Many people with dementia and carers are feeling socially disconnected and stigmatised, according to a new survey.

Social prejudice still exists towards people living with dementia, causing many patients to feel socially disconnected, research shows.

Nearly 1500 people completed an Alzheimer's Australia online survey that investigated the challenges dementia patients face as well the impact any stigma has on them.

It found Australians living with dementia and their carers often experience embarrassing situations as a result of the illness, leading to feelings of loneliness and uselessness.

Most respondents (94 per cent) who had a diagnosis said they had encountered embarrassing situations because of their illness, while almost 60 per cent of carers had found themselves in embarrassing situations because they were looking after someone with dementia.

Many of those affected by dementia, either personally or in a caring capacity, also said they struggled with feeling disconnected from others.

One respondent said: "Having dementia, I have lost friends and family members who don't want to know about the dementia journey. People often talk about me to others and not to me when I am sitting right next to the person."

Maree McCabe, national chief executive of Alzheimer's Australia, says dementia does not define a person and the general public needs to improve its understanding of the disease.

"The way we respond as a community can leave people with dementia and their carers feeling socially embarrassed and uncomfortable," Ms McCabe said.

"Dementia is a chronic disease of the brain and is a challenging experience; the social prejudice that is evident in these survey results only adds to the challenge."