Greater Risk of Dementia When Spouse Has Dementia? The Cache County Study

OBJECTIVES To examine the effects of caring for a spouse with dementia on the caregiver's risk for incident dementia. DESIGN Population-based study of incident dementia in spouses of persons with dementia. SETTING Rural county in northern Utah. PARTICIPANTS Two thousand four hundred forty-two subjects (1,221 married couples) aged 65 and older. MEASUREMENTS Incident dementia was diagnosed in 255 subjects, with onset defined as age when subject met Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, criteria for dementia. Cox proportional hazards regression tested the effect of time-dependent exposure to dementia in one's spouse, adjusted for potential confounders. RESULTS A subject whose spouse experienced incident dementia onset had a six times greater risk for incident dementia as subjects whose spouses were dementia free (hazard rate ratio (HRR)=6.0, 95% confidence interval (CI)=2.2-16.2, P <.001). In sex-specific analyses, husbands had higher risks (HRR=11.9, 95% CI=1.7-85.5, P=.01) than wives (HRR=3.7, 95% CI=1.2-11.6, P=.03). CONCLUSION The chronic and often severe stress associated with dementia caregiving may exert substantial risk for the development of dementia in spouse caregivers. Additional (not mutually exclusive) explanations for findings are discussed.