Marital status late in life has been related to the risk of dementia or cognitive decline in the next 3-10 years. People who were classified as unmarried,1 single,2 3 and single living alone4 are at increased risk of dementia or cognitive decline. This association was true even after adjustment for activities, social engagement, and living conditions and was independent of other risk factors for dementia.

Marital status seems to be only one risk factor among others, with a relatively small contribution to the development of dementia (relative risk 1.5-2.5). A change in marital status for cognitive reasons is probably rare in late life, but reverse causation cannot be excluded because of the long prodromal phase of dementia, particularly Alzheimer’s disease.5

In the linked study (doi:10.1136/bmj.b2462, Håkansson and colleagues evaluated marital status more than 20 years before the onset of dementia or cognitive impairment and thus dealt with the problem of …