The comments came after a poll showed three quarters of Britons think dementia services are at risk of cutbacks in the government's austerity drive.
The survey found that 72% of 2,003 adults fear cuts may hit dementia services. 83% thought patients with dementia and their carers need more support.
Survey organisers the Dementia Action Alliance (DAA), a national partnership that counts the DoH as a partner, said more should be done to protect services.
It warned that if fears are realised hundreds of thousands of people will be left without care in their own homes. This would mean no help for activities such as eating, washing and going to the toilet, or not being able to access quality residential care when needed.
Jeremy Hughes, chief executive of the Alzheimer's Society, a DAA member organisation, said: 'No one can ignore the dire economic situation we are in but good quality dementia care makes financial sense.
'It can prevent people needing hospital care or having to go into a care home earlier than necessary. Even more importantly it helps people have a quality life. We have to get this right.'
David Sims, from London, organises care at home for his mother who is living with vascular dementia.
He said: 'We want my mum to live in the family home for as long as possible, and so we employ care staff to help her with everyday, vital things such as preparing meals.
'I hate to think what we would do without her support.'
The DAA launched in October last year and counts 80 participants including charities, public and private sector organisations.
There are 750,000 people living with dementia in the UK. Estimates suggest there will be over one million by 2021.