The patients, who suffered with ischaemic heart disease, arrythmia, heart valve disease or previous heart failure, answered surveys about their physical and mental health, plus lifestyle factors like smoking and their social support.
According to the study, social support was measured by answers to questions about feeling lonely, living alone, or having someone to talk to.
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“It was important to collect information on both, since people may live alone but not feel lonely while others cohabit but do feel lonely,” study author Anne Vinggaard Christensen said in a news release.
The researchers concluded that feelings of loneliness were associated with poor heart health overall, even after adjusting for other diseases, age, education levels, body mass index, or smoking/drinking habits.
Furthermore, the study found that women who reported high levels of loneliness doubled their mortality risk — and men’s risk nearly doubled. And both men and women who reported being lonely were three times more likely to report being anxious or depressed, significantly lowering their quality of life.
People socially isolated or disconnected are also at higher risk of developing or dying prematurely of coronary artery disease. According to researchers, patients’ inability to look after themselves and take medications on time may play a role. But in the end, the results show a strong link to feelings of loneliness.
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“We live in a time when loneliness is more present and health providers should take this into account when assessing risk,” Vinggaard Christensen said.
Loneliness has also previously been associated with an increase in Type 2 diabetes and stroke.
In May's massive study from health insurer Cigna, surveys from 20,000 adults found that working too often or not enough greatly contributed to loneliness, suggesting workplaces may be a major source for fostering social relationships and ensuring a work-life balance.
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Survey respondents who said they exercise more or less than desired also had higher loneliness scores than people who reported exercising “just the right amount.” The same went for those spending more or less than desired time with family.
Another important predictor of loneliness: sleep. Those getting as much asleep as they desired were less likely to feel a lack of companionship, according to the research.
Younger adults born between the mid-1990s and the early 2000s had higher loneliness scores compared to respondents ages 72 and older.
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While previous research suggests social media may play a role in the rise of loneliness or depression among young Americans, the Cigna survey didn't find a correlation between social media use and loneliness.
"If you're passively using it, if you're just scrolling feeds, that's associated with more negative effects," Brigham Young University psychologist Julianne Holt-Lunstad told NPR. "But if you're using it to reach out and connect to people to facilitate other kinds of [in-person] interactions, it's associated with more positive effects."
More about the European Society of Cardiology study at escardio.org.