Almost four out of five adults haven't thought about what would happen to them if they became seriously ill or frail.
A survey by Safeguarding Ireland reveals 70% of us are also confused about who takes the decisions in these cases.
The advocacy organisation says it shows there is a need for a change in attitudes to consent in care.
"The older you get, the higher the levels of abuse and you see that from the limited data that we have," said Patricia Rickard Clarke, chairperson of Safeguarding Ireland.
"That's the message we want to deliver, to safeguard yourself against abuse so you plan in advance and you say what your wishes are," she added saying it was important that older people make their plans known so relatives and loved ones can put them in place when necessary.