Medical Cannabis and Autism Spectrum Disorder: Latest Findings from the UK Medical Cannabis Registry
Autism affects around 1 in 100 people in the UK. It usually begins in childhood and often continues through adult life. Many autistic people also live with problems like poor sleep, anxiety or low mood. Standard treatments do not always help, and some people do not get on with them.
Due to this, researchers are looking at other options. One of these is medical cannabis. A new study from the UK Medical Cannabis Registry looked at how a group of autistic adults got on after being prescribed medical cannabis.
Key Takeaways:
- What the study looked at: Researchers reviewed real-world records from 130 autistic adults prescribed medical cannabis, and followed them for up to 18 months.
- What patients reported: On average, people reported better sleep, less anxiety and improved quality of life compared with before they started treatment.
- Side effects: About 1 in 5 people reported at least one side effect. Most were mild or moderate. About 4 in 5 people reported none.
- What it means: This was an observational study with no comparison group. It cannot prove that medical cannabis caused these changes. Larger, controlled trials are still needed.
What is Autism Spectrum Disorder?
Autism Spectrum Disorder (ASD), often just called autism, is a lifelong condition. It affects how a person experiences the world, communicates and relates to other people. Autism is a spectrum. This means it affects each person differently. Some people need a lot of daily support; others need very little.
Alongside the core features of autism, many people also experience other difficulties. Anxiety and low mood are common. Sleep problems are too, with studies suggesting between 50% and 83% of autistic people have trouble sleeping, which can make other symptoms harder to manage. Together, these can lower a person’s quality of life.
How is autism usually treated?
No medicine treats the core features of autism itself. Instead, treatment focuses on the difficulties that many autistic people live with, such as anxiety, low mood or sleep problems.
Doctors may use medicines such as antidepressants (SSRIs) or certain antipsychotics. These can help some people. But they do not suit everyone, and research suggests around 30% to 50% of people do not get enough benefit from them. This is one reason researchers are exploring other approaches.
What is the UK Medical Cannabis Registry?
In 2018, the law in the UK changed. Since then, specialist doctors have been able to prescribe cannabis-based medicinal products for certain conditions when other treatments have not worked well enough.
In 2019, Curaleaf Clinic set up the UK Medical Cannabis Registry. It collects real-world information from patients prescribed medical cannabis, so that researchers can study how people get on over time. An earlier registry study in 2022 followed autistic patients for six months. This new study, published in Neuropasychopharmacology Reports, builds on that work by following adults for up to 18 months.
What did the new study look at?
The study set out to describe changes in three main areas among autistic adults prescribed medical cannabis:
- Anxiety — measured with a short questionnaire called the GAD-7.
- Sleep quality — measured with a simple 0-to-10 sleep rating.
- Overall quality of life — measured with a standard health questionnaire (the EQ-5D-5L).
Patients also rated how much they felt their health had changed since starting treatment. These ratings are called “patient-reported outcomes”.
People filled in these questionnaires before starting treatment. They then filled them in again at 1, 3, 6, 12 and 18 months. Any side effects were recorded along the way.
What were the findings of the analysis?
The study included 130 autistic adults. Their average age was 34. About two in three were men (88 people), and about one in three were women (42 people).
The most common additional condition was anxiety and/or low mood, reported by around two in three people (65%). Most participants had used cannabis before starting treatment.
On average, the group reported improvements after starting medical cannabis:
- Sleep quality improved from the first month and stayed better than the starting point throughout the 18 months.
- Anxiety scores improved. The change looked largest in the early months and eased back a little over time, though scores stayed better than at the start.
- Quality of life scores improved, with the anxiety-and-mood part of the questionnaire showing the biggest improvement by 18 months.
One area (physical mobility) did not change much. This makes sense, as the treatment was aimed at symptoms like anxiety and sleep, not movement.
It is important to be careful about what these numbers mean. The scores show what patients reported while taking medical cannabis. Because there was no comparison group taking a dummy treatment, the study cannot show that medical cannabis was the cause of the changes. Other things, including time, other support, or simply expecting to feel better, could also play a part.
Were there any side effects?
Yes. Side effects are an important part of the picture, and the study recorded them carefully.
About 1 in 5 people (19%) reported at least one side effect. About 4 in 5 people (81%) reported none at all. In total, 232 side effects were recorded across the group.
Most of these were mild or moderate. A smaller number were rated severe, and three were rated as serious (life-threatening or disabling). The most commonly reported side effects were:
- Trouble sleeping (insomnia) – 14%
- Dry mouth – 12%
- Tiredness (lethargy) – 12%
What do these results mean for patients?
This study adds to a small but growing body of real-world research on medical cannabis and autism. In this group, medical cannabis was linked with reported improvements in sleep, anxiety and quality of life over 18 months, and most people did not experience side effects.
But “linked with” is not the same as “caused by”. Because of how the study was designed, it cannot prove that medical cannabis was responsible for the improvements. The people in the study also came from a single private clinic, and most had used cannabis before, so the results may not apply to everyone.
Findings like these are genuinely useful. They help doctors and researchers understand what to study next, and they support the case for larger, more rigorous trials. But they are not proof that medical cannabis works for autism, and they are not a recommendation to try it.
If you are struggling with symptoms linked to autism, the most important step is to talk to a healthcare professional who knows your medical history. They can talk through all of your options and what might suit you.
Learn more
If you would like to understand more about medical cannabis and whether a consultation could be right for you, you can complete our online eligibility check. A specialist will always take your medical history into account before discussing any treatment.
