Depressive symptoms and incidence of mild cognitive impairment and probable dementia in elderly women: the Women's Health Initiative Memory Study

OBJECTIVES: To examine whether significant depressive symptoms in postmenopausal women increases the risk of subsequent mild cognitive impairment (MCI) and dementia. DESIGN: Prospective cohort study. SETTING: Thirty nine of the 40 Women's Health Initiative (WHI) clinical centers that participated in a randomized clinical trial of hormone therapy. PARTICIPANTS: Six thousand three hundred seventy‐six postmenopausal women without cognitive impairment aged 65 to 79 at baseline. MEASUREMENTS: Depressive disorders were assessed using an eight‐item Burnam algorithm and followed annually for a mean period of 5.4 years. A central adjudication committee classified the presence of MCI and probable dementia based on an extensive neuropsychiatric examination. RESULTS: Eight percent of postmenopausal women in this sample reported depressive symptoms above a 0.06 cut point on the Burnam algorithm. Depressive disorder at baseline was associated with greater risk of incident MCI (hazard ratio (HR)=1.98, 95% confidence interval (CI)=1.33–2.94), probable dementia (HR=2.03, 95% CI=1.15–3.60), and MCI or probable dementia (HR=1.92, 95% CI=1.35–2.73) after controlling for sociodemographic characteristics, lifestyle and vascular risk factors, cardiovascular and cerebrovascular disease, antidepressant use, and current and past hormone therapy status. Assignment to hormone therapy and baseline cognitive function did not affect these relationships. Women without depression who endorsed a remote history of depression had a higher risk of developing dementia. CONCLUSION: Clinically significant depressive symptoms in women aged 65 and older are independently associated with greater incidence of MCI and probable dementia.