The mutual influences on loneliness have been set out in a new model, with experts saying a better understanding of how these factors interact would improve care.

The ‘model of loneliness’ identifies the interplay between social impairment, a dysregulated oxytocin system – which is responsible for the ‘feel-good hormone’ oxytocin – and illness.

The authors say these areas are interconnected and “in order to understand loneliness, it is necessary to consider them together”.

The research team carried out a review of previous studies of loneliness, with their key findings including:

  • Lonely people show social impairment in cognitions, such as negativity bias or hypervigilance to social cues, and behaviour, such as avoidance
  • A dysregulated oxytocin system in lonely people, which affects their social functioning, serves as a neurobiological mechanism of loneliness
  • Loneliness considerably increases the probability for psychiatric and physical morbidity and vice versa
  • Loneliness can be both a cause and consequence of these three areas – social impairment, dysregulated oxytocin system and illness.

The ‘model of loneliness’ was developed using the neurobiological, psychological and behavioural results drawn from the review.

Loneliness is described by the Global Initiative on Loneliness and Connection as “a subjective unpleasant or distressing feeling of a lack of connection to other people, along with a desire for more, or more satisfying, social relationships.”

Loneliness and social impairment

Depending on how long someone has experienced loneliness, lonely people react to social situations differently. Some view social interactions negatively and avoid them, while others experience more good feelings when they are around people close to them because of the need to form relationships.

Lonely people often ‘comfort eat’ or use illegal substances, demonstrating loneliness may be a physiological response to an absence of social connections.

People with acute loneliness actively seek social connections, while those with chronic loneliness tend to avoid other people.

The impact of oxytocin

Oxytocin levels increase in people with loneliness, suggesting it compensates for emotional deficiency which is the result of social isolation.

The increase in oxytocin production related to isolation triggers an increase in the relevance of social stimuli. In people with chronic loneliness, their oxytocin levels adapt by falling.

The oxytocin system both underlies and also reacts to the changes in people with loneliness, such as a negative perception of social interactions.

Social touch initiates oxytocin release. A dysregulated oxytocin system adds to the negative view lonely people have of social touch.

Illness and loneliness

People with loneliness are at greater risk of both mental and physical illness. They are more at risk of depression, anxiety, personality disorders, and cardiovascular disease.

Mental illness can trigger loneliness or make it worse, while loneliness also puts people at greater risk of dementia.

Loneliness can also prevent people from managing medical illnesses properly, which can be fatal.

The team behind the German study concluded: “Impaired social interaction, the oxytocin system and illness are interconnected in lonely people and recognising these links is central to understanding the complex construct of loneliness.

“More work is needed both in research into the underlying mechanisms of loneliness as well as into how to treat it effectively, both on its own and as part of clinical psychiatric care.”

Read more in Neuroscience & Biobehavioral Reviews.

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