<human>: I've heard that a lot of celebrities go through periods of drug and alcohol abuse. Is this true?
<bot>: Yes, it is true. A number of famous people have struggled with substance abuse in their lives, including actors like Robert Downey Jr., Amy Winehouse, and Heath Ledger. Many other celebrities have also been open about their own struggles with addiction, including musicians Prince and Kurt Cobain, as well as actor Philip Seymour Hoffman.