"Marriage and having close friends may help protect against dementia, according to Loughborough University researchers," BBC News reports.
The news comes from a study looking at the link between social relationships and the risk of developing dementia.
The study included a large group of adults aged over 60 who didn't have dementia. They were asked about their marital status and the number of close relationships they had.
Researchers then followed the participants for an average of 6 years to see how many developed dementia.
They found people who weren't married and those with higher loneliness scores had a higher risk of developing dementia.
But this can't prove that being married will protect you against dementia. A combination of many biological, health, lifestyle and environmental factors is likely to influence our risk of developing dementia.
As the causes of some types of dementia – particularly Alzheimer's disease – remain poorly understood, it's difficult to isolate the effect of a single factor like marital status.
It seems more likely that the quality of the marriage and family and social relationships is likely to be the important factor, not just the presence of these relationships.
An unhappy marriage may do little to benefit your wellbeing, and you don't have to be married to have a happy and fulfilling relationship.
Overall, this study does little to further our understanding of the causes of Alzheimer's, but will add to the body of literature looking at how our relationships and social networks are linked to our health.
If you feel lonely and isolated, there are a number of resources you can use to help connect with other people.
The study was conducted by researchers at University College London and Loughborough University in the UK, and Universidade Federal de Santa Catarina in Brazil.
The cohort studies informing this research received funding from the UK Economic and Social Research Council, the National Institute for Health Research, and the National Institute on Aging.
It was published in the peer-reviewed Journals of Gerontology: Social Sciences and is available to read free online.
BBC News' reporting of the study was accurate, and included some interesting feedback from independent commentators.
This cohort study looked at whether social relationships and loneliness affect the likelihood of a person developing dementia.
But it's difficult to isolate the specific effects of single factors, such as marital status or loneliness, as many different factors may be involved in a person's dementia risk.
The study used data collected by the English Longitudinal Study of Ageing (ELSA), which the researchers say is a representative sample of people aged 50 and over living in England.
The study began in 2002 with follow-up every 2 years until 2012, resulting in a total of 6 "waves" of results.
Loneliness was first assessed in 2004. People not diagnosed with dementia completed questionnaires about social isolation and the number of close relationships they had.
This included relationships with family and friends, frequency and type of contact, and involvement in social organisations.
Marital status wasn't part of the questionnaire and they were asked about this separately.
An additional short assessment scale produced a loneliness score. Dementia was assessed at follow-up by asking participants whether a doctor had ever diagnosed the condition.
Researchers asked the individual or family to complete a short 16-item questionnaire on the person's cognitive ability compared with how it was 2 years ago (for example, being able to remember different family members).
All follow-up sessions also included cognitive tests used to identify possible cases of dementia.
The researchers looked at the link between social relationships and isolation in 2004 (wave 2) and development of dementia up to 2012-13 (wave 6).
Analyses took account of various confounding factors, including socioeconomic status, educational level, and medical health and disability.
The final analysis included 6,677 participants, who were 66 years old on average at first assessment.
During an average 6-year follow-up, 3.3% of the sample (220 people) were diagnosed with dementia or had the diagnosis indicated by questionnaires.
Not surprisingly, most of these diagnoses were among participants who were over the age of 80 at the start of the study.
Others factors linked to the development of dementia included heart and vascular disease, impaired mobility, and lower educational levels.
The researchers found people who developed dementia were also less likely to be married, had fewer social relationships, and reported greater loneliness.
In models fully adjusted for other factors, being unmarried was linked to about a doubled risk (hazard ratio [HR] 2.11, 95% confidence interval [CI] 1.52 to 2.92) and a higher loneliness score was linked to about a third higher risk (HR 1.33, 95% CI 1.02 to 1.73).
Having more close relationships was generally associated with a lower risk of dementia.
The researchers concluded: "Dementia risk is associated with loneliness and having fewer close relationships in later life.
"The underlying mechanisms remain to be elucidated, but efforts to enhance older peoples' relationship quality may be relevant to dementia risk."
The general findings that marriage and having more social relationships seem to be linked to better health and wellbeing is in line with the results of much previous research.
But there are several important things to keep in mind:
The results of this study are of interest, but can't tell us that staying married will prevent dementia.
While the causes of Alzheimer's are unknown, there are more established things you can do to try to reduce your risk of vascular dementia: