"There's reason to worry," said Wyss. "But my best guess is that we sort of muddle through this."

Wyss said that in his worst case scenario, the unemployment rate would climb to 7.5 percent by early 2009, up from its current level of 5 percent.

But, Wyss-Coray says, many studies are beginning to support the idea that a biomarker outside the brain could allow earlier and easier diagnosis.