J Korean Med Sci.  2019 Nov;34(44):e293. 10.3346/jkms.2019.34.e293.

Decline in the Incidence of All-Cause and Alzheimer's Disease Dementia: a 12-Year-Later Rural Cohort Study in Korea

Affiliations
  • 1Department of Psychiatry, Seoul National University College of Medicine, Seoul, Korea. mjcho@snu.ac.kr, benji@snu.ac.kr
  • 2Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Korea.
  • 3Department of Psychiatry, Kyungpook National University School of Medicine, Daegu, Korea.
  • 4Department of Neuropsychiatry, Seoul National University Bundang Hospital, Seongnam, Korea.
  • 5Department of Brain and Cognitive Science, Seoul National University College of Natural Sciences, Seoul, Korea.
  • 6Department of Public Health Medical Service, Seoul National University Hospital, Seoul, Korea.
  • 7Department of Psychology, Sogang University, Seoul, Korea.
  • 8Department of Neuropsychiatry, Seoul Metropolitan Boramae Medical Center, Seoul, Korea.

Abstract

BACKGROUND
There has been no study on the time trends of dementia incidence in Korea. We report the 5-year incidence and its correlates of all-cause and Alzheimer's disease (AD) dementia, and compared our results with those of a 12-year-prior cohort study conducted in the same area.
METHODS
A total of 751 community-dwelling older adults were followed up for a mean duration of 5.4 years. The age-, gender-, and educational attainment-specific incidence of all-cause and AD dementia were reported as cases per 1,000 person-years. We performed univariate and multivariate cox proportional hazard regression analyses to determine whether baseline sociodemographic, lifestyle, and clinical variables were associated with the risk of all-cause and AD dementia. A 12-year-prior cohort study was used for descriptive comparison to indicate the time trends of dementia incidence.
RESULTS
The incidence rates were 16.2 and 13.0 cases per 1,000 person-years for all-cause and AD dementia, respectively. The baseline diagnosis of mild cognitive impairment increased the 5-year incidence of all-cause dementia by more than 4-fold. Old age and low baseline global cognitive function were noted as risk factors for both all-cause and AD dementia.
CONCLUSION
Upon comparing the results with those from the earlier cohort study in Yeoncheon, the incidence of all-cause and AD dementia decreased by approximately 40% over 12 years; it has been mainly driven by the increase in the educational level of older adults. The declining time trends of incidence should be taken into account for estimating the future prevalence of dementia in Korea.

Keyword

Dementia; Alzheimer's Disease; Incidence; Time Trends; Risk Factors

MeSH Terms

Adult
Alzheimer Disease*
Cognition
Cohort Studies*
Dementia*
Diagnosis
Humans
Incidence*
Korea*
Life Style
Mild Cognitive Impairment
Prevalence
Risk Factors
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