07 January 2012

Vascular dementia and high blood pressure

A cure is a long way off but new research shows that there is a lot you can do to help keep Alzheimer’s at bay. Source - The Times Appeal

High blood pressure and high cholesterol are strong risk factors particularly for vascular dementia, the second most common form after Alzheimer’s
Dr Anne Corbett lets slip a small sigh of frustration as we discuss the way that reports about “breakthrough cures” for dementia constantly fill the media. It is her role at the Alzheimer’s Society to try to leaven such breathless optimism with reality. The fact is, she says, we don’t have any cures for Alzheimer’s. And we are still a considerable way from them. What’s more, eating blueberries (or whatever the next “magic brain-boosting food” might be) won’t help, either.

Our popular belief in an instant cure is propelled by a huge weight of expectation. It feels only right that we should by now be curing dementia, which afflicts about 750,000 people in Britain. After all, in the past few decades there have been great advances in treatments for global scourges such as cancer and Aids. Yet Alzheimer’s remains stubbornly intractable. It was first identified in 1906, but we still don’t know exactly what causes it. Instead of cures, the past quarter of a century has brought false dawns. In 1986, scientists at Albert Einstein College of Medicine in New York claimed to have identified a protein, christened Alz-50, that caused the condition. They hailed it as the key to defeating the disease. They were sadly wrong. The same year, scientists at Toronto University pumped artificial chemical transmitters into the brains of 100 dementia patients to act as a mind-restoring “pacemaker”. It didn’t work.

On top of false hopes, we have had decades of groundless scares, most notoriously the belief in the 1990s that cooking with aluminium pans caused Alzheimer’s. This boosted the fortunes of scrap dealers and cookware stores, but saved no lives. Yet still we get false reassurance from regular “medical breakthrough” stories promising treatments that are only on the drawing board.

Nevertheless, we can do much to reduce our risk of Alzheimer’s and other common forms of dementia, explains Dr Corbett, the Alzheimer’s Society’s research communications manager. You can’t buy the answer, but you can be it — because all the evidence shows that adopting healthy habits in diet and exercise can work wonders.

The lesson is straightforward: your brain is the most complex piece of thinking equipment in the known Universe. Your body is its life-support system. The human brain is a very hungry piece of kit. While it constitutes only about 2 per cent of your body’s mass, it uses more than a fifth of its energy production. Efficient supply and maintenance are vital. If your physical health declines, your brain is in serious danger of following suit.

“This is why preventing dementia is all about everyday healthy living,” explains Dr Corbett. “We have strong evidence for what medical conditions increase your risk. They are high blood pressure, stroke, diabetes, high cholesterol and depression. If you have these from midlife onwards you are at higher risk of dementia.”

Not only are high blood pressure and high cholesterol risk factors in themselves, they also significantly raise a person’s odds of suffering a stroke. One person in three who has a stroke will go on to develop dementia, she explains. “We are not entirely sure of the link yet, but the evidence is strong that if you prevent stroke, then you should prevent dementia.”

Diabetes is also strongly associated with dementia. “There may be good reasons for this,” Dr Corbett says. “People who develop type 2 diabetes in midlife are more likely to be overweight, to smoke or have an unhealthy lifestyle. There is also evidence that insulin plays a role in dementia. We are not sure exactly how yet, but it regulates chemical pathways in the brain that keep brain cells healthy. The important message with diabetes is that it is diagnosed early and treated well.

“If you can prevent those physical problems, you stand a very good chance of preventing dementia,” she adds. After all, genetics are responsible for only about a quarter of Alzheimer’s cases. The other major risk factor is clinical depression. This may precipitate chemical changes in the brain that are similar to those seen in dementia. “On top of this, people who are depressed may have lifestyles that are unhealthy and socially isolated,” says Dr Corbett.

Worryingly, Department of Health figures predict that cases of depression, diabetes and stroke will soar. For example, over the next 40 years, incidences of Alzheimer’s are expected to triple, according to a recent report in the journal Lancet Neurology.

A great deal of this could be prevented through simple and easy changes in habit. Just taking a little more exercise could make a huge difference for millions of people.

“More than 13 studies show that exercise can reduce risk by up to 45 per cent,” says Dr Corbett. “Evidence shows that the exercise does not have to be strenuous to have this benefit: it can involve active walking for around 30 minutes a day. The exercise just has to raise the heartbeat by a little.”

Adopting healthy eating habits can also significantly reduce the risk of dementia. The evidence from a range of studies indicates that Mediterranean-style diets work best because they are low in fat and salt and high in oily fish. And there is good news where drinks are concerned. “While we hesitate to say this, the evidence for alcohol reducing risk is good,” says Dr Corbett.

“The conclusion from 15 separate studies shows that moderate drinking (with the emphasis on moderate) may cut your dementia risk by around 25 per cent. There is a similar sort of rationale about caffeine in green tea and coffee, when drunk in moderate amounts.”

Enjoying your drinks in good company seems important, too. Evidence shows that being socially active may lower your risk of dementia. This is particularly true of people (men especially) after they retire, where they are at risk of becoming less engaged with others.

Similarly, in midlife, making friends with your GP is a good idea. High blood pressure and high cholesterol are strong risk factors particularly for vascular dementia, the second most common form after Alzheimer’s, so people are urged to have regular check ups both in the surgery and where possible by regular home monitoring. Getting a routine test for homocysteine levels in your blood can also make a real difference. Raised levels of this amino acid have been linked with loss of brain volume and dementia. But in a study last year, Professor Celeste de Jager, of Oxford University, found that taking vitamin B supplements can lower the danger significantly. In older people with high homocysteine, taking the supplement daily reduced their brain shrinkage by four fifths. The people taking extra B vitamins also did better in memory tests.

Some much-touted preventatives are, however, only myths. Beware any claim about a single food, says Dr Corbett. Only last year, an important report in the Journal of the American Medical Association punctured the idea that ginkgo biloba is a brain-saver. The study of more than 3,000 adults found that it made no difference at all.

Likewise, expensive computerised “brain-training games” have failed to prove any medical benefit. Studies show that you may get better at playing the games, but the benefits go no farther. It is the same with crosswords and Su Doku. They should be enjoyed for themselves, rather than taken as a substitute for a healthy diet and exercise.

For Dr Corbett, the most important message to put across is that preventing dementia involves doing things a little, and early. “It’s not too late to change your habits by the time you’re 50, but we are finding that early in midlife — in your forties — is the really critical time. That is when lifestyle-related risks begin to increase significantly.”

There is little point waiting instead for the medical cavalry to come charging over the horizon with a wonder cure. There won’t be one coming any time soon, sadly. Worse, the sector is under-financed, thanks perhaps to the condition’s “unsexy” image as an illness. “Research into dementia is largely under-invested,” says Dr Corbett. “Cancer research gets about eight times as much funding.

We need far more clinical trials and more potential treatments being developed.

“There are some interesting new approaches. But on average, out of every ten potential treatments to enter clinical trials, only one will come through the process and be approved for use on patients. There are only three treatments in the penultimate stage of clinical trials at the moment. By the law of numbers, that is not very promising.”

Instead, it remains for all of us as individuals to take responsibility to reduce our own risk. But can that really be so bad? It just means making small changes in ways that stave off a whole gamut of dismally debilitating illnesses — and which can only give us a better quality of life all round.