How effective is smell training at curing anosmia?

Around 5% of us will lose our sense of smell because of a viral infection, ageing, nasal polyps or a head injury. Anosmia can affect quality of life and lead to mental health problems like depression. Prof Thomas Hummel, an ear, nose and throat expert at the University of Dresden in Germany, explains how smell training can help some people with the condition regain their sense of smell.

Listen to CrowdScience: Do you smell what I smell? from BBC World Service.