Losing a spouse can be a heartbreaker, and new research suggests it's also tough on the brain.
The study found that when a husband or wife dies, the surviving mate's mental acuity could start to decline.
In fact, people who are widowed and have high levels of beta-amyloid plaque, a hallmark of Alzheimer's disease, appear to experience cognitive decline three times faster than similar people who have not lost a spouse, the researchers added.
"The associations of widowhood and amyloid were compounded, not simply additive, indicating that widowhood is a specific risk factor for cognitive decline due to Alzheimer's disease," explained lead researcher Dr Nancy Donovan, chief of the Division of Geriatric Psychiatry at Brigham and Women's Hospital in Boston.
Rebecca Edelmayer, director of scientific engagement at Alzheimer's Association, reviewed the findings and said this small study can't prove that being widowed causes cognitive decline, but it may well be a factor.
Donovan said the specific mechanisms by which widowhood increases the risk of cognitive decline isn't known.
"Some studies suggest that having close relationships, such as a close sibling or adult child, helps to protect against cognitive decline among widows, though we didn't find this in our study," Donovan said.
It is likely that being married has beneficial effects by providing daily emotional support, stimulating companionship, better health behaviours and larger social networks, she said.
For people who lose a spouse, Donovan recommends "what we know to be beneficial overall for older adults: exercise, social engagement, cognitively stimulating activities, a healthy diet, manage stress levels and reduce cardiovascular risk factors."
Dr Marzena Gieniusz, a geriatrician and internist at Northwell Health in Manhasset, New York, said she often sees cognitive decline in surviving spouses in her practice.
Mild cognitive impairment
"I think being married is likely a protective factor, which is lost when the spouse passes away," she said.
It's possible that the beginnings of thinking declines were already present in the surviving spouse, but hidden, said Gieniusz, who wasn't involved with the study.
"Passing of a spouse likely leads to an unmasking of mild cognitive impairment, which went previously unnoticed," she said.
Having a spouse seems to be an extra layer of support throughout life in general, "which makes sense", Gieniusz said. "Two people tackling life together is easier than one doing it alone and also likely functions to help slow cognitive decline."
Also, people become more isolated when a spouse passes away. "I'm sure that contributes to cognitive decline," Gieniusz said.
For the study, Donovan and her colleagues collected data on nearly 260 seniors who took part in the Harvard Aging Brain Study. All the participants had their levels of brain beta-amyloid determined at the start of the study.
The researchers monitored the participants' cognitive performance each year for four years.
Care and support structures
They found that cognitive performance declined among those who were widowed, while no difference was seen among those who were married or single.
Also, cognitive decline among people with the highest beta-amyloid levels was three times faster among those widowed as those married. This finding remained significant after the researchers took age, sex, socioeconomic status and depression into account.
The report was published online in the journal JAMA Network Open.
This study highlights one factor that can affect cognitive decline, Edelmayer said.
"It is important that we continue to study Alzheimer's disease and all dementia, from all angles, because that's the only way that we will be able to provide the right type of care and support structures that are going to be necessary for these populations. And it's also going to be important for us to truly understand the types of risk factors that are driving the disease process," Edelmayer said.
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