Higher levels of objectively measured sedentary behavior is associated with worse cognitive ability: Two-year follow-up study in community-dwelling older adults

Background: A number of cross-sectional studies have suggested that higher levels of sedentary behavior (SB) are associated with worse cognitive abilities in older age. There is a paucity of longitudinal studies investigating this relationship utilizing objectively assessed SB. This study investigated the relationship between objectively assessed SB and future cognitive abilities in a cohort of older adults. Methods: A longitudinal study over 22.12 +/- 1.46 months including 285 community-dwelling older adults across 14 regions in Taiwan was undertaken. Cognitive ability was ascertained using a Chinese version of the Ascertain Dementia 8-item Questionnaire (AD8) and SB captured by 7 days accelerometer data. Multivariable negative binomial regression models adjusted for confounders were undertaken. Results: 274 community-dwelling older adults finished the study (age = 74.6 +/- 6.2, % female = 54.4%). At baseline, 20.1% (n = 55), 48.5% (n = 133) and 31.4% (n = 86) of the sample engaged in high (11 + h), medium (7-10.99 h) and low (< 7 h) of SB respectively. In the fully adjusted model, higher levels of SB were associated with an increased risk of worse cognitive ability at follow up (adjusted rate ratio (ARR) 1.09 (95% CI: 1.00-1.19)), with the strongest relationship evident in those engaging in over 11 h of SB (ARR 2.27 (95% CI: 1.24-4.16)). The relationship remained evident after adjusting for depressive symptoms and physical activity. Conclusion: Our data suggests that objectively assessed SB, particularly when over 11 h a day, is independently associated with worse cognitive ability over a two year period. Our data adds to the pressing reasons to reduced SB in older age.