David Cameron has called on businesses to join his \"national fightback\" against dementia. The Prime Minister said that companies should do more to make their services dementia-friendly. Mr Cameron declared that tackling the disease, which is thought to affect 670,000 people in England, was one of his personal priorities. During a meeting with a group working to help sufferers in their communities, Mr Cameron said changing the \"national culture\" surrounding the disease should be the first step. He said: \"Dementia is a terrible, heart-breaking disease - and tackling it is a personal priority of mine. Two months ago I promised that we\'d lead an all-out, national fightback against dementia - and it\'s happening. We\'re putting more money into research and more thought into dementia care. \"We\'re also encouraging more businesses to join this fightback. I\'m delighted to see the progress being made here. \"Already 20 big organisations like Lloyds Group, Tesco and E.On have signed up to become more dementia-friendly - and over the coming months I want to see many more follow suit. Throughout this fightback I am staying heavily involved - driving forward new ideas, mobilising action and making sure we make real progress. \"For the sake of millions in our country we\'ve got to keep this spirit of energy and defiance alive: we\'re going to keep searching for treatments, keep looking for ways to make life easier for those with this disease - and keep taking the fight to dementia.\" Various business leaders were present at the meeting in east London as were two of the Prime Minister\'s dementia champions - presenter Angela Rippon and Alzheimer\'s Society chief executive Jeremy Hughes. In March, Mr Cameron said that funding for research into dementia is to be more than doubled by 2015.