Nearly half of people in Ireland who care for a spouse with dementia spend all their waking time doing so, a new study has found.
The research also found 15% had given up their jobs to look after their spouse.
The findings are contained in the largest study ever carried out in Ireland into the health and wellbeing of people looking after their spouse with dementia.
There are currently 55,000 people in Ireland with dementia, but that number is expected to more than double to 113,000 by 2036.
The work by researchers at Trinity College Dublin also aimed to measure the level of stress the carers were experiencing, their lives and health, the positive aspects of the caring, and the impact it has on their daily lives.
Nearly two thirds of those who have dementia live at home and there are 180,000 people in Ireland who are currently or have been carers for a family member or partner with dementia.
The De-Stress study also found almost eight out of every ten carers provide between 81% and 100% of the care their spouse needs, with women more commonly giving this amount of help than men.
A range of mental illnesses were experienced by the carers, the research discovered, with depression and anxiety the most common.
De-Stress also found that most of those carers it spoke to were taking prescribed medication.
In the case of those carers who had chronic conditions like arthritis or high blood pressure, their quality of live was more often lower and the carer burden higher.
One in every three of respondents had problems with one core caring activity, like managing money, shopping or preparing food.
Over a 12-month period, carers saw their cognitive function drop. However, this was not linked to a genetic susceptibility to developing Alzheimer's disease or to stress, the study says.
Despite the many challenges they faced, the majority of the carers pointed to positive aspects of the role.
These included feeling useful, needed and appreciating life more.
The report recommends that the needs of family carers in Ireland should be more thoroughly assessed and addressed as a matter of urgency.
"Carers are an invaluable resource, but sadly they are not adequately supported in their role and consequently their health may be affected," said Professor Sabina Brennan, Director of the NEIL Memory Research Unit, Trinity College Dublin.
"If we are serious about supporting people to live well and die in their chosen setting then we need to invest in quality services to support both carers and those being cared for."
The findings were released to mark Carers' Week which is taking place this week.