A scan of the brain of a patient affected by Alzheimer's disease. | BSIP/UIG Via Getty Images For decades, research into Alzheimer’s disease has made painfully little progress. More than 7 million Americans are living with the disease, which is the most common cause of dementia. It’s incurable, and treatments have been hampered by groupthink, as well as by systemic fraud from some of the field’s most famous researchers. But there are finally signs that the field is turning a corner, including two new drugs, rolled out in the last few years, that can treat Alzheimer’s directly. “If so...