What is the Longitudinal Relationship between Gait Abnormalities and Depression in a Cohort of Community-Dwelling Older People? Data From the Irish Longitudinal Study on Ageing (TILDA)

Objective: Does baseline gait disturbance predict incident depression in a cohort of community-dwelling older people? Methods: This is a longitudinal study, embedded within the Irish Longitudinal Study on Ageing (TILDA), examining the association between baseline depression and incident gait abnormalities, as well as between baseline gait abnormalities and incident depression at 2 year follow-up. Depression was defined as a score of >= 16 on the Centre for Epidemiological Studies Depression Scale (CES-D). Gait abnormality was defined as a Timed Up and Go Test (TUG) >= 12 seconds. Assessments were carried out at baseline and at 2 year follow-up. Results: 7% (179/2,638) had baseline depression and 11% (296/2,638) had a gait abnormality at baseline. The incidence of new-onset depression and gait abnormality at Wave 2 was 4% (95/2,364) and 13% (308/2,342) respectively. Logistic regression models demonstrated that baseline gait abnormality was a significant predictor of incident depression with an Incidence Rate Ratio (IRR) of 2.00 (95% CI: 1.18 - 3.40, p = 0.010, t = 2.57, df = 625), which was not attenuated after controlling for covariates. Baseline depression was a predictor of incident gait abnormality at Wave 2 with an IRR of 1.68 (95% CI: 1.16 -2.43, p = 0.006, t = 2.75, df = 625) but this association was no longer statistically significant when analysis was adjusted for clinical variables. Conclusions: This study demonstrates that baseline gait disturbance, measured by TUG, predicts incident depression, defined by CES-D, in a population-representative cohort of community-dwelling older people. Possible biological mechanisms for this relationship include white matter disease and executive dysfunction.