06 May 2010

Researchers in the US found that people caring for a spouse with dementia were six times more likely to develop it themselves compared to similar older married adults whose spouse never develops it.

A paper on the study, led by Dr Maria Norton of Utah State University, is about to be published in a May issue of the Journal of the American Geriatrics Society, which is available online.

Norton and colleagues also found that husbands looking after wives with dementia were at higher risk of developing it themselves than wives looking after husbands with the condition.

The authors wrote that while many studies have shown dementia caregivers are at higher risk of poor physical and mental health, none has looked at the specific risk of dementia in caregivers.

Looking after someone with dementia is physically and mentally demanding, and caregivers in this situation tend to report more personal sacrifices and stress than those caring for physically impaired elderly people who do not have dementia.

For the study, Norton and colleagues recruited 2,442 participants (1,221 married couples) aged 65 and over living in Northern Utah. None of the participants had dementia at the start of the study, and they were followed for 12 years.

During follow up, 30 cases (60 individuals) of dementia were diagnosed in both spouses, plus 125 where only the husband developed it, and 70 where only the wife developed the condition.

After adjusting for socioeconomic status (a factor that is known to significantly affect dementia risk and other health outcomes), the researchers found that:
• Incident dementia was not only significantly linked to older age, but also to having a spouse with dementia.
• After adjusting for age, gender, genetic factors (APOE genotype), in addition to socioeconomic status, having a spouse with dementia was linked to a six times higher risk of developing dementia.
• For men caring for a spouse with dementia, the risk was 11.9 times higher, while for women it was 3.7 times.

Norton told the media that more research is needed to find out how much of this risk is due to caregiver stress and how much is due to a shared environment.

She also stressed that on the positive side, most of the participants whose spouses developed dementia did not themselves develop the condition, and therefore "more research is needed to explore which factors distinguish those who are more vulnerable".

"Given the significant public health concern of Alzheimer's disease and other dementias, and the upcoming shift in population age composition, continued research into the causes of dementia is urgent," she added.