in the US, it's all about medical "billing codes" so that doctors can be reimbursed for services. What is diagnosed as AD is often the result of vascular issues. Or even long term oxygen deprivation during the night due to sleep apnea. Like cancer, there may not be a single "silver bullet" - it's a situation more like Parkinson's, which Oliver Sacks described as a "constellation" of factors. Whole books on the topic - good ones by conscientious MDs - have been written. One example is, "What if it's not Alzheimers" - good reading if an elder relative is having issues.