Ancient Babylonian tablets describe remedies & rituals for its treatment, Emperor Tiberius left Rome because of it, and Churchill was stalked by the “black dog”. But what is depression and how far have we come in understanding it over the last 4000 years?

Depression is not a modern phenomenon but it is becoming one of the greatest global health challenges we face. As a leading cause of disability worldwide, depression costs the global economy an estimated $1 trillion each year. However, depression remains poorly understood.

What exactly is depression? Depression and anxiety are extremely common in our society but the lack of clear definitions makes them hard to diagnose and treat. In fact there are over 256 profiles of symptoms of depression and this huge variation means that it’s very hard to put your finger on what actually depression is and who has it. Are some people and communities more susceptible to it and what role do our genes play? 

In this Garden Talk. Dr Harry Costello a leading Psychiatrist, and expert on the grey area between neurological and psychiatric illness delves into the 'invisible illness' - depression. Why is depression so challenging to understand and how is science trying to unravel its causes to identify better treatments?