A new Lancet journal found that high-intensity physical labor may increase the risk of dementia!

Dementia is a common neurological disease in the aging population, among which Alzheimer's disease is the most common. Its patients are unable to take care of themselves due to a series of symptoms such as memory loss, weakened learning ability, emotional regulation disorders, and loss of motor ability.

In China, there are more than 10 million people with dementia. Globally, according to data from the World Health Organization, there are currently more than 55 million people suffering from dementia. This figure will increase as the population ages, and is expected to rise to 78 million by 2030 and 139 million by 2050.

Because the cause is unknown and there has been a long-term lack of effective treatment drugs, to a certain extent, Alzheimer's disease is even more terrifying than some cancers.

Why are humans susceptible to dementia? Scientists have been working to find the factors that influence dementia.

Physical labor may be a very important influencing factor. A paper recently published in The Lancet Regional Health-Europe, a subsidiary of The Lancet, put forward the view through a survey of 7,005 research subjects that high-intensity physical labor may increase the risk of dementia.

The study included 7,005 subjects aged 70 and above, of whom 902 were diagnosed with dementia and 2,407 were diagnosed with mild cognitive impairment.

To clarify the relationship between morbidity and physical labor, the researchers divided the subjects into four types based on their occupational activity trajectories between the ages of 33 and 65:

1. Stable low-level labor, that is, the type of work that requires little physical effort in long-term work, such as primary school teachers;

2. Increase first and then decrease, that is, the type where the level of physical input changes with the nature of the work, such as secretaries;

3. Stable middle-level labor, such as sales staff;

4. Stable high-level labor, such as caregivers, growers, etc.

Under this classification system, the researchers found that people with high levels of labor had a significantly higher risk of developing dementia or mild cognitive impairment than other people.

Among the four types of people with labor trajectories, the risks of dementia and mild cognitive risk among people with stable low-level labor were 8.8% and 27.4%, respectively; for people whose labor level first increased and then decreased, the risks were 8.2% and 33.3%, respectively; for people with stable medium-level labor, the risks were 16% and 33.3%, respectively; and for people with stable high-level labor trajectories, the risks were 15.4% and 40.2%, significantly higher than those of people with other labor types.

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Why does high physical labor affect the brain? Researchers have also given several possible guesses.

One possibility is that there are certain differences in genetics, socioeconomic factors and environmental exposure between individuals engaged in high physical labor and those engaged in medium and low physical labor, and this difference may be the real influencing factor.

Another possibility is that people who engage in these high-physical labor activities have relatively lower cognitive abilities in their early years, which in turn affects their opportunities in school and the job market, ultimately making them high-physical laborers. In other words, it is their relatively low cognitive level that leads to a high risk of dementia, and high physical labor is just a manifestation of this characteristic.

In addition, another possibility is that people who engage in high-physical labor usually have high work intensity, rigid schedules, high pressure, and high risk of burnout. Compared with people engaged in low-physical labor such as teaching, engineering, and administration, they receive less cognitive stimulation at work, which may also affect their brain health in the later stages.

Although the specific mechanism of the connection between physical labor and dementia risk has not yet been clarified, researchers have also suggested that the impact of labor intensity on health can be reduced through flexible adjustments, job rotation, and forced breaks.

This article is a work of Science Popularization China-Starry Sky Project

Produced by: Science Popularization Department of China Association for Science and Technology

Producer｜China Science and Technology Press Co., Ltd., Beijing Zhongke Xinghe Culture Media Co., Ltd.

Author: Shi Nanping, a popular science writer

Reviewer: Tang Qin, Director and Researcher of the Science Popularization Department of the Chinese Medical Association