Linking Alzheimer's to insulin is a new one to me - I've heard about plaque on the brain and toxic proteins called beta amyloid…the question around all of these is still whether they're a symptom or a cause.
To simplify the path to a cure: they've found the genetic predisposition towards Alzheimer's and dementia, step two will be narrowing down the epigenetic markers that trigger the condition, and step three will be preventing the condition being triggered in the first place. I predict within 10 years we'll have a pill. (I hope! I spend a lot of time in a high care nursing home visiting a much loved family member, and the cost of this devastating disease affects not just the afflicted, but family members and society as a whole as our population ages and resources are stretched).