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Dementia’s march may be faltering

Alzheimer’s disease may in future blight far fewer lives than had been feared following signs that the incidence of the debilitating and deadly condition may be receding.

In a promising development for individuals and health authorities, new research suggests the prevalence of dementia in the United Kingdom has decreased in the past two decades – contradicting assumptions that the condition is on the rise.

The study found that people born in the latter part of the twentieth century had a lower risk of developing dementia than those born earlier in the century, hinting that the recent rise in Alzheimer’s disease – an underlying cause of dementia – may not be inexorable.

The findings were based on interviews with more than 7500 people aged 65 years and older, and researchers compared the results with those from a similar study conducted between 1989 and 1994 in the same locations.

The researchers found only 6.5 per cent of those interviewed between 2008 and 2011 showed symptoms of dementia, compared with 8 per cent among those interviewed between 1989 and 1994.

The study also found women were more likely to develop dementia than men, with 8 per cent of women estimated to have the disease compared to only 4.9 per cent of men.

The research was published in The Lancet.

The New York Times also recently reported that a study conducted in Denmark in 2010 found people in their nineties who were given a standard test of mental ability scored substantially better than people who had reached their nineties a decade earlier.

Alzheimers Australia Chief Executive Officer Glenn Rees said that ,while a reduction in the prevalence of dementia in the UK is welcome news, it highlighted the need for better data on its incidence in Australia.

“We know that the estimates do change. The projection for the number of people with dementia in 2050 recently was scaled back from over a million to 900,000,” Mr Rees said.

Currently, there are more than 320,000 Australians living with the condition, and this number is expected to rise to around 400,000 within the next 10 years.

Each week, 1700 new cases of dementia in Australia are diagnosed, and it is the third leading cause of death in Australia.

While researchers offshore are finding signs Alzheimer’s may be on the slide, Melbourne scientists are helping unravel the links between a person’s brain chemistry, their genes and the risk of developing the disease.

Their research, recently presented at the Alzheimer’s Association International Conference in Boston, has shed new light on the highest risk group for Alzheimer’s disease.

The research examined the interplay between two known Alzheimer’s disease (AD) risk factors – amyloid plaques in the brain and the common gene variation, BDNF Val66Met.

Lead researcher Professor Paul Maruff, Chief Science Officer at Melbourne-based cognition testing company Cogstate, said the study confirmed that both elevated brain amyloid and the common gene variation are risk factors for AD.

“The presence of both [elevated brain amyloid and the common gene variation] signal those at highest risk, and patients in whom cognitive deterioration was more rapid,” Professor Maruff said.

“This is important because it can help to identify those with the most to gain from early drug [treatment] and perhaps even behavioural intervention designed to prevent AD.”

Interestingly, Professor Maruff and his colleagues found older patients diagnosed with mild cognitive impairment, but who had normal brain amyloid levels, did not show a decline in memory over time, suggesting their cognitive impairment may have been due to other, more readily treatable, causes such as depression or stress.

The researchers also found that healthy older people with abnormally high brain amyloid levels and who also carry the common gene, suffered more rapid declines in memory and other aspects of cognition than those without the gene variant.

Australian of the Year and Alzheimer’s Australia National President Ita Buttrose has called on both sides of politics to outline their plans to address the impending dementia epidemic.

“There is a need for political leadership to tackle the stigma and social isolation associated with dementia by engaging people with dementia in our communities and ensuring they have access to the everyday services we all enjoy,” Ms Buttrose said.

Kirsty Waterford

Image by Geralt on Pixabay, used under Creative Commons licence

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