Tuesday, January 15, 2013

The media are influential... on everyone else, say Alzheimer's specialists

A new survey of dementia specialists caught my eye for two reasons.

One, most said they intend to use a newly-approved $3000 test for anyloid deposits in the brain, even though they concede the results can be misleading (for instance, while a lack of amyloid found on this test means a person probably doesn't have Alzheimer's, many people have the deposts, but not Alzheimer's, so the meaning of a positive result is unclear).

Two, half of them "felt media coverage of testing would influence whether amyloid imaging became commonly used in clinical practice." But not a single respondent (0 of 135) "felt their decision to use amyloid imaging would be influenced by media coverage."

Let's take that second point first. It's very human. Most people believe they are above-average drivers, when that simply can't be true. It's also consistent with other studies of physician attitudes and behavior. Studies consistently link conflicts of interest with differences in how physicians give advice, reach conclusions, and practice... but they tend to say such conflicts don't affect them. (Browse the work of Lisa Bero and colleagues.)

There's also a lesson here for journalists. We have to be careful about how we report on tests and treatments, because our stories likely influence even professionals who should know better.

And that brings me back to the first point... that dementia specialists intend to use this test, if they can find someone to foot the bill. (The study authors calculate that screening just a quarter of Americans 75 and older would cost $16 billion a year.) The survey report said most of the specialists who intend to use the test say it would help make them more confident about their diagnosis. That's nice, but what will it do for patients and families.

Does being more confident about an Alzheimer's diagnosis change treatment? Probably not. To begin with, there isn't any treatment that can change the course of the disease. The available drugs can help some people function a bit better for a period of time, but the effects are individual. The official diagnosis isn't the final word. That means trying a drug to see how it works in an individual patient... for good or ill (and there can be serious side effects, including disabling falls caused by balance problems).

Someday there may be effective treatments for Alzheimer's disease. But until then, I'm wary of diverting money to testing, mostly so that doctors can check off a box with more confidence.

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