Longitudinal study of cognitive decline among women with and without urinary incontinence.

BACKGROUND: Cross-sectional and short-term cohort studies have demonstrated an association between urinary incontinence and dementia as well as lower performance on cognitive testing. The Health and Retirement Study, a longitudinal study of community-dwelling older adults, offers an opportunity to assess the temporal association between these conditions, as this study included an assessment of incontinence symptoms as well as biennial assessments of cognitive function.

OBJECTIVES: This study aimed to evaluate if urinary incontinence before age 70 had an effect on changes in cognitive function among women participating in the Health and Retirement Study.

STUDY DESIGN: This secondary analysis included data from female respondents in the Health and Retirement Study ages 58 to 67 years with ≥2 cognitive assessments. Urinary incontinence was defined as any involuntary loss of any urine in the preceding 12 months. A control group without incontinence was reweighted for better comparability using coarsened exact matching for age and comorbidities. Validated methods, including neuropsychological test data, estimated a Memory score and DP for each participant biennially. Coprimary outcomes were the changes in Memory score and dementia probability. Linear regression models were used to estimate the association of urinary incontinence with change in Memory score and dementia probability, adjusting for baseline demographics and comorbidities. A subgroup analysis was performed to assess the effects of urinary incontinence frequency on these outcomes. The infrequent subgroup reported less than fifteen days of leakage per month and the frequent subgroup reported fifteen or more days of leakage per month.

RESULTS: Among eligible female respondents, 40.6% reported urinary incontinence between ages 58 to 69 years. Baseline Memory scores and dementia probability were similar between those with urinary incontinence (n=1706) and controls (n=2507). Memory score declined significantly in both cohorts, indicating poorer memory over time -0.222 among those with incontinence (95% confidence interval (CI) -0.245, -0.199) versus -0.207 in controls (95% CI: -0.227, -0.188). The decline of Memory score was not statistically different between cases and controls (mean difference -0.015, 95% CI: -0.045, 0.015). Dementia probability increased significantly in both groups, indicating a greater probability of dementia: 0.018 among those with incontinence (95% CI: 0.015, 0.020) and by 0.020 among controls (95% CI: 0.017, 0.022). The change in DEMENTIA PROBABILITY was not significantly different between groups (mean difference -0.002, 95% CI: -0.006, 0.002). Frequent urinary incontinence was reported in 105/1706 (6%) with urinary incontinence. Memory score declined and dementia probability increased with time (p<0.001) in frequent and infrequent UI subgroups. There was no dose-response relationship.

CONCLUSIONS: Measures of cognitive performance declined with approximately 10 years of observation; the changes in performance were not associated with the presence of urinary incontinence in their younger years.