Alzheimer's Club

Treatments for Alzheimer's disease are improving, but experts don't know if progress is fast enough. Ben Sheehan reports

FORGET all those tired old jokes about Alzheimer's, the ones about hiding your own Easter eggs or losing the car keys. Australia is staring down the barrel of an epidemic, exactly 100 years since the disease was discovered.

Alzheimer's does not pose the contagious threat of bird flu, but more Australians are getting it and medicine can't pinpoint a cause.

So where does this leave the baby boomers, the single largest generation in Australia's history, as they trundle forward into old age and the higher risk of developing the disease?

Alzheimer's expert and chairman of the federal Government's Aged Care Committee Mark Yates is not sure. "We don't know how prepared we are (for) an epidemic," he says. "Services are expanding, and the federal Government has made it a national health priority. But we certainly don't know if we'll crack a treatment agent in the near future."

In 2000 there were an estimated 146,800 Australians aged 65 and over who had dementia, according to the Australian Institute of Health and Welfare. Over half of these had Alzheimer's.

But rates have been increasing sharply, a function both of greater recognition of the disease among patients and doctors and also the demographic shifts towards an older population.

According to a report by Access Economics last year, 210,000 Australians of all ages now live with dementia, the majority of whom would have Alzheimer's.

The report, commissioned by Alzheimer's Australia, found there are 1000 new cases every seven days. US data suggests as many as 10 per cent are under 60, a few are even in their 30s. Once you are over 65, there's a one in 50 chance it will be you, and every five years after that your chances of getting it will double.

These and similar statistics are galvanising experts into action. In December experts from the Institute of Psychiatry at King's College, London, called for governments to work together to tackle the disease.

The rationale is simple. Populations are ageing, and few of the available drugs do more than treat symptoms.

Despite the ubiquity of Alzheimer's, it is not considered a part of normal ageing. Theories in the past as to what may cause the disease have included the accumulation in the brain of metals such as aluminium, lead, mercury and other substances, but these notions have now been disproved.

There is no proven way to prevent or cure Alzheimer's, although a study published in The Lancet last week did appear to offer new hope of progress on treatments. The paper (doi:10.1016/S0140-6736(06) 68350-5) was the first to assess the effectiveness of donepezil, a drug already used to treat mild to moderate Alzheimer's, in more severe cases.

The researchers assigned 95 patients with severe Alzheimer's to donepezil – available in Australia under the brand name Aricept – and another 99 to a placebo.

The study, funded by Pfizer, Aricept's maker, found that after six months patients given donepezil had improved cognition and ability to carry out daily tasks. The researchers said the findings showed not only could the drug slow progress of the disease, but could also reverse "some aspects" of mental deterioration.

However, Australian experts have cautioned this falls a long way short of a cure. And there is thus increasing interest in what might we might be able to do to reduce the chances of developing the disease in the first place.

According to Lynette Moore, a member of the federal Government's Dementia Health Priority Task Force, there's a distinct possibility we can stave off the illness through a healthy diet and exercise.

"A growing body of evidence suggests that around mid-life, high cholesterol and blood pressure are associated with Alzheimer's in later life," Moore says. Vascular disease is also regarded as a key risk factor.

Moore believes the evidence so far suggests that avoiding these risk factors and building up more brain cells through mental exercise improves your chances of avoiding Alzheimer's. Yates also thinks that maintaining diversity of thought and activities after retirement might help.

While much remains to be discovered about the causes of Alzheimer's, the best treatments and preventive measures, our ability to diagnose the disease with confidence has improved enormously since Dr Alois Alzheimer in 1906 first described the brain plaques and tangles that have become the hallmarks of the disease.

Catriona McLean, director of the National Neurological Tissue Resource Centre, says while the brain is the only part of the body affected, clinical diagnosis – based on a detailed patient assessment by an experienced specialist, imaging tests and after excluding other possible causes of dementia – can be 80 to 90 per cent accurate.

But the professor says the "only 100 per cent accurate way to make a diagnosis is to examine the brain at autopsy", using tests that mark out the accumulation of abnormal proteins that are characteristic of the disease. McLean, who is also professor of pathology at Monash University and director of the Alfred Hospital's anatomical pathology department, has spent around 90 minutes studying each of hundreds of Alzheimer-affected brains at the centre.

"Because we are still unsure about the causes of the disease, we still need to use human brains to do the relevant research," she says. "It's important for people to understand that some of the advances that have been made have been possible through people who have donated their brains for research."

She says experts now have a much better understanding of the genetic factors involved in Alzheimer's progression, and how the proteins develop in abnormal ways.

But while many experts, including Yates, say earlier detection is vital there are others who question the need to make a firm diagnosis in the early stages of the disease, at least while the treatment options are so limited. Rod Pearce, chairman of the Australian Medical Association's council of general practice, believes that medical intervention is often pointless.

Total disablement from Alzheimer's is common. While the average lifespan after diagnosis is eight to 10 years, some patients live with the disease for 20 years or more.

"This is GPs responding to the reality of what they can do, and often making that diagnosis isn't going to be helpful," Pearce says. "If a GP picks Alzheimer's up but then can't get access to the treatment the patient needs, then what's the advantage of putting a label on it? It's distressing for all involved."

One source of Pearce's frustration is that GPs are unable to prescribe donezepil, or the other Alzheimer's drugs galantamine (Reminyl) and rivastigmine (Exelon) under current Pharmaceutical Benefits Scheme criteria.

Patients require assessment by a gerontologist or psychiatrist and a six-month trial to demonstrate "noticeable improvement" before their doctor is given the green light to write scripts. "When people need help and the treatment is appropriate, the system puts a lot of barriers in the way," says Pearce.

One of these barriers is cost.

Patients with a concession card can get a month's supply of Aricept, Reminyl or Exelon for $4.70. Without the subsidy, the cost of these drugs escalates to between $160 and $190 per month. Another drug called memantine (Ebixa), which is used in conjunction with any one of the three, costs users an additional $170 per month and is not funded by the PBS.

"The cost of medication means that most people end up waiting for their assessment (to gain the PBS subsidy and start medication)," says Pearce, himself a GP. But not all wait. A survey of 1226 patients last year by Alzheimer's Australia found that 27 per cent of sufferers had paid for the drugs out of their own pockets.

Another concern is that patients are often left to decide for themselves if, and when, they give up their car keys. The prospect of losing the ability to drive appals many patients, and many find it difficult to contemplate such a move; but as the need to surrender the car keys grows, the nature of the disease means patients are less equipped to make the decision to do so. Driving assessments are voluntary and cost $180.

Former federal minister for ageing Julie Bishop concedes that many elderly people find losing a driving licence "a highly traumatic event". "One elderly couple who were both diagnosed with dementia skipped their state, Thelma and Louise-style, rather than give up their licence," she says.

Source: Alzheimer's hits a century, not out. Alzheimers.org.au (1 April 2006) [FullText]