depression symptoms are intangible

But neuroscientists still don't have a complete pictureof what causes depression.It seems to have to do with a complex
interaction between genes and environment,but we don't have a diagnostic tool that can accurately predict where or when it will show up. And because depression symptoms are intangible,
it's hard to know who might look fine but is actually struggling.
According to the National Institute of Mental Health,it takes the average person suffering with a mental illness over ten years to ask for help.But there are very effective treatments.