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Brain injury rehabilitation: Where does cannabis come in?

By Natalia Masztalerz, Assistant Psychologist (Outcome Measures) and Jessica Farrell, Assistant Psychologist

The therapeutic use of cannabis has increasingly been considered in various health settings.

The therapeutic use of cannabis has increasingly been considered in various health settings. However, there are other aspects to consider when it comes to brain injury rehabilitation. We have reflected on this since attending May 2023, Let’s Talk About Cannabis! The event was convened by BIS Services after looking at the scientific literature on the topic.

Cannabis as a risk factor

In the UK, cannabis is a class B drug, illegal for recreational use. However, low-concentration cannabidiol-infused products (CBD) are legally and readily available in supermarkets and are widely advertised. But how does this substance affect people with brain injury?

Many people who use cannabis after brain injury have reported using it before their brain injury [1, 2]. The use of cannabis has been identified as a possible risk factor for road traffic accidents [3], although other studies have failed to find a link [4].

Cannabis as Therapy

In contrast, CBD is soothing, with preliminary laboratory findings in mice linking its use with reduced pain and improved sleep following brain injury. The study’s authors suggested that this was due to reduced cell death and the overall volume of trauma to the brain [5]. Nevertheless, research on the effectiveness of the therapeutic use of cannabinoids for people with brain injury is still in its infancy, and careful consideration of risks is essential, given the potential for misuse.

Recreational use after brain injury

Recreational users of cannabis who have a brain injury report that their main reason for using it is symptom relief. Targeted symptoms include anxiety, irritability, insomnia, pain, and spasticity [6, 7]. However, early laboratory studies have suggested detrimental effects, which has led to warning users of the risks of worsening cognitive deficits resulting from brain injury [2, 8].

Concerns have been raised about individuals with pre-existing substance misuse disorder when cannabis can increase an existing risk of experiencing psychiatric symptoms and lead to increased alcohol consumption [9]. However, further studies have suggested a link between CBD use and a reduction in cortisol [6]. Cortisol is a stress hormone, and this reduction offers some insight into why users report decreased anxiety and irritability and better sleep.

The latest evidence from the conference and clinical implications

At the “Let’s Talk About Cannabis!” event, leading speakers shared current findings in cannabis research, the benefits and challenges of medicinal cannabis, and practical implications. It was particularly impactful to hear the talks from two experts by experience.

The day it was started with a discussion of the historical uses of medical cannabis for ailments such as menstrual cramping, inflammation, migraines, and low mood. Medical cannabis is highly regulated and can only be prescribed as a last resort by physicians on a specialist register.

Evidence supporting the use of medicinal cannabis includes successful reductions in intensity and duration of seizures for severe cases of epilepsy. However, it has been stressed that the known risks associated with cannabis may affect physicians’ confidence in its administration, even when another medication is ineffective.

The talks also covered the key areas of neuropsychological functioning most detrimentally affected by acute and non-acute cannabis use. These include learning, working memory, attention, concentration and psychomotor control. The validity of using tests that rely on accuracy and speed was questioned, as the impact of cannabis on psychomotor skills may have been overlooked as a confounding variable.

Furthermore, recent research has found that the long-term effects of cannabis use on functioning may be reversible for some people in a matter of days or weeks. However, it was noted that even relatively minor effects on functioning could significantly impact people with a brain injury.

Rehabilitation support workers and the experts, by experience, spoke about how authoritarian and disciplinary approaches to cannabis may only disadvantage the people we support, as they encourage negative biases that can affect the quality of care. The speakers highlighted how the taboo nature of cannabis use in the UK could perpetuate barriers to talking about drug use, reducing opportunities for building therapeutic relationships and gathering information relevant to the person’s care.

Vital information, such as the type of drug being used, methods and intentions of use, financial difficulties, experiences, and perceived implications for the person’s health, well-being and social integration, are often not discussed with clients. It was suggested that the earlier conversations about cannabis use are facilitated in a person’s recovery, the better the engagement with rehabilitation services. Strategies such as behavioural contracts, specific cannabis and brain injury care plans, and specific staff training have been found to positively affect outcomes, engagement, and the quality of care.

The clear take-home message from the day was the importance of encouraging open-minded, reflective practice and meaningful conversations about cannabis – between professionals and people we support. In short, let’s keep talking about cannabis!

The Let’s Talk About Cannabis! event is now available as online training.


  1. Hergert, D. C., Robertson-Benta, C., Sicard, V., Schwotzer, D., Hutchison, K., Covey, D. P., Quinn, D. K., Sadek, J. R., McDonald, J., & Mayer, A. R. (2021). Use of Medical Cannabis to Treat Traumatic Brain Injury. Journal of Neurotrauma, 38(14), 1904–1917.
  2. Palazzo, E., Iannotta, M., Belardo, C., Infantino, R., Ricciardi, F., Boccella, S., Guida, F., Luongo, L., & Maione, S. (2022). Cannabidiol in traumatic brain injury. In R. Rajendram, V. R. Preedy and C. R. Martin (Eds.) Diagnosis and Treatment of Traumatic Brain Injury: The Neuroscience of Traumatic Brain Injury, 463–475.
  3. Asbridge, M., Hayden, J. A., & Cartwright, J. L. (2012). Acute cannabis consumption and motor vehicle collision risk: systematic review of observational studies and meta-analysis. BMJ344, e536.
  4. Brubacher, J. R., Chan, H., Erdelyi, S., Macdonald, S., Asbridge, M., Mann, R. E., … & Purssell, R. A. (2019). Cannabis use as a risk factor for causing motor vehicle crashes: a prospective study. Addiction, 114(9), 1616-1626.
  5. Belardo, C., Iannotta, M., Boccella, S., Rubino, R. C., Ricciardi, F., Infantino, R., Pieretti, G., Stella, L., Paino, S., Marabese, I., Maisto, R., Luongo, L., Maione, S., & Guida, F. (2019). Oral cannabidiol prevents allodynia and neurological dysfunctions in a mouse model of mild traumatic brain injury. Frontiers in Pharmacology, 10(Mar), 352.
  6. Friedman, L. K., Peng, H., & Zeman, R. J. (2021). Cannabidiol reduces lesion volume and restores vestibulomotor and cognitive function following moderately severe traumatic brain injury. Experimental Neurology, 346, 113844.
  7. Roy, S. J., Livernoche Leduc, C., Paradis, V., Cataford, G., & Potvin, M. J. (2022). The negative influence of chronic alcohol abuse on acute cognitive recovery after a traumatic brain injury., Brain Injury, 36(12–14), 1340–1348.
  8. Cury R. M., Pamplona, F. A., Loss, C. G., da Silva, E. G., & Nascimento, F. P. (2019). Cannabinoid Microdosing Improve Spasticity in a Traumatic Brain Injury Patient: A Case Study. Journal of Pharmaceutics and Therapeutics, 5(1), 326–335.
  9. Jacotte-Simancas, A., Fucich, E. A., Stielper, Z. F., & Molina, P. E. (2021). Traumatic brain injury and the misuse of alcohol, opioids, and cannabis. International Review of Neurobiology, 157, 195–243.
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