The Duke of Cambridge told the Davos World Economic Forum that "a lot" of stars were approached, but none wanted to be associated with mental illness.
He also said the wartime generation may have helped create some of the stigma.
People preferred not talk about such "horrendous" events, a stoic attitude passed on to their children.
The prince created Heads Together, launched to help combat the stigma of mental health, in 2017 with the Duchess of Cambridge and Prince Harry.
