WHY A DOG IS YOUR BRAIN’S BEST FRIEND: PEOPLE OVER THE AGE OF 65 WHO OWN A POOCH ARE 40% LESS LIKELY TO DEVELOP DEMENTIA, STUDY FINDS

We all know that dogs are man’s best friends, and now research suggests this could be due to health benefits canines give to our brains.

Scientists in Japan found that owning a dog of any breed – but not a cat – reduces the risk of older people getting dementia by 40 per cent, compared with people without one.

Having a dog increases the likelihood of getting out the house, which leads to more interactions with other humans and in turn exercises the brain, they say.

This has a ‘suppressive effect’ on the development of the debilitating condition, which affects more than 55 million people worldwide.

Previous research also suggests dog ownership among older adults has a protective effect on frailty disability and death of any cause.

The new study was led by researchers at the Tokyo Metropolitan Institute of Gerontology in Japan, who say it’s the first to show that dog ownership protects against dementia.

‘Dog owners with an exercise habit and no social isolation had a significantly lower risk of disabling dementia,’ they say in their paper.

‘Dog care might contribute to the maintenance of physical activity, including having an exercise habit, and social participation even in the face of restrictions to interactions such as those experienced during the Covid-19 pandemic.’

Dementia is an umbrella term for symptoms that occur when there’s a decline in brain function, but Alzheimer’s is the most common dementia condition.

Many dementia conditions, including Alzheimer’s, are associated with an abnormal build-up of proteins in the brain.

But exercise reduces this build-up, while also maintaining adequate blood flow to the brain and stimulating brain cell growth and survival.

Other than getting plenty of physical activity, staying mentally and socially active is another common bit of health advice to stave off dementia.

Mental activity helps to build your ‘cognitive reserve’ – the brain’s ability to cope and keep working.

For the study, the researchers recruited 11,194 older adults in Japan, aged between 65 and 84 years.

Participants, all physically and cognitively independent at the start of the study, were sent questionnaires to complete about whether they owned a cat or dog.

They were also asked about any types of exercise they engaged in more than once per week, from walking and running, to yoga swimming, cycling and stretching.

About four years later their health was assessed, including the development of any dementia conditions.

For the entire sample, researchers worked out the ‘odds ratio’, which indicates the risk of developing dementia, for both dog and cat owners.

After adjusting for background factors, the odds ratio was 0.6 for dog owners but much higher – 0.98 – for cat owners and 1 for those who did not own dogs or cats.

As expected, how much the participants exercised also had an effect on their risk of dementia – but this made the all-important difference for dog owners.

Dog owners with a regular exercise habit had an low dementia odds ratio of 0.37 compared with people without dogs who got no exercise.

But dog owners with no exercise habit had a much higher odds ratio of 0.89 compared with people without dogs who got no exercise.

And current dog owners with no social isolation had an odds ratio of 0.41 compared with people without dogs who were socially isolated.

In other words, dog owners with an exercise habit and no social isolation have the lowest risk of disabling dementia.

However, the results show that having a dog doesn’t protect against the disease if you get little exercise and are social isolated, the team warn.

‘Dog owners without daily lifestyle habits related to dog care, such as no exercise habit and social isolation, did not experience positive effects related to dementia prevention,’ they write.

The researchers note that the proportion of dog and cat ownership in Japan is smaller than that in Western countries, such as the US.

‘It will thus be important to assess whether the relationships found in Japan are also present in Western and other countries,’ they say.

According to the World Health Organisation (WHO), there around 50 million people with dementia globally, and there are nearly 10 million new cases every year.

A 2021 study estimated that global dementia cases will nearly triple to reach more than 152 million by 2050, driven by an ageing population.

The highest increase in dementia prevalence is projected to be in eastern sub-Saharan Africa, North Africa and the Middle East, the University of Washington experts said.