Humans are social creatures, and interacting with others is crucial to our survival and wellbeing. As a result, social isolation and the perception of isolation known as loneliness can have large negative impacts on health and can increase the risk of developing many diseases such as Alzheimer’s Disease or heart disease. Due to social distancing and stay-at-home orders necessitated by the COVID-19 pandemic, more and more people are reporting feeling lonely or lacking social connection. In fact, in a June 2020 survey, more than 50% of older adults reported that they felt lonely, which is double the 27% that was reported in 2018. Because of the scope and potential impact of this problem, scientists are interested in figuring out whether certain areas of the brain change in a person who feels isolated, since this could inform ways of identifying and measuring isolation, as well as treating its effects on the body.
Humans rely on others in many ways, so what happens when a person does not have that social network to rely on?
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Recently, scientists from McGill University were interested in studying loneliness and how it affects the brain to better understand if and where there are differences between lonely and isolated individuals. The data they used came from a resource called the UK Biobank, which is a database containing surveys, brain scans, and other information about the bodies and brains of 40,000 middle-aged and older adults. By comparing the MRI images of patients who reported often feeling lonely to the MRI images of patients who did not, the researchers found significant differences in a brain region called the default network, which processes a person’s internal thoughts. It is involved in reminiscing, imagining, planning for the future, and thinking about other people. Study participants who reported feeling more lonely had stronger connections and increased brain volume in the default network. The researchers theorized that since people who identified as lonely were less likely to receive satisfying external support, they would instead turn inwards and use imagination or reminisce about past memories to offset the sensation of loneliness. This self-reflection in turn would cause the default network of the person’s brain to become more robust and well-developed. It is not yet known what kind of an impact a more developed default network will have on overall health.
Loneliness is a major risk factor for many diseases. A prevalent theory explaining this phenomenon is that loneliness activates a physiological stress response in our body, causing hormones such as cortisol to be released, increasing blood pressure. Long-term stress causes strain on the body’s systems, leaving people more susceptible to disease. With this study from McGill University, scientists have gained a better understanding of the differences between the brains of lonely and non-lonely people. A better grasp of these neurological differences could have many potential applications, from identifying lonely individuals, to designing more effective intervention programs for these individuals, and to implementing better treatments for diseases linked to loneliness.
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