Hanover, N.H.

EARLY diagnosis has become one of the most fundamental precepts of modern medicine. It goes something like this: The best way to keep people healthy is to find out if they have (pick one) heart disease, autism, glaucoma, diabetes, vascular problems, osteoporosis or, of course, cancer — early. And the way to find these conditions early is through screening.

It is a precept that resonates with the intuition of the general public: obviously it’s better to catch and deal with problems as soon as possible. A study published with much fanfare in The New England Journal of Medicine last week contained what researchers called the best evidence yet that colonoscopies reduce deaths from colon cancer.

Recently, however, there have been rumblings within the medical profession that suggest that the enthusiasm for early diagnosis may be waning. Most prominent are recommendations against prostate cancer screening for healthy men and for reducing the frequency of breast and cervical cancer screening. Some experts even cautioned against the recent colonoscopy results, pointing out that the study participants were probably much healthier than the general population, which would make them less likely to die of colon cancer. In addition there is a concern about too much detection and treatment of early diabetes, a growing appreciation that autism has been too broadly defined and skepticism toward new guidelines for universal cholesterol screening of children.

The basic strategy behind early diagnosis is to encourage the well to get examined — to determine if they are not, in fact, sick. But is looking hard for things to be wrong a good way to promote health? The truth is, the fastest way to get heart disease, autism, glaucoma, diabetes, vascular problems, osteoporosis or cancer ... is to be screened for it. In other words, the problem is overdiagnosis and overtreatment.