London, May 6 (IANS) People who nurse a spouse with dementia are at six times increased risk of developing the devastating condition themselves, says a new study.

According to researchers, physical and mental stress of caring for a loved one with Alzheimer's and other forms of the condition can do lasting damage to the brain's memory centre.

Although all forms of caring are hard, watching the mental decline of dementia is particularly tough, with men feeling the effects particularly keenly, the researchers said.

During the study, researchers from Utah State University tracked the health for 12 years, of more than 1,200 couples who had been married for an average of 49 years.

None had dementia at the start of the study, but by the end 225 people were affected. In 125 of these, the husband was diagnosed and in 70 it was the wife. But in 30 couples, both spouses were affected.

The study found husbands to be three times more vulnerable than wives.

The researchers believe the emotional stress of watching the mental decline of a loved one could be at least partly to blame. In addition, dementia usually strikes later in life, making the psychological burden heavier for ageing spouses.

"It should be made clear that the majority of participants whose spouse had dementia did not develop the condition," Rebecca Wood of the Alzheimer's Research Trust was quoted as saying by dailymail.co.uk.

"Scandinavian researchers have found that being married in old age generally reduces risk, maybe because of the greater social interaction couples experience," Wood said.

The study appears in the Journal of the American Geriatrics Society.