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β-Amyloid PET and 123I-FP-CIT SPECT in Mild Cognitive Impairment at Risk for Lewy Body Dementia
Qin Chen1, Val J Lowe1, Bradley F Boeve1
1From the Department of Neurology (Q.C.), West China Hospital of Sichuan University, Chengdu; Departments of Radiology (Q.C., V.J.L., M.L.S., C.R.J., H.-K.M., C.G.S., J.L.G., K.K.), Neurology (B.F.B., T.M., J.G.-R., R.S., D.S.K., D.J., R.C.P.), Health Sciences Research (S.A.P., T.G.L., W.K.K.), and Psychology and Psychiatry (J.A.F.), Mayo Clinic, Rochester, MN; and Departments of Psychology and Psychiatry (T.J.F.) and Neurology (N.R.G.-R.), Mayo Clinic, Jacksonville, FL.
Objective:
To determine the clinical phenotypes associated with the β-amyloid PET and dopamine transporter imaging (123I-FP-CIT SPECT) findings in mild cognitive impairment (MCI) with the core clinical features of dementia with Lewy bodies (DLB; MCI-LB).
Methods:
Patients with MCI who had at least 1 core clinical feature of DLB (n = 34) were grouped into β-amyloid A+ or A- and 123I-FP-CIT SPECT D+ or D- groups based on previously established abnormality cut points for A+ with Pittsburgh compound B PET standardized uptake value ratio (PiB SUVR) ≥1.48 and D+ with putamen z score with DaTQUANT <-0.82 on 123I-FP-CIT SPECT. Individual patients with MCI-LB fell into 1 of 4 groups: A+D+, A+D-, A-D+, or A-D-. Log-transformed PiB SUVR and putamen z score were tested for associations with patient characteristics.
Results:
The A-D+ biomarker profile was most common (38.2%), followed by A+D+ (26.5%) and A-D- (26.5%). The least common was the A+D- biomarker profile (8.8%). The A+ group was older, had a higher frequency of APOE ε4 carriers, and had a lower Mini-Mental State Examination score than the A- group. The D+ group was more likely to have probable REM sleep behavior disorder. Lower putamen DaTQUANT z scores and lower PiB SUVRs were independently associated with higher Unified Parkinson's Disease Rating Scale-III scores.
Conclusions:
A majority of patients with MCI-LB are characterized by low β-amyloid deposition and reduced dopaminergic activity. β-Amyloid PET and 123I-FP-CIT SPECT are complementary in characterizing clinical phenotypes of patients with MCI-LB.
Insights
Mild cognitive impairment with dementia with Lewy body features often shows low amyloid and dopamine transporter levels. Combining β-amyloid PET and 123I-FP-CIT SPECT imaging helps define clinical phenotypes in MCI-LB patients.
Area of Science:
- Neuroimaging
- Neurology
- Biomarker Discovery
Background:
- Mild cognitive impairment (MCI) is a transitional stage between normal cognition and dementia.
- Dementia with Lewy bodies (DLB) is a common neurodegenerative disorder characterized by cognitive decline, parkinsonism, and REM sleep behavior disorder.
- Identifying MCI with DLB core clinical features (MCI-LB) is crucial for early diagnosis and management.
Purpose of the Study:
- To investigate the clinical phenotypes associated with β-amyloid PET and dopamine transporter imaging (123I-FP-CIT SPECT) in patients with MCI-LB.
- To determine the utility of combining these imaging modalities for characterizing MCI-LB.
Main Methods:
- Patients with MCI and at least one DLB core clinical feature were categorized based on β-amyloid PET (A+ or A-) and 123I-FP-CIT SPECT (D+ or D-) findings.
- Biomarker profiles (A+D+, A+D-, A-D+, A-D-) were analyzed in relation to patient characteristics.
- Log-transformed PiB SUVR and putamen z scores were correlated with clinical variables.
Main Results:
- The A-D+ profile was most common (38.2%), followed by A+D+ and A-D- (26.5% each).
- The A+ group was older, had more APOE ε4 carriers, and lower Mini-Mental State Examination scores.
- Reduced dopaminergic activity (D+) was linked to probable REM sleep behavior disorder, and lower imaging scores correlated with higher Parkinson's disease symptom severity.
Conclusions:
- Most MCI-LB patients exhibit reduced β-amyloid deposition and dopaminergic activity.
- β-Amyloid PET and 123I-FP-CIT SPECT are complementary tools for defining MCI-LB clinical phenotypes.
- These imaging biomarkers aid in understanding the heterogeneity of MCI-LB.
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