Could anxiety or depression be ‘transmitted’ between classmates? Having one person in a school class with a mental health condition has been linked to a higher risk of such a diagnosis in their peers. But are these illnesses contagious, asks Clare Wilson
IF THERE is one thing most people know about teenagers and their mental health, it is that things are getting worse. Rates of several mental health conditions are on the rise in this group, especially in the US, but also in Australia, the UK and many other European countries.
Many possible causes have been debated, but now further evidence has emerged for a possibility that has long been suspected, but has been hard to quantify: that mental health problems can, in a way, be transmitted between friends.
If this is right, it would mean our approaches to helping troubled teens with conditions such as depression need re-examining. Some methods may even make things worse.
So, how strong is the evidence?
There is no shortage of explanations proposed for young people’s worsening mental health. They include the explosion of social media use, as well as longer-term societal changes, such as growing pressure to do well at school or changing parenting styles that may leave children less resilient.
The transmission idea doesn’t imply that mental health conditions are literally contagious, caused by bacteria or viruses (see page 17 for more on this). It proposes that when teens see friends develop such a condition, it becomes more likely that they follow them down the same route, says Christian Hakulinen at the University of Helsinki in Finland.
It has long been known that some conditions, such as eating disorders, can spread through friends. More recently, they have been shown to spread through online networks too. Previous studies have also found that anxiety and depression can cluster among groups of friends. But this could be because someone who is prone to anxiety, for example, may be drawn to other anxious people.
To tease out what is happening, Hakulinen and his colleagues tracked the school and health records of more than 700,000 people – all Finnish children who turned 16 between 2001 and 2013 – to see if correlations also happened within school classes, because pupils can’t choose their classmates.
Sure enough, over the first year, if one person in a class had any mental health condition, there was a 9 per cent higher chance that their classmates would also get one. Those with more than one affected classmate had an 18 per cent higher risk of being diagnosed themselves.
The effects were stronger when considering specific conditions: in other words, if one pupil ha
