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Abstract
Objectives Dementia is common in people over the age of 65 years, with 80% of people with dementia older than 75 years. Previous studies have linked dementia to late-life depression, but the association between dementia and mid-life depression is poorly understood. Depression is a preventable and treatable medical condition, which means it is a modifiable factor that can potentially prevent or delay dementia. This study aimed to identify the association between dementia and depression within the life course.
Design A nationwide, retrospective propensity score matched cohort study associating dementia with depression. Depression diagnosed between the ages of 45 and 64 years was classified as ‘mid-life’ and ‘late-life’ if diagnosed at 65 years or older. Patients were considered to have depression when one or more International Statistical Classification of Diseases and Related Health Problems, 10th revision codes for depression were recorded as primary or secondary diagnosis.
Setting National Health Insurance Service-National Sample Cohort database of the National Health Insurance Service in South Korea, containing patient data from 2002 to 2013.
Participants The study included 1824 and 374 852 patients in the case and control groups, respectively. A logistic regression analysis with complex sampling design was performed after adjusting for covariates, using the propensity score matching method without callipers, with a 1:1 nearest neighbour matching algorithm.
Primary and secondary outcome measures The association of mid-onset and late-onset depression with dementia in terms of sociodemographic characteristics, such as sex and age, within the Korean population.
Results Dementia was significantly associated with the presence of depression (OR=2.20, 95% CI=1.53–3.14); in particular, female patients with depression and patients aged 45–64 years with depression had increased odds of dementia (OR=2.65, 95% CI=1.78–3.93 and OR=2.72, 95% CI=1.41–5.24, respectively)
Conclusion Depression is an associated factor for dementia, especially among people aged 45–64 years (mid-life).
- epidemiology
- depression & mood disorders
- dementia
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Footnotes
Contributors I-HH and BJ contributed to the overall conception and design of the study protocol. O-CY and BJ contributed to the specific study design and data analysis. O-CY and BJ wrote the first draft of the manuscript. HG and MP contributed to interpretation of the analyses and revisions of the final manuscript. All authors gave final approval of the version to be submitted.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval This study was approved by the Institutional Review Board of Jaseng Hospital of Korean Medicine in Seoul, Korea (JASENG 2018-12-005), with a waiver for informed consent because the data were obtained from a public database (https://www.khp.re.kr:444/eng/data/data.do); all personal information was de-identified by the NHIS prior to public release. The principles expressed in the Declaration of Helsinki have been adhered to in this study.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available in a public, open access repository. The datasets generated and analysed during the current study are available on the National Health Insurance Sharing Service. NHIS provides support to research activities in various sectors of society, including the economy, environment and industry, as well as policy and academic research in the health sector, by providing sample cohort databases. The research database consists of five types of databases: sample cohort, medical check-up cohort, elderly cohort, working women cohort and infant medical check-up cohort. Each cohort database consists of the following four detailed data sets: qualification, treatment, medical check-up and clinic.The present study utilised the sample cohort database, which is third-party data, not owned by the authors. The sample cohort database is available upon approval for data sharing from the health insurance corporation. For the purposes of policy and academic research, a fee is paid to obtain the data from the NHIS website (https://nhiss.nhis.or.kr/bd/ab/bdaba022eng.do).