Two in three say people they know have been avoiding or excluding them.

Maree McCabe from Dementia Australia, which conducted the survey, said it would not take much to turn the distressing findings around.

"What these findings say is that discrimination stems from a lack of understanding and knowledge of dementia - what it is and how it impacts people," Ms McCabe said on Monday.

"A little bit of support can make a really big difference to someone with dementia."

The survey also found four in five family members, friends and carers felt that people in shops, cafes and restaurants treated people with dementia differently.

And 90 per cent said their friend or relative living with dementia was treated with less respect than other people.

Almost 500,000 Australians live with dementia and that number is expected to double in the next 25 years.

Australian Associated Press