TOPLINE:

Engaging in mentally active behaviors, such as office work and knitting, while sedentary was associated with significantly lower dementia risk than mentally passive behavior, such as watching television, new research showed.

METHODOLOGY:

• Data were analyzed for nearly 21,000 adults from the Swedish National March Cohort (mean age, 51 years; 69% women).
• Passive sedentary behaviors (television viewing, listening to music, and sitting in a bathtub) and mentally active sedentary behaviors (office work, sitting in meetings, and knitting or sewing) were assessed through questionnaires about daily time spent in these activities.
• Light and moderate-to-vigorous physical activity (PA) were estimated using questions about weekly time spent in exercise, athletics and sports, and outdoor PA.
• Incident dementia cases (n = 569) were identified through linkage with two Swedish registers, with a median follow-up of 19 years. The analysis was adjusted for such factors as sex, age, BMI, and comorbid chronic diseases.

TAKEAWAY:

• Participants reported a mean of 116.3 and 239.9 minutes per day of passive and mentally active sedentary behavior, respectively. Each additional hour per day of mentally active sedentary behavior was associated with a lower risk of developing dementia (adjusted hazard ratio [aHR], 0.96; P < .05).
• Increasing mentally active sedentary behavior by 1 hour per day while maintaining constant passive sedentary behavior and PA was associated with a lower risk for incident dementia (aHR, 0.89; 95% CI, 0.81-0.97).
• Substituting 1 hour per day of passive sedentary behavior with an equal amount of mentally active sedentary behavior was also linked to a reduction in incident dementia risk (aHR, 0.93; 95% CI, 0.87-0.99).
• A significant age interaction indicated that the protective effect of mentally active sedentary behavior was stronger in participants aged 50-64 years than in those aged 35-49 years.

IN PRACTICE:

“Our study adds the observation that not all sedentary behaviors are equivalent; some may increase the risk of dementia, while others may be protective,” study investigator Mats Hallgren, PhD, Karolinska Institute, Stockholm, Sweden, said in a press release. 

“It is important to remain physically active as we age, but also mentally active — especially when we are sitting,” Hallgren added.

SOURCE:

The study was led by André O. Werneck, PhD, School of Public Health, Universidade de São Paulo, São Paulo, Brazil. It was published online on March 25 in the American Journal of Preventive Medicine.

LIMITATIONS:

The baseline questionnaire was completed in 1997 and did not capture modern sedentary behaviors; and sedentary behavior was measured at a single timepoint, introducing misclassification bias over the 19-year follow-up period. The reliance on medical registers may have led to underreporting of dementia cases. Cognitive assessments were not conducted at baseline, so prevalent cases of dementia may have existed in the sample. Additionally, potential unmeasured confounders such as baseline cognitive function may have caused residual confounding in the associations observed. 

DISCLOSURES:

ICA AB and Ericsson provided financial support for the original project. The investigators reported having no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.