TeachableMedicalNews article 05312021

Teachable moment in classrooms:

  1. brain chapter – locations of storing short and long term memory in the brain
  2. nervous system chapter – functioning of neurons
  3. introduction to the human body chapter – basics of PET scan technology

The news item:  Recently the availability of a blood test for Alzheimer’s disease was reported:

First blood test to help diagnose Alzheimer’s goes on sale

How is Alzheimer’s diagnosed? New blood test to help diagnose Alzheimer’s is not approved by the FDA.

 

 

The article states that this test is the first commercially available blood test for Alzheimer’s disease, and that it is a more practical alternative to the PET scan, but the test is not officially approved by the FDA, and the accuracy is still under study. The article also states that the test, developed by the company C2N,  measures amyloid and other protein.

So, Why Do I Care??  There are more than 6 million people afflicted with Alzheimer’s disease in the US. This number will increase as the proportion of older people increases in the US. Early detection of this disease could allow the implementation of preventative strategies such as changes in lifestyle, or even new medications.  Therefore the development of a blood test for early diagnosis is an exciting development, despite the fact that the accuracy of this test needs to be fully proven.

Plain English, Please!!! First, let’s talk about what Alzheimer’s disease is. Dementia type disorders result in the loss of memory, the ability of the patient to recall names or past events. Alzheimer’s disease is a form of dementia disorders; most people with dementia suffer from Alzheimer’s. Because the storage and recall of memory is done by our nervous system, specifically the brain, Alzheimer’s disease is a disorder of the brain. Typically, amyloid proteins accumulate in the brain during the progression of this disease.

Second, let’s talk about memory. The cells of our nervous system that manage information flow are the neurons. The neurons that store memory have specific locations in the brain.  Short term memory is stored mostly in the hippocampus, while long term memory is stored at several locations in the cerebrum.  When neurons store a memory, a special groups, circuits, of neurons send nerve impulses to activate each other in a sequential fashion. Think about a string of Christmas tree lights that flash in a sequence; one lightbulb lights up after another. As neurons die during the disease, individual lightbulbs go out in that Christmas tree light, and the entire circuit goes dark, thus, the memory is lost. The dying neurons make the amyloid proteins.

Third, let’s talk about early diagnosis of Alzheimer’s disease. Once a person shows symptoms of dementia, the specific type of dementia can be diagnosed by analyzing amyloid proteins in  cerebrospinal fluid. There are no curative treatments for Alzheimer’s disease, so, early diagnosis, before the symptoms appear, is important if we want to change lifestyle of the person to delay the onset of symptoms. The standard diagnosis of early Alzheimer’s is the PET (positron emission tomography) brain scan for amyloid proteins, and this requires an injection of a radioactive material into the patient, and the scan itself is expensive.  The development of a blood test would make testing more practical and more widely available.