Watching Amyloid

Increasing rates of Alzheimer disease (AD) threaten to overwhelm our health care system domestically and worldwide, but exactly what causes the condition remains controversial, as does diagnosis and monitoring.  Now a study in JAMA Neurology Rick and I discuss on PodMed this week adds more to our understanding of the pathology of AD in perhaps pointing the way toward monitoring more effectively.  Researchers recruited more than 500 'cognitively normal' people enrolled in the Mayo Clinic Study of Aging, median age 78 years.  Each of them had undergone a number of imaging studies, including MRI and two types of PET scanning as well as cognitive assessment. The data analyzed in this study were collected between January 2006 to January 2014.

A positive relationship between increasing amyloid levels and cognitive decline emerged, with those individuals having evidence of more amyloid accumulation more cognitively impaired.  In these same folks reduced hippocampal volume, slower metabolism of FDG-PET, and enlargement of the ventricles of the brain were also observed. These associations were independent of APOE4 carrier status.

The results clearly suggests means of monitoring those at risk for AD, although many of these studies are expensive and seem unlikely to provide a practical means of screening.  Rick points out that we still don't know whether amyloid causes AD or is simply a bystander, but we're both hopeful that studies underway attempting to reduce amyloid and examine impact on the development of AD will shed some light. Other topics this week include ACP recommendations on generic prescription in Annals of Internal Medicine, increasing colorectal cancer screening rates in Cancer, and folic acid supplementation and neural tube defects in the BMJ.  Until next week, y'all live well.