Risk of major depression in partners of people with Alzheimer's disease: a national cohort study.

BACKGROUND: Alzheimer's disease (AD) may cause significant psychosocial distress not only in the patient but also their partner. However, long-term risks of major depression in partners of AD patients are largely unknown. METHODS: A national cohort study was conducted of all 145 289 partners of people diagnosed with all-cause dementia, including 57 113 partners of people diagnosed with AD, in Sweden during 1998-2017, and 1 300 561 population-based controls. Cox regression was used to compute hazard ratios (HRs) for subsequent risk of major depression identified from nationwide outpatient and inpatient diagnoses through 2018, adjusting for sociodemographic factors and prior mental disorders. RESULTS: The 10-year cumulative incidence of major depression was 5.4% in partners of people with AD, 5.6% in partners of people with all-cause dementia, and 3.9% in controls. The adjusted relative rate of major depression was increased ~1.5-fold in partners of people with AD (HR, 1.53; 95% CI, 1.35-1.72) or all-cause dementia (1.45; 1.34-1.57), compared with controls. These risks were elevated among both women (AD: HR, 1.41; 95% CI, 1.22-1.64; all-cause dementia: 1.36; 1.24-1.50) and men (AD: 1.81; 1.46-2.25; all-cause dementia: 1.73; 1.48-2.01). Risks remained significantly elevated ≥3 years later in both women (1.3- to 1.5-fold) and men (1.5-fold). Risks were generally highest in partners aged ≥85 years. CONCLUSIONS: In this large national cohort, partners of people diagnosed with AD or all-cause dementia had ~1.5-fold risks of major depression, which remained elevated several years later. Partners of people with dementia need psychosocial support and long-term follow-up for timely detection and treatment of depression.