SPENDING time in mentally engaging activities may help lower dementia risk, as long term data show that not all sedentary behaviour is equal, with passive habits linked to worse outcomes and active behaviours offering potential protection.
Dementia Risk and Sedentary Behaviour Patterns
Dementia risk has been associated with lifestyle factors, yet the role of sedentary behaviour remains complex. This study explored how mentally passive activities such as television viewing compare with mentally active behaviours like office work in influencing dementia risk over time.
Methods and Results
Data were drawn from the Swedish National March Cohort including 20811 adults aged 35 to 64 years at baseline in 1997, with follow up through 2016 and median follow up of 19.2 years totalling 393104 person years. Incident dementia cases numbered 569 and were identified via national registers. Sedentary behaviour and physical activity were assessed by questionnaire, and associations were analysed using Cox proportional hazards models including single, partition, and substitution approaches.
Mentally passive sedentary behaviour showed increased dementia incidence in crude models (hazard ratio:1.16; 95% CI:.11 to 1.22) but not adjusted models (hazard ratio:1.04; 95% CI: 0.98 to 1.10). Each additional hour per day of mentally active sedentary behaviour was associated with lower dementia risk (hazard ratio: 0.96; 95% CI: 0.93 to 0.98). Partition models showed a reduction (hazard ratio: 0.89; 95% CI: 0.81 to 0.97). Substitution analysis showed (hazard ratio: 0.93; 95% CI: 0.87 to 0.99).
Clinical Implications for Dementia Prevention
These findings suggest that dementia prevention strategies should consider not only reducing sedentary time but also modifying its nature. Encouraging mentally stimulating activities during sedentary periods may offer a practical and accessible intervention, particularly for older adults. The stronger protective effect observed among participants aged 50 to 64 years indicates that midlife may represent a critical window for intervention. Future research should further explore mechanisms linking cognitive stimulation to neuroprotection and evaluate how behavioural interventions can be effectively implemented at population level to support healthy ageing and reduce dementia burden.
Reference
Werneck AO et al. Mentally active versus passive sedentary behavior and risk of dementia: 19-year cohort study. American Journal of Preventive Medicine. 2026:108317.
Featured image: Jason on Adobe Stock
