The dangers of looking to closely

They’re called incidental findings in brain imaging research on “normal volunteers”. In today’s NY Times Gina Kolata looks at microbleeds in the brain:

“If there were more than we knew of in the general population, that might — and I want to stress might — have important consequences,” Dr. Breteler said. “That is why we started to look for them.”

For more than a decade, Dr. Breteler and her colleagues have followed a group of Rotterdam residents age 45 and older. The goal is to do repeated brain scans on 8,000 people; so far they have scanned nearly 4,000 and are analyzing those data.

“What we found came as a big surprise,” Dr. Breteler said. Previous estimates were that 5 to 7 percent of healthy older people had microbleeds. The Rotterdam study found them in more than 20 percent. And the older the person, the more likely the microbleeds. They were present in 18 percent of 60-year-olds and nearly 40 percent of those over 80.

“We now know that these changes are there and that they are frequent,” Dr. Breteler said. “But we don’t know yet what their clinical impact is, what their prognosis is.”