A study reveals that living alone and single may increase your risk of dementia.

Being married halves the chance of developing Alzheimer's disease, it says.

A team at Karolinska Institute (Sweden) has carried out this study and found the importance of close companionship in midlife.

It also says that those who stay alone after divorce have a threefold risk of suffering Alzheimer's in later life.

The study highlights a risk of developing cognitive problems for those who live alone, whether single, divorced or widowed, the reason being in social isolation.

"A couple relationship a form of social and intellectual stimulation. If social and cognitive challenges protect against dementia, so should living as a couple," it challenges.

"This study points to the beneficial effects of a married life as a protective factor against dementia," lead researcher Krister Hakansson said.