Flickr/Jane Rahman Several tech startups have entered the mental health space in recent years, but few have made a real impact. Woebot is an artificially intelligent chatbot designed by Stanford researchers. It uses one of the most heavily researched clinical approaches to treating depression. This week, the company announced that a co-founder of the Google Brain project will serve as Woebot's new chair. Depression is the leading cause of disability worldwide, and it can kill.