A QUICK and cheap test that’s already used to check sports players for concussion could double as a means of spotting whether someone will get Alzheimer’s disease, years before the first symptoms of dementia appear. It may help companies develop drugs to prevent the disease.
At the moment there is no straightforward way to detect the very earliest stages of Alzheimer’s. And without such a test, it’s hard to discover whether a drug can delay the onset of the disease, rather than just relieve the symptoms. “By the time we give drugs nowadays, people need carers,” says neurologist David Darby of CogState, the Melbourne company that developed the test.
The 18-minute test evaluates three aspects of brain function: attention, memory and executive function (the ability to plan and integrate information), all based on how fast people pick out playing cards on a computer screen. CogState already sells the test as a tool for managing sports concussion. Players do a baseline test, and repeat it if they get hit on the head. The test has been adopted by sporting organisations such as South Africa’s Springbok rugby team, the British Jockey Club and Millwall Football Club in London.
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But CogState’s main interest is Alzheimer’s. The company has assessed the test’s ability to pick up the early signs of the disease in apparently healthy volunteers aged around 70 who had gone through a battery of cognitive tests over five years. The tests revealed that 15 had mild cognitive impairment, which often heralds Alzheimer’s disease, while the other 35 did not.
The volunteers then did the card test four times, spread over a year. All the volunteers with mild cognitive impairment showed a progressive decline in test performance, unlike the normal volunteers. The results were reported at an Alzheimer’s conference in Stockholm this week.
“Here’s a group of people who are probably within five to ten years of getting Alzheimer’s disease. The beauty is that once you’ve excluded other causes like depression, you can now consider treating them with drugs that would delay the onset of the disease,” says Darby.
The current gold standard for diagnosing Alzheimer’s is a full-blown cognitive examination by a specialist. It takes over an hour, and even then it can’t pick up a mild impairment unless the exam is repeated over several years. A number of groups are developing ways of imaging living brains to look for the plaques characteristic of the disease (91av, 19 January, p 22). But these tests are expensive and time-consuming.
Other alternatives being developed include phone consultations and monitoring urine for levels of a protein that the brain releases when nerves degenerate.
