Renate R. Zilkens

Objective: To examine the association of mid-life exposure to several psychiatric disorders with the development of late-life dementia. Methods: A matched case-control study using Western Australian state-wide hospital inpatient, outpatient mental health and emergency records linked to death records. Incident dementia cases (2000-2009) aged 65 to 84 years were sex- and age-matched to an electoral roll control. Records as far back as 1970 were used to assess exposure to medical risk factors before age 65 years. Candidate psychiatric risk factors were required to be present at least 10 years before dementia onset to ensure direction of potential causality. Odds ratios were estimated using conditional logistic regression. Results: 13, 568 dementia cases (median age 78.7 years, 43.4 % male) were matched to a control. Depression, bipolar disorder, schizophrenia, anxiety disorder and alcohol dependence were found to be significant and independent risk factors for late-life dementia after adjusting for diabetes, heart disease, cerebrovascular disease and smoking risk factors. The effect of a history of depression, schizophrenia and alcohol dependency on dementia risk varied with age, being strongest for earlier onset late-life dementia and waning at older ages. Conclusion: Severe depression, anxiety disorder, bipolar disorder, schizophrenia and alcoholic dependency disorder treated by specialists in psychiatric facilities in mid-life are important risk factors for late-life dementia. These psychiatric conditions need to be considered in future studies of the risk and prevention of late-life dementia.

Diabetes is a risk factor for dementia, but relatively little is known about the epidemiology of the association. A retrospective population study using Western Australian hospital inpatient, mental health outpatient, and death records was used to compare the age at index dementia record (proxy for onset age) and survival outcomes in dementia patients with and without preexisting diabetes (n = 25,006; diabetes, 17.3%). Inpatient records from 1970 determined diabetes history in this study population with incident dementia in years 1990–2005. Dementia onset and death occurred an average 2.2 years and 2.6 years earlier, respectively, in diabetic compared with nondiabetic patients. Age-specific mortality rates were increased in patients with diabetes. In an adjusted proportional hazard model, the death rate was increased with long-duration diabetes, particularly with early age onset dementia. In dementia diagnosed before age 65 years, those with a ≥15-year history of diabetes died almost twice as fast as those without diabetes (hazard ratio = 1.9, 95% confidence interval: 1.3, 2.9). These results suggest that, in patients with diabetes, dementia onset occurs on average 2 years early and survival outcomes are generally poorer. The effect of diabetes on onset, survival, and mortality is greatest when diabetes develops before middle age and after 15 years' diabetes duration. The impact of diabetes on dementia becomes progressively attenuated in older age groups.

Dementia-related healthcare planning requires accurate information on dementia patient characteristics and hospitalization trends at a population level. This population-based retrospective cohort study was designed to evaluate factors associated with

Background/Aim: To use health record data linkage to improve case ascertainment and death rate estimates of deaths with dementia. Methods: Retrospective population study. Western Australians older than 20 years who died between 1990 and 2005 with a dementia diagnosis in Western Australian hospitals and/or death records using the Western Australian Data Linkage System were classed as having a lifetime history of dementia. Cases with dementia documented on death certificates were classified as having dementia as a contributory cause of death (COD). Age-standardized death rates (ASDR) were estimated. Results: 29,884 decedents were identified with a lifetime history of dementia. 88.2% had hospital records and 55.9% had death records indicating dementia. The ASDRs for dementia as a contributory COD increased from 50 to 81 per 100,000 person-years from 1990 to 2005. ASDR for lifetime history of dementia increased from 80 to 140 per 100,000 person-years over the same time period. In 2005, 50.1% (95% confidence interval: 47.2–53.1) of all females and 39.2% (35.8–42.7) of all males aged 85+ years died with dementia. Conclusion: Data linkage nearly doubled case ascertainment of deaths with dementia because people hospitalized with dementia often lacked dementia documentation at death. These results have important implications for strategic healthcare planning. Data linkage methodology could improve studies of hospitalisation trends in dementia.