Facebook friend numbers linked to depression by new study

Study finds a link between cortisol and depression in later life

What did you talk about on Facebook this year? (Chris Jackson/Getty Images)

Teenagers with more than 300 Facebook friends are at a higher risk of stress and depression than those who have fewer, a study has found.

Researchers from Montreal University asked 88 people aged between 12 and 17 how many friends they had on social media and how they interacted with them.

Samples of the teenagers’ cortisol levels were also taken four times a day over three consecutive days.

Those with more Facebook friends were found to have higher levels of cortisol - which studies have shown can cause depression in later life.

While none of the teenagers taking part in the study suffered from depression, Professor Sonia Lupien, who headed up the study, said: “While other important external factors are also responsible, we estimated that the isolated effect of Facebook on cortisol was around eight per cent.

“We were able to show that beyond 300 Facebook friends, adolescents showed higher cortisol levels; we can therefore imagine that those who have 1,000 or 2,000 friends on Facebook may be subjected to even greater stress.”

Previous studies have found young people with high levels of cortisol are 37% more likely to suffer from depression by the age of 16.