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Prediction of dementia in MCI patients based on core diagnostic markers for Alzheimer disease
Annapaola Prestia1, Anna Caroli, Wiesje M van der Flier
1LENITEM-Laboratory of Epidemiology Neuroimaging and Telemedicine, IRCCS Centro San Giovanni di Dio FBF, Brescia, Italy.
Objectives:
The current model of Alzheimer disease (AD) stipulates that brain amyloidosis biomarkers turn abnormal earliest, followed by cortical hypometabolism, and finally brain atrophy ones. The aim of this study is to provide clinical evidence of the model in patients with mild cognitive impairment (MCI).
Methods:
A total of 73 patients with MCI from 3 European memory clinics were included. Brain amyloidosis was assessed by CSF Aβ42 concentration, cortical metabolism by an index of temporoparietal hypometabolism on FDG-PET, and brain atrophy by automated hippocampal volume. Patients were divided into groups based on biomarker positivity: 1) Aβ42- FDG-PET- Hippo-, 2) Aβ42+ FDG-PET- Hippo-, 3) Aβ42 + FDG-PET + Hippo-, 4) Aβ42 + FDG-PET+ Hippo+, and 5) any other combination not in line with the model. Measures of validity were prevalence of group 5, increasing incidence of progression to dementia with increasing biological severity, and decreasing conversion time.
Results:
When patients with MCI underwent clinical follow-up, 29 progressed to dementia, while 44 remained stable. A total of 26% of patients were in group 5. Incident dementia was increasing with greater biological severity in groups 1 to 5 from 4% to 27%, 64%, and 100% (p for trend < 0.0001), and occurred increasingly earlier (p for trend = 0.024).
Conclusions:
The core biomarker pattern is in line with the current pathophysiologic model of AD. Fully normal and fully abnormal pattern is associated with exceptional and universal development of dementia. Cases not in line might be due to atypical neurobiology or inaccurate thresholds for biomarker (ab)normality.
Insights
This study validates the Alzheimer disease (AD) biomarker model in mild cognitive impairment (MCI) patients. Findings show a clear link between biomarker abnormality progression and dementia development, supporting the current AD pathophysiologic model.
Area of Science:
- Neurology
- Biomarker Research
- Neurodegenerative Diseases
Background:
- The established Alzheimer disease (AD) model posits a specific biomarker sequence: amyloidosis, then hypometabolism, and finally atrophy.
- Clinical validation of this model in early-stage neurodegeneration, such as mild cognitive impairment (MCI), is crucial for understanding disease progression.
Purpose of the Study:
- To provide clinical evidence supporting the current Alzheimer disease pathophysiologic model in patients with mild cognitive impairment (MCI).
- To assess the relationship between biomarker abnormality patterns and the progression to dementia in an MCI cohort.
Main Methods:
- Included 73 MCI patients from European memory clinics.
- Assessed brain amyloidosis (CSF Aβ42), cortical metabolism (FDG-PET temporoparietal hypometabolism index), and brain atrophy (hippocampal volume).
- Categorized patients into groups based on biomarker positivity and analyzed dementia progression rates and timing.
Main Results:
- Of 73 MCI patients, 29 progressed to dementia over follow-up.
- Incident dementia rates increased significantly with greater biological severity (4% to 100%, p < 0.0001).
- Progression to dementia occurred earlier in patients with more advanced biomarker abnormalities (p = 0.024).
Conclusions:
- The observed biomarker patterns align with the current pathophysiologic model of Alzheimer disease.
- A fully normal biomarker profile was associated with exceptional outcomes, while a fully abnormal profile predicted universal dementia development.
- Deviations from the model may indicate atypical neurobiology or issues with biomarker abnormality thresholds.
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