The former prime minister, who stood down after losing the referendum on European Union membership last summer, said yesterday that he was taking up the position with Alzheimer’s Research UK.
Mr Cameron marked his new role with a visit to the charity’s Cambridge Drug Discovery Institute, at Addenbrookes Hospital, where he heard from scientists working to fast-track research breakthroughs into new treatments.
The role will allow Mr Cameron to continue the mission he initiated through the Prime Minister’s Challenge On Dementia.
Speaking about his appointment, he said: “Tackling dementia was a major focus while I was prime minister and, although improvements in attention and research innovation have been rapid, it remains one of our greatest health challenges.
“Dementia is not inevitable and research is our greatest weapon against it.
“I’m committed to helping Alzheimer’s Research UK transform the lives of those affected by this life-shattering condition.”
He added: “We must win the battle for priorities.
“Cancer research and stroke research deserve all their funding – but dementia shouldn’t be so far behind.
“Dementia steals people’s lives, turns their relationships upside down, destroys their hopes and dreams.
“We owe it to them, their families and their carers to find a solution.”
Alzheimer’s Research UK chief executive Hilary Evans said: “David Cameron’s support of our work will help us continue our positive growth and further bolster our research efforts, through which we will end the fear, harm and heartbreak of dementia.”
It is the second role Mr Cameron has taken on since standing down as MP for Witney in Oxfordshire.
In October, he became chairman of National Citizen Service Patrons.
Following Mr Cameron’s call, Prime Minister Theresa May’s official spokeswoman said: “We are committed to taking forward the plans that have been already set out for increased support for helping people with dementia and tackling this vital issue.”