NHS England's dementia expert Professor Alistair Burns has welcomed the prime minister's pledge to fund research into the condition.
Announcing the next phase of the 'challenge on dementia' programme, Mr Cameron pledged £300 million of investment into dementia research over the next parliament, a new global fund on dementia, and the training of one million NHS staff to deal with the condition.
There will also be faster initial dementia assessments, which will take place in an average of six weeks, followed by better support post-diagnosis.
People with the condition will be given better information about the services available in their local areas, while advice and support will be provided for carers.
Professor Burns, who is NHS England's clinical director for dementia, said: "We are beginning to change the way society respects and treats people with dementia.
"We can change the lives of tens of thousands of people for the better if we can continue to raise awareness, invest in the search for new treatments, and most importantly improve the lives of people with dementia and their carers."
There has been a steady rise in the number of people diagnosed with dementia, with 398,597 people added to the dementia register as of January - up from 250,000 in 2009.
The numbers have climbed significantly from 349,000 in March 2014, with between 5,000 and an extra 10,000 people a month now being added to the dementia register.
Under the plans announced by the prime minister, the global fund on dementia will bring together investors from the public and private sectors unite to fund a range of research projects.
The number of people with dementia globally is estimated at 44 million - and this number is set to almost double by 2030.
It already consumes a large amount of healthcare budgets, with costs estimated at estimated £370 billion - about one per cent of the world's gross domestic product.
Read more about Barchester's dementia care homes.