Psychoplastogen

What is a psychoplastogen?

A psychoplastogen is any substance that rapidly promotes the growth of new neural connections — dendrites, dendritic spines, and synapses — typically after a single administration. The term was coined in 2018 by researcher David Olson at UC Davis.

Breaking down the word:

• Psycho = mind
• Plasto = to mold/form
• Gen = to produce

Literally: "mind-molding generators" — substances that generate structural changes in the brain associated with psychological change.

Why this concept is important

The neuroplasticity revolution

Traditional antidepressants (SSRIs) take 4-6 weeks to work and have modest efficacy. Psychoplastogens represent a potential paradigm shift — substances that produce rapid, robust structural changes in neurons that correlate with rapid behavioral and mood improvements.

Beyond subjective effects

The psychoplastogen concept separates the structural/therapeutic effects of psychedelics from their perceptual/hallucinogenic effects. This has profound implications:

• Could it be possible to create a psychoplastogen that promotes neuroplasticity without producing a psychedelic experience?
• Could microdosing work primarily through the psychoplastogenic mechanism rather than the subjective experience?
• Could non-psychedelic compounds be designed that have the same structural brain benefits?

The Olson lab's key findings

David Olson's lab at UC Davis demonstrated that:

1. Multiple psychedelics (DMT, LSD, psilocin, DOI) promote rapid dendrite growth and synapse formation in cortical neurons
2. These structural changes are comparable to or greater than those produced by ketamine (a known fast-acting antidepressant)
3. The effects are mediated by 5-HT2A → TrkB → mTOR signaling
4. Non-hallucinogenic analogs can be engineered that retain the structural effects — opening the door to psychoplastogens without trips

Psychoplastogens and microdosing

The structural hypothesis

One theory of how microdosing works:

1. Sub-perceptual doses still activate 5-HT2A receptors
2. This triggers the psychoplastogenic signaling cascade (even if no perceptual effects occur)
3. New dendrites and synapses form
4. These structural changes produce gradual improvements in mood, cognition, and flexibility
5. Repeated microdosing amplifies these structural changes over weeks

Evidence and limitations

• Animal studies support that even low doses promote some structural changes
• Human evidence at microdose levels is still very limited
• It's unclear whether the psychoplastogenic effect at sub-perceptual doses is sufficient to produce clinically meaningful changes
• The relationship between structural changes and functional/behavioral improvements isn't fully mapped

Known psychoplastogens

Substance	Class	Psychoactive?
Psilocybin/psilocin	Tryptamine psychedelic	Yes
LSD	Lysergamide psychedelic	Yes
DMT	Tryptamine psychedelic	Yes
DOI	Phenethylamine psychedelic	Yes
Ketamine	Dissociative	Yes
MDMA	Empathogen	Yes
Tabernanthalog (TBG)	Non-hallucinogenic analog	Minimal
AAZ-A-154	Engineered analog	No

The last two entries are especially exciting — they suggest it may be possible to decouple neuroplasticity from hallucination.

The bigger picture

The psychoplastogen concept connects microdosing to the broader frontier of neuropsychiatric medicine:

• Depression = loss of synaptic density in prefrontal cortex → psychoplastogens restore it
• PTSD = rigid fear memories → psychoplastogens may help rewire them
• Addiction = entrenched neural circuits → psychoplastogens may help form new ones
• Cognitive decline = loss of neural connections → psychoplastogens may counteract it