About one in every 33 New Zealand adults is expected to be suffering from dementia by 2050, with much of the increase due to Kiwis living longer, health authorities say.
Country data from the Global Burden of Disease (GBD) 2010 study released on Wednesday showed deaths from Alzheimer's disease had increased by 346 per cent in New Zealand between 1990 and 2010.
In 1990, Alzheimer's disease was the country's 16th biggest killer. In 2010 it had jumped to fifth place, killing about 1463 people every year.
Dr Chris Murray, who led the GBD study for the University of Washington's Institute for Health Metrics and Evaluation, said New Zealand's rising Alzheimer's rates reflected similar trends across the world, including a 241 per cent increase in Australia and a 485 per cent increase in the United States.
"Probably most of it is [caused by] increased life expectancy and probably it's better diagnosis as well."
Alzheimer's New Zealand executive director Catherine Hall said about 50,000 people were living with dementia in New Zealand, with Alzheimer's accounting for 50 to 70 per cent of all cases. A recent report commissioned by Alzheimer's New Zealand estimated the total cost of dementia in 2011 at $954.8 million.
With the number of cases expected to rise to 150,000 by 2050, the challenges for the country were huge, Hall said.
"The fact the population is ageing has a lot to do with it . . . and as people live longer dementia becomes more common. There's been a lot of attention and a lot of work done in the dementia area [in the last 20 years], so we're better at diagnosing it now as well."
Statistics New Zealand population projection data suggest there could just under 5 million people aged 15 and over in New Zealand by 2051, meaning about one in every 33 of those people could have dementia.
Hall said more research was needed into diagnosis, treatment and finding a cure and the Government needed to invest more into ensuring there was enough support for those with the disease.
Ministry of Health chief medical officer Dr Don Mackie said more Alzheimer's cases had been expected as the population aged and people lived longer.
The ministry was still considering the data, but the results were consistent with what it already knew.
The top four causes of death in New Zealand were the same in 2010 as they were 20 years previously - heart disease, cancer, COPD (chronic obstructive pulmonary disease) and stroke.
The GBD study also showed Australians can expect to live eight months longer than New Zealanders on average, but Mackie said it was difficult to analyse such small differences between countries.
"Life expectancy and health expectancy in New Zealand continues to improve. The gap in life expectancy between New Zealand and Australia has closed over the last three decades."
- © Fairfax NZ News
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