Alzheimer’s Disease and dementia do not suddenly occur; both are often proceeded by several years of mild impairment of our cognitive abilities – a pre-dementia phase. The current literature supports the idea that only 50% of patients will develop full-blown dementia during a three year period of pre-dementia. What is a front-line clinician, a neurologist or primary care physician, to tell patients and their families? Can we offer any prognostic information? After all, knowing that 50% of patients will get worse or stay the same is a coin flip. This difference in clinical outcome has prompted scientists to search for markers that may help clinicians advise patients and their families. Evidence of brain atrophy on MR studies as well as increased amounts of amyloid and tau proteins in the spinal fluid are commonly used markers.
Spinal fluid and MR findings correlate with prognosis for the aggregated groups that have been studied; this information is difficult to apply to the patient in front of you. And like much of our clinical work, many patients fall into a grey area, that flip of a coin area. As a clinician, you wind up spouting generalizations, which are usually not helpful in resolving the real concerns and anxiety of these patients and the families. What should we tell our patients?
A study Interpreting Biomarkers Results in Individual Patients with Mild Cognitive Impairment in the Alzheimer’s Biomarkers in Daily Practice (ABIDE) Project in this week’s JAMA Neurology attempts to answer that question. The researchers looked at 525 patients making use of their demographics, their score on memory tests as well as measurements of their spinal fluid and imaging of their brains. In the patient group, 11% progressed to Alzheimer’s Disease dementia in year one and 30% by year 3. In retrospectively viewing their collected data they developed a model that took all of these “biomarkers” into account. The model was able to identify 73% of the patients that progressed.
Now the value of their model being is that by including specific characteristics of the patient, their age, gender, educational level and memory scores clinicians have a more readily applied personalized model that helps identify the 50% of patients who develop dementia within the time frame about 70% of the time.
It is a small step forward and may improve the plight of our front-line physicians. The study suggests some of the difficulties physicians have in counseling our patients. Providers offer platitudes; physicians try to find ways to deliver something more than comfort and reassurance. Hopefully, this model will be helpful. It will be replaced by others as we incrementally learn more.