Prosecutors played audio and video clips Monday of Roger Clemens making a host of statements to congressional investigators that the government will try to establish were lies. "I haven't done steroids or growth hormone," Clemens says on his 2008 congressional deposition."

Pitcher Andy Pettitte acknowledged under cross-examination Wednesday that he might have misunderstood Roger Clemens when Pettitte said he heard his former teammate say he used human growth hormone.

The judge in the Roger Clemens perjury trial has ruled that key prosecution witness Brian McNamee can identify two players who confirmed under oath the strength trainer's claim that he injected them with human growth hormone.

A fat-derived hormone may be a risk factor for dementia and Alzheimer's, new research suggests.