The Dutch, young and old, love their bikes. On average they ride more than 1.5 miles a day through cities like Amsterdam that are friendlier to bikes than cars.

Compare that to the United States, where people bike an average of less than 110 yards a day.

So it sort of figures Dutch neurologists are using biking as a way to measure something that’s long perplexed them: How to tell the difference between two very similar types of Parkinson’s disease.

In a study published recently in The Lancet, Dutch neurologist Bastiaan Bloem and coauthors suggest that physicians trying to figure out whether a patient has “regular” Parkinson’s disease or atypical parkinsonism can ask this simple question:

Can you still ride a bicycle?

Bloem, the medical director of Parkinson Center Nijmegen, and his colleagues looked at 111 parkinsonism patients who cycled regularly before it struck.

Of those, the 34 who said they couldn’t cycle anymore had been diagnosed with atypical parkinsonism. Meanwhile, only two out of 45 who had been diagnosed with Parkinson’s reported trouble cycling. The researchers concluded that “loss of the ability to cycle after disease onset might serve as a new red flag, signalling the presence of atypical parkinsonism.”

Early on, Parkinson’s disease and atypical parkinsonism look quite similar, Bloem says. But the difference, according to the National Parkinson Foundation, is that people with atypical parkinsonism can have a different mix of symptoms. The more common form of Parkinson’s disease also has a better prognosis, and it responds better to treatment than atypical Parkinson’s, Bloem noted.

Biking takes coordination and balance, which is harder with the subtle problems caused by atypical Parkinsonism. Bloem says the advantage of the bicycle test is that it is less invasive and cheaper than other diagnostic tests.

And it’s especially well suited to Holland, where “literally millions of people ride their bikes to and from work.”

But is this something American neurologists might use too to differentiate between the two diagnoses? Not likely.

“Even if [the research] is valid, it wouldn’t be that applicable to the U.S.,” says William Weiner, director of the Maryland Parkinson’s Disease and Movement Disorders Center. That’s because it would be hard to compare cycling abilities before and after symptoms appear because most Americans bike so little to begin with.

But there are other simple yet powerful tests that could get traction here.  A study published earlier this month in JAMA, the Journal of the American Association, showed that how fast an older person walks turns out to be a very useful thing to know. Faster is better when it comes to life expectancy, the researchers found.

Dr. Farzaneh Sorond, a stroke neurologist at Brigham and Women’s Hospital, told the Boston Globe: “With this new information, I’d think seriously about implementing gait speed as part of a routine assessment.” Copyright 2011 National Public Radio. To see more, visit http://www.npr.org/.