Read a book – or drive a taxi – to avoid Alzheimer’s disease

It’s that time of the year when most of us get the chance to sit back and enjoy some well-deserved down time. But whether you reach for the TV controller, or a favourite book, your choice could have implications for your long-term brain health, say researchers at the University of South Australia.

Assessing the 24-hour activity patterns of 397 older adults (aged 60+), researchers found that the context or type of activity that you engage in, matters when it comes to brain health. And specifically, that some sedentary (or sitting) behaviours are better for cognitive function than others.

When looking at different sedentary behaviours, they found that social or mentally stimulating activities such as reading, listening to music, praying, crafting, playing a musical instrument, or chatting with others are beneficial for memory and thinking abilities. Yet watching TV or playing video games are detrimental.

Researchers believe that there is likely a hierarchy of how sedentary behaviours relate to cognitive function, in that some have positive effects while others have negative effects.

It’s a valuable insight that could help reduce risks of cognitive impairment, particularly when at least 45% of dementia cases could be prevented through modifiable lifestyle factors.

In Australia, about 411,100 people (or one in every 1000 people) are living with dementia. Nearly two-thirds are women. Globally, the World Health Organization estimates that more than 55 million people have dementia with nearly 10 million new cases each year.

UniSA researcher Dr Maddison Mellow says that not all sedentary behaviours are equal when it comes to memory and thinking ability.

“In this research, we found that the context of an activity alters how it relates to cognitive function, with different activities providing varying levels of cognitive stimulation and social engagement,” Dr Mellow says.

“We already know that physical activity is a strong protector against dementia risk, and this should certainly be prioritised if you are trying to improve your brain health. But until now, we hadn’t directly explored whether we can benefit our brain health by swapping one sedentary behaviour for another.

Mental Exercise

“We found that sedentary behaviours which promote mental stimulation or social engagement – such as reading or talking with friends – are beneficial for cognitive function, whereas others like watching TV or gaming have a negative effect. So, the type of activity is important.

“And, while the ‘move more, sit less’ message certainly holds true for cardiometabolic and brain health, our research shows that a more nuanced approach is needed when it comes to thinking about the link between sedentary behaviours and cognitive function.”

Now, as the Christmas holidays roll around, what advice do researchers have for those who really want to indulge in a myriad of Christmas movies or a marathon of Modern Family?

“To achieve the best brain health and physical health benefits, you should prioritise movement that’s enjoyable and gets the heart rate up, as this has benefits for all aspects of health,” Dr Mellow says.

“But even small five-minute time swaps can have benefits. So, if you’re dead set on having a Christmas movie marathon, try to break up that time with some physical activity or a more cognitively engaged seated activity, like reading, at some point. That way you can slowly build up healthier habits.”

This research was conducted by a team of UniSA researchers including: Dr Maddison Mellow, Prof Dot Dumuid, Dr Alexandra Wade, Prof Tim Olds, Dr Ty Stanford, Prof Hannah Keage, and Assoc Prof Ashleigh Smith; with researchers from the University of Leicester, and the University of Newcastle.

Spacial Processing

Another study, published in the Christmas edition of the British Medical Journal argues that taxi drivers and ambulance drivers, whose jobs require frequent spatial and navigational processing, have the lowest levels of death due to Alzheimer’s disease compared with other occupations.

This observation doesn’t confirm a direct link, but the researchers say they raise the possibility that memory intensive driving occupations, such as taxi and ambulance driving, might be associated with some protection against mental decline and dementia.

The hippocampus is a brain region used for spatial memory and navigation and has been shown to be enhanced in London taxi drivers compared with the general population.

It is also one of the brain regions involved in the development of Alzheimer’s disease, raising the possibility that occupations that demand frequent spatial processing may be associated with decreased Alzheimer’s disease mortality.

To investigate this, a team of US researchers analysed death certificates for adults from 443 different occupations between 1 January 2020 and 31 December 2022. Data included cause of death, usual occupation (in which the decedent spent most of their working life), and sociodemographic information (eg, age, sex, race, ethnic group, and educational attainment).

Of nearly 9 million people who had died with occupational information, 3.9% (348,328) had Alzheimer’s disease listed as a cause of death. Of 16,658 taxi drivers, 171 (1.03%) died from Alzheimer’s disease, while among ambulance drivers, the rate was 0.74% (10 of 1,348).

After adjusting for age at death and other sociodemographic factors, taxi and ambulance drivers had the lowest proportion of deaths from Alzheimer’s disease of all occupations examined (1.03% and 0.91% respectively) and compared with the general population (1.69%).

The researchers note that this trend was not seen in other transport-related jobs such as bus drivers or aircraft pilots (possibly due to their reliance on predetermined routes) or with other forms of dementia, suggesting that neurological changes in the hippocampus or elsewhere amongst taxi and ambulance drivers may account for the reduction in Alzheimer’s risk.

This is an observational study, so no firm conclusions can be drawn about cause and effect. And the authors acknowledge various limitations, including that individuals who are at higher risk of developing Alzheimer’s disease may be less likely to enter or remain in memory intensive driving occupations such as taxi and ambulance driving. However, they say this is unlikely given that Alzheimer’s disease symptoms typically develop after working age.

“We view these findings not as conclusive, but as hypothesis generating,” they say.

“Further research is necessary to definitively conclude whether the spatial cognitive work required for these occupations affect risk of death from Alzheimer’s disease and whether any cognitive activities can be potentially preventive.”