¶ title: Excitotoxicity Comparison Across Neurodegenerative Diseases
description: Comparison matrix showing how excitotoxicity manifests across AD, PD, ALS, FTD, and HD
published: true
tags: kind:mechanism, section:mechanisms, state:published
editor: markdown
pageId: 100000
dateCreated: "2026-03-25T18:45:00.000Z"
dateUpdated: "2026-03-25T18:45:00.000Z"
refs:
mattson2004:
authors: Mattson MP
title: Pathways towards and away from Alzheimer's disease
journal: Nature
year: 2004
doi: 10.1038/nature03089
blandini1998:
authors: Blandini F, Greenamyre JT
title: Prospects for glutamate antagonism in Parkinson's disease
journal: Drug Aging
year: 1998
rothstein1995:
authors: Rothstein JD
title: Excitotoxicity and ALS
journal: Adv Neurol
year: 1995
bezard2003:
authors: Bezard E, Brotchie J
title: Excitotoxicity and Huntington's disease
journal: Prog Neuropsychopharmacol Biol Psychiatry
year: 2003
Excitotoxicity is a pathological process where excessive glutamate receptor activation leads to neuronal damage and death. While the core mechanism—glutamate-induced neuronal injury—is conserved across neurodegenerative diseases, the specific manifestations, trigger factors, and therapeutic responses differ significantly. This comparison matrix highlights these disease-specific features.
| Feature |
Alzheimer's Disease |
Parkinson's Disease |
ALS |
Huntington's Disease |
FTD |
| Primary Trigger |
Aβ oligomers, Tau pathology |
Dopaminergic neuron loss, α-synuclein |
TDP-43, SOD1 mutations |
Mutant huntingtin |
Tau, FUS |
| Key Glutamate Receptor |
NMDA (extrasynaptic) |
mGluR5, NMDA |
AMPA, NMDA |
NMDA, mGluR1 |
NMDA |
| Transporter Dysfunction |
EAAT2 impairment |
EAAT1/2 reduced |
EAAT2 loss |
EAAT1 reduction |
EAAT2 |
| Calcium Dysregulation |
Mitochondrial overload |
Cav1.3 L-type channels |
AMPA receptor permeability |
NMDAR-mediated |
NMDAR-mediated |
| Therapeutic Target |
Memantine |
mGluR5 antagonists |
Riluzole |
MAST inhibitors |
Memantine |
| Evidence Level |
Strong |
Moderate |
Strong |
Moderate |
Emerging |
Primary Features:
- Aβ oligomers impair glutamate transporter function (EAAT2)
- Enhanced NMDA receptor surface expression
- Synaptic NMDA receptor loss with compensatory extrasynaptic activity
- Tau pathology increases neuronal vulnerability to excitotoxic damage
Key Evidence:
- Memantine approved for moderate-to-severe AD
- NMDA receptor antagonists show neuroprotection in models@mattson2004
Primary Features:
- Loss of dopaminergic modulation increases cortical excitability
- α-synuclein affects astrocytic glutamate uptake
- mGluR5 overactivity contributes to excitotoxicity
- L-type calcium channel (Cav1.3) dysfunction
Key Evidence:
- mGluR5 antagonists (mavoglurant) tested for levodopa-induced dyskinesia
- Amantadine provides glutamatergic modulation
Primary Features:
- Progressive loss of EAAT2 (astrocytic glutamate transporter)
- Mutations in SOD1 cause motor neuron vulnerability
- Impaired RNA editing of GluA2 (Q/R site)
- Cell-to-cell propagation via exosomes
Key Evidence:
- Riluzole approved (modest survival benefit)@rothstein1995
- Edaravone reduces oxidative/excitotoxic damage
Primary Features:
- Mutant huntingtin affects NMDA receptor function
- Enhanced excitability of medium spiny neurons
- Mitochondrial dysfunction amplifies calcium influx
- mGluR1/5 dysregulation
Key Evidence:
- MAST inhibitors in development
- Riluzole tested with mixed results@bezard2003
Primary Features:
- Tau pathology associated with excitotoxicity
- FUS mutations cause RNA splicing abnormalities
- TDP-43 pathology affects neuronal excitability
- Less glutamate-centric than other diseases
Key Evidence:
- Memantine trials showed limited efficacy
- Research ongoing
| Drug/Approach |
AD |
PD |
ALS |
HD |
FTD |
| NMDA antagonists |
✓ |
- |
- |
✓ |
✓ |
| AMPA modulators |
- |
- |
✓ |
- |
- |
| mGluR5 antagonists |
- |
✓ |
- |
✓ |
- |
| Glutamate release inhibitors |
- |
- |
✓ |
- |
- |
| Transporter enhancers |
✓ |
✓ |
✓ |
- |
- |
The following excitotoxic mechanisms are common to multiple diseases:
- Glutamate Transporter Dysfunction: EAAT2 impairment is observed in AD, PD, ALS, and HD
- Calcium Dysregulation: Mitochondrial calcium overload across all five diseases
- Oxidative Stress: Amplifies excitotoxic damage in all conditions
- Neuroinflammation: Microglial activation contributes to excitotoxicity
- AD: Synaptic vs extrasynaptic NMDA receptor balance is critical
- PD: Loss of dopaminergic inhibition increases excitability
- ALS: Rapid progression with prominent EAAT2 loss
- HD: Enhanced NMDAR signaling in striatal neurons
- FTD: Less prominent glutamate dysfunction compared to other proteinopathies