> David was successfully treated in this way: his motivation levels went back up after taking a drug that stimulates dopamine receptors in the brain. Because of this, he was able to get a new job, become independent and even find a partner

I've always wanted to hear the stories of patients like David. What happens when you can tell your family and friends - I'm not a screwup, this has a physical cause? How do people interact with you who've previously only seen you in your decline?

A long time ago I read an account by a financial journalist who'd had some kind of brain injury and temporary lost his faculties. It damaged his professional relationships and the implication was, most of his former colleagues remained unduly sceptical - even after years of normal functioning.