A reliable global cognitive decline and cortisol as an associated risk factor for patients with late-life depression in the short term: A 1-year prospective study

Background: Late-life depression is a risk factor of dementia. It may increase the risk of reliable cognitive decline in the short term, and its associated risk factors remain unclear. Cortisol level may be one of the important predictors.

Objectives: To estimate whether patients with late-life depression are at an increased risk for reliable global cognitive declines in 1 year, and explore associated risk factors predicting cognitive declines.

Methods: This prospective 1-year follow-up study involved 148 participants (67 with late-life depression and 81 normal elderly). Global cognitive function was assessed by the Mini-Mental State Examination (MMSE). The reliable global cognitive decline was defined by the reliable change index (RCI) of the MMSE. Factors related to cognitive function (e.g., age, gender, education, duration of depression and severity of depression) were obtained. Serum cortisol levels were measured at baseline.

Results: At the 1-year follow-up assessment, 19 patients with late-life depression (28.4%) showed reliable global cognitive declines, a risk that was 6.4 times (95% CIs = 1.3-31.1, p = 0.021) higher than that of normal elderly. Elevated serum cortisol levels and older age were associated with the risk of cognitive decline that was 1.6- and 1.2-times higher (95% CIs = 1.07-2.5, p = 0.02, and 95% CIs = 1.04-1.4, p = 0.01 respectively).

Limitations: Serum cortisol levels were measured only in the morning.

Conclusions: Late-life depression is associated with a greatly increased risk of reliable cognitive decline in short term. Cortisol dysregulation may contribute to the pathology of cognitive decline.