LIFETIME DEPRESSION AND RISK OF ALZHEIMER’S DISEASE: A 44-YEAR LONGITUDINAL POPULATION STUDY OF WOMEN

Abstract

It has been suggested that depression may increase the risk of Alzheimer's disease (AD). Longitudinal studies on this association are however lacking. The analyses originate from the Prospective Population Study of Women in Gothenburg, Sweden. A representative sample of 800 women was examined at baseline 1968 (aged 38 to 54 years), and re-examinations (n=6) were done until 2012. Both dementia and depression was diagnosed according to DSM-III-R criteria, and based on information from neuropsychiatric examinations, informant interviews, hospital records, and registry data. For those who had an episode of depression before baseline hospital registers were used. Sub-type of AD dementia was diagnosed according to NINCDS-ADRDA criteria. During the 44-years of follow-up, 133 women developed AD and 598 died. Sixty-seven percent of the women had any-type depression during life-span (44% had major depression). Mean age of first depressive episode was 42 years. History of major depression increased the risk of developing AD with above 90%, compared to those without depression. Minor depression was not associated to AD. The risk of AD was related to age of onset of depression. Compared to women without depression, HR (95% CI) for AD was 3.35 (1.70–6.59) in women with first depressive episode before age twenty, 1.66 (1.06–2.59) in women with first episode in early midlife (20–49 years), and 2.16 (1.22–3.79) in women with first episode after age 70. Those with depression onset in late midlife (50–69 years) had no increased risk of AD. Depression was not associated with vascular dementia or other types of dementia. All analyses were adjusted for age, education and ApoE genotype. We found that major depression, early-life depression, early midlife depression, and late-life depression were associations with higher incidence of AD.