This page provides a comprehensive comparative analysis of the major tauopathies—Alzheimer's Disease (AD), Corticobasal Degeneration (CBD), Progressive Supranuclear Palsy (PSP), and Frontotemporal Lobar Degeneration with tau pathology (FTLD-tau). These disorders share the common feature of abnormal tau protein accumulation but differ significantly in their clinical presentations, anatomical distributions, tau isoforms involved, and genetic risk factors[1].
The tau protein exists in six isoforms in the adult human brain, generated by alternative splicing of exons 2, 3, and 10 in the MAPT gene. The key distinction is between three-repeat (3R) and four-repeat (4R) tau isoforms, determined by the inclusion or exclusion of exon 10[2].
| Disease | Primary Tau Isoform | 3R:4R Ratio | Key Distinction |
|---|---|---|---|
| Alzheimer's Disease | Mixed 3R + 4R | 1:1 | Both 3R and 4R tau in NFTs |
| CBD | 4R tau | 0:1 | Exclusively 4R tau |
| PSP | 4R tau | 0:1 | Exclusively 4R tau |
| FTLD-tau | Variable (mutation-dependent) | Variable | Depends on MAPT mutation |
Recent cryo-electron microscopy studies have revealed distinct tau filament folds in each tauopathy, supporting the tau strain hypothesis[3]:
| Disease | Filament Type | Structural Features |
|---|---|---|
| AD | Paired Helical Filaments (PHFs) | Classic helical structure, cross-β sheet |
| CBD | CBD Fold | Distinct helical filament architecture |
| PSP | PSP Fold (Globose NFTs) | 4R tau filaments, compact tangles |
| FTLD-tau | Variable | Depends on underlying mutation |
| Modification | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Hyperphosphorylation | +++ | +++ | +++ | ++ |
| Acetylation | ++ | + | + | ++ |
| Truncation | ++ | + | + | ++ |
| Glycation | + | - | - | + |
| Ubiquitination | ++ | + | + | ++ |
| Brain Region | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Frontal Cortex | Late (neocortex) | ++ (early) | + (premotor) | +++ (early) |
| Parietal Cortex | Late | ++ | - | ++ |
| Temporal Cortex | Early (entorhinal) | + | - | ++ |
| Occipital Cortex | Late | - | - | + |
| Hippocampus | +++ (early) | - | - | + |
| Basal Ganglia | + | +++ | +++ | ++ |
| Substantia Nigra | + | +++ | +++ | + |
| Brainstem | + (later) | + | +++ | + |
| Cerebellum | - | + (dentate nucleus) | + (dentate) | - |
Alzheimer's Disease:
Corticobasal Degeneration:
Progressive Supranuclear Palsy:
FTLD-tau:
| Feature | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Cognitive Decline | ++ (memory prominent) | ++ (executive) | + (executive) | +++ (executive/social) |
| Motor Symptoms | + (late) | +++ (asymmetric) | +++ (akinesia) | + (if present) |
| Eye Movement | - | - | +++ (vertical gaze palsy) | - |
| Postural Instability | - | ++ | +++ (falls early) | - |
| Language | + (anomia) | + | - | +++ (aphasia) |
| Behavior | + (late) | + | + | +++ (early) |
| Asymmetry | - | +++ | - | -/+ |
Alzheimer's Disease:
Corticobasal Degeneration:
Progressive Supranuclear Palsy:
FTLD-tau:
| Metric | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Typical Onset (years) | 65-80 | 50-70 | 60-70 | 45-65 |
| Disease Duration (years) | 8-15 | 5-10 | 5-10 | 6-12 |
| Survival from Onset | 8-12 years | 6-8 years | 5-7 years | 6-11 years |
| Gene | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| MAPT | Risk (H1 haplotype) | ++ (H1) | ++ (H1) | ++ (mutations) |
| APOE | ++ (ε4 risk) | - | - | - |
| GRN | - | + | - | ++ (mutations) |
| LRRK2 | + (risk) | + | + (risk) | - |
| C9orf72 | - | - | - | ++ (expansion) |
| TARDBP | - | - | - | + |
| VCP | - | - | - | + |
The H1 haplotype of MAPT is a significant risk factor for sporadic tauopathies[4]:
Specific MAPT mutations cause familial FTLD-tau:
| Mutation | Exon | Effect | Phenotype |
|---|---|---|---|
| P301L | 10 | Increased aggregation | CBD/PSP/FTD |
| P301S | 10 | Increased aggregation | CBD/FTD |
| V337M | 12 | Altered splicing | FTD |
| R406W | 13 | Reduced binding | FTD/AD-like |
| Approach | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Symptomatic | Donepezil, memantine | Limited | Limited | Limited |
| Tau Aggregation Inhibitors | In trials | Preclinical | Preclinical | Preclinical |
| Immunotherapy | Phase 2/3 | Preclinical | Preclinical | Preclinical |
| Kinase Inhibitors | GSK-3β in trials | Preclinical | Preclinical | Preclinical |
Active/Recent Anti-Tau Trials for AD:
Disease-Modifying Approaches:
| Symptom | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Cognitive | Cholinesterase inhibitors | None | None | None |
| Motor | None | Dopamine agonists | Limited | None |
| Behavioral | Antidepressants | Antidepressants | Antidepressants | SSRIs |
| Sleep | Melatonin | Clonazepam | Melatonin | Varies |
| Marker | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Total tau | Elevated ++ | Normal/+ | Normal/+ | Normal/+ |
| p-tau181 | Elevated +++ | Normal/+ | Normal/+ | Normal/+ |
| p-tau217 | Elevated +++ | Normal | Normal | Normal |
| p-tau231 | Elevated ++ | Normal | Normal | Normal |
| NfL | Elevated ++ | Elevated ++ | Elevated ++ | Elevated + |
| Tracer | Target | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|---|
| ^18F-AV-1451 | PHF tau | ++ | + | + | + |
| ^18F-MK-6240 | PHF tau | ++ | + | + | + |
| ^18F-GT1 | 4R tau | - | ++ | ++ | Variable |
| ^11C-PBB3 | All tau | ++ | ++ | ++ | ++ |
| Feature | AD | CBD | PSP | FTLD-tau |
|---|---|---|---|---|
| Memory loss | First/dominant | Late/mild | Late/mild | Late/mild |
| Motor onset | Late | Early (asymmetric) | Early (symmetric) | Variable |
| Eye movements | Normal | Normal | VSGP | Normal |
| Speech | Anomia | Dysarthria | Hypophonia | Aphasia |
| Personality | Preserved | Preserved | Apathy | Disinhibited |
NINDS-SPSP Criteria for PSP:
Core Clinical Features for CBD:
Goedert M, et al. Tauopathies: Update and perspective. Brain Res Bull. 2022;182:34-48. 2022. ↩︎
Wang Y, Mandelkow E. Tau in physiology and pathology. Nat Rev Neurosci. 2016;17(1):5-21. 2016. ↩︎
Fitzpatrick M, et al. Cryo-EM structures of tau filaments from Alzheimer's disease brain. Nature. 2017;547(7662):185-190. 2017. ↩︎
Connor L, et al. MAPT haplotype H1 is associated with increased risk of PSP and CBD. Neurology. 2004;63(1):166-167. 2004. ↩︎