The Alzheimer’s Society published figures on Tuesday showing that Northern Ireland has a diagnosis rate of 63%, well above the UK average of 46%.
Health secretary Jeremy Hunt criticised the 'extreme variation' across the rest of the UK.
Health minister Edwin Poots said: ‘The Alzheimer’s Society study indicates that we appear to be more complete than the other countries in terms of our recording of dementia. Fundamentally, higher recording means that people’s needs are being recognised by GPs, and that is something which should be welcomed.’
He added: ‘Two of our local health and social care trusts - Belfast and Western - were in fact the 1st and 5th best ranked areas respectively for rates of diagnosis across the whole of the UK.’
The Alzheimer's Society calculated diagnosis rates using estimates of dementia incidence for each area and the number of people on GP practice lists.
Mr Hunt warned that the worst performing areas needed to wake up to the dementia 'time bomb'.
He said: ‘It’s time for the worst performing local areas to wake up to the dementia time bomb we are all facing. While many areas do excellent work, the worst is diagnosing just one third of people with dementia, delaying and preventing them from accessing vital treatment and causing unnecessary suffering.'
Mr Hunt said that he will soon visit every region in the UK to meet health professionals in a bid to improve diagnosis rates.
The Alzheimer’s Society's interactive map, published on Tuesday, reveals the number of people who had a diagnosis of dementia in 2012 across the UK.