Alzheimer's Disease & Dementia Subtypes
Clinical biomarkers, cognitive assessments, and differential diagnosis in Alzheimer's.
Clinical Summary
Alzheimer's disease (AD) is characterized by amyloid plaques and neurofibrillary tangles. The AT(N) framework uses biomarkers to define the disease biologically.
AT(N) Biomarker Framework
The National Institute on Aging–Alzheimer's Association (NIA-AA) research framework groups biomarkers into three categories:
- A (Amyloid): CSF Aβ42, or amyloid PET
- T (Tau): CSF phosphorylated tau (p-tau), or tau PET
- (N) (Neurodegeneration): CSF total tau (t-tau), FDG-PET, or structural MRI
Cognitive Screening
The Montreal Cognitive Assessment (MoCA) is highly sensitive for detecting mild cognitive impairment (MCI), a prodromal stage of dementia.
Related Tools
Common Clinical Mistakes
- Premature anchoring on common diagnoses without evaluating red flags.
- Over-reliance on neuroimaging while neglecting detailed physical exams.
- Suboptimal dosing of first-line agents before declaring treatment failure.
Frequently Asked Questions
- When is immediate specialist referral required?
- Urgent referral is indicated for sudden onset of severe symptoms, rapidly progressive deficits, or when standard therapies fail.
- What are the primary outcome measures in recent clinical trials?
- Most contemporary trials focus on slowing disease progression (e.g., EDSS in MS, UPDRS in Parkinson's) and reducing relapse/event rates.
- How does this condition impact patient life expectancy?
- While highly variable, modern disease-modifying therapies have significantly improved long-term survival rates across neurodegenerative and neuroimmunological disorders.