There may be more people living into their 80s and 90s, but they could be less likely to get dementia than previous generations (Image: BSIP/UIG/Getty)

It’s one public health message that has seeped in. There’s a dementia tsunami on the way, an inevitable consequence of our steadily greying population.

Those spreading the word range from medical researchers to charities, and even the UK prime minister David Cameron.


But the figures tell a different story. And this misunderstanding may be contributing to a dementia strategy that is taking a cruel toll on those affected, some doctors say.

Four out of five large studies in different European countries have now suggested that our chance of getting dementia by any particular age is less than that of previous generations.

The UK study found that this sufficiently counterbalanced the rise in the number of people living into their 80s and 90s so that the total number of people with dementia stays roughly stable.

As the Alzheimer’s Society has pointed out, that picture could still change in future, perhaps driven by health trends such as rising rates of obesity and diabetes.

Yet even so it’s in stark contrast to the usual doom and gloom, says Carol Brayne of the University of Cambridge, who was involved in the UK study. “Taken collectively they do seem to be pointing towards a more optimistic picture.”

Protect yourself early

So why has the risk of dementia decreased? There are several possible contributing factors. Our physical health has improved markedly over the past century, due to less malnutrition and infectious disease; and more recently we’ve made progress to improve the health of our hearts and blood vessels, which also helps to protect the brain. In addition, we are more mentally stimulated than ever before, from childhood through to old age.

Pinning down just which of these has greatest impact could do more to prevent cases of dementia than the current focus on discovering new drugs and screening for the condition, say Brayne and other scientists writing in The Lancet Neurology. “We need to work out where we get the best bang for our buck,” she says.

That view is lent weight by another study out this week, which suggests there are many things that we could potentially do to reduce our risk of developing the condition, starting from early on in life.

In a reanalysis of 323 previous studies, the authors estimate that two-thirds of Alzheimer’s cases, the most common form of dementia, were attributable to nine risk factors. Some of these were things that are possible for people to change, such as smoking and having high blood pressure. Others are harder to tackle, such as low educational achievement, developing depression or ending up physically frail in later life.

On the bright side, says Martin Brunet a doctor in Surrey, UK, it’s encouraging that many of the things we can do to reduce our dementia risk also improve our general health. “If you look after your heart you’re looking after your brain,” he says.

Diagnosis push

Brunet says efforts to improve general public health would be more useful than current moves in the UK to diagnose more people with dementia. It is estimated that over half of people with the condition are not formally diagnosed, and UK family doctors are being pushed to screen for it in older people when they attend an appointment for other reasons.

But in January the UK National Screening Committee warned that the screening test – which involves checking people’s memory – was not good enough because it wrongly identifies too many people as having dementia. Typically, people with a “false positive” diagnosis have only mild memory problems or word-finding difficulties that are not bothering them, says Brunet, and this doesn’t mean that they will go on to develop dementia.

And even those who really do have dementia probably gain little from their diagnosis, he says, seeing as there are no drug treatments that work very well. “Giving them this label has a big impact on their lives,” he says. “They’re terrified.”

“For people who are seeking a diagnosis because they’re concerned about their memory, fine. But screening is a very different thing.”

Screening concerns

The government, for its part, says the memory tests are “case finding” rather than screening. But Brunet and other doctors have said in the BMJ that they clearly meet the definition of screening, in that they offer health tests to people who were not seeking them. “There’s not even informed consent,” he says.

Brunet says the scheme was introduced because the government needed to be seen to be doing something. “It’s much cheaper to [screen] than to put real money into caring for people.”

Brayne is equally sceptical. “The evidence base isn’t there to say that making a diagnosis leads to better outcomes,” she says. “Attention to health in early life is probably a better investment.”

Journal reference: The Lancet Neurology, DOI: 10.1016/S1474-4422(15)00092-7