Objectives: To determine if providing informal care to a co-resident with dementia symptoms places an additional risk on the likelihood of poor mental health or mortality compared with co-resident non-caregivers.; Design: A quasi-experimental design of caregiving and non-caregiving co-residents of individuals with dementia symptoms provides a natural comparator for the additive effects of caregiving on top of living with an individual with dementia symptoms.; Methods: Census records, providing information on household structure, intensity o