Is depression contagious?
The latest figures from a survey by the UK's Office for National Statistics show that one in six people are reporting moderate or severe symptoms of depression, a 60% increase from three years earlier.
The dramatic rise has been variously blamed on the increased mental stress caused by Covid-19 lockdowns and the subsequent cost of living crisis, according to the Daily Mail. But psychologists in Finland suggest that the rising rates of depression could have another reason: depression can be contagious, just like a cold or flu.
The Depression Contagion
In an article published in the prestigious journal JAMA Psychiatry, the Finnish team of scientists, led by Kristian Hakulainen, associate professor of psychology at the University of Helsinki, wrote that they tracked the health records of more than 700,000 children for 11 years, starting at the age of 16.
The analysis found that if one student in a class showed clear signs of depression, there was at least a 9% higher chance that their classmates would also develop it. Those who had more than one classmate with depression or anxiety had at least an 18% higher risk of being diagnosed with the condition over the 11-year study.
Even when the numbers were adjusted for factors that could have influenced it, such as income, the association between a depressed student and increased depression among their classmates remained. What’s more, while the effect declined over time, it persisted for up to 11 years after the students left school.
Good research
Previous studies have suggested that depression may be contagious. For example, a 2014 US study published in the journal Clinical Psychological Science found that depressive thinking may spread among college roommates. Psychologists at the University of Notre Dame in Indiana studied 108 randomly selected freshmen who shared dorm rooms. The students answered online surveys about their thinking patterns, stress levels and moods during the first month, and again three and six months later. In particular, the researchers looked at a type of thinking linked to depression, called rumination, which involves thinking about things.
The researchers found that if a flatmate started their university days meditating regularly, their roommate who had never meditated was more likely to pick up the habit. They also had more than twice as many depressive symptoms as the students who had never meditated.
Negative thinking and catastrophizing
As Dr Jack Andrews, a developmental psychologist at the University of Oxford who researches social contagion, explains: “Depression may actually spread through shared rumination – sharing the process of repeatedly engaging in negative thinking and catastrophizing, without coming to a resolution.”
And it’s not just students, Dr Andrews told Good Health: “Scientists have found evidence of this from social networking sites, where you can map relationships between people – and it shows that mood spreads in adults too.” Dr. Andrews points to further evidence of emotional contagion from the Framingham Study, which has collected medical information on those living in Framingham, Massachusetts, since 1948.
Symptoms of Depression
“The researchers collected information about depressive symptoms, such as low mood and hopelessness — and asked individuals to name their close friends and family,” says Dr. Andrews.
In 2012, researchers mapped the city’s social network—tracking who spent time together—and then examined whether levels of depressive symptoms among friends were linked.
In a 2010 article in the journal Molecular Psychiatry, psychiatrists from Harvard Medical School showed that Framingham residents were more likely to have depressive symptoms if a close friend also had them.
“This was true even for three degrees of separation—having a depressed friend also increased the person’s chances of becoming depressed,” says Dr. Andrews. The same is true for happiness levels.
Scientists are still debating the mechanisms by which depression might be contagious.
