Jim Al-Khalili talks to psychiatrist Vikram Patel about the global campaign he is leading to tackle mental health. He reflects on his early career working in Zimbabwe, when he doubted any western diagnoses or treatments for peoples' distress would be of much use. However, his subsequent research made him question this and come to the realisation that some conditions, like depression and psychosis, could be tackled universally. Now based in India, Vikram's research guides the public health approach he is taking. Yet critics question the application of Western categories for diagnosis and treatment to other parts of the world.Producer: Beth Eastwood.