I was giving a talk last week and asked the question of whether Alzheimer’s disease can be diagnosed by means of an alpha-beta PET scan.  This refers to the use of a brain scan with amyloid markers in the detection of early Alzheimer’s disease before clinical symptoms appear.  A review by Steven Peterson (Journal of the American Medical Association Internal Medicine, 2014, 174, 133-134) concludes that it cannot. 

 I have already had a couple of clients who presented to me after they had obtained a PET scan with an amyloid marker and told, despite the fact that they had no symptoms or neuropsychological assessment, that they had early Alzheimer’s disease.  Of course, this was very alarming and they sought assessment and council.  After careful testing, these two clients had superb short-term memory, the loss of which is the hallmark and necessary symptom of Alzheimer’s disease.  I reassured them and suggested they track their memory over time similar to tracking blood sugars or cholesterol.

Dr. Peterson concludes that a positive PET scan is not diagnostic of Alzheimer’s disease.  Furthermore, a positive scan is not useful in predicting the conversion of Mild Cognitive Impairment to Alzheimer’s disease.  He adds that a negative PET scan is associated with a reduced risk that existent cognitive impairment is a result of Alzheimer’s disease. Current scans are not a diagnostic tool for Alzheimer’s disease.

The most recent statement from Medicare (CMS) also concludes that the evidence is not sufficient to use PET imaging studies as reasonable and necessary for either the diagnosis or the treatment of Alzheimer’s disease.  Therefore, Medicare will not cover amyloid imaging by PET scan in the diagnosis of Alzheimer’s disease.  Medicare will cover one PET scan to differentiate between Alzheimer’s disease and frontotemporal dementia in appropriate cases and clinical studies that address treatment and prevention under very restrictive prior approval.

There are four problems with the current evidence base for PET scans for Alzheimer’s disease.  1. There are too few studies available.  2. Currents studies do not address the benefits and harms of making a diagnosis based on imaging data.  What if the scan is positive and the client never develops a memory disorder?  3. Current studies have very restrictive selection criteria.  They do not address the full spectrum of typical clinical clients – they are not representative samples.  4. There is no evidence that a positive scan changes clinical management or provides any health benefits.

PET scans for Alzheimer’s disease are useful and intriguing research tools.  They are not clinical tools at this time.  Don’t forget to monitor your memory.  I have developed a focused, thorough short-term memory assessment that is brief and affordable.  Contact my office for details if you want to check out your memory.