Medicinal Cannabis: Weeding Out The Hype

This week, medical uses of cannabis. What's the hype and what's the reality? We hear from the people who grow it, and the people who want to use it. Plus in the news, scientists grow replacement lungs in a lab, why a knock on the head can lead to dementia years later, and the very tiny thing that elephants are terrified of - and no, it's not a mouse!