The treatment of dementia has “entered a new era” according to Fumio Kishida, the Japanese prime minister, as the country’s health ministry approved the use of Leqembi, the first drug shown to slow the progression of Alzheimer’s. Made by US biotech firm Biogen and Japanese drugmaker Eisai, the drug’s sign-off in Japan follows its FDA approval in the US earlier this year. The warning label: the drug is (very) expensive, is only for specific early-stage cases of Alzheimer’s and comes with a potential risk of dangerous brain swelling. Eisai is conducting a survey of patients given Leqembi as part of the Japanese approval process. The big picture: over 6 million people in the US have dementia caused by Alzheimer’s while the number of dementia patients over 65 years old in Japan will increase from 6 million to 7 million in the next two years. Eisai forecasts revenues of $7 billion from Leqembi by 2030 as it seeks approval for the drug in the UK, EU and China.