Dementia danger: Where you live in NZ could be worsening your brain health

• National cases of dementia are projected to jump from around 70,000 today to at least 170,000 by 2050, but nearly half that burden could be avoided with intervention efforts.
• A major new study has linked socioeconomic data to risk of cognitive decline, finding neighbourhood deprivation can predict that danger independent of personal factors.
• The Massey University researchers behind the study say the public health focus on exercise and eating for brain health could be missing the bigger picture.

Where we live in New Zealand can shape our danger of dementia, a pioneering new study has found – and once again, it’s those in our most deprived neighbourhoods with the highest level of risk.

Cases of dementia are projected to jump from around 70,000 today to at least 170,000 by 2050, with the associated economic toll similarly soaring from $2.5 billion to $5.9b.

Research has suggested nearly half those cases could be avoided by tackling modifiable risk factors like smoking, alcohol intake and diet – with Māori and Pasifika people showing the highest prevention potential.

In one recent analysis, University of Auckland researchers calculated the risk of dementia in Māori and Pasifika people was a staggering 45-80% higher compared to Pākehā, due to higher rates of risk factors.

They also noted that more than 40% of Māori and Pasifika people happened to live in areas of high deprivation.

The latest research, part of the New Zealand Health, Work and Retirement Study, put this hidden picture into sharper focus.

“We sought to understand whether where you live, not just your personal circumstances, affects your cognitive health as you age,” said its lead author, Associate Professor Susanne Roehr of Massey University.

A major new study has linked socioeconomic data to risk of cognitive decline, finding neighbourhood deprivation can predict that danger independent of personal factors.

The study, involving more than 780 people aged 48 to 75, focused on mid-life to early late-life adults, given this group represented a critical period where dementia rates were still relatively low.

Using an index of area-based deprivation, the researchers found those living in worse-off areas scored lower on cognitive tests – and were more likely to experience decline over two years.

That held true even after accounting for individual factors like income, education and lifestyle choices.

“Māori were overrepresented in high-deprivation areas, highlighting the persistence of systemic inequities,” Roehr said.

“What surprised us was the consistency of this effect: neighbourhood deprivation independently predicted cognitive decline.

“The most concerning aspect is that these declines could worsen inequalities in brain health and dementia outcomes – particularly for communities already facing systemic disadvantages.”

The researchers noted deprived neighbourhoods often came with a tangle of challenges, from limited access to healthcare to fewer green spaces and higher pollution.

While much of the public health focus has been on lifestyle improvements like exercising and eating better, that could be missing the bigger picture.

“People in deprived areas often face barriers to healthy lifestyles, such as limited access to nutritious food, healthy housing standards, safe exmercise spaces, and quality healthcare,” Roehr said.

“We suggest that addressing such environmental and structural factors could help reduce the risk of cognitive decline and dementia.”

“Supporting brain health is not just about individual actions – it is about creating environments that make healthy choices easier and more accessible for everyone.”

Jamie Morton is a specialist in science and environmental reporting. He joined the Herald in 2011 and writes about everything from conservation and climate change to natural hazards and new technology.

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