Four Drugs, One Target: GSK3β and the Accidental Discovery of Why Psychedelics Treat Depression

Why ketamine, psilocybin, MDMA, and lithium all make the world feel brighter — and what that means for treatment

Carla — Draft, April 2026

The Observation

Four pharmacologically distinct substances produce a strikingly similar subjective experience in people with depression: the world feels brighter, colors are more vivid, things feel worth doing again, and the flat gray film that depression lays over experience lifts. These substances are:

• Ketamine — an NMDA receptor antagonist
• Psilocybin — a serotonin 5-HT2A receptor agonist
• MDMA — a serotonin/dopamine/norepinephrine releaser
• Lithium — a direct enzyme inhibitor

They bind different receptors. They affect different neurotransmitter systems. They are studied by different research communities who rarely cite each other. The ketamine people think the mechanism is glutamate. The psilocybin people think it’s serotonin. The MDMA people think it’s empathogenic bonding. The lithium people think it’s mood stabilization.

They are all wrong about why their drug works. Or rather, they are all partially right about their drug’s entry point and collectively blind to the shared destination.

All four converge on a single downstream target: glycogen synthase kinase 3 beta (GSK3β).

What Is GSK3β?

GSK3β is a kinase — an enzyme that phosphorylates other proteins, modifying their function. It was originally discovered in the context of glycogen metabolism, but it is now known to regulate an extraordinary range of cellular functions: neuronal survival, synaptic plasticity, neurotransmitter receptor trafficking, circadian rhythm, inflammation, and gene transcription. GSK3β has over 100 known substrates. It is expressed in every cell in the body but is particularly abundant in the brain, where a neuron-specific isoform (GSK3β2) predominates.

The critical property of GSK3β is that it is constitutively active. Unlike most kinases that are turned on by a signal, GSK3β is always on unless something is actively suppressing it. It is the default destruction mode. When left unopposed, GSK3β promotes apoptosis, degrades synaptic proteins, impairs BDNF signaling, disrupts circadian rhythms, and promotes neuroinflammation. The cell must continuously suppress GSK3β to maintain normal function.

The primary endogenous suppression pathway runs through cortisol: cortisol → glucocorticoid receptor (GR) → PI3K/Akt → phosphorylation of GSK3β at Ser9 → inhibition. When cortisol signaling is adequate and GR is functioning, GSK3β stays suppressed and the brain works normally. When cortisol is low, or GR is desensitized, or the upstream chain is broken for any reason, GSK3β becomes overactive.

Overactive GSK3β in the brain produces: reduced BDNF, dendritic spine retraction, impaired synaptic plasticity, disrupted dopamine and serotonin signaling, neuroinflammation, and circadian fragmentation. In animal models, GSK3β overactivation specifically in the nucleus accumbens (ventral striatum) produces depression-like behavior (Polter et al., 2010). Conversely, GSK3β knockin mice — animals engineered so GSK3β cannot be inhibited — show heightened vulnerability to stress-induced depression.

GSK3β is not “a factor in depression.” It may be the convergent molecular endpoint of depression itself.

Four Entry Points, One Target

Ketamine → GSK3β

Ketamine blocks NMDA receptors, which triggers a cascade: NMDA antagonism → disinhibition of glutamate release → AMPA receptor activation → BDNF release → TrkB activation → PI3K/Akt activation → phosphorylation of GSK3β at Ser9 → inhibition.

This was demonstrated directly by Beurel et al. (2011), who showed that ketamine’s antidepressant effect in mice requires GSK3β inhibition. When they used GSK3β knockin mice (where GSK3β cannot be inhibited by phosphorylation), ketamine’s antidepressant effect was abolished. The drug still blocked NMDA receptors. It still released glutamate. It still activated AMPA. But without the ability to inhibit GSK3β at the end of the chain, none of it mattered.

The primary brain regions affected: prefrontal cortex and hippocampus, where NMDA receptor density and the specific interneuron circuitry that mediates disinhibition are strongest.

Psilocybin → GSK3β

Psilocin (the active metabolite of psilocybin) agonizes serotonin 5-HT2A receptors. 5-HT2A activation engages the PI3K/Akt signaling pathway → phosphorylation of GSK3β at Ser9 → inhibition.

Psilocybin also increases BDNF, which feeds back through TrkB to further suppress GSK3β. The acute psychedelic experience and the sustained antidepressant effect may operate through different mechanisms: the trip is 5-HT2A-mediated perception alteration; the lasting benefit is GSK3β-mediated synaptic remodeling.

The primary brain regions affected: cortical layer V pyramidal neurons, where 5-HT2A density is highest. Visual cortex is particularly dense in 5-HT2A, which explains the vivid visual effects. Less direct effect on the striatum.

MDMA → GSK3β

MDMA floods the synapse with serotonin, dopamine, and norepinephrine simultaneously by reversing their respective transporters. The serotonin surge activates 5-HT receptors → Akt → GSK3β inhibition. The dopamine surge additionally engages D2 receptor-mediated Akt signaling in the striatum → GSK3β inhibition.

MDMA is the only one of the four that produces massive dopamine release in the ventral striatum (nucleus accumbens), making it the substance most likely to inhibit GSK3β specifically in the reward circuit. This may explain why MDMA uniquely restores the feeling that social connection is rewarding and worth pursuing — it is hitting GSK3β in the brain region responsible for assigning value to social behavior.

The primary brain regions affected: broadly distributed due to multi-transmitter release, but with particular strength in the striatum and nucleus accumbens due to dopamine. This distinguishes MDMA from ketamine and psilocybin, which primarily affect cortical and hippocampal regions.

Lithium → GSK3β

Lithium inhibits GSK3β directly through competition with magnesium at the enzyme’s catalytic site. No receptor. No signaling cascade. No intermediate steps. Lithium binds GSK3β and stops it from working.

Lithium also inhibits GSK3β indirectly by increasing inhibitory Ser9 phosphorylation through disruption of the Akt/protein phosphatase 1 complex. Both mechanisms converge on the same result: GSK3β suppression.

The primary brain regions affected: everywhere. Lithium has no regional selectivity. It inhibits GSK3β in whatever cell it reaches. This is its unique advantage: it covers the prefrontal cortex (like ketamine), the visual cortex (like psilocybin), AND the striatum (like MDMA) simultaneously.

The Comparative Table

Why This Matters

The psychiatric establishment has spent over a decade and billions of dollars proving that GSK3β inhibition treats depression. They just don’t know that’s what they proved.

The ketamine research community has run hundreds of clinical trials showing rapid antidepressant effects. The psilocybin community has produced landmark trials showing sustained remission from treatment-resistant depression. The MDMA community has achieved breakthrough therapy designation for PTSD. Each community believes their molecule is special. Each has built an entire clinical infrastructure around their specific substance.

None of them has stepped back and asked: what if they all work for the same reason?

If the convergent target is GSK3β, then the question is not “which psychedelic is best for depression.” The question is: what is the safest, most accessible, most sustainable way to keep GSK3β inhibited?

By every practical measure, the answer is lithium orotate.

Lithium Orotate: The Maintenance Protocol

Lithium orotate is a lithium salt in which lithium is bound to orotic acid. It is available as an over-the-counter nutritional supplement at doses of 1-20mg. It is not prescription lithium carbonate, which is used at doses of 600-1200mg for bipolar disorder and requires therapeutic drug monitoring, blood draws, and kidney/thyroid surveillance.

A 2025 study in Nature (Aron et al., 2025) found that lithium orotate reaches brain tissue at therapeutic concentrations at approximately 1/1000th the dose of lithium carbonate. The orotate salt crosses the blood-brain barrier more efficiently and avoids sequestration by amyloid plaques that traps lithium carbonate. In mice, low-dose lithium orotate reversed memory loss, restored synapses, and prevented cognitive decline without evidence of toxicity over nearly the entire adult lifespan.

Lithium orotate at supplement doses (5-20mg) is pharmacologically and clinically distinct from prescription lithium:

• No therapeutic drug monitoring required
• No known renal toxicity at supplement doses
• No known thyroid toxicity at supplement doses (though monitoring is prudent with long-term use)
• Available without prescription
• Costs approximately $12 per month

The hypothesis: daily lithium orotate at 5-20mg provides sustained, continuous GSK3β inhibition equivalent to what periodic psychedelic sessions provide intermittently. It is the maintenance version of what ketamine, psilocybin, and MDMA do acutely. It does not produce a trip. It does not require a clinic. It does not require a therapist. It does not require breaking the law. It requires swallowing a pill before bed.

Beyond GSK3β Inhibition: What Lithium Does Downstream

When GSK3β is inhibited, several downstream effects follow:

BDNF upregulation. GSK3β inhibition → CREB activation → BDNF gene transcription. BDNF (brain-derived neurotrophic factor) is the primary growth and maintenance signal for dendritic spines — the synaptic connections that make neural circuits functional. Low BDNF is one of the most replicated findings in depression. Lithium raises it.

Dendritic spine maintenance. BDNF maintains dendritic spines in the striatum, prefrontal cortex, and hippocampus. Without adequate BDNF, spines retract, synapses are lost, and circuits degrade. This is the structural basis of depression: the hardware erodes. GSK3β inhibition via lithium provides activity-independent BDNF supply, maintaining spines even when the circuits themselves are quiet.

GR priming. Jeanneteau et al. (2015) demonstrated that BDNF directly phosphorylates glucocorticoid receptors (GR) at sites essential for neuroplasticity gene transcription. This means lithium-driven BDNF does not just maintain spines — it improves the sensitivity of cortisol receptors, making whatever cortisol IS present more effective. For individuals with low cortisol signaling (burnout, chronic stress recovery, FKBP5 T-allele carriers), this is particularly relevant: lithium makes the weak signal more audible rather than requiring the signal to be louder.

Glutamate regulation. Lithium modulates glutamate reuptake, preventing excitotoxicity while maintaining normal excitatory transmission. This may contribute to the subjective experience of “clarity” that lithium users report — noise is reduced without signal being suppressed.

Circadian stabilization. GSK3β phosphorylates core clock proteins including BMAL1 and Rev-erbα. Overactive GSK3β fragments circadian rhythms. Lithium stabilizes them. This may explain why lithium improves sleep quality and why many users report that taking it before bed produces better mornings.

Who Might Benefit

GSK3β overactivation is not limited to a single diagnostic category. Based on the mechanism, the following populations may benefit from sustained GSK3β inhibition via lithium orotate:

Depression (broadly). If overactive GSK3β is a convergent endpoint of depressive pathology regardless of upstream cause, then GSK3β inhibition may provide benefit across depression subtypes. This does not mean lithium replaces antidepressants for all patients. It means it may help the subset whose depression is driven by GSK3β-mediated synaptic degradation rather than monoamine deficiency.

Burnout recovery. Chronic stress depletes cortisol signaling → GR desensitization → loss of GSK3β suppression → BDNF falls → striatal spines retract → motivational collapse. Lithium provides the GSK3β inhibition that cortisol is no longer delivering. (See FKBP5.com for the full mechanistic model.)

Seasonal affective disorder. Reduced winter light → reduced cortisol drive → reduced GR-mediated GSK3β suppression → everything feels dim. Lithium provides GSK3β inhibition independent of photoperiod. It may not eliminate the seasonal oscillation in receptor sensitivity, but it raises the floor so that winter doesn’t drop below the functional threshold.

FKBP5 T-allele carriers with childhood adversity. These individuals have a permanently elevated cortisol activation threshold AND lower baseline cortisol production. Their GR chronically under-suppresses GSK3β regardless of environment or season. Lithium provides the downstream effect their cortisol-GR chain cannot. This may be a lifelong supplementation need, not a time-limited intervention. (See FKBP5.com for genotype details.)

Post-psychedelic maintenance. Patients who respond well to ketamine, psilocybin, or MDMA but relapse after weeks to months may be experiencing the return of unopposed GSK3β activity as the acute drug effect fades. Daily lithium orotate between sessions could maintain GSK3β suppression during the inter-session period, potentially extending the duration of benefit and reducing the frequency of sessions needed.

Alzheimer’s prevention. The Harvard 2025 study (Aron et al., 2025) found that lithium depletion in the brain is an early event in Alzheimer’s pathogenesis, that GSK3β activation drives amyloid and tau accumulation, and that lithium orotate reversed these changes in mice. Lithium orotate for neuroprotection in aging is a separate and significant application that is likely to be studied in clinical trials in the near future.

What Lithium Orotate Does Not Do

Lithium orotate is not a psychedelic. It does not produce altered states of consciousness, visual changes, emotional catharsis, or mystical experiences. The psychedelic experience itself may have independent therapeutic value — ego dissolution, perspective shifts, emotional processing — that GSK3β inhibition alone does not provide. Some patients may need the full psychedelic experience for trauma processing or perspective change. Lithium orotate would not replace this.

Lithium orotate at supplement doses is not a treatment for acute mania, psychosis, or severe bipolar I disorder. These conditions may require the higher brain lithium levels achievable with prescription lithium carbonate at therapeutic doses.

Lithium orotate is not proven effective for depression in humans through randomized controlled trials. The mechanistic argument is strong and the convergent evidence from four pharmacologically distinct GSK3β inhibitors is compelling, but direct clinical evidence for lithium orotate specifically for depression does not yet exist. The Harvard 2025 study was in mice for Alzheimer’s. Extrapolation to human depression is a hypothesis, not an established fact.

The Practical Protocol

Based on clinical experience from practitioners who prescribe lithium orotate (Greenblatt, Emmons, and others), user reports, and the mechanistic reasoning above:

Starting dose: 5mg lithium orotate taken at night before bed.

Titration: If no side effects after one week, increase to 10mg. If still no side effects after another week, increase to 15-20mg. Maximum supplement dose: 20mg.

Timing: Before bed. The acute GSK3β inhibition peaks approximately 2 hours after dosing. Taking it at night means the peak inhibition occurs during sleep, when synaptic remodeling and spine stabilization are most active. Any transient brain fog from the glutamate modulation occurs during sleep rather than during the day.

What to monitor: Water retention (the most common side effect at supplement doses), thyroid function (prudent to check TSH after 3 months of daily use), and morning clarity (the primary outcome measure — do you feel different before coffee?).

Duration: Unknown. For burnout recovery, a 4-6 week loading period may be sufficient if the structural gains (spine regrowth, GR priming) persist after cessation. For FKBP5 T-allele carriers with permanently elevated thresholds, ongoing daily supplementation may be necessary. For seasonal depression, seasonal use (September through April) may be appropriate. These are hypotheses, not established protocols.

Combination with alcohol: Moderate alcohol raises BDNF in the dorsolateral striatum through a RACK1-mediated pathway that is mechanistically distinct from lithium’s CREB-mediated BDNF pathway. However, alcohol acutely activates GSK3β — the opposite of lithium’s effect. Lithium may partially buffer against alcohol’s GSK3β activation, reducing the molecular cost of each drink. The combination is not contraindicated at supplement lithium doses. (See FKBP5.com for the full alcohol-BDNF analysis.)

Proposed Studies

1. Lithium orotate for treatment-resistant depression. Randomize patients with treatment-resistant MDD to lithium orotate (10-20mg/day) versus placebo for 8 weeks. Measure depression scores, GSK3β phosphorylation in peripheral blood mononuclear cells (as a proxy for brain GSK3β status), and serum BDNF. Prediction: lithium orotate group will show significant improvement in depression scores with increased GSK3β Ser9 phosphorylation and BDNF levels.

2. Lithium orotate as post-ketamine maintenance. Randomize ketamine responders to lithium orotate (10-20mg/day) versus placebo following their final infusion. Measure time to relapse. Prediction: lithium orotate group will show significantly longer duration of benefit, as daily GSK3β inhibition maintains the synaptic gains produced by the ketamine series.

3. Lithium orotate for seasonal affective disorder. Randomize SAD patients to lithium orotate (10-20mg/day) versus placebo beginning in September, before symptom onset. Measure depression scores monthly through March. Prediction: lithium orotate group will show attenuated winter symptom severity, as direct GSK3β inhibition compensates for reduced photoperiod-driven cortisol-GR-GSK3β suppression.

4. GSK3β phosphorylation as a biomarker of psychedelic response. Measure GSK3β Ser9 phosphorylation in peripheral blood before and after ketamine, psilocybin, and MDMA administration. Prediction: all three substances will produce increased Ser9 phosphorylation, and the degree of phosphorylation will correlate with clinical response, confirming GSK3β as the convergent target.

5. Lithium orotate versus lithium carbonate for brain delivery. Replicate the Aron et al. (2025) finding in humans using MRI spectroscopy to measure brain lithium concentrations following equivalent elemental lithium doses of orotate versus carbonate. Prediction: orotate will achieve higher brain concentrations at lower serum levels, confirming superior blood-brain barrier penetration in humans.

6. GSK3β genotyping and depression treatment response. Genotype depressed patients for GSK3β-related polymorphisms and assess treatment response to SSRIs versus lithium. Prediction: patients with variants associated with higher baseline GSK3β activity will show preferential response to lithium (direct GSK3β inhibitor) over SSRIs (which affect GSK3β indirectly and incompletely).

The Bigger Picture

The psychiatric establishment classifies depression as a serotonin problem, a dopamine problem, a glutamate problem, or a neuroplasticity problem depending on which department you ask. Each classification spawns its own treatment paradigm, its own clinical trials, and its own pharmaceutical industry. SSRIs for the serotonin model. Stimulants for the dopamine model. Ketamine clinics for the glutamate model. Psychedelic retreat centers for the neuroplasticity model.

What if they are all downstream of the same upstream target?

GSK3β sits at the convergence point. Serotonin suppresses it through 5-HT → Akt. Dopamine modulates it through D2 → Akt. Glutamate regulates it through NMDA → AMPA → Akt. Cortisol suppresses it through GR → PI3K → Akt. BDNF suppresses it through TrkB → PI3K → Akt. Every major neurotransmitter system implicated in depression feeds into the same kinase.

This does not mean GSK3β is the “cause” of depression. Depression has many causes — trauma, loss, inflammation, hormonal disruption, chronic stress, genetic vulnerability. But these diverse causes may converge on a shared molecular endpoint: overactive GSK3β producing synaptic degradation in circuits that maintain mood, motivation, and the subjective sense that life is worth living.

If this is correct, then the treatment question simplifies dramatically. Instead of trying to determine which upstream neurotransmitter system is dysfunctional in each individual patient — a task that has proven nearly impossible after decades of trying — clinicians could target the convergent endpoint directly.

The most accessible, sustainable, and safest way to do this is lithium orotate.

A $12 bottle. No prescription. No trip. No clinic. Taken before bed.

The most important psychiatric drug of the 21st century might already be on Amazon.

Key References

Aron, L. et al. (2025). Lithium deficiency and the onset of Alzheimer’s disease. Nature, 645(8081), 712-721.

Beurel, E., Song, L. & Jope, R.S. (2011). Inhibition of glycogen synthase kinase-3 is necessary for the rapid antidepressant effect of ketamine in mice. Molecular Psychiatry, 16(11), 1068-1070.

Jeanneteau, F. et al. (2015). BDNF and glucocorticoids regulate corticotrophin-releasing hormone (CRH) homeostasis in the hypothalamus. Proceedings of the National Academy of Sciences, 109(4), 1305-1310.

Jope, R.S. (2003). Lithium and GSK-3: one inhibitor, two inhibitory actions, multiple outcomes. Trends in Pharmacological Sciences, 24(9), 441-443.

Nardou, R. et al. (2019). Oxytocin-dependent reopening of a social reward learning critical period with MDMA. Nature, 569, 116-120.

Polter, A. et al. (2010). Deficiency in the inhibitory serine-phosphorylation of glycogen synthase kinase-3 increases sensitivity to mood disturbances. Neuropsychopharmacology, 35(8), 1761-1774.

This paper is a mechanistic hypothesis, not medical advice. Lithium orotate has not been evaluated by the FDA for the treatment of depression. Consult a healthcare provider before starting any supplement, particularly if you are taking psychiatric medications.

For the upstream genotype model explaining why some individuals are particularly vulnerable to GSK3β overactivation, see FKBP5.com.

The author is not a physician or neuroscientist. She is a software engineer, an FKBP5 rs1360780 T/T carrier, and a person who noticed that four different substances made the world feel brighter and wanted to know why.