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Key Takeaways
- The Harmony Study shows that NTI164, a medicinal cannabis extract, can significantly improve core symptoms of Autism Spectrum Disorder (ASD) in children and adolescents.
- NTI164 works by interacting with the endocannabinoid system, helping to regulate mood, social behavior, and stress responses associated with ASD.
- Participants experienced significant improvements in overall ASD severity, social behavior, and emotional well-being after using NTI164 for eight weeks.
- The study indicated that NTI164 not only helped children but also improved the quality of life for their families.
- Future research includes a Phase III trial to confirm these findings and explore NTI164’s potential as a disease-modifying therapy for ASD.
For families navigating an Autism Spectrum Disorder (ASD) diagnosis, the treatment options have long been limited and imperfect. The two FDA-approved medications for ASD, risperidone and aripiprazole, only target irritability. They say nothing about the hallmark difficulties that define the condition: social communication challenges, repetitive behaviors, emotional dysregulation, and restricted interests. Many families are left managing these core symptoms with a patchwork of behavioral therapies, occupational support, and hope. That picture may be starting to shift. A new clinical trial out of Australia has produced some of the most compelling evidence yet that a medicinal cannabis extract can meaningfully improve the core symptoms of Autism Spectrum Disorder (ASD) in children and adolescents.
The study, known as the Harmony Study, was published in the journal Neurotherapeutics and its results are worth paying attention to. The extract at the center of the trial is called NTI164, developed by Neurotech International and tested through the Monash Children’s Clinical Trial Centre at Monash Health in Victoria, Australia.
Unlike many cannabis products, NTI164 is a standardized full-spectrum plant extract, meaning it contains a blend of cannabinoids working together rather than a single isolated compound. The cannabinoid profile includes cannabidivarin (CBDV), cannabidiolic acid (CBDA), cannabigerolic acid (CBGA), CBD, and trace levels of THC, all below 0.3%.
What Is NTI164, and How Does It Work in the Brain?
The endocannabinoid system (ECS) plays a large role in regulating mood, social behavior, immune function, and cognitive processing. Research has found that children with ASD tend to have lower circulating endocannabinoid levels than neurotypical children, according to a 2019 study pointed researchers toward cannabinoid-based therapies as a potentially relevant treatment pathway.
NTI164 works by interacting with CB1 and CB2 receptors throughout the brain and nervous system. Activating these receptors suppresses neuroinflammation, reduces pro-inflammatory cytokines, supports healthy GABA levels, and regulates the hypothalamic-pituitary-adrenal axis, which governs stress responses. Elevated inflammatory markers and disrupted stress reactivity characterize ASD, meaning these mechanisms directly target the biological factors researchers are working to address.
The full-spectrum formulation is thought to produce a stronger combined effect than isolated compounds. Multiple studies have found that whole-plant extracts with multiple cannabinoids working in concert tend to outperform single-compound products as anti-inflammatory and immunomodulatory agents.
What Did the Harmony Study Find About Overall ASD Severity?
Sixty-one participants between the ages of 8 and 17, all with a confirmed Level II or III ASD diagnosis, were enrolled at Monash Children’s Hospital. Fifty-four completed the 8-week double-blind phase, split equally between the NTI164 group and the placebo group.
The primary outcome measure was the Clinical Global Impression-Severity scale (CGI-S), a 7-point clinician-rated tool assessing overall illness severity. At baseline, participants averaged a score of 5.4, placing most in the markedly to severely ill range.
After 8 weeks, the NTI164 group showed a statistically significant reduction in CGI-S scores compared to placebo. The least-squares mean difference between groups was -1.65 points (95% CI: -2.29 to -1.01, p less than 0.001). That corresponds to roughly a one-category improvement on the 7-point scale. To put that in practical terms, clinicians rated participants as moving from severely ill toward moderately ill. The placebo group, by contrast, showed almost no change.
How Did NTI164 Affect Social Behavior and Adaptive Functioning?
Social communication and interaction are central to what makes ASD difficult to live with. On the Vineland Adaptive Behavior Scales (Vineland-3), which measures real-world functioning across communication, daily living skills, and socialization, NTI164 produced statistically significant gains across all three core domains and the total Adaptive Behavior Composite at Week 8 (p less than 0.05 for each domain).
The Social Responsiveness Scale (SRS-2) also showed encouraging patterns. Significant improvements were found in Social Cognition (p = 0.033) and in Restricted Interests and Repetitive Behavior (p = 0.037). These two subdomains sit at the core of what clinicians and researchers identify as defining ASD traits. Positive trends, though not reaching statistical significance in the double-blind phase, were also observed in Social Awareness and Social Communication.
When participants who had received placebo during the double-blind phase crossed over to NTI164 in the open-label phase, their SRS-2 Total T-score dropped by a mean of 9.82 points (p less than 0.001), with improvements across every social subdomain. That kind of consistency across both study phases is hard to dismiss.
What Were the Anxiety and Mood Improvements Seen With NTI164?
Anxiety, depression, and mood disruption are highly prevalent in ASD and contribute significantly to impairment and family stress. The Anxiety, Depression, and Mood Scale (ADAMS) showed some of the clearest treatment effects in the Harmony Study.
NTI164 produced significant improvements across four of five ADAMS subdomains during the double-blind phase: Depressed Mood (p = 0.019), Social Avoidance (p = 0.006), General Anxiety (p less than 0.0001), and Compulsive Behavior (p = 0.001). The ADAMS Total Score showed a group difference of -18.47 points (p less than 0.001), a strong signal of broad emotional improvement.
The Anxiety Scale for Children-ASD (ASC-ASD-P) showed significant reductions in Uncertainty (p = 0.008) and Separation Anxiety (p = 0.020). These are meaningful quality-of-life improvements for children and their caregivers.
Did NTI164 Also Benefit Families, Not Just Children?
One finding that stands out in the Harmony Study data is the effect NTI164 had on the families of participants. Caregiver-reported outcomes were measured using the Autism Family Experience Questionnaire (AFEQ), which captures family quality of life, parenting experience, and household wellbeing.
The NTI164 group showed a statistically significant improvement in AFEQ Total Score compared to placebo (p = 0.008). Significant gains were specifically seen in Family Life (p = 0.017) and Child Development, Understanding and Social Relationships (p = 0.016).
This matters for a few reasons. Raising a child with moderate-to-severe ASD carries enormous caregiver burden, and improvements that ripple outward to the whole family unit are clinically meaningful in a way that symptom checklists alone cannot capture. The fact that both clinicians and caregivers reported consistent improvements across independent assessment tools adds weight to the overall findings.
Was NTI164 Safe for Children With Autism?
The safety profile of NTI164 in this trial was about as clean as you could hope for. Of the 61 enrolled participants, 88.5% completed the full 8-week double-blind phase. No serious adverse events were reported at any point during the study.
The adverse events that did occur, totaling 41 across 26 participants, were all classified as mild, transient, and self-resolving. The most common were nausea (21.9%), headache (19.5%), abdominal pain (17.1%), and anxiety (14.6%). Notably, adverse events were distributed evenly across both the NTI164 and placebo groups, which the study authors noted may indicate those symptoms were related to the olive oil vehicle rather than the cannabis extract itself.
No clinically significant changes appeared in lab values or vital signs throughout the study. And at the end of the trial, 44 of 54 participants opted into an ongoing open-label extension phase. That level of continued participation says something meaningful about how families experienced the treatment.
What Does This Research Mean for the Future of Cannabis-Based Autism Treatment?
The Harmony Study is not a standalone result. Observational studies and smaller trials from Israel, Brazil, and the United Kingdom have reported similar improvements in ASD symptoms following cannabinoid-based treatments. Taken together, the evidence is building toward a more consistent picture.
That said, the Harmony Study itself had limitations that the authors were transparent about. The double-blind period was 8 weeks, which is relatively short for a condition as complex as ASD. The trial involved a single site and 54 completing participants, which limits how broadly the results can be generalized. And because the maximum tolerated dose was patient-specific, participants had varying exposure levels by Week 8.
What comes next is significant. A multi-centre Phase III trial of NTI164 in ASD is already in development (ClinicalTrials.gov ID: NCT07257939). This next study will involve a larger, formally powered patient population, a 12-week treatment period, and multi-omics analyses to dig deeper into how NTI164 affects gene expression and immune pathways at the biological level.
The researchers also noted that NTI164 may operate as a disease-modifying therapy rather than a purely symptomatic one, based on its anti-inflammatory and epigenetic properties. A companion study found that NTI164 modulated immune and epigenetic cellular pathways in children with pediatric acute-onset neuropsychiatric syndrome, more than half of whom had a comorbid ASD diagnosis. If those findings hold up in ASD-specific research, the implications for long-term treatment could be substantial.
NTI164 is currently unregistered and only accessible in Australia through clinical trials or compassionate use programs. Availability will depend on the results of confirmatory trials. But the Harmony Study represents a genuinely meaningful step forward in a field that has long been short on rigorous, placebo-controlled evidence.
Where Does Medicinal Cannabis for Autism Go From Here?
ASD affects roughly 1 in 31 eight-year-old children in the United States, according to 2025 CDC surveillance data, with a male-to-female ratio of approximately 4:1. The demand for treatments that address core symptoms, not just irritability, is significant and growing.
The Harmony Study adds to a body of evidence that full-spectrum, low-THC cannabis extracts deserve serious clinical attention as adjunctive therapies for neurodevelopmental disorders. Both the depth of improvements and the favorable safety profile seen in this trial support continued research.
For those following the science of medicinal cannabis, this is a study that warrants attention. The next Phase III trial will be the real test. But for now, the data out of Monash Children’s Hospital gives researchers, clinicians, and families real reasons to stay tuned.
Frequently Asked Questions
NTI164 is a medicinal cannabis extract developed by Neurotech International. It contains multiple cannabinoids, including CBD, CBDA, CBDV, and CBGA, with less than 0.3% THC. Research suggests that this full-spectrum formulation may produce stronger anti-inflammatory and immune-supporting effects than isolated compounds like CBD alone.
A 2026 study published in Neurotherapeutics found that NTI164 significantly improved social cognition and reduced repetitive behaviors in children with moderate-to-severe ASD. When placebo participants switched to NTI164, their social responsiveness scores dropped by an average of 9.82 points, reflecting meaningful improvements across all social subdomains.
In the Harmony Study, NTI164 showed a safety profile similar to placebo, with no serious adverse events. Minor side effects like nausea, headache, and abdominal pain were mild and resolved on their own. The study had an 88.5% completion rate, with 44 of 54 participants opting to continue into an open-label extension phase.
In the Harmony Study, NTI164 did not significantly improve sleep disturbance. Sleep outcomes, measured by the Sleep Disturbance Scale for Children, remained largely unchanged over the 8-week double-blind period. The authors noted that this suggests the other improvements observed were likely direct treatment effects rather than secondary benefits of improved sleep.
