Early intervention for cardiovascular disease, depression, mental inactivity, physical inactivity, smoking and sleep disturbance can reduce the risk of developing dementia, research shows.

Neuropsychology researcher Professor Sharon Naismith, who established the Healthy Brain Ageing Program at the Brain and Mind Centre at the University of Sydney, says reducing the impact of each risk factor by 10 per cent per decade would reduce the prevalence of Alzheimer’s disease by more than eight per cent.

Professor Naismith, a keynote speaker at the Australian Psychological Society’s 2016 Congress, says while there are no cures for dementia, targeting the modifiable risk factors early, in the decades before clinical symptoms of dementia manifest, will boost dementia prevention.

“We really have to be doing more at a population level to try and prevent dementia,” she says.

“One thing we know about dementia now is that the processes leading to dementia start accumulating about 20 years before your symptoms actually manifest.

“So people can’t wait until they start to notice there are some changes in their memory. If they are noticing that, then they’ve probably already got some brain changes, which you can’t reverse.

“What you need to do essentially is adopt the same principles that we talk about for heart disease, and that is really just trying to do as much as you can from a prevention perspective, so that we don’t get dementia in the first place.”

Dementia is the second leading cause of death in Australia and the single greatest cause of disability in older Australians.

More than 353,800 Australians are now living with dementia and, without a medical breakthrough, that figure is expected to rise to almost 900,000 by 2050.

Professor Naismith, who also works at the Charles Perkins Centre which focuses on research into obesity, cardiovascular disease and metabolic disturbance, says the modifiable risk factors should be tackled with a range of lifestyle, medical and psychological interventions.

Studies show obesity in mid-life can increase the brain age by 10 or 20 years. Professor Naismith says one of the wonder drugs to combat obesity is physical exercise.

“We know physical exercise can lead to neurogenesis, so the growth of new neurons, and studies have shown that if we could get people to exercise at a certain level that we could reduce dementia prevalence by 40 per cent.

“It’s quite astounding if you look at targeting even one vascular risk factor that we can actually reduce the rates of dementia.”

Another risk factor that is often under-recognised is depression. Professor Naismith says depression is toxic for the brain if left untreated.

“A lot of people don’t know that - actually suffering with depression causes the brain to release cortisol for example and that actually attacks the hippocampus; the key memory structure in the brain.

“All the studies now show that if your brain is treated, then you’ll have less brain degeneration than if you’re depression is untreated.”

Sleep disturbance is another emerging risk factor that can also lead to brain problems.

Professor Naismith says more psychologists should up-skill to treat sleep disturbance.

“We know that obstructive sleep apnea is particularly problematic, because it actually leads to hypoxia in the brain, so permanent brain damage that can’t necessarily be reversed,” she says.

“As for the rest of sleep disturbance, we know that it also seems to co-exist with the levels of amyloid in the brain, so amyloid is the main protein that’s implicated in Alzheimer’s disease.

“There are some good studies now that seem to show that sleep disturbance seems to be related to the amount of amyloid in the brain.

“What we don’t know yet about sleep disturbance is whether it just co-exists with brain degeneration or how much it directly contributes to brain degeneration, so that’s the kind of thing that we’re still trying to work out.”

Professor Naismith says it’s important psychologists understand the biology of depression, particularly when it occurs for the first time later in life.

“If someone has a first onset of depression after the age of 50 it’s probably due to underlying cardiovascular disease and the affects that that’s had in the brain,” she says.

“The data shows that people who get depression for the first time in later life tend to go on and get dementia, particularly vascular dementia, and tend to have a poor response to treatment so it should really be a bit of a red flag that this person needs medical intervention, including dietitians and exercise physiologists - professionals who can really address their whole cardiovascular risk factor profile.

“Instead of only focusing on the psychology, it should be more of a holistically-informed model that incorporates those medical components as well.”

It’s imperative health professionals routinely screen for depression and consider cognitive assessment, Professor Naismith says.

Most importantly, it’s crucial practitioners educate patients about the modifiable risk factors for dementia before it’s too late.

“I think it’s giving people the message that actually these cardiovascular risk factors are not just a problem for your blood vessels, they can lead to dementia,” she says.

“Some people are not that concerned about whether they get diabetes but they are concerned about whether they get dementia.”