Alzheimer's and dementia, 'active' sedentariness works to protect the mind

It is easy to say sedentary. Or rather: moving regularly is certainly a viaticum for well-being at all ages, provided of course that the efforts are not excessive and are commensurate with the psychophysical condition of the subject. But we should not make the mistake of considering as 'non-sedentary' only those who wear overalls and walk, or perhaps ride a bike or swim in a pool. Because there would be two types of sedentariness, depending on the attitude of the brain and the mind: in short, one must overcome laziness of thought. This also creates a different (negative) risk profile in terms of the likelihood of developing cognitive impairment and Alzheimer's disease.

Indicating how much and how keeping the mind active is crucial even if the limbs are not fully trained is research that distinguishes between passive and mentally active sedentariness in relation to dementia. The study finds that adults who engage in mentally passive sedentary behaviour for prolonged periods, perhaps by remaining supine and unthinking while watching TV or spending hours on the sofa have a higher risk of developing cognitive impairment. Not only that, if one replaces passivity with mental engagement, even without particularly significant physical movement, the risk for cognitive impairment drops.

The research appeared in the American Journal of Preventive Medicine and was co-ordinated by Mats Hallgren, from the Department of Public Health Sciences at the Karolinska Institutet, Sweden, and the Baker-Deakin Department of Lifestyle and Diabetes, Institute for Physical Activity and Nutrition (IPAN) at Deakin University, Australia. This is the first analysis to distinguish between passive and mentally active sedentariness by relating them to cognitive impairment. The survey may therefore offer useful insights for public health guidelines and preventive strategies, especially considering that the population is ageing and dementia is the third leading cause of mortality and the seventh leading cause of disability among the elderly worldwide. Specifically, the research examined data from a longitudinal study of 20,811 adults aged 35-64 years, followed for 19 years (1997-2016). The initial survey included questions on sedentary behaviour, physical activity and other behaviours associated with dementia. The occurrence of dementia was identified by linking data from the 1997 survey with the Swedish National Patient Register and the Swedish Causes of Death Register.

Analysis of the data makes it clear that mentally active sedentary behaviour is associated with a reduced risk of developing dementia in middle-aged and older adults. Not only that: favouring an increase in time spent in mentally active sedentary behaviours was observed to be associated with a significant reduction in the risk of dementia, keeping the levels of passive sedentary behaviour and light to moderate physical activity unchanged. Finally, replacing time spent in mentally passive sedentary behaviour with an equivalent time spent in mentally active sedentary behaviour was also found to be associated with a reduction in the risk of developing dementia. The working hypothesis, therefore, is simple. 'Sedentariness is a ubiquitous but modifiable risk factor for many diseases, including dementia,' the expert notes. 'Our study adds the observation that not all sedentary behaviours are equivalent; some may increase the risk of dementia, while others may be protective. It is important to remain physically active as we age, but also mentally active, especially when sitting'.

The tendency not to engage in any activity is increasingly widespread, impacting on people's psyche and physique, as well as on the quality of life of many adults and caregivers. That is why it is necessary to analyse the risk factors potentially at play. While until recently there was a tendency to consider all sedentary behaviours as being associated with an increased risk of developing dementia, recent studies have shown that mentally passive sedentary behaviours (such as watching TV) increase the risk of depression, while mentally active sedentary behaviours (such as reading and working in the office) seem to have a protective effect. What is certain is that many of us spend many hours a day sitting, with a higher risk of metabolic and cardiovascular diseases. For cognitive impairment, however, this study opens up a very interesting area of prevention. Using different statistical models, the researchers examined the associations between (statistical) substitution of passive and mentally active sedentary behaviour and dementia. 'The design of the prospective study allowed us to establish the direction of these relationships and not to establish a causal relationship,' the expert points out. Controlled studies are needed to confirm these important findings of the observational study'.