Hormone test a marker for depression

Teenage boys who are showing symptoms of depression could be identified by a test for the stress hormone cortisol, according to new research from the University of Cambridge published today.

The research, which followed a 10-year study of nearly 2,000 young people in Cambridgeshire, is the first time a “bio-marker” – dubbed by the scientists as “a biological signpost” – has been found for clinical depression.

Over time, the teenagers were broken down into four groups – the last of which displayed “high” symptoms of depression along with high levels of cortisol, a hormone which is produced in stressful situations and which suppresses the immune system.

The fourth group, comprising 17 per cent of those surveyed, were 14 times more likely to suffer from major depression than those teenagers who admitted to few feelings of depression and had low levels of cortisol in their system.

The youths in the most-at- risk group were “particularly poor” at remembering autobiographical details and tended “to give very little and more general non-specific information”, which supports older evidence that cortisol suppresses autobiographical memory.

"Depression in young people is important because it is the period when depression first emerges," said professor of child and adolescent psychiatry at the University of Cambridge, Ian Goodyer, "By studying 13-18 year olds, we get to capture a large proportion of individuals at risk."

The combination of checking for depressive symptoms, coupled with the test for cortisol, offers psychiatrists "a new way of looking at mental illness", said Prof Joe Herbert, Cambridge's former director of studies in medicine.

“[This would be] not based solely on what a patient tells you but also what you can measure inside the patient. That is something that has been long sought,” he told reporters at the Wellcome Foundation in London.

Cortisol is vital for life, but too much of it can cause problems, Prof Herbert told The Irish Times . "Without it you are dead, but we also know that people with high levels are at high risk of depression."

A cortisol-like hormone found in the animal kingdom “increases the impact of negative events”, which is necessary so that they remember dangerous situations.

In humans, though, an excess of cortisol “pushes the person towards a more negative view of the world”, he added. In time, the new research could be a boon for GPs struggling to identify cases among teenagers.

Three-quarters of people who struggle with "persistent, chronic and life-long" depression exhibited their first problems before they were 24 years old, said Cambridge's professor of clinical neuropsychology, Barbara Sahakian.

“We are very aggressive about physical illness, but we are very bad about mental illness. Depression is a much bigger problem than heart disease, or cancer and it is much more expensive,” she said.