Wendy A Davis1, Renate R Zilkens2, Sergio E Starkstein3, Timothy M E Davis1, David G Bruce4,5. 1. School of Medicine and Pharmacology, The University of Western Australia, PO Box 480, Fremantle, WA, 6959, Australia. 2. Centre for Population Health Research, School of Public Health, Curtin University of Technology, Perth, WA, Australia. 3. School of Psychiatry and Clinical Neurosciences, The University of Western Australia, Fremantle Hospital, Fremantle, WA, Australia. 4. School of Medicine and Pharmacology, The University of Western Australia, PO Box 480, Fremantle, WA, 6959, Australia. David.Bruce@uwa.edu.au. 5. School of Medicine and Pharmacology, Fremantle Hospital, PO Box 480, Fremantle, Western Australia, 6959, Australia. David.Bruce@uwa.edu.au.
Abstract
AIMS/HYPOTHESIS: The study aimed to assess the incidence, age of onset, survival and relative hazard of dementia in well-categorised community-based patients with type 2 diabetes compared with a matched cohort of individuals without diabetes. METHODS: A longitudinal observational study was undertaken involving 1291 participants with type 2 diabetes from the Fremantle Diabetes Study and 5159 matched residents without documented diabetes. Linkage with health-related databases was used to detect incident dementia. Relative hazards were assessed using both cause-specific and subdistribution proportional hazards models. RESULTS: During 13.8 ± 5.8 years of follow-up, incident dementia occurred in 13.9% and 12.4% of the groups of participants with and without diabetes, respectively (p = 0.15). With type 2 diabetes, the incidence of dementia was higher (incidence rate ratio [IRR] 1.28, 95% CI 1.08, 1.51), as was the competing risk of death (IRR 1.50, 95% CI 1.38, 1.64). The ages when dementia was first recorded and when death with dementia occurred were both earlier with diabetes, by 1.7 (95% CI 0.6, 2.9) and 2.3 (95% CI 1.1, 3.6) years, respectively (both p ≤ 0.004). Type 2 diabetes was associated with an adjusted subdistribution HR of 1.18 (95% CI 1.00, 1.39), and a cause-specific HR of 1.51 (95% CI 1.27, 1.78) for all-cause dementia. CONCLUSIONS/ INTERPRETATION: Type 2 diabetes is associated with an increased incidence of dementia, and dementia onset occurs at a younger age. The relative hazards of both dementia and premature mortality are increased and, as a consequence, the increased risk of dementia in type 2 diabetes is not as marked as suggested by cause-specific HRs.
AIMS/HYPOTHESIS: The study aimed to assess the incidence, age of onset, survival and relative hazard of dementia in well-categorised community-based patients with type 2 diabetes compared with a matched cohort of individuals without diabetes. METHODS: A longitudinal observational study was undertaken involving 1291 participants with type 2 diabetes from the Fremantle Diabetes Study and 5159 matched residents without documented diabetes. Linkage with health-related databases was used to detect incident dementia. Relative hazards were assessed using both cause-specific and subdistribution proportional hazards models. RESULTS: During 13.8 ± 5.8 years of follow-up, incident dementia occurred in 13.9% and 12.4% of the groups of participants with and without diabetes, respectively (p = 0.15). With type 2 diabetes, the incidence of dementia was higher (incidence rate ratio [IRR] 1.28, 95% CI 1.08, 1.51), as was the competing risk of death (IRR 1.50, 95% CI 1.38, 1.64). The ages when dementia was first recorded and when death with dementia occurred were both earlier with diabetes, by 1.7 (95% CI 0.6, 2.9) and 2.3 (95% CI 1.1, 3.6) years, respectively (both p ≤ 0.004). Type 2 diabetes was associated with an adjusted subdistribution HR of 1.18 (95% CI 1.00, 1.39), and a cause-specific HR of 1.51 (95% CI 1.27, 1.78) for all-cause dementia. CONCLUSIONS/ INTERPRETATION:Type 2 diabetes is associated with an increased incidence of dementia, and dementia onset occurs at a younger age. The relative hazards of both dementia and premature mortality are increased and, as a consequence, the increased risk of dementia in type 2 diabetes is not as marked as suggested by cause-specific HRs.
Entities:
Keywords:
Case cohort study; Dementia; Longitudinal study; Type 2 diabetes
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