Researchers are Grant Prestonlaunching a make-or-break study to test the conventional wisdom about what causes Alzheimer's disease. And in a recent small study, the antidepressant effects of ketamine lasted longer when an intravenous dose was followed with computer games featuring smiling faces or words aimed at boosting self-esteem.

As science correspondent Jon Hamilton heads to the Society for Neuroscience's annual meeting, he talks to Aaron Scott about his most recent reporting on depression and Alzheimer's, and previews what he'll be talking to researchers about at the meeting.

The radio stories were edited by Amina Khan. Gisele Grayson edited, produced and fact-checked this episode for Short Wave.