May 31, 2011

AUSTRALIA: Healthy heart, healthy brain

SYDNEY, NSW / The Sydney Morning Herald / Wellbeing / May 31, 2011

Chew On This

By Paula Goodyear

Mental health ... exercise is good for your brain as well as your body

Not all the news about dementia is gloomy. The flipside of scary statistics like a predicted doubling of dementia cases by 2030 is that we’re not entirely helpless when it comes to keeping our minds as we age – we just don’t realise it.

We might have grasped the fact that keeping the brain active can help prevent its decline, but there’s another important message that hasn’t got through – that healthy blood pressure from mid-life onwards is one of our best anti-dementia defences. That’s why a new NSW Health campaign to boost awareness of the blood pressure-dementia link is aiming at 40-somethings, not just the over-60s.

“Only around 20 per cent of us understand that we can reduce the risk of dementia by keeping blood pressure levels healthy,” says neuroscientist Dr Michael Valenzuela, senior research fellow with the School of Psychiatry at the University of NSW. “But many risk factors for dementia that we do have influence over like blood pressure and cholesterol levels and being overweight can start to have an impact in our 40s and 50s – often decades before people start worrying about dementia.

“Pharmacological treatment of high blood pressure is the only medical treatment found so far to reduce the incidence of dementia,” he adds.

So what is it about high blood pressure that can ultimately mess with our minds? In a nutshell, the same damage it inflicts on arteries that leads to heart disease can also affect the brain – hence the Healthy Heart Healthy Mind name given to the new dementia prevention campaign underway in the Illawarra and Shoalhaven areas south of Sydney.

High blood pressure contributes to the second most common type of dementia after Alzheimer’s disease – vascular dementia that’s caused by having a stroke. But there’s also some evidence that keeping blood pressure levels healthy can help prevent Alzheimer’s disease as well, says Valenzuela. One theory is that micro-haemorrhages from tiny blood vessels feeding into our brain tissue could cause the damage that kicks off Alzheimer’s, he says.

‘These micro-bleeds are strongly linked to high blood pressure and the thinking is that they affect the blood supply to the brain. This not only means the brain gets less nutrients, but also that there’s less clearance of toxins from the brain. Another explanation is that the leaking blood may also have a toxic effect on brain tissue,” he explains.

Valenzuela is the author of Maintain Your Mind, a new guide to preventing dementia to be published by ABC Books later this year – and which has really good news about the protective role of exercise.

“The assumption was that physical activity helps prevent dementia because it helps lower blood pressure and improves the blood flow to the brain. But there’s evidence that exercise can also have more direct effects on the brain, stimulating new brain cells to grow as well as increasing connections between the cells in the hippocampus - the brain’s memory centre,” he says. "Some of these effects could be due to the positive role of growth factors and molecules called cytokines that are stimulated after exercise.”

Are some kinds of exercise better than others? Most studies suggest that aerobic exercise is important, but Valenzuela’s recommendation is for at least three brisk 30-minute walks and at least one session of resistance (strength) training each week. A combination of both is good for health generally – and also helps prevent diabetes which is another risk factor for dementia, he says.

So while you’re tossing up whether to learn Mandarin or mah-jong in the interests of maintaining your brain, don’t forget to schedule a few brisk walks as well.

Blood pressure – what’s normal?

As a general guide, the Heart Foundation suggests:

Normal blood pressure: generally less than 120/80 mmHg

Normal to high blood pressure: between 120/80 and 140/90 mmHg.

High blood pressure: 140/90 mmHg or higher. If your blood pressure is 180/110 mmHg or higher, you have very high blood pressure.

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