University of Sydney: 3.7 minutes of vigorous daily activity linked to 48% lower dementia risk

A study review presented by DeutschesGesundheitsPortal and reported by ad-hoc-news.de summarises the link between physical activity and dementia risk. In a University of Sydney analysis of UK Biobank data on 22,618 adults, mostly in their early 60s, 3.7 minutes of vigorous everyday movement per day went with a 48 percent lower dementia risk than in inactive people ad-hoc-news.dead-hoc-news.dead-hoc-news.deOpen source ↗. Over about eight years of follow-up, dementia rates were 2.5 percent without sport, 0.71 percent with vigorous everyday movement and no separate training, and 0.59 percent with planned sport combined with everyday exertion.

What the studies show

An international analysis of 74 studies, with data on more than 4.2 million people from 30 countries, found that a higher level of leisure-time activity went with a 24 percent lower dementia risk compared with the least active group. Occupational physical activity, based on five studies, went with a 20 percent higher risk. Active commuting on foot or by bicycle showed a 10 percent higher risk in two studies, while housework looked favourable in a single study. Suggested explanations for the work-related result include a lack of control over workload and breaks, static strain, noise and stress.

A companion observational cohort of more than 10,000 participants over 28 years showed that activity levels often fall nine years before a dementia diagnosis. In the Harvard Aging Brain Study, 296 people aged 50 to 90 were followed for about nine years: 3,000 to 5,000 steps per day, roughly 2.4 kilometres, delayed cognitive decline by three years, and 5,000 to 7,500 steps by seven years. A sedentary lifestyle was also associated with tau protein deposits on imaging.

Researchers at Taipei Tzu Chi Hospital studied 555 adults with cerebrovascular disease. Conversion to dementia was 23.1 percent with 15 to 30 minutes or 1,500 to 3,000 steps of daily activity, 37.9 percent with activity on one to two days a week, and 42.7 percent with none. Minimal daily activity lowered the relative risk by 52 percent ad-hoc-news.dead-hoc-news.dead-hoc-news.deOpen source ↗.

Limits of the evidence

The review notes that the strength of the evidence varies by type of activity and that the research has methodological limitations. Scientists at the German Cancer Research Center (DKFZ) used accelerometer data from more than 63,000 participants of the NAKO health study. Under the older WHO guidelines 35 percent met the activity targets; under the guidelines in force since 2020 it was 99 percent, because endurance activity no longer has to last at least ten minutes at a time. The authors said this change alters the informative value of the recommendations and blurs differences between groups, so objective thresholds still need testing.

The WHO estimates that up to 45 percent of global dementia risk is attributable to modifiable factors. At a symposium of the DGN congress in Berlin, Prof. Kathrin Reetz of Aachen said about 38 percent of dementia cases are linked to eleven modifiable factors, led by hearing loss, high blood pressure, depression, obesity and smoking. In mild cognitive impairment and early Alzheimer's disease, cognitive stabilisation is achieved most consistently through physical activity, she said. The WHO does not recommend supplements such as vitamin B, vitamin E, omega-3 fatty acids or multivitamins without a diagnosed deficiency, citing a lack of evidence.