Ji-Yeon Lee1, Kyungdo Han2, Eugene Han3, Gyuri Kim4, Hanna Cho5, Kwang Joon Kim6, Byung Wan Lee1,7, Eun Seok Kang1,7, Bong-Soo Cha1,7, Carol Brayne8, Yong-Ho Lee1,7. 1. Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. 2. Department of Biostatistics, The Catholic University, Seoul, Republic of Korea. 3. Division of Endocrinology, Department of Internal Medicine, Keimyung University School of Medicine, Daegu, Republic of Korea. 4. Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. 5. Department of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Republic of Korea. 6. Division of Geriatrics, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Republic of Korea. 7. Institute of Endocrine Research, Yonsei University College of Medicine, Seoul, Republic of Korea. 8. Department of Public Health and Primary Care, University of Cambridge, Cambridge, England.
Abstract
CONTEXT: The risk for dementia among subjects who are obese with normal metabolic profiles, or called metabolically healthy obese (MHO), remains uninvestigated. OBJECTIVE: To determine the association between late-life metabolic health and obesity status and risk of incident dementia. DESIGN: Retrospective cohort study. SETTING: The National Health Insurance System, Republic of Korea. PATIENTS: A total of 12,296,863 adults >50 years old who underwent health examinations from 2009 to 2012 without baseline history of dementia. MAIN OUTCOME MEASURE: Incident overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD). RESULTS: Among subjects ≥60 years old, 363,932 (6.4%) developed dementia during a median follow-up of 65 months (interquartile range 51 to 74 months). The MHO group showed the lowest incidence of overall dementia [hazard ratio (HR) 0.85; 95% CI, 0.84 to 0.86] and AD (HR 0.87; 95% CI, 0.86 to 0.88), but not VaD, compared with the metabolically healthy nonobese group. All components of metabolic syndrome except obesity significantly elevated the risk of dementia, and these associations were more pronounced in VaD. In particular, being underweight dramatically increased the risk of dementia. CONCLUSIONS: The MHO phenotype in late life demonstrated lower risk of overall dementia and AD but not VaD. Additional studies in other populations are warranted to elucidate current results and may predict individuals most at risk for developing dementia.
CONTEXT: The risk for dementia among subjects who are obese with normal metabolic profiles, or called metabolically healthy obese (MHO), remains uninvestigated. OBJECTIVE: To determine the association between late-life metabolic health and obesity status and risk of incident dementia. DESIGN: Retrospective cohort study. SETTING: The National Health Insurance System, Republic of Korea. PATIENTS: A total of 12,296,863 adults >50 years old who underwent health examinations from 2009 to 2012 without baseline history of dementia. MAIN OUTCOME MEASURE: Incident overall dementia, Alzheimer's disease (AD), and vascular dementia (VaD). RESULTS: Among subjects ≥60 years old, 363,932 (6.4%) developed dementia during a median follow-up of 65 months (interquartile range 51 to 74 months). The MHO group showed the lowest incidence of overall dementia [hazard ratio (HR) 0.85; 95% CI, 0.84 to 0.86] and AD (HR 0.87; 95% CI, 0.86 to 0.88), but not VaD, compared with the metabolically healthy nonobese group. All components of metabolic syndrome except obesity significantly elevated the risk of dementia, and these associations were more pronounced in VaD. In particular, being underweight dramatically increased the risk of dementia. CONCLUSIONS: The MHO phenotype in late life demonstrated lower risk of overall dementia and AD but not VaD. Additional studies in other populations are warranted to elucidate current results and may predict individuals most at risk for developing dementia.