The pandemic has led to a significant and irreversible deterioration in the condition of many people living with dementia, according to the Alzheimer Society of Ireland.
Research has also found the mental and physical wellbeing of family carers have been "seriously affected".
Seventeen people living with dementia and 240 family carers took part in the study - 'Caring and Coping with Dementia during Covid-19' - which was conducted in February and March.
In the report, 81% of respondents expressed concern about a decline in the person with dementia; 54% of family carers reported a decline in their own mental health, and 40% in their physical health.
54% of family carers said they were worried about how they would continue to cope, with 28% considering a move to long term care for the person with dementia.
65% of family carers said that this had become a consideration sooner due to the pandemic.
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The Alzheimer Society of Ireland has made a number of recommendations.
It said necessary capital and revenue resources are required immediately for day care reopening and suggests better assistance for family carers through support groups and therapeutic services including counselling.
It also recommends urgent additional dementia appropriate home care hours.
CEO Pat McLoughlin said the research shows the need for practical support for family carers which almost tripled in the past year.
He also called for access to emotional support for family carers, including counselling services.
Speaking on RTÉ's Morning Ireland, he said there has been a "crisis in dementia care" and there is a need to boost national funds to support its work.
Mr McLoughlin said Covid-19 restrictions have made it impossible to reopen all of its centres and that for the past 15 months all of the day-to-day services outside the home have been closed.
He said many of the centres need remedial works carried out for necessary upgrades and to comply with Covid safety measures.
Mr McLoughlin said that while some services were reopened during the summer, the organisation had been unable to open any of its 48 daycare centres, which were closed in March last year.
He said the organisation is ready to reopen 14 of its daycare centre, having invested around €300,000 in remedial works.
Supports ended in lockdown

Aisling Harmon is a full-time carer of her mother Carmel who has Parkinson's and dementia.
What little support she had 15 months ago were ended due to the first lockdown.
The problem is that day services for people with Alzheimer's and Dementia haven't resumed, so Aisling like thousands of others caring for loved ones at home feel unsupported.
"We haven't got our services back, we haven't got day care, we haven't got rest bite, we haven't got easy access to all of the allied health care supports in the community", she said. "So the things that give you a glimmer of contact as a carer, somebody who you can hold a full conversation with, that hasn't come back."
Aisling describes last year as an annus horribilis because she became critically ill.
It meant she had to scramble for some form of emergency respite for her mother for several weeks.
Sadly, Carmel regressed in her new surroundings.
Her ability to verbalise has been lost and while she can follow a conversation and likes to listen she can no longer solicit or contribute to one.
Physically she has also regressed according to Aisling because she wasn't mobilised much each day.
"I would say her deterioration just accelerated by a year and a half to two years," Aisling said.
Last year, as Covid-19 spread in congregated settings, the Government acknowledged the importance of care in the home.
However, Aisling feels there is less acknowledgement for family carers and no back-up support.
She finds the disconnect frustrating.
"The ability to be offered statutory home care, to be offered a fair deal in your own home, just seems so far away," she said.
She points out that there are 55,000 carers in Ireland looking after somebody with dementia in a family home.
"And yet despite that number we can't influence or move that debate on," she said.
The pandemic has led to a significant and irreversible deterioration in the condition of many people living with dementia, according to the Alzheimer Society of Ireland.
Research has also found the mental and physical wellbeing of family carers have been "seriously affected". Seventeen people living with dementia and 240 family carers took part in the study - 'Caring and Coping with Dementia during Covid-19' - which was conducted in February and March.
In the report, 81% of respondents expressed concern about a decline in the person with dementia; 54% of family carers reported a decline in their own mental health, and 40% in their physical health.
54% of family carers said they were worried about how they would continue to cope, with 28% considering a move to long term care for the person with dementia.
65% of family carers said that this had become a consideration sooner due to the pandemic.
The Alzheimer Society of Ireland has made a number of recommendations.
It said necessary capital and revenue resources are required immediately for day care reopening and suggests better assistance for family carers through support groups and therapeutic services including counselling.
It also recommends urgent additional dementia appropriate home care hours.
CEO Pat McLoughlin said the research shows the need for practical support for family carers which almost tripled in the past year.
He also called for access to emotional support for family carers, including counselling services.
Speaking on RTÉ's Morning Ireland, he said there has been a "crisis in dementia care" and there is a need to boost national funds to support its work.
Mr McLoughlin said Covid-19 restrictions have made it impossible to reopen all of its centres and that for the past 15 months all of the day-to-day services outside the home have been closed.
He said many of the centres need remedial works carried out for necessary upgrades and to comply with Covid safety measures.
Mr McLoughlin said that while some services were reopened during the summer, the organisation had been unable to open any of its 48 daycare centres, which were closed in March last year.
He said the organisation is ready to reopen 14 of its daycare centres, having invested around €300,000 in remedial works.
The Department of Health welcomed the publication of the report by the Alzheimer Society of Ireland.
It said that in recognition of the need to enhance supports for people living with dementia, in particular in the context of the Covid-19 pandemic, an additional €12.9m had been invested in a range of measures in 2021.
In a statement it said it was the intention of the HSE that 101 day centres would reopen by the week of 5 July.
More centres are expected to resume over the weeks of July and August, according to the Department, with any remaining services that require adaptation works reopening before the end of the year.
"These developments will assist people with dementia and their family carers," it said.