Introduction
One of the most significant discoveries in psychedelic science is that these compounds do not merely alter consciousness temporarily -- they physically change the structure of neurons. In 2018, David Olson's laboratory at UC Davis published a landmark study demonstrating that psychedelics from multiple chemical classes promote the growth of dendrites (the branching extensions of neurons), increase dendritic spine density, and stimulate the formation of new synapses. This finding -- that a single dose of a psychedelic can produce lasting structural changes in the brain -- may explain why brief psychedelic experiences can produce enduring therapeutic benefits.
The Problem of Neural Atrophy
Chronic stress, depression, and anxiety are associated with structural changes in the brain. Neurons in the prefrontal cortex and hippocampus show reduced dendritic branching, decreased spine density, and loss of synapses. This neural atrophy is not merely a correlate of mood disorders -- it appears to be causally involved. Animal models show that chronic stress produces dendritic retraction in prefrontal cortical neurons, and that this retraction precedes behavioral signs of depression.
Ronald Duman at Yale demonstrated that the prefrontal cortex of depressed patients shows reduced volume and fewer synapses at post-mortem examination. The logical therapeutic question became: can we reverse this atrophy?
