Landmark study finds way to predict and hopefully prevent dementia in later life

A world-first study has found that poor physical fitness and obesity in childhood may predict declined cognitive functioning and dementia in later life.

The 30-year research from Monash University followed over 1200 people from childhood up to 2019 to track their cognitive performance.

Back in 1985, the seven-to-fifteen-year-olds performed long jumps and pushups, ran a 1.5-kilometre route and 50-metre sprint so researchers could assess their cardiorespiratory fitness and muscular strength.

Three decades later, the now middle-aged participants underwent a series of computerised tests to gauge their cognitive abilities, such as working memory and attention. 

"We found that people with better physical functioning and lower abdominal obesity performed much better on tests of processing speed and attention in midlife," Associate Professor Michele Callisaya says.

"Developing strategies that improve low fitness and decrease obesity levels in childhood are essential because they could contribute to improvements in cognitive performance in midlife.

"The study also indicates that protective strategies against future cognitive decline may need to start as far back as early childhood so that the brain can develop sufficient reserves against developing conditions such as dementia in older life."

Dementia is the leading cause of death among people aged 85 and over, and the risk increases as people age.

Most drugs on the market target the build-up of amyloid in the brain which is often seen in dementia pathology. However, over the past 20 years, all anti-amyloid drugs produced have failed to prove they can stop or slow the disease.

Michele calls for earlier intervention as recent research suggests the pathology of dementia starts at least 20 to 30 years before diagnosis.

"We're going to have to intervene a lot earlier than when someone actually gets a diagnosis because, by that time, the pathology has built up so much that it's hard to recover," she says.

"It may be starting even earlier than that, and at the moment, we don't have good ways of measuring dementia during the early stages."

Aside from well-known risk factors such as excessive alcohol use and smoking, exercise and fitness also help stave off the onset of dementia. 

"We know that physical activity has a direct positive effect on the brain by improving the blood flow and producing new neurons and better connections between the neurons," Michele explains.

While the study tried to control for these risk factors on the results, Michele says other external factors still could have played a role.

"It could be that these people that had poorer levels of physical activity and weren't eating as well went on to develop diseases like diabetes or high blood pressure, which is bad for the brain.

"Whereas 'healthier' people in childhood continued their healthy behaviours into midlife.

"Another reason could be that better performance on these physical tests could be due to genetics, which is also related to better brain health."

Ensuring people from a young age enjoy exercise will positively affect their mental health as they'll maintain physical activity through their adolescence and midlife.

"There's a lot of kids that aren't good at sport, and so it's important to give children a positive experience and make sure that it's fun for them," she says.

"Children must have the opportunity to be physically active and not on their computer all day."

Luckily, it's never too late to improve your physical fitness.

In the future, the researchers plan to keep following the people throughout their life to monitor their health.

"I guess it would be great to see if they did develop further cognitive decline or not.

"It would also be really interesting to check them for blood biomarkers for dementia that are not nearly as invasive as brain scans. 

"So it would be great to see if these measures at childhood are related to blood biomarkers of dementia as well."

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