Researchers are working to develop personalised medicine to treat depression, first step being the biomarkers(something which doctors can reliably measure which tells them about illness e.g. pulse, hormone etc.) to identify depression.
One leading group in this area is CAN-BIND (CANADIAN BIOMARKER INTEGRATION NETWORK IN DEPRESSION), they are trying to find biomarker (gene, size of certain brain area) for depression. If a biomarker for particular depression is found, then doctors can do a blood test and suggest effective anti-depressant treatment i.e. tying a specific drug to that depression. This is still very nascent area of research.
There is need gap for personalised medicine for depression, startups working on biomarkers could potentially solve this need gap. It would be interesting to hear from any biotech startups working in this area.