Insomnia and incident young-onset dementia in a population-based study with 18-year follow-up: the Korean Genome and Epidemiology Study

초록

Introduction: Young-onset dementia is defined as the occurrence of dementia symptoms under the age of 65 years. Although prevalence of young-onset dementia is low compared with late-onset dementia, 3 to 8% of all people with dementia are currently aged under 65. Identification of modifiable and nonmodifiable risk factors would aid in developing targeted interventions to prevent young-onset dementia, but previous research has focused on genetic factors. Meanwhile, sleep disturbance has been suggested to have a relationship with cognitive impairment and dementia, but young-onset dementia is unclear. The aim of the present study is to examine the associations between insomnia and incident young- or late-onset dementia through middle-aged to older general population. Method: A total 9859 participants of the Korean Genome and Epidemiology Study – Ansan and Ansung (mean age, 52.2 ± 8.9), who have been linked to the Health Insurance Review and Assessment Service national database to assess incident all-cause and sub-type of dementia were analyzed. Prevalent cases of insomnia were defined using one (or more) of symptoms of insomnia (difficulty initiating sleep, difficulty falling back asleep and early morning awakening). In multivariate Cox regression analysis with competing risk analysis, we adjusted for age, sex, area, marital status, education level, socioeconomic status, apolipoprotein E, body mass index, smoking and drinking statuses, regular exercise, various comorbidities including hypertension, diabetes, depression, hyperlipidemia, heart, and cerebrovascular disease at baseline. Results: During the mean follow-up of 17.6 years, dementia was diagnosed in 1293 participants (611 with Alzheimer's disease). Among total participants at baseline, 13.0% were 65–69 years of age and 52.4% were women. Overall insomnia was associated with greater risk of dementia among total participants (hazard ratio [HR] = 1.22; 95% confidence interval [CI], 1.03–1.44) in the final model. Furthermore, insomnia was associated with greater risk of young-onset dementia among total participants (HR = 1.75; 95% CI, 1.09–2.83) and women (HR = 2.15; 95% CI, 1.24–3.72). However, there was no association with late-onset dementia as well as men. Conclusion: Our findings suggest that insomnia was prospectively associated with an increased risk of young-onset dementia, especially among women.