Understanding Mild Cognitive Impairment and Alzheimer's Disease
The early stages of Alzheimer’s disease (AD) represent a critical window for detection.1
AD is a progressive neurodegenerative disease marked by cognitive and functional impairment that eventually interferes with daily living. The underlying pathology begins years before the symptoms appear.1
Stages of AD1
Stages 1 & 2
Stages 1 & 2
Preclinical AD
Evidence of AD pathological biomarkers, but no symptoms
Stage 3
Stage 3
MCI due to AD
Mild cognitive symptoms appear, but do not interfere with daily activities
The mild cognitive impairment (MCI) stage of AD is the first symptomatic stage
Stage 4
Stage 4
Mild AD dementia
Cognitive symptoms interfere with some daily activities1
Stage 5
Stage 5
Moderate AD dementia
Daily activities become more difficult, behavior may change, and some care partner assistance may be required
Stage 6
Stage 6
Severe AD dementia
Physical health is affected and care partner assistance becomes necessary
Signs and symptoms of MCI may include1:
AD Pathology
2023 Revised Clinical Criteria Have Placed Greater Emphasis on Biomarkers to Diagnose Alzheimer’s Disease
In 2023, the NIA-AA working group published draft revised Clinical Criteria for Alzheimer’s Disease to redefine an AD diagnosis based on biological markers rather than solely on clinical symptoms. This shift allows for the diagnosis of AD through the identification of biomarker abnormalities, known as the AT(N) framework.1,2
Abnormal amyloid beta accumulation results from an imbalance between its production and clearance in the aging brain which may start up to 20 years before clinical symptoms appear. (Biomarker tests include Amyloid PET, CSF Aβ42/40, Blood Aβ42/40)1-3
Abnormal tau proteins, which accumulate inside the neuron exacerbating brain damage throughout.1 (Biomarker tests include Tau PET, CSF p-Tau(s), Blood p-Tau 217)1,3,4
As the proliferation of toxicity continues, this ultimately leads to neurodegeneration. As neurons and connections are lost, the brain’s ability to process and store information becomes impaired, resulting in the inability to form or retrieve memories. (Biomarker tests include FDG PET structural MRI, CSF t-Tau)1,3,4
A full clinical workup is still necessary; as with any biomarker, simply detecting biological changes is insufficient for definitive diagnosis.3
See the role of amyloid beta (Aβ) in the pathophysiology of Alzheimer’s disease
Blood biomarker (BBM) tests may help identify patients at risk for Alzheimer’s disease in the primary care setting5
- Recent advancements in biomarker detection now enable the use of blood tests to aid in clinical diagnosis, providing previously inaccessible insights5,6
- Amyloid beta concentration may be measured via BBM tests in symptomatic individuals and may aid in the collection of evidence to triage a patient to a specialist. Available assays will measure amyloid by the marker of Aβ 42/406
- Some tests also measure p-Tau protein 217 in plasma with high accuracy and correlate with AD pathology5-7
- BBM tests are not intended as stand-alone diagnostic tests and should be integrated with patient history, brain imaging, routine laboratory tests, and other tests as appropriate5,7
Additional tests may be done in the specialized setting to verify diagnosis
- Including but not limited to PET imaging or a lumbar puncture to collect cerebral spinal fluid (CSF) to confirm brain amyloid pathology or MRI imaging to measure the severity of the disease1,4,5
What to do if you suspect signs of MCI due to AD?
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