THC improved memory and movement recovery after traumatic brain injury in mice | Research

The takeaway

Mice given THC after a controlled brain injury showed significant recovery of working memory and locomotor function, associated with increased brain repair factors.

TBI researchers, neuroscientists, and those interested in the neuroprotective potential of cannabinoids.

Motor function normalized by 2 weeks in THC-treated mice

What the researchers found

THC-treated mice exhibited marked improvement in Y-maze working memory performance and recovered to normal rotarod performance by 2 weeks after brain injury. THC upregulated neurotrophic factors G-CSF, BDNF, and GDNF and increased endocannabinoid 2-AG levels in the brain.

Why it matters

Traumatic brain injury has limited treatment options. This study suggests THC may promote brain self-repair by upregulating the same neurotrophic factors that have been shown to mediate recovery after TBI and stroke.

The numbers in context

THC dose: 3 mg/kg IP for 3 days post-injury. Working memory recovered significantly in THC-treated mice. Rotarod performance normalized at 2 weeks. G-CSF, BDNF, and GDNF all significantly upregulated in cerebral cortex, striatum, and hippocampus. 2-AG levels also increased.

How the study worked

C57BL/6J mice underwent controlled cortical impact (CCI) and received THC (3 mg/kg IP) for 3 days. Working memory (Y-maze spontaneous alternations) and locomotor function (rotarod) measured at baseline and 3, 7, and 14 days post-injury. Brain tissue analyzed for neurotrophic factors and endocannabinoid levels.

What this study cannot tell us

Animal study with a single THC dose. The injury model (controlled cortical impact) represents only one type of TBI. The timeline was short (14 days). Human TBI is far more complex and variable.

How to read the evidence

Preliminary: single animal study with one dose and short follow-up.

When this study was published

Published in 2022.

The bigger picture

While most cannabis research focuses on potential harms, this study suggests THC may have neuroprotective and neuroregenerative properties that could be harnessed therapeutically, at least in the context of acute brain injury.

Questions still open

Would THC benefit human TBI patients? What is the optimal timing and dose for neuroprotective effects? Could the same recovery be achieved with CBD or other cannabinoids without psychoactive effects?

Common questions

How did THC help after brain injury?

THC increased levels of three neurotrophic factors (G-CSF, BDNF, GDNF) that promote brain repair, as well as the endocannabinoid 2-AG. These changes were associated with recovery of memory and movement.

Was THC given before or after the injury?

After. THC was administered for 3 days following the controlled cortical impact, making this a treatment study rather than a prevention study.

Could this lead to THC treatment for human head injuries?

It is too early to say. Animal TBI models provide important initial data, but human clinical trials would be needed to determine if THC has similar effects in people with brain injuries.

Read the original research

Administration of Δ9-Tetrahydrocannabinol Following Controlled Cortical Impact Restores Hippocampal-Dependent Working Memory and Locomotor Function.

Cannabis and cannabinoid research, 7(4), 424-435

View on PubMed ↗Publisher’s paper ↗

Citation

Song, Shijie; Kong, Xiaoyuan; Wang, Bangmei; Sanchez-Ramos, Juan. (2022). Administration of Δ9-Tetrahydrocannabinol Following Controlled Cortical Impact Restores Hippocampal-Dependent Working Memory and Locomotor Function.. Cannabis and cannabinoid research, 7(4), 424-435. https://doi.org/10.1089/can.2021.0053