AMPA receptor shifts link ketamine to symptom relief in treatment resistant depression
Mar 9th 2026
A PET study using the new tracer [11C]K-2 mapped AMPA receptor distribution in people with treatment resistant depression and found that ketamine’s antidepressant effect aligns with region-specific increases and decreases in AMPA receptors, notably reductions in the habenula and increases in parietal and occipital cortex.
- Researchers used a new PET tracer, [11C]K-2, to measure cell surface AMPA receptor density in 34 Japanese patients with treatment resistant depression and 49 healthy controls.
- Lower baseline AMPA receptor density across frontal, parietal, occipital cortices and cerebellum correlated with greater depression severity.
- Compared with controls, TRD patients showed regionally reduced AMPA density in anterior insula, cingulate and parts of frontal-parietal-occipital cortex and increased density in cerebellum, temporal lobe, thalamus and basal ganglia.
- Repeated ketamine infusions (0.5 mg/kg twice weekly for two weeks) produced region-specific AMPA receptor changes that correlated with clinical improvement, including increases in parietal, occipital and middle cingulate cortex.
- Reduction of AMPA receptors in the habenula and some reward regions after ketamine was associated with better antidepressant response, consistent with prior animal studies.
- Higher pre-treatment AMPA receptor density in several cortical and basal ganglia regions predicted greater symptom improvement with ketamine.
- Limitations include a small imaging sample, a single-ethnicity cohort, and potential unblinding from ketamine side effects, so findings need replication in larger and more diverse samples.