Investigating Cannabis and Autism: What 2026 Research Shows

Researchers have been investigating cannabinoids as a possible treatment for symptoms associated with autism spectrum disorder (ASD) for several years. Much of the early evidence came from small observational studies, parent reports, and open label trials.

A new 2026 randomized, double-blind, placebo-controlled clinical trial, however, provides considerably stronger evidence and results.

Published in Neurotherapeutics, the Harmony Study examined a full spectrum medicinal cannabis extract called NTI164 in children and adolescents with moderate to severe, Level II or Level III autism. Importantly, this was not conventional marijuana or a high THC cannabis product. NTI164 contains several cannabinoids including CBD, CBDA, CBGA, and CBDV with less than 0.3% THC.

How Was the Study Conducted?

Researchers enrolled 61 participants between 8 and 17 years old at a pediatric neurology clinic in Victoria, Australia. Participants were randomly assigned to receive either NTI164 or a visually identical placebo.

Treatment began at 5 mg/kg per day and was gradually increased to a maximum tolerated dose of 20 mg/kg per day. The blinded portion of the study lasted eight weeks. 

Fifty four participants completed that phase. Researchers evaluated them using several established clinical tools. This included things, but was not limited to autism severity, communication, and daily living skills.

What Did Researchers Find?

The primary outcome measured overall clinical severity using the Clinical Global Impression Severity scale (CGIS). After eight weeks, the NTI164 group showed significantly greater improvement than the placebo group. 

The adjusted difference between the groups was 1.65 points in favor of NTI164, a statistically significant result (p<0.001).

The CGIS produced a similar result. The average score among participants receiving NTI164 was 2.62. This represented an improvement between “minimally improved” and “much improved.” The placebo group’s average was 4.04, essentially indicating no change.

Researchers also reported statistically significant improvements in several areas of adaptive functioning.

Using the Vineland Adaptive Behavior Scales, NTI164 produced improvements over placebo in communication, up 2.92 points. Daily living skills went up 3.56 points. There were other results in the study such as measuring social functioning. This resulted in a positive result of 3.47 points.

The placebo group was later allowed to take NTI164 during an open label extension. Those participants subsequently showed improvements similar to those seen in the original treatment group. These open label results are scientifically weaker because participants knew they were receiving the active product.

What About Side Effects?

NTI164 appeared reasonably well tolerated during the relatively short study.

Researchers recorded 41 adverse events among 26 participants. These were classified as mild, temporary, and non serious. Common complaints included nausea, headache, abdominal discomfort, and anxiety. No serious treatment related adverse events were reported. Laboratory testing and vital signs did not show clinically significant changes.

That is encouraging but eight weeks is not sufficient to determine long term safety in children.

How Does This Compare With Earlier Research?

The Harmony Study does not exist in isolation.

A 2026 systematic review evaluated 12 studies of cannabinoid treatments in autistic children and adolescents, including four randomized controlled trials. One previous trial of a high CBD cannabis preparation found global clinical improvement in 49% of treated participants. This compared with 21% receiving placebo, along with improvements in social communication. However, other outcomes, including sleep and overall symptom severity did not consistently improve. The review concluded that the evidence remains limited and that larger standardized trials are needed.

Another controlled trial published in 2025 provides an important counterpoint. Researchers studying pharmaceutical CBD in autistic boys with severe behavioral problems found no statistically clear advantage over placebo on the study’s primary behavioral measures and observed a substantial placebo response.

That means the scientific evidence is promising, but not uniform.

An Important Conflict of Interest Consideration

The Harmony Study was financially supported by Fenix Innovation Group and Neurotech International, companies involved with NTI164.

Several investigators disclosed financial relationships with those companies, including employment or financial support, consulting work, and stock ownership. The authors reported that the sponsors were not involved in data collection or statistical analysis.

Industry funding does not invalidate a clinical trial, but it makes independent replication particularly important.

What Does the Study Actually Prove?

The Harmony Study is one of the more scientifically rigorous cannabinoid autism studies published to date. It provides evidence that a specific, standardized, very low THC cannabis extract may improve certain measures of clinical severity, communication, social functioning, and adaptive behavior in some children and adolescents with moderate-to-severe autism.

It does not establish that marijuana generally treats autism. It does not tell us whether THC rich cannabis would produce the same results. It does not establish long term safety. A study with 54 participants completing the blinded phase is still relatively small.

Therefore, the 2026 results are best described as promising clinical evidence that deserves independent confirmation in larger and longer trials.

Study citation: Keating BA, Ogru Y, Isikgel E, et al. NTI164, a novel medicinal cannabis extract, improves core symptoms of autism spectrum disorder: Results from a double-blind, randomised, controlled trial (The Harmony Study).Neurotherapeutics. 2026;23(5). DOI: 10.1016/j.neurot.2026.e01033.