Bioethics Blogs

A Blood Test to Predict Alzheimer’s Disease: What’s the Elephant in the Room?

I recently gave a talk about Alzheimer’s disease and asked people to imagine two individuals, Manny and Sue. Manny died at 85; he was showing signs of age but living independently and was mentally “all there.” Sue lived until 99. From the time she was 88, she began a slow cognitive decline. By 93, she could no longer live independently. By 95 she could not recognize friends and family. Eventually she became incontinent and was unable to walk, speak, or feed herself. She lived two more years in that state until she died in her sleep.

I asked my audience which they would rather be, Manny or Sue. To a person, they chose Manny. Although Sue had lived much longer than Manny, for most people her long decline into dementia outweighed her extra time on earth. I have given this talk a number of times and it is the rare person who would prefer to live and die like Sue.

I have been thinking of this because of the article in Nature Medicine by a group of scientists who have identified a blood test to predict whether someone will get Alzheimer’s disease in the near future. Basically, they took 525 healthy people age 70 or older. Over five years, 74 of them were diagnosed with either mild cognitive impairment (often a precursor to Alzheimer’s) or Alzheimer’s. Their blood test was able to predict cognitive decline with 90 percent accuracy.

Biomarkers to predict Alzheimer’s disease are not new, but up to now they have been expensive, invasive, time-consuming, or all three.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.