Marc Tessier-Lavigne told shareholders in 2009 that his research would “turn our current understanding of Alzheimer’s upside down.” Now, the former Stanford president and his co-authors have retracted the paper he once heralded, conceding they do not have confidence in its data. The prominent journal Nature announced the retraction in a Dec. 18 note signed by all four co-authors. The note acknowledged a number of image anomalies and biostatistical errors, but denied that the study had included f...