A new study published in The Lancet suggests that physically demanding jobs may increase the risk of dementia later in life, contrary to the belief that regular physical activity protects the brain.
Researchers found that people who worked in roles requiring medium to high physical activity—such as salespeople, nursing and care assistants, crop farmers, and animal producers—had a 72% higher risk of developing dementia or mild cognitive impairment (MCI) in their 70s compared to those in office jobs.
The study, which analysed data from the HUNT4 70+ Study in Norway, included 7,005 participants aged 33 to 65. Of these, 92 were clinically diagnosed with dementia and 2,407 with MCI. The physical demands included climbing, lifting, balance, walking, and stooping.
While no definitive reason was given, the authors suggested that the strain of physical labour, lack of downtime, and resulting exhaustion could lead to 'wear and tear' on both body and mind. Additionally, such jobs often involve long periods of standing, manual labour, stress, and exposure to hearing loss and pollution, all of which can adversely affect cognition.
Dr Vegard Skirbekk, study author and professor at Columbia Public Health, said: 'Our findings extend those from previous studies by incorporating a life-course perspective into research on occupational physical activity and cognitive impairment.'
The study highlights the need for strategies to prevent cognitive decline in people with physically demanding jobs, as approximately one million people in the UK have a type of dementia.
