Can brain training reduce dementia risk?

The BBC gains access to Iran for the first time since anti-government protests were brutally crushed. The country is marking the 47th anniversary of the Islamic Revolution in the shadow of last month's deadly crackdown and looming threats of US military action. Also: nine people are killed in a school shooting in Canada; Russia limits access to Telegram; England returns some of the bronzes looted from Benin; how to train your brain to reduce the risk of getting dementia; and what to watch at the Berlin Film Festival.