The article I wrote two weeks ago, “Timeline for the Development of Alzheimer’s Disease,” got me thinking. I have known for some time that most progressive dementing conditions unfold over the time span of decades, but having concrete data makes the natural history of Alzheimer’s disease all the more clear.

Brain changes associated with Alzheimer’s disease are found 25 years before onset of symptoms. One way to use these data is to label the changes as being Alzheimer’s disease early on. Indeed, this is what has been done with the new diagnostic criteria. There are many unfortunate effects of doing this. We do not know the base rate of those who have these brain changes and don’t go on to show symptoms of Alzheimer’s disease. Recall that imaging studies produce a high rate of false alarms when completed on general populations rather than selected study groups (“Brain Scans Lead to Misdiagnosis of Alzheimer’s Disease” April 2012). Part of the problem is that, according to the time line, imaging studies don’t appear to detect changes until 15 years before symptoms.

Earlier diagnosing is not a good solution. Early labeling someone as having Alzheimer’s disease decades before symptoms appear will do more harm than good. There are a number of psychological implications of diagnosing too early: stigmatization, feelings of hopelessness and despair, and misdiagnosis. Early identification of brain changes that are associated with Alzheimer’s disease indicate that intervention studies need to be started when participants are in midlife – for late onset Alzheimer’s disease – and cover a time course of at least 15-20 years. This is a far cry from current intervention studies that may, at best, cover a five year span and only begin after symptoms have arisen. We need intervention studies that fit the model of longitudinal aging studies such as the nun studies. This would finally clarify the benefits of interventions such as cognitive stimulation, exercise, supplements, etc.

The dilemma as I see it is that medical interventions carried out by this model are risky. We would be permanently altering the physical characteristics of the brain without knowing what the long term and possible detrimental effects might be. Furthermore, we would be intervening on some who will never show symptoms. I am not sure how to resolve these issues.

On a practical level, the good news from the time line is that memory loss shows up ten years before symptoms of Alzheimer’s disease. It’s clear that not all memory loss is due to Alzheimer’s disease and that not all memory loss will go on to produce dementia. While we wait for better data on long term life style and medical interventions, we need to change our mindset. We regularly consent to blood tests and physicals to monitor our health. Yet we leave memory to chance. Why isn’t memory evaluation a part of everyone’s wellness program?

The screening tests available are for memory loss and Alzheimer’s disease (the most common being the Mini-Mental State Exam) are too superficial, are not diagnostic, and don’t show changes until 5 years before symptoms of Alzheimer’s disease occur. Next week, I will lay out a simple plan for being proactive based on what we know now.