Age of major depression onset, depressive symptoms, and risk for subsequent dementia: results of the German study on Ageing, Cognition, and Dementia in Primary Care Patients (AgeCoDe).

BACKGROUND: Whether late-onset depression is a risk factor for or a prodrome of dementia remains unclear. We investigated the impact of depressive symptoms and early- v. late-onset depression on subsequent dementia in a cohort of elderly general-practitioner patients (n = 2663, mean age = 81.2 years). METHOD: Risk for subsequent dementia was estimated over three follow-ups (each 18 months apart) depending on history of depression, particularly age of depression onset, and current depressive symptoms using proportional hazard models. We also examined the additive prediction of incident dementia by depression beyond cognitive impairment. RESULTS: An increase of dementia risk for higher age cut-offs of late-onset depression was found. In analyses controlling for age, sex, education, and apolipoprotein E4 genotype, we found that very late-onset depression (aged ≥ 70 years) and current depressive symptoms separately predicted all-cause dementia. Combined very late-onset depression with current depressive symptoms was specifically predictive for later Alzheimer's disease (AD; adjusted hazard ratio 5.48, 95% confidence interval 2.41-12.46, p < 0.001). This association was still significant after controlling for cognitive measures, but further analyses suggested that it was mediated by subjective memory impairment with worries. CONCLUSIONS: Depression might be a prodrome of AD but not of dementia of other aetiology as very late-onset depression in combination with current depressive symptoms, possibly emerging as a consequence of subjectively perceived worrisome cognitive deterioration, was most predictive. As depression parameters and subjective memory impairment predicted AD independently of objective cognition, clinicians should take this into account.

Net costs of dementia by disease stage.

OBJECTIVE: To estimate net costs of dementia by degree of severity from a societal perspective, including a detailed assessment of costs of formal and informal nursing care. METHOD: In a cross-sectional study, costs of illness were analysed in 176 dementia patients and 173 matched non-demented control subjects. Healthcare resource use and costs were assessed retrospectively by means of a questionnaire. Dementia patients were classified into three disease stages, and linear regression models were applied to estimate net costs of dementia by degree of severity. RESULTS: Annual net costs of dementia by stage were approximately €15 000 (mild), €32 000 (moderate) and €42 000 (severe), corresponding to US-$21 450, 45 760 and 60 060 respectively. Across disease stages, nursing care accounted for approximately three-quarters of total costs, of which half resulted from informal care. In sensitivity analyses using different valuation methods for nursing care, total costs decreased or increased by more than 20%. CONCLUSION: Net costs more than double across stages of dementia. Informal care accounts for a considerable share of nursing care costs, and the approach to valuation of informal care has a large impact on cost-of-illness estimates.