High blood pressure raises dementia risk
Middle-aged people who smoke, have high blood pressure or diabetes massively increase their risk of developing dementia, medical experts warn.
Under-55s who smoke increase their risk five-fold, and diabetes will more than triple it, reports the Journal of Neurology, Neurosurgery and Psychiatry.
The US study of more than 11,000 people is a stark warning to those leading unhealthy lifestyles in midlife.
Meanwhile, other work shows brain exercises can delay dementia onset.
Doing crosswords, playing cards or similar "mind-stretching" activities may delay the start of memory decline in people who develop dementia, according to a study in Neurology.
In the UK alone, 700,000 people now live with dementia, and the figure is going up fast.
Experts predict the number for the UK will rise to more than 1 million people by 2025 and 1.7 million by 2051.
But these latest studies suggest there is something that can be done to offset this.
Researchers from the universities of Minnesota and North Carolina along with Johns Hopkins hospital and the University of Mississippi Medical Center followed the health of more than 11,000 people aged 46-70.
Over a period of 12 to 14 years, 203 of the people in the study were diagnosed with dementia, and lifestyle factors during middle age appeared to play an important role.
Smoking, high blood pressure and diabetes were all strongly linked with dementia, which the researchers say is not unexpected since these can damage the brain and the small blood vessels that supply it.
Current smokers were 70% more likely than those who had never smoked to develop dementia, people with high blood pressure were 60% more likely than those without high blood pressure, and people with diabetes were more than twice as likely than those without diabetes to develop it.
"Our results emphasise the importance of early lifestyle modification and risk factor treatment to prevent dementia," the researchers said.
Neil Hunt of the Alzheimer's Society said: "Dementia is one of people's biggest fears in later life but very few people realise that there are things they can do to reduce their risk of developing this devastating condition.
"This study adds weight to the growing evidence that a healthy heart means a healthy brain."
Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: "There is a growing body of evidence suggesting that looking after our hearts may be the most effective way to reduce dementia risk.
"Although this latest research recommends mid-life as a critical time to change our lifestyles, it's never too early, or late, to take steps towards improving heart-health.
"We should all consider stopping smoking, taking regular exercise and adopting a healthy, Mediterranean-style diet."
On brain exercise study, she said: "This adds to the 'use it or lose it' hypothesis that we can reap the benefits of stimulating our minds regularly, perhaps by doing crosswords, playing chess or adding up the shopping before getting to the till.
"With more research we may be able to find ways of preventing dementia."