Life Satisfaction and the Relationship between Mild Cognitive Impairment and Disability Incidence: An Observational Prospective Cohort Study

The relationship between the incidence of disability and cognitive function has been clarified, but whether life satisfaction is related to this relationship is unclear. Therefore, the purpose of this study was to clarify whether life satisfaction is related to the relationship between the incidence of disability and mild cognitive impairment. We included 2563 older adults from the National Center for Geriatrics and Gerontology–Study of Geriatric Syndromes. Baseline measurements included cognitive, life satisfaction, and demographic characteristics. Life satisfaction was measured using the Life Satisfaction Scale, which was stratified into three levels based on the score: lower, moderate, and higher. Associations between disability incidence and mild cognitive impairment were examined for each group according to life satisfaction, and monthly assessment for disability was monitored through long-term care insurance certification for at least 2 years from the baseline. At a 35.5-month mean follow-up, 150 participants had developed a disability. The potential confounding factors adjusted hazard for incidence of disability in the group with lower life satisfaction was 1.88 (CI: 1.05–3.35; p = 0.034) for mild cognitive impairment. Mild cognitive impairment was associated with disability incidence, and the effect was more pronounced among older adults with lower life satisfaction.