An Alzheimer’s Association workgroup has released the final version of the new diagnostic guidelines for the disease that take into account findings from the latest research.
In the new paper published in the journal Nature Medicine, medical researchers linked to the nonprofit for the first time call on doctors to factor in blood-based biomarkers (BBM) when diagnosing symptomatic patients.
Doctors have for long relied mainly on symptoms rather than conducting physical tests when trying to diagnose early-stage Alzheimer’s disease. The latest research, however, has revealed protein-based biomarkers that could assist with more accurate diagnoses of the disorder.
The researchers noted that their intention for sharing the revised diagnosis criteria at this time – while work continues to build knowledge of the disease – was to improve patient care and lessen the disease’s societal impact.
The latest update features an improved disease staging system.
A new biological diagnosis
The 2024 update of the diagnostic criteria for Alzheimer’s disease is a much-awaited one, at least in some quarters. This is because diagnosing with plasma biomarkers has been the standard for many other diseases for a long time.
Disorders that biomarkers are used for their diagnoses include diabetes, heart disease, and cancer. Researchers note that this method is fast becoming a unifying idea for all neurodegenerative diseases.
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The authors of this new paper state that research in recent years shows that these markers could help for Alzheimer’s as well. Researchers have discovered some that are reliable enough for making a diagnosis.
“An unchanging principle is that effective treatment will always rely on the ability to diagnose and stage the biology driving the disease process,” said lead author Dr. Clifford Jack, Jr., of Mayo Clinic.
Categories of biomarkers
According to the updated criteria, Alzheimer’s disease is a biological process that starts with brain changes that occur before patients even show symptoms. The progression of these changes leads to symptoms that later appear.
The paper authors classify diagnostic biomarkers into three main groups. The first are core markers specific to neuropathological changes linked to the disease. In the second category are non-core markers that are critical to immune activation, inflammation, or neurodegeneration that are not specific to Alzheimer’s. The last group of markers are those of common non-Alzheimer’s co-pathologies.
In addition, the team of medical researchers divided the category of core markers into two: Core 1 and Core 2.
The Core 1 sub-category includes markers that are typically present early in the progression of the disease. They include specific proteins in cerebrospinal fluid and amyloid buildup as well as phosphorylated tau in plasma. The authors also define criteria for these markers – for example, a 42/40 ratio for cerebrospinal fluid’s amyloid beta.
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Core 2 markers are those that become anomalous later in the progression of the disease and have a stronger link to symptoms. Tau PET and tau fragments in cerebrospinal fluid or plasma are examples.
A combination of Core 1 and Core 2 biomarkers will both help to diagnose and reveal the severity of Alzheimer’s, the researchers state. These revised criteria are mainly for diagnosing symptomatic patients. The guidelines are not likely to be used for prescribing early therapies.
This update is a much-needed one. Relying on symptoms to diagnose this disease – which has been the practice for long – is inadequate. Symptoms seen in patients may also be caused by other conditions. The use of biomarkers looks to produce more accurate diagnoses.
References
Jack, C.R., Andrews, S.J., Beach, T.G. et al. Revised criteria for the diagnosis and staging of Alzheimer’s disease. Nat Med (2024). https://doi.org/10.1038/s41591-024-02988-7
Alzheimer’s Association Workgroup Publishes Biology-Based Criteria for Diagnosis and Staging of Alzheimer’s Disease (2024). https://www.alz.org/news/2024/revised-alzheimers-diagnostic-staging-criteria
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