What loneliness looks like in the brain? 'Signature' makes it different

A new study, published in the journal Nature Communications on December 15, suggests a sort of signature in the brains of lonely people that make them different in fundamental ways. Researchers found the default networks of lonely people were more strongly wired together.

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Humans use the default network when remembering the past, envisioning the future or thinking about a hypothetical present. (Image for representation: Reuters)

With curbs and coronavirus dampening festival joys, this holiday season seems to be a lonely one for many. In this year of isolation, the Covid-19 pandemic fueled loneliness among most of the people across the world, with several studies indicating how Covid-19 impact our brain. Amid this, a team of researchers studied how brains of lonely people are different from other people. There are many differences.

A new study, published in the journal Nature Communications on December 15, suggests a sort of signature in the brains of lonely people that make them different in fundamental ways.

According to the study, the brain manifestations of people were centred on the "default network" -- a set of brain regions involved in inner thoughts such as reminiscing, future planning, imagining and thinking about others. Humans use the default network when remembering the past, envisioning the future or thinking about a hypothetical present.

"Researchers found the default networks of lonely people were more strongly wired together and surprisingly, their grey matter volume in regions of the default network was greater," a report in Science Daily said.

"Loneliness also correlated with differences in the fornix -- a bundle of nerve fibres that carries signals from the hippocampus to the default network. In lonely people, the structure of this fibre tract was better preserved," the report quoted from the study.

The structure and function of the default network are positively associated with loneliness. This "maybe because, lonely people are more likely to use imagination, memories of the past or hopes for the future to overcome their social isolation".

Nathan Spreng from The Neuro (Montreal Neurological Institute-Hospital) of McGill University, and the study's lead author, explained, "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."

"So this heightened focus on self-reflection, and possibly imagined social experiences, would naturally engage the memory-based functions of the default network," Nathan Spreng was quoted as saying.

This study could help in understanding how loneliness manifests itself in the brain. This could be key to preventing neurological disease and developing better treatments.

"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 Danilo Bzdok, a researcher at The Neuro and the Quebec Artificial Intelligence Institute, and the study's senior author, was quoted as saying.

Loneliness is recognised as a major health problem. Previous studies have shown older people who experience loneliness have a higher risk of cognitive decline and dementia.

Several studies revealed that many coronavirus survivors are likely to be at greater risk of developing mental illness. A large study, published in The Lancet Psychiatry journal in November, had found that 20 per cent of those infected with the coronavirus are diagnosed with a psychiatric disorder within 90 days.

Anxiety, depression and insomnia were most common among recovered Covid-19 patients in the study who developed mental health problems. The researchers from Britain’s Oxford University also found significantly higher risks of dementia, a brain impairment condition.

(With inputs from Reuters)