.

“We are just beginning to understand the impact of loneliness on the brain. Expanding our knowledge in this area will help us to better appreciate the urgency of reducing loneliness in today’s society,” says the study’s senior author Danilo Bzdok.

The study appears in the journal Nature Communications.

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