When you read the literature about Alzheimer’s disease, two things remain constant.

Despite the hype of some recent breakthroughs, there are no drug treatments that significantly slow or reverse or prevent the damage done by this form of dementia.

The other thing: Exercise appears to deliver the kind of results that drugs as yet cannot.

As University of Maryland researchers called it in 2013: “Exercise may be the best medicine for Alzheimer’s disease.”

Best and only medicine … for the moment.

Here’s just a sample of the research

A 2013 study found that keeping active can slow the progression of memory loss in people with Alzheimer’s disease.

A 2016 study found that exercise can reduce protein build-ups linked to Alzheimer’s.

A 2019 study: Exercising several times a week may delay brain deterioration in people at high risk for Alzheimer’s disease. This was a study of patients with mild cognitive impairment.

For a detailed 2020 overview of the research, see here.

The most positive message so far

The UK’s Alzheimer’s Society and Australia’s dementia.org.au run pretty hard with this message – that regular exercise protects against dementia – as the research becomes more nuanced.

There are emerging theories as to why exercise might have these benefits. What’s the mechanism at work here beyond the obvious, that exercise pumps more blood into the brain.

And there’s a clearer picture about how much – and what sort of exercise – we should be doing.

On your bike

I’m forever nagging TND readers about the benefits and joys of going for a regular walk – while pointing to a mountain that gets bigger by the day.

In August, the world’s largest study found “the more you walk, the lower your risk of death”.

Which is great. But you might need to do more than a leisurely stroll if you want to save your brain from damaging decay.

Emerging evidence suggests you have go hard. That is, up the intensity of your walking, running or cycling. More puff, more sweat.

In January, a study out of New Zealand found that six minutes of high-intensity exercise “could extend the lifespan of a healthy brain and delay the onset of neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease”.

The researchers found that “a short but intense bout of cycling increases the production of a specialised protein that is essential for brain formation, learning and memory, and could protect the brain from age-related cognitive decline”.

New study suggests a sweet spot

An international team of researchers, including Professor Emmanuel Stamatakis from the University of Sydney, appear to have found the sweet spot for how long and how hard we need to exercise to lower our chances of dying from Alzheimer’s disease.

In short: 20 minutes of vigorous exercise a day.

As conclusion of their paper their new paper declared: “The optimum amount of vigorous activity to perform every week to reduce your risk of Alzheimer’s disease was 140 minutes”.

How did they get there?

According to a prepared statement from the University of Sydney: The researchers pooled data from 22 consecutive waves of the US National Health Interview Survey from 1997 to 2018.

This amounted to more than 90,000 participants whose physical activity levels were linked to their risk of dying from Alzheimer’s.

Moderate physical activity “counted as anything that induced light sweating or a moderate increase in breathing and/or heart rate for at least 10 minutes”.

Vigorous activity was classed as “anything that caused heavy sweating or large increases in breathing and/or heart rate for at least 10 minutes”.

Moderate physical activity was associated with a lower Alzheimer’s-associated death risk, but this link was statistically insignificant.

However, vigorous physical activity did appear to significantly reduce death rates after as little as 20 minutes of activity per week.

After a certain amount of exercise, this risk reduction association became less significant, and in some cases actually increased disease-associated mortality.

From these results, the team calculated that just 40 minutes of vigorous physical activity every week would prevent 12,238 deaths every year in the US.

And 140 minutes a week would prevent 37,710 deaths a year.