Swiss scientists have shown that the lack of certain chemical markers in the brain can cause different types of depression, with different symptoms. They say this finding could help match the right drugs to the right type of depression, thus increasing their effectiveness.
“We have many anti-depressant options but we don't know which drug will work in which patient and that leads to very long trial-and-error phases for treatment optimisation,” Gregor Haslerexternal link, a professor of psychiatry at the University of Bern, who co-led the research, told swissinfo.ch. “So it’s really an important need to have biomarkers to predict the response to particular antidepressants.”
“We showed that it is feasible: that the depression related to a serotonin deficit is a different in terms of symptoms and neuroactivation compared with, for example, a depression caused by a lack of noradrenaline (norepinephrine).”
Until now it had not been possible to distinguish between the two types, leading to, in some cases, the wrong anti-depressant being prescribed – one that targeted the wrong neurotransmitter system and so wasn’t effective.
The results of Hasler and co-author Philipp Homan’s study, the first of its kind to show which symptoms were linked to which depression, were announced by the University on Tuesdayexternal link. The research has also been published in the latest edition of Translational Psychiatryexternal link, a sister publication of Nature.
Mood and anxiety
The two researchers undertook two large trials to study the effects of reducing the two chemical markers.
“When you reduce serotonin you have a lot of sadness, a depressed mood, you have these classical depressive symptoms,” Hasler said.
“But if you reduce catecholamine: norepinephrine and dopamine, you see concentration difficulties, problems with motivation, or lassitude where people are tired.”
These might appear more secondary symptoms, but actually difficulty concentrating is the prime reason for people with depression not being able to work, explained the professor.
According to the Federal Statistics Office,external link 18% of the population suffer from psychological distress and 6% from depression. One in ten women have been treated for depression during their lifetime; for men it is one in 16.
The results of the Bern study come at a time when there has been much debate about the effectiveness of anti-depressants. In the short-term, there is often a placebo effect in patients, rather than a medical one; but some patients do respond well to medication in the long-term.
“It is very difficult to find new drugs or, if you like, we have an innovation problem,” Hasler said. “But we have a lot of available drugs and one step to really increase effectiveness is what we call personalised medicine, i.e., to just identify the best of the available drugs for an individual patient.”