Parkinson's disease, smoking, certain head injuries and even normal aging can influence our sense of smell. But certain patterns of loss in the ability to identify odors seem pronounced in Alzheimer's, researchers say. CSA Images/Color Printstock Collection/Getty Images hide caption

toggle caption CSA Images/Color Printstock Collection/Getty Images

A Sniff Test For Alzheimer's Checks For The Ability To Identify Odors

  • Download
  • <iframe src="https://www.npr.org/player/embed/487391863/487522870" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

"I'm afraid there's a growing sense that the path to health is through testing," says Dr. H. Gilbert Welch, a Dartmouth Institute internist who has written books on the pitfalls of overdiagnosis. Encouraging the worried well to order their own blood tests feeds that mindset, he says. TEK Image/Science Photo Library/Getty Images hide caption

toggle caption TEK Image/Science Photo Library/Getty Images

A medical researcher prepares tests for various diseases including Zika. Arnulfo Franco/AP hide caption

toggle caption Arnulfo Franco/AP

How Best To Test For Zika Virus?

  • Download
  • <iframe src="https://www.npr.org/player/embed/469549176/469972607" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Studies show that having too many tests done too frequently is a recipe for getting sick, not staying healthy. Medicimage/Science Source hide caption

toggle caption Medicimage/Science Source

Magnified 25,000 times, this digitally colorized scanning electron micrograph shows Ebola virus particles (green) budding from an infected cell (blue). CDC/NIAD hide caption

toggle caption CDC/NIAD

Blood Test For Ebola Doesn't Catch Infection Early

  • Download
  • <iframe src="https://www.npr.org/player/embed/359567808/359632749" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

Doctors used a rapid DNA test to identify a Wisconsin teen's unusual infection with Leptospira bacteria (yellow), which are common in the tropics. CDC/Rob Weyant hide caption

toggle caption CDC/Rob Weyant

Quick DNA Tests Crack Medical Mysteries Otherwise Missed

  • Download
  • <iframe src="https://www.npr.org/player/embed/319210230/319222889" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

After genetic testing revealed a heightened risk for breast cancer, Angelina Jolie had a precautionary double mastectomy. Alastair Grant/AP hide caption

toggle caption Alastair Grant/AP

Disease susceptibility varies among ethnic groups, but medicine hasn't always recognized that. Jo Unruh/iStockphoto hide caption

toggle caption Jo Unruh/iStockphoto

Stacy Riggs of Fairfax, Va., is prepped for a screening for atrial fibrillation by Life Line Screening medical assistant Kennea Blake at Messiah United Methodist Church in Springfield, Va. Jenny Gold/Kaiser Health News hide caption

toggle caption Jenny Gold/Kaiser Health News

Some Health Screenings May Harm More Than Help

  • Download
  • <iframe src="https://www.npr.org/player/embed/239861764/241319364" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript

A broken hip like the one at left is a big health worry for older women. iStockphoto.com hide caption

toggle caption iStockphoto.com

Anne Jones, 62, and Robin Jones, 73, at their home in Menlo Park, Calif. He took a test that revealed proteins typical of Alzheimer's disease. Ramin Rahimian for NPR hide caption

toggle caption Ramin Rahimian for NPR

Finding Simple Tests For Brain Disorders Turns Out To Be Complex

  • Download
  • <iframe src="https://www.npr.org/player/embed/198086616/199929844" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
  • Transcript