In April the National Institute on Aging (NIA) and Alzheimer’s Association released revised criteria and guidelines for diagnosing Alzheimer’s Disease (AD). Spread over several documents, the revisions are written in the usual impenetrable language of medical research journals – which makes sense, since the target audience is the medical research professional community.
Here at MyBrainTest we have taken a stab at explaining what the revised guidelines mean on a practical level for the average consumer:
Stages of Dementia and Alzheimer’s Disease
Stage 1 – Preclinical: Normal cognitive functioning, but some identifiable biomarker changes in the brain (these changes can occur more than a decade before cognitive functioning is harmed). See below for the diagnostic utility of biomarker tests.
Stage 2 – Mild Cognitive Impairment (MCI): Measureable memory impairment and cognitive decline, but generally no large impact on daily life (such as dressing, bathing, cooking, social activities). MCI can be a portal to Alzheimer’s Disease, so it is critical to catch the earliest signs of MCI through routine cognitive testing.
Stage 3 – Dementia due to AD: Significant and increasing cognitive decline, major impact on daily life (unable to live independently due to major cognitive impairment).
Types of Diagnostic Tests for MCI and Alzheimer’s Disease
There are several types of tests that can be used to detect early signs of cognitive impairment associated with dementia:
Cognitive Assessments: Typical tests for MCI and early signs of AD measure episodic (short term) memory capability, along with some executive function (planning and reasoning) skills. There is a large body of paper tests available that can be administered by a skilled clinician, such as a neurologist or neuropsychologist. This testing method usually takes two to three hours to administer, score, and interpret the results.
There are also some newer computerized cognitive testing batteries that show promise for use in standard primary care settings like the physician’s office and community health clinic. Most of the computer tests take less than 30 minutes to administer and are scored automatically through the software program, so this can be a very efficient cognitive health screening method for large (1+ million) populations. Medicare has implemented a new wellness visit benefit starting in 2011 that includes “detection of cognitive impairment”. With over 45 Million people on Medicare rolls, having a standardized, simple cognitive testing process will become increasingly important.
The NIA guidelines also recommend a longitudinal cognitive evaluation, a fancy term for creating a historical cognitive health record. Imagine being able to see a patient’s performance on a standard cognitive test battery over five or more years – the ability to see a decline in recent performance vs. five years ago would be very useful information for health care professionals.
Genetic Testing: If there is a strong family history of early-onset (before age 65) Alzheimer’s Disease (also known as Familial Alzheimer’s Disease – FAD), then genetic testing would be a good idea. FAD is quite rare, so most people won’t have a pressing need to take this genetic test. Genetic testing can also identify APOE4 gene carriers – APOE4 is implicated in late-onset (after age 65) AD, but the link between AD and APOE4 is pretty weak compared to the FAD genes.
Bottom line: Consider genetic testing when there is a strong family history of FAD.
Biomarker Tests: There has been significant media attention on using biomarkers to predict dementia and AD. Biomarker tests fall into two main categories – direct measurement of beta-amyloid and tau protein levels, and a variety of imaging techniques. The direct measurement method requires a sample of cerebrospinal fluid (CSF), while non-invasive imaging tests include MRI, PET, and SPECT scans.
The NIA guidelines do not recommend using biomarker tests for clinical diagnosis in the doctor’s office, but instead only for research and structured clinical trials. This is a wise and prudent choice – there are simply too many conflicting problems with biomarker tests right now. Along with an experimental blood test for predicting AD, biomarker tests will take a few more years to produce a reliable, standard, cost effective solution.
Part Two of this topic will include a description of the signs and symptoms of dementia and Alzheimer’s Disease.