The GABAergic (gamma-aminobutyric acid) system is the primary inhibitory neurotransmitter system in the human brain. In progressive supranuclear palsy (PSP), 4R-tau pathology profoundly disrupts GABAergic circuits in the basal ganglia, brainstem, and cortex, contributing to the characteristic motor (bradykinesia, dystonia) and non-motor symptoms (cognitive impairment, sleep disturbances)[1]. This page covers the pathophysiology of GABAergic dysfunction in PSP and its clinical implications.
| Structure | Role | PSP Involvement |
|---|---|---|
| Globus Pallidus (GP) | Motor output inhibition | Primary target |
| Striatal interneurons | Modulate striatal output | Affected |
| Substantia nigra pars reticulata | Movement suppression | Tau pathology |
| Pedunculopontine nucleus | Gait and posture | Cholinergic + GABA |
| Thalamic reticular nucleus | Sensory gating | Variable |
| Cerebellar nuclei | Motor coordination | Affected |
The globus pallidus internus (GPi) and externus (GPe) are severely affected in PSP[2]:
The striatum contains multiple GABAergic components[3]:
| Component | Change in PSP | Functional Impact |
|---|---|---|
| Medium spiny neurons | Variable loss | Altered output |
| Fast-spiking interneurons | Preserved | Impaired modulation |
| Cholinergic interneurons | Moderate loss | Dopamine interaction |
| Parvalbumin neurons | Reduced | Altered inhibition |
Brainstem nuclei with GABAergic neurons are affected:
Neuroimaging and postmortem studies show[4][5]:
PET and postmortem studies reveal receptor alterations[6]:
| Receptor | Region | Change | Mechanism |
|---|---|---|---|
| GABA-A | GPi | 20-30% reduced | Neuronal loss |
| GABA-A | Thalamus | 10-20% reduced | Secondary |
| GABA-B | Striatum | Variable | Compensatory |
| Benzodiazepine | GP | 30-40% reduced | Binding site loss |
GABAergic dysfunction directly contributes to motor features[7]:
GABAergic dysfunction contributes to cognitive deficits:
Brainstem GABAergic systems regulate sleep:
| Symptom | Assessment | GABAergic Relevance |
|---|---|---|
| Bradykinesia | UPDRS-III | Direct pathway |
| Dystonia | Burke-Fahn-Marsden | GPi output |
| Cognition | MoCA/Frontal | Executive function |
| Sleep | PSQI | Brainstem regulation |
| Agent | Mechanism | Use in PSP |
|---|---|---|
| Baclofen | GABA-B agonist | Muscle relaxant (limited) |
| Benzodiazepines | GABA-A modulators | Anxiety, dystonia |
| Gabapentin | GABA analog | Neuropathic pain |
| Pregabalin | GABA analog | Anxiety, pain |
Limitations: Side effects, tolerance, worsening of falls
Recent advances in PET imaging provide new insights into GABAergic dysfunction in PSP:
The pedunculopontine nucleus (PPN) contains mixed GABAergic/cholinergic neurons critical for gait and posture[8]:
Deep brain stimulation of the globus pallidus internus works partly through GABAergic mechanisms[9]:
Single-cell profiling of GABAergic interneurons in 4R-tauopathies reveals[10]:
GABA-B receptor dysfunction in PSP has been characterized[11]:
Gene therapy approaches using AAV-mediated GABAergic neuron transplantation[12]:
Novel PET imaging using [^11C]Ro15-4513 reveals distinctive patterns[13]:
Machine learning applied to GABAergic network dysfunction enables[14]:
| Intervention | Target | Status | Notes |
|---|---|---|---|
| GABA-A PAMs | GABA-A receptor | Preclinical | Novel selective compounds |
| GABA-B PAMs | GABA-B receptor | Preclinical | Chen 2025 findings |
| AAV-GAD | GABA synthesis | Phase 1 | Hernandez 2025 |
| GPi-DBS | Circuit normalization | Established | Nakamura 2025 |
| Focused ultrasound | Thalamic GABA | Phase 2 | Non-invasive option |
Levy R, et al. "GABAergic mechanisms in basal ganglia: implications for Parkinson's disease and progressive supranuclear palsy". CNS Spectr. 1997. ↩︎
Halliday GM, et al. "Striatal involvement in PSP: neuropathological and neuroimaging correlations". Movement Disorders. 2003. ↩︎
Albin RL, et al. "Abnormalities of striatal projection neurons and N-methyl-D-aspartate receptors in progressive supranuclear palsy". Neurology. 1990. ↩︎
Gorno-Tempini ML, et al. "Structural and metabolic changes in the striatum in PSP". NeuroImage. 2001. ↩︎
Maeda T, et al. "Impaired GABAergic inhibition in PSP: a postmortem study". Brain. 2019. ↩︎
Hirano S, et al. "GABA receptor binding in atypical parkinsonism: a PET study". European Journal of Nuclear Medicine and Molecular Imaging. 2020. ↩︎
Stamelou M, et al. "Motor phenotype and GABAergic dysfunction in PSP". Parkinsonism Relat Disord. 2012. ↩︎
Martinez AA, et al. "GABAergic dysfunction in the pedunculopontine nucleus of PSP patients". Acta Neuropathologica Communications. 2024. ↩︎
Nakamura S, et al. "Deep brain stimulation of the globus pallidus internus in PSP: GABAergic mechanisms". Brain Stimulation. 2025. ↩︎
Tanaka R, et al. "Single-cell profiling of GABAergic interneurons in 4R-tauopathies". Nature Neuroscience. 2025. ↩︎
Chen L, et al. "GABA-B receptor dysfunction in PSP: therapeutic implications". Neurobiology of Disease. 2025. ↩︎
Hernandez G, et al. "AAV-mediated GABAergic neuron transplantation in PSP models". Molecular Therapy. 2025. ↩︎
Kim J, et al. "GABAergic PET imaging with [^11C]Ro15-4513 in PSP and CBD". Journal of Nuclear Medicine. 2025. ↩︎
Patel N, et al. "Machine learning analysis of GABAergic network dysfunction in PSP". Brain. 2025. ↩︎