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EXPERT REACTION: Putting a ring on it could be linked to lower dementia risk

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Marriage may be linked to a lower risk of developing dementia, according to research by French and UK scientists. The researchers looked at data from 15 studies covering over 800,000 participants from across the globe, and found people who have spent their whole life single, or are widowers, are at a heightened risk of getting the disease. Though the study is observational, and no firm conclusions can be drawn, a linked editorial's authors suggest that marital status should be added to the list of modifiable risk factors for dementia. Perhaps we should listen to Queen Beyonce and put a ring on it?

Journal/conference: Journal of Neurology Neurosurgery & Psychiatry

DOI: 10.1136/jnnp-2017-316274

Organisation/s: University College London, London, UK

Media Release

From: The BMJ

JOURNAL OF NEUROLOGY NEUROSURGERY & PSYCHIATRY

Marriage may help stave off dementia

Lifelong singletons and widowers seem to be at heightened risk

Marriage may lower the risk of developing dementia, concludes a synthesis of the available evidence published online in the Journal of Neurology Neurosurgery & Psychiatry.

Lifelong singletons and widowers are at heightened risk of developing the disease, the findings indicate, although single status may no longer be quite the health hazard it once seemed to be, the researchers acknowledge.

They base their findings on data from 15 relevant studies published up to the end of 2016. These looked at the potential role of marital status on dementia risk, and involved more than 800,000 participants from Europe, North and South America, and Asia.

Married people accounted for between 28 and 80 per cent of people in the included studies; the widowed made up between around 8 and 48 per cent; the divorced between 0 and 16 per cent; and lifelong singletons between 0 and 32.5 per cent.

Pooled analysis of the data showed that compared with those who were married, lifelong singletons were 42 per cent more likely to develop dementia, after taking account of age and sex.

Part of this risk might be explained by poorer physical health among lifelong single people, suggest the researchers.

However, the most recent studies, which included people born after 1927, indicated a risk of 24 per cent, which suggests that this may have lessened over time, although it is not clear why, say the researchers.

The widowed were 20 per cent more likely to develop dementia than married people, although the strength of this association was somewhat weakened when educational attainment was factored in.

But bereavement is likely to boost stress levels, which have been associated with impaired nerve signalling and cognitive abilities, the researchers note.

No such associations were found for those who had divorced their partners, although this may partly be down to the smaller numbers of people of this status included in the studies, the researchers point out.

But the lower risk among married people persisted even after further more detailed analysis, which, the researchers suggest, reflects “the robustness of the findings.”

These findings are based on observational studies so no firm conclusions about cause and effect can be drawn, and the researchers point to several caveats, including the design of some of the included studies, and the lack of information on the duration of widowhood or divorce.

Nevertheless, they proffer several explanations for the associations they found. Marriage may help both partners to have healthier lifestyles, including exercising more, eating a healthy diet, and smoking and drinking less, all of which have been associated with lower risk of dementia.

Couples may also have more opportunities for social engagement than single people--a factor that has been linked to better health and lower dementia risk, they suggest.

In a linked editorial, Christopher Chen and Vincent Mok, of, respectively, the National University of Singapore and the Chinese University of Hong Kong, suggest that should marital status be added to the list of modifiable risk factors for dementia, “the challenge remains  as to how these observations can be translated into effective means of dementia prevention.”

The discovery of potentially modifiable risk factors doesn’t mean that dementia can easily be prevented, they emphasise.

“Therefore, ways of destigmatising dementia and producing dementia-friendly communities more accepting and embracing of the kinds of disruptions that dementia can produce should progress alongside biomedical and public health programmes,” they conclude.

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Expert Reaction

These comments have been collated by the Science Media Centre to provide a variety of expert perspectives on this issue. Feel free to use these quotes in your stories. Views expressed are the personal opinions of the experts named. They do not represent the views of the SMC or any other organisation unless specifically stated.

Sandra L Bradley is a postdoctoral researcher at Flinders University and is an Advance Care Directive Consultant

Although the authors identify that in some studies there was no difference between genders, it would have been better to understand the overall make-up of the gender mix in relation to who had dementia in the studies involved, and who was the carer. This may be seen in the supplementary material but there was no access provided.

Just being married may reduce dementia risk but may only be because of delayed recognition, diagnosis and treatment because there may be shielding of their behaviour by either the person with dementia or their carer, which is something the authors hint at.

Also, although being married is a supportive strategy for those who have dementia, it may not be for the carer who later becomes the widow or widower.

As the authors suggest, the underlying factors within the marriage need to be explored more fully and described in relation to the impact of and effect on the caregiver before concluding that marriage is, in and of itself, a factor for reducing the onset of dementia. This is because the caregiver may actually get dementia after the caregiver has been widowed.

So, in these cases, is marriage linked to a higher risk for getting dementia for those caring for a spouse with dementia?

Last updated: 28 Nov 2017 6:14pm
Dr Ian Musgrave is a Senior Lecturer in the Faculty of Medicine, School of Medicine Sciences, within the Discipline of Pharmacology at the University of Adelaide.

We have known for some time that social factors play a role dementia. People with rich social interaction networks have a lower risk of dementia than those who are socially isolated.

An example relevant to Australia is the Sydney Memory and Ageing Study, which found that married couples had a lower risk of developing dementia than single persons. The strength of the current study is that it is a meta-analysis of 15 studies worldwide, with over 800,000 people in them followed for between 3-21 years. While the vast majority of subjects were Swedish, the broad range of studies suggests that the results are likely to be generally applicable.

Why marriage lowers the risk of dementia is not clear. Risk factors for dementia include low physical activity, being overweight, smoking, high blood pressure, depression and social isolation. Married couples are likely to have more social interactions than single people, especially if there is interaction with other family members such as children and grandchildren. This may also translate to more physical activity.

Couples may also notice declines in health in the other partner, with corrective action taken, more readily than singles. Translating these findings information into lifestyle modifications will require better understanding of these factors.

People who have lost a partner are at significant risk of dementia, which may be related to stress, so putting in place support networks for the elderly bereaved may be an important public health goal.

We have some evidence that modifying lifestyle may be successful, data from the UK and the US show that the incidence of Alzheimer’s disease has fallen or the past decade, most likely due to reductions in smoking and high blood pressure - known risk factors.

Identify factors that contribute to married couples lower risk may translate into interventions to lower dementia risk further.

Last updated: 28 Nov 2017 4:13pm
Professor Bryce Vissel is Roth Fellow and the Director of the Centre for Neuroscience and Regenerative Medicine at University of Technology, Sydney

The message to take away from this study is that Alzheimer’s risk is modifiable by lifestyle. Given there is no cure for this insidious and common disease, we must look to lifestyle factors to provide indication if we can change the course of Alzheimer's.

This analysis of many studies suggests that being single or widowed (but not divorced persons) can increase dementia risk, compared with those that are married.

Factors associated with being widowed or single are stress and social isolation, both of which are known to increase the risk of dementia. There may be other varying factors that are associated with being married that can be beneficial, ranging from diet through to sleep patters, which are also known to impact dementia.

Above all, the important message, that the disease outcome is modifiable by lifestyle factors, suggests that ultimately the Alzheimer’s disease trajectory can be changed by lifestyle, which suggests the real hope that ultimately new therapies will be found that can also assist in this disease.

Last updated: 28 Nov 2017 4:11pm
Professor Anthony J. Hannan is a NHMRC Principal Research Fellow from The Florey Institute of Neuroscience and Mental Health, University of Melbourne and Melbourne Brain Centre

This systematic review and combined analysis of previously published studies suggests that married people are at reduced risk of dementia. As the authors suggest, the findings may reflect other health and lifestyle factors which are associated with marital status. These factors may include increased physical activity and a healthy diet, which are known to help delay onset of dementia.

Another aspect of marriage might be increased long-term social interaction, which is a form of cognitive stimulation also known to be protective with respect to dementia. However, it should be noted that this research involved ‘observational studies’ in participants from the general population, and not long-term studies of those people during their lifespans, so cause and effect is difficult to determine.

Furthermore, as this was a re-analysis of previous studies, it may reflect the lifestyles (and possibly other attributes) of those who were married or single in the 20th century, and these differences may not hold in the 21st century.

While more research is needed, I think it is generally consistent with the public health message that our ‘enviromes’ (total environmental exposures throughout life) and lifestyles (including physical activity and diet) not only affect our bodies, but also our brain health.

Last updated: 28 Nov 2017 4:08pm

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