One of the three outside academic researchers whose names grace a Vioxx study appears to be having a hard time deciding whether he was intimately involved in compiling the paper. This particular paper was cited in a study published in JAMA this week that found academics often lent their names to Vioxx studies that were assembled by Merck scientists or ghostwriters.

The study in question was designed to see whether Vioxx may blunt the progression of Alzheimer’s. One of the three outside academics listed was Steven Ferris, a New York University psychiatry professor who heads a dementia research center. But he has given differing accounts of his involvement in the study.

In a statement, Merck maintains that “the absence of their names on the draft document author list or in the acknowledgment section shown in the article in no way indicates that these scientists were guest authors on this publication.”

Ferris tells The New York Times that he played an active role in the research and writing, and he reviewed data on hundreds of patients enrolled in the study to determine whether their mild cognitive impairment had progressed to Alzheimer’s. Later, he told the paper, he was substantially involved in helping shape the final draft. “It’s simply false that we didn’t contribute to the final publication,” Ferris says.

But Ferris also spoke to USA Today, which writes that he was unaware his study showed an increased risk of death among Alzheimer’s patients. “I can’t say that because I never had in my hands - I didn’t request it and I wasn’t given it - the reams of statistical analyses that gets digested into a draft manuscript,” he tells the paper. Ferris says he played a more limited role, serving on a committee that judged the accuracy of Alzheimer’s diagnoses.