Background: Depression is the most common mental health problem and often co-occurs with dementia in old age. This study investigates the in fluence of late-life depression on risk of dementia.

Methods: A total of 16210 dementia-free participants aged 60+ from the Survey of Health, Aging, and Retirement in Europe were followed up for 10 years to detect incident dementia. Depression was assessed by a 12-item Europe-depression scale, dementia was determined by physician diagnosis reported by the participants and their informants. Fine and Gray model was performed to explore the association between depression and incident dementia taking into account competing risk of death.

Results: During an average of 8 years follow-up, 1030 (6.35%) incident dementia were identi fied. Late-life depression was related to higher subdistribution hazard ratio (sHR) of dementia (sHR=1.52, 95%CI: 1.32-1.75) after adjusting for age, gender, country, education, smoking, drinking, living arrangement, BMI, chronic disease, and physical activity. Further, the risk was only existed in those below age of 80 (sHR=1.75, 95%CI: 1.47-2.07). In addition, a dose-response association was observed between the severity of depression and dementia risk (p for trend<0.001).

Limitation: The ascertainment of depression and dementia was based on information reported by the participants and/or their informants, which might result in information bias. The causal relationship could not be determined because limited follow-up time.

Conclusions: Late-life depression is associated with higher incidence of dementia in a dose-response fashion. Interventions targeting depression patients aged 60-79 years and those with severe depression may be e ffective strategies to prevent dementia.