Last updated 3 September 2026 · Originally published 5 October 2022
CBD and neuroplasticity have become a marketing pair: the claim that CBD helps the brain rewire, grow and repair itself turns up on product pages, podcasts and wellness blogs. The claim is not invented from nothing. It rests almost entirely on mice, plus one small human brain-scan study that is regularly described as more than it was. Here is the real picture.
What neuroplasticity actually is
Neuroplasticity is the brain’s ability to change: to strengthen connections you use, prune ones you don’t, and adapt after damage. It is not a special state you switch on; it is how the brain works all the time, and it is the reason you can learn anything at all. More plasticity is not automatically better, either: harmful habits, addiction and chronic pain can also involve the brain learning and reinforcing new patterns. One specific corner of it — the birth of new neurons in the hippocampus, the region central to memory — gets most of the attention, and it is worth knowing that even the basic science there is contested: researchers still disagree about how much new-neuron growth adult human brains do at all.
So when a product says it “supports neuroplasticity”, the first question is which of these things it means. Usually it means none of them in particular, which is what makes the phrase safe to print.
Where the CBD claim comes from: mice
In rodent studies, CBD has repeatedly increased the formation of new neurons in the hippocampus. The most interesting of these experiments found that in chronically stressed mice, CBD both restored new-neuron growth and reduced anxiety-like behaviour — and that when the new growth was blocked, the behavioural benefit disappeared, suggesting the two were connected. Rodent work has also found CBD altering BDNF, a protein that helps brain cells survive and form connections.
That is genuinely interesting biology. It is also nearly all in animals. The only human test of CBD and BDNF we could find was a small, unpublished master’s study, in which 50 mg of CBD daily for eight weeks did not raise blood levels of BDNF in 35 healthy adults. Blood BDNF is not a direct measure of what is happening in the brain, but the result gives the marketing claim no support. Mouse results cannot tell us whether the same thing happens in people.
The one human brain-scan study
The study behind most “CBD regrows your brain” headlines is from 2018. Eighteen regular cannabis users took 200 mg of CBD daily for about ten weeks, with brain scans before and after, while continuing their usual cannabis use. Chronic heavy cannabis use is associated with smaller hippocampal volume, so the question was whether CBD could push back against that.
The results, precisely: the hippocampus as a whole did not change. One small area within the left hippocampus appeared to grow by 1.58% — a result that became uncertain once the researchers accounted for all the comparisons they had made — and the apparent growth was clearer in the heaviest users. The study had no placebo group, everyone knew they were taking CBD, and the authors themselves said the finding needs a placebo-controlled replication, which seven years later has not appeared.
At most, it is a hint that CBD may influence hippocampal structure in regular cannabis users. A change in size on a scan cannot show that new brain cells grew or that damage was repaired, and without a placebo group the study cannot show that CBD caused the difference. It is not evidence that CBD grows or repairs a healthy brain, and it says nothing about the 25 mg gummy sold on the strength of it.
What this does not license
Three claims ride on this evidence that it will not carry. First, that CBD improves memory or learning in healthy people: controlled trials have not shown that, and our article on what CBD does to the mind covers what they have shown — at a typical serving, usually nothing measurable. Second, that CBD raises “your BDNF”: animal findings do not establish that, and the one small human test found no increase in blood BDNF. Third, that any of this happens at retail doses: the human study used 200 mg a day, roughly ten times a typical serving, and the gap between trial and bottle is a reason for caution, not a licence to take more.
It is also worth saying what honest uncertainty looks like here: nobody knows what regular CBD use does to human brain structure over months or years, in either direction. One small, uncontrolled, ten-week study in cannabis users is the entire published human imaging evidence for CBD changing brain structure.
What about THC?
THC has its own plasticity story, and it runs in both directions. In people, heavy long-term cannabis use is associated with smaller volume in parts of the hippocampus, and a three-year imaging study of young heavy users found some of those areas shrinking faster over time. That finding is concerning, although a small observational study cannot establish that THC caused the changes.
In mice, the direction flips with age. In a famous 2017 experiment, a chronic low dose of THC restored the learning ability of old mice: the number of connections between their brain cells increased, and patterns of gene activity in their brains looked younger. A follow-up found the same dose strengthened connections in old mice and disrupted them in young ones. It is one of the most striking preclinical findings in cannabis research, a human trial in older people has yet to report, and there is no proof any of it translates to people.
What users report
Nobody can feel their neurons rewiring, so reports here are about what people can notice: some describe a clearer head and fog lifting, others describe the opposite with regular use. Both are worth recording, and neither can confirm or refute anything about plasticity — feeling sharper is compatible with better sleep, less anxiety, expectation, or a cellular change. A report about how thinking feels is real evidence about how thinking feels. It is not a brain scan.
If neuroplasticity is what you want
The irony of the marketing is that the things actually shown to drive neuroplasticity in humans are not for sale in a dropper bottle. Exercise is the best-evidenced — it raises BDNF, boosts your body’s own cannabinoids, and is linked to hippocampal growth in controlled human studies — along with learning demanding new things and getting enough sleep. If a supplement’s pitch is “support your brain’s ability to change”, those three are the interventions with human evidence, and they are free.
None of this makes CBD’s neuroplasticity research worthless. The mouse findings are a reason to run the human trials, and the 2018 study is a reason to run a proper version of it. Until someone does, “CBD supports neuroplasticity” is a lab result wearing a health claim’s clothes — the same pattern as every receptor story on every label: mechanism is a reason to investigate, not proof that anything works.
Nothing in this article is medical advice.
