Prospective study of sedentary behavior, risk of depression, and cognitive impairment

Modern-day lifestyles are characterized by large amounts of prolonged sedentary activities, which may pose a risk to health in its own right, although little is known about their effects on mental health. We examined the association between several types of common sedentary behaviors (TV viewing, Internet use, reading) and different aspects of mental health.

We conducted a 2-yr follow-up of 6359 (age 64.9 ± 9.1 yr) men and women from the English Longitudinal Study of Ageing, a cohort of community-dwelling older adults. Self-reported TV viewing time, reading, and use of the Internet was assessed at baseline. Mental health was assessed using the eight-item Centre of Epidemiological Studies Depression scale to measure depressive symptoms and neuropsychological tests of memory and verbal fluency to assess cognitive function.

At baseline, TV viewing time (≥ 6 vs. <2 h · d(-1)) was associated with higher depressive symptoms (coefficient = 0.49, 95% confidence interval [CI] = 0.63 to 0.35) and poorer global cognitive function (coefficient = -1.16, 95% CI = -1.00 to -1.31). Conversely, participants using the Internet reported lower depressive symptoms (coefficient = -0.58, 95% CI = -0.50 to -0.66) and higher global cognitive function (coefficient = 1.27, 95% CI = 1.37 to 1.18). There was no association between any sedentary behaviors at baseline and change in mental health measures over follow-up, suggesting that the difference in scores persisted but did not increase over time.

Some, but not all sedentary behaviors, are linked to adverse mental health. It is likely that these associations are being driven by the contrasting environmental and social contexts in which they occur.