Dementia with Lewy Bodies (DLB), Parkinson's Disease (PD), and Alzheimer's Disease (AD) represent the three most common neurodegenerative disorders, each with distinct pathological hallmarks but significant clinical and mechanistic overlap. This comparison page synthesizes evidence across these conditions, highlighting shared mechanisms, biomarker profiles, clinical features, and therapeutic responses.
| Pathology |
DLB |
PD |
AD |
| Lewy bodies (α-syn) |
Cortical + limbic |
Brainstem + limbic |
Limited |
| Tau neurofibrillary tangles |
30-50% cases |
Variable |
Universal |
| Amyloid plaques |
30-50% cases |
20-30% |
Universal |
| Neuritic plaques |
Common |
Less common |
Universal |
flowchart LR
A["PD"] -->|"cognitive decline"| B(PDD)
A -->|"early dementia"| C(DLB)
A -->|"late dementia"| D(LBD)
C -.->|co-pathology| E["AD"]
style A fill:#90EE90
style C fill:#FFD700
style E fill:#FFA500
| Neurotransmitter |
DLB |
PD |
AD |
| Dopamine |
Severe loss |
Severe loss |
Mild |
| Acetylcholine |
Severe loss |
Moderate |
Moderate-severe |
| Serotonin |
Moderate-severe |
Moderate |
Variable |
| Norepinephrine |
Severe |
Moderate |
Mild |
| Biomarker |
DLB |
PD |
AD |
Interpretation |
| α-synuclein (CSF) |
↓↓ |
↓↓ |
→ |
Synucleinopathy marker |
| Total tau (CSF) |
↑ |
→ |
↑↑ |
Axonal damage |
| Phosphorylated tau (CSF) |
↑ |
→ |
↑↑ |
Tau pathology |
| NFL (CSF) |
↑↑ |
↑ |
↑↑ |
Neurodegeneration |
| β-amyloid 1-42 (CSF) |
↓ |
→ |
↓↓ |
Amyloid pathology |
| YKL-40 (CSF) |
↑ |
↑ |
↑↑ |
Neuroinflammation |
Legend: → normal, ↑ elevated, ↑↑ highly elevated, ↓↓ markedly reduced
| Modality |
DLB |
PD |
AD |
| DaTscan (DAT binding) |
↓↓ |
↓↓↓ |
↓ |
| MIBG cardiac scintigraphy |
↓↓ |
↓↓↓ |
→ |
| FDG-PET |
Occipital ↓ |
Posterior putamen ↓ |
Posterior cingulum ↓ |
| Amyloid PET |
30-50% + |
20-30% + |
80-90% + |
| Tau PET |
Variable |
Variable |
Universal |
- REM Sleep Behavior Disorder (RBD): 70-80% in DLB, 50-60% in PD, rare in AD
- Olfactory dysfunction: Severe in DLB/PD, moderate in AD
- Visual hallucinations: Core feature in DLB, late in PDD, rare in AD
| Feature |
DLB |
PDD |
AD |
| Cognitive fluctuation |
Core |
Common |
Rare |
| Visual hallucinations |
Core |
Common (late) |
Rare ( psychosis) |
| Parkinsonism |
Core |
Core |
Rare |
| RBD |
Core |
Common |
Rare |
| Orthostatic hypotension |
Common |
Common |
Variable |
| Domain |
DLB |
PDD |
AD |
| Attention |
Severe impairment |
Moderate |
Variable |
| Executive |
Severe |
Moderate-severe |
Moderate |
| Visuospatial |
Severe |
Moderate |
Moderate |
| Memory |
Variable |
Moderate |
Severe |
| Language |
Mild-moderate |
Mild |
Moderate-severe |
| Feature |
DLB |
PD |
AD |
| Bradykinesia |
Core |
Core |
Rare |
| Rigidity |
Common |
Core |
Rare |
| Tremor |
Less common |
Core |
Rare |
| Gait |
Early |
Progressive |
Late |
| Falls |
Early |
Variable |
Late |
| Treatment |
DLB |
PD/PDD |
AD |
Notes |
| Levodopa |
Moderate response |
Good response |
No response |
DLB less responsive |
| Cholinesterase inhibitors |
Strong response |
Moderate |
Good |
DLB > AD > PDD |
| Memantine |
Moderate |
Limited |
Moderate |
Variable |
| Antipsychotics |
Avoid |
Avoid |
Use cautiously |
DLB severe sensitivity |
| Clonazepam/RBD |
Effective |
Effective |
Not used |
For RBD only |
- Cholinesterase Inhibitors: DLB shows strongest response (up to 70% improvement), particularly for attentional deficits
- Levodopa: PD/PDD responds well, DLB shows moderate and often delayed response
- Antipsychotic Sensitivity: DLB patients show extreme vulnerability to antipsychotic-induced Parkinsonism and mortality
- Sleep Medications: Clonazepam effective for RBD in DLB/PD but not in AD
The continuum from PD to DLB to PDD reflects α-synuclein burden:
- PD: Brainstem-predominant
- PDD: Limbic + cortical spread
- DLB: Early cortical involvement with variable AD co-pathology
All three conditions show microglial activation:
- DLB + AD: Most common mixed pathology (30-50%)
- PD + AD: Less common but well-documented
- ** biomarker implications**: Co-pathology affects treatment response
| Feature |
DLB |
PD |
AD |
| Primary proteinopathy |
α-syn |
α-syn |
Tau/Aβ |
| Core cognitive feature |
Fluctuation |
Executive |
Memory |
| Visual hallucinations |
Early |
Late |
Rare |
| Parkinsonism |
Present |
Core |
Absent |
| RBD |
Very common |
Common |
Rare |
| Cholinesterase response |
Excellent |
Moderate |
Good |
| DaTscan |
↓↓ |
↓↓↓ |
↓ |
| Treatment priority |
Cholinesterase |
Dopamine |
Aβ-target |
Related diseases:
Related mechanisms: