The evidence base for immunoglobulin therapy in ASD is larger than most clinicians realise. This page presents the Rossignol & Frye 2021 meta-analysis in depth, characterises the responder population, and examines the Fourie & Armstrong 2024 IMIG case report in full clinical detail.
The 2021 systematic review and meta-analysis by Rossignol and Frye, published in the Journal of Personalized Medicine, is the most comprehensive synthesis of IVIG evidence in ASD to date. It reviewed 27 publications — four prospective controlled studies, six prospective uncontrolled studies, and fifteen retrospective case series and reports — representing the full published literature through the analysis date.
The consistent finding across study types was clinically meaningful improvement in behavioural outcomes, with the strongest effects in children with documented immune abnormalities. The meta-analysis combined the two retrospective case series with prospectively collected outcomes (total n=46) to produce pooled effect size estimates.
| Outcome Domain | Effect Size (d') | Magnitude | p-value |
|---|---|---|---|
| Total aberrant behaviour | 0.80 | Large | <0.001 |
| Irritability | 0.87 | Large | <0.0001 |
| Hyperactivity | 0.67 | Medium–large | 0.001 |
| Social withdrawal | 0.54 | Medium | 0.01 |
For context: risperidone and aripiprazole — the only FDA-approved medications for ASD-associated irritability — show effect sizes of approximately 0.60–0.85 on the ABC-Irritability subscale in their pivotal trials. The IVIG effect sizes are directly comparable, in an unselected population that includes non-responders. In the immune-dysregulated subpopulation, the signal is expected to be considerably stronger.
The most consistent finding across the IVIG literature is that response is strongly associated with documented immune abnormalities at baseline. This is not a treatment for autism broadly defined. The responder population is a biologically characterised subgroup whose immune dysregulation is measurable through standard clinical laboratory testing.
The cascade framework's testing protocol — detailed in the Biology of Autism suite — provides an evidence-based clinical pathway for identifying this subpopulation before treatment. Biomarker-stratified patient selection is built into the proposed trial design from the outset, addressing the most common criticism of prior IVIG research: that mixed populations diluted the treatment signal in unselected cohorts.
In 2024, the first published case report of intramuscular immunoglobulin specifically in ASD and PANS appeared in Medical Research Archives (European Society of Medicine), DOI: 10.18103/mra.v12i9.5984. The report describes a monthly IMIG protocol and presents outcomes for twelve children across two diagnostic groups.
Protocol: A 16% IgG IMIG formulation administered intramuscularly at 0.2 mL/kg body weight on a 4–6 weekly basis. The 16% IgG concentration is higher than standard IVIG (5–10%), administered in small volumes (1–5 mL) via intramuscular injection rather than intravenous infusion. Established 16% IgG IMIG formulations are available from multiple manufacturers globally at approximately $50–$80 per equivalent dose.
The differential response between PANS (+4.4) and ASD (+2.9) is interpreted as a timing effect, not a mechanism difference. PANS presents acutely, with a recent identifiable trigger. ASD neuroinflammation typically begins in early development — by the time IMIG is initiated, years of inflammatory loading have accumulated. The prediction follows directly: earlier intervention, in younger children with recently elevated biomarkers, should produce a response closer to the PANS ceiling.
Fourie & Armstrong, Medical Research Archives, 2024 — authors' interpretationThis prediction is directly testable. It is the central hypothesis of the Proposed IMIG for Autism Controlled Pilot Study. Biomarker-stratified patient selection — prioritising younger children with recently elevated inflammatory markers and shorter duration of active neuroinflammatory loading — is designed specifically to test whether earlier intervention closes the gap between the ASD and PANS response profiles. See the Trial page for the full design.
The following citations are the primary published sources for the evidence presented on this page. They are drawn from the Biology of Autism suite's immunoglobulin evidence section and are reproduced here for readers who want to go directly to the source material without leaving the IMIG initiative site.
Research context — not clinical guidance. This page summarises published peer-reviewed research. Effect sizes are from published meta-analyses; case report findings are preliminary. IMIG for ASD is investigational and not approved for this indication in any jurisdiction. All clinical decisions require qualified medical and specialist oversight.