Study Links Passive Screen Time to Increased Dementia Risk - Video

A new study published in American Journal of Preventive Medicine highlights that not all sitting behaviors carry the same risk for Dementia. Researchers found that mentally passive sedentary activities-such as watching television-are linked to a higher risk of dementia, while mentally active behaviors like reading or desk work may help reduce that risk.

Led by Mats Hallgren from Karolinska Institute, the study analyzed data from over 20,800 adults aged 35–64 years over a 19-year period. The researchers examined how different types of sedentary behavior influenced long-term cognitive health. Dementia cases were identified through national health and mortality records, ensuring robust longitudinal tracking.

The findings showed that individuals who spent more time in mentally passive activities had a significantly higher likelihood of developing dementia. In contrast, increasing time spent in mentally engaging sedentary activities was associated with a lower risk—even when overall sitting time remained the same. Importantly, replacing passive sitting with mentally active tasks led to measurable reductions in dementia risk.

These results challenge the long-standing assumption that all sedentary behavior is equally harmful. While prolonged sitting is already linked to conditions like cardiovascular disease and type 2 diabetes, this study suggests that brain engagement during sedentary time plays a crucial role in cognitive outcomes.

Globally, dementia remains a leading cause of disability and mortality among older adults, making prevention strategies essential. The study emphasizes that sedentary behavior is a modifiable risk factor. Staying physically active is important, but maintaining mental engagement—even while sitting—may be equally critical for protecting long-term brain health and reducing dementia risk.

REFERENCE: Werneck, A. O., et al. (2026). Mentally Active Versus Passive Sedentary Behavior and Risk of Dementia: 19-Year Cohort Study. American Journal of Preventive Medicine. DOI: 10.1016/j.amepre.2026.108317. https://www.ajpmonline.org/article/S0749-3797(26)00060-7/fulltext