China has launched a national plan to address the rapidly growing prevalence of dementia, which authorities say is becoming "a widespread societal concern" and poses "significant challenges" to the well being of the elderly and their families. Ageing has become a growing concern in the world's second-largest economy, with China's cohort of people 60 and older expected to rise at least 40% to more than 400 million by 2035, equal to the populations of Britain and the United States combined. Fifteen Chinese government departments, including the National Health Commission, contributed to the plan to tackle dementia.