Headshot depicting a woman living with Alzheimer's disease
Headshot depicting a woman living with Alzheimer's disease

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

Stage 1-2 Prelinical AD brain icon Stage 1-2 Prelinical AD brain icon

Stages 1 & 2

Preclinical AD

Evidence of AD pathological biomarkers, but no symptoms

Stage 3

Stage 3 MCI stage of AD brain icon Stage 3 MCI stage of AD brain icon

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

Explore the often subtle symptoms of MCI due to AD

Stage 4

Stage 4 Mild AD Dementia brain icon Stage 4 Mild AD Dementia brain icon

Stage 4

Mild AD dementia

Cognitive symptoms interfere with some daily activities1

Stage 5

Stage 5 Moderate AD Dementia brain icon Stage 5 Moderate AD Dementia brain icon

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 brain icon Stage 6 Severe AD Dementia brain icon

Stage 6

Severe AD dementia

Physical health is affected and care partner assistance becomes necessary

Signs and symptoms of MCI may include1:

Missing appointments calendar icon
Missing appointments
Asking questions icon
Asking the same questions repeatedly
Forgetting names icon
Forgetting names, places, and common items
Following instructions icon
Difficulty following instructions
Change in mood icon
Change in mood
Dates and time alarm clock icon
Confusion regarding dates and time
Apathy icon
Apathy

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

A for Aβ biomarker icon

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

T for Tau icon

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

N for Neurogeneration or Neuronal injury icon

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
Aβ=amyloid beta; AD=Alzheimer’s disease; AT(N)=amyloid-tau-neurodegeneration; FDG-PET=fluorodeoxyglucose positron emission tomography; MCI=mild cognitive impairment; MRI=magnetic resonance imaging; p-Tau=phosphorylated tau; t-Tau=total tau.

What to do if you suspect signs of MCI due to AD?

Find MCI diagnosis options

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