A major source of unintended confusion about Alzheimer’s disease is the inconsistent definition from one article to the next.
In many instances, the author uses a definition that the reader might not fully understand.
The problem is that research scientists think about the disease in terms of “pathology” and speak about it in those terms. Given the long underlying process of amyloid accumulation in the brain, they contend that AD begins decades prior to the first clinical symptoms of memory loss.
Physicians, on the other hand, use a strict “clinical” definition of the disease, stating that AD begins when the underlying pathology (amyloid accumulation) has caused enough brain damage to render the patient demented. In this scenario, the disease begins many years after the first clinical symptoms.
Most lay people default to a symptom-based understanding and consider the disease present when the symptoms first appear. This occurs at some mid-point between the other two perspectives.
When you read the news, it is important to understand the potential for confusion in this regard. Here are a few of the many examples of how confusion arises:
If an article says that a drug is useful in treating early-stage AD, you should be careful to understand what the author means by “early-stage.” They might mean “30 years prior to symptoms” or they might mean “the point at which the patient becomes demented.” Unfortunately, such claims often breed false hope and are usually not meaningful to those recently diagnosed with AD because, by all definitions, we rarely diagnose the disease early.
When you read that AD is difficult to distinguish from normal aging, be aware that this is true for some definitions of AD but not for others. There is certainly a clear distinction from normal aging once clinical symptoms appear.
When you read about mild cognitive impairment and that it may or may not convert to AD, don’t be accidentally misled. Focus on any information indicating the cause of the MCI. If it is AD pathology, then scientists would agree that the patient already has the disease … while physicians would argue against an AD diagnosis until the symptoms progress to dementia.
Keep in mind these multiple definitions for AD that are commonly used in the press and it will help you to avoid misleading conclusions about otherwise clear news items.
THis column is part of a five-part series by Dennis Fortier. Here are the links to the other four columns:
Part 2 of 5: Don’t be Mislead by Data on Treatment Efficacy
Part 3 of 5: Common Assertions about Diagnostic Accuracy Hide Truth
Part 4 of 5: The Term “Dementia” Cannot be Interpreted Loosely
Part 5 of 5: “No Cure” Not as Bad as it Sounds