Evidence for Adult PANDAS
There is insufficient evidence to support the existence of PANDAS in adults, and the concept of PANDAS itself remains an unproven hypothesis even in children. 1
Current Understanding of PANDAS
PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections) was first proposed in 1998 as a hypothesis suggesting that childhood obsessive-compulsive disorder (OCD) and/or tics may arise as a result of a post-streptococcal autoimmune process. The proposed mechanism involves autoimmune responses that cross-react with brain tissue following Group A Streptococcus (GAS) infection, similar to the mechanism believed responsible for Sydenham chorea 1.
Key characteristics of PANDAS include:
- Sudden onset of OCD and/or tic disorders
- Pre-pubertal symptom onset
- Episodic course of symptoms
- Temporal association with GAS infections
- Associated neurological abnormalities 2
Evidence in Adults
The evidence for adult PANDAS is extremely limited:
- Only isolated case reports exist, such as a 2001 report of a 25-year-old with onset of OCD after severe pharyngitis 3 and a 2023 case report of a 26-year-old female 4
- These cases are not sufficient to establish adult PANDAS as a clinical entity
- The original definition of PANDAS specifically includes pre-pubertal onset as a diagnostic criterion 2
Scientific Status of PANDAS
According to the American Heart Association's scientific statement:
- "The PANDAS hypothesis has stimulated considerable research, as well as considerable controversy"
- "The current state of knowledge dictates that the concept of PANDAS should be considered only as a yet-unproven hypothesis" 1
The committee does not recommend:
- Routine laboratory testing for GAS to diagnose PANDAS
- Long-term antistreptococcal prophylaxis to prevent PANDAS
- Immunoregulatory therapy (e.g., intravenous immunoglobulin, plasma exchange) to treat exacerbations 1
Diagnostic Challenges
Several issues complicate the diagnosis of PANDAS in adults:
- Lack of clear diagnostic criteria specific to adults 5
- Difficulty establishing temporal relationship between infection and symptom onset in adults
- Absence of large-scale studies validating the concept in adult populations
- Pre-pubertal onset is a defining feature of PANDAS, making adult-onset cases definitionally problematic 2
Proposed Mechanisms and Related Conditions
The proposed pathophysiology involves molecular mimicry, where antibodies directed at streptococcal antigens cross-react with brain tissue, particularly in the basal ganglia 6. This mechanism is similar to that proposed for other post-infectious neuropsychiatric conditions.
Some evidence suggests possible neuroinflammatory changes:
- A post-mortem examination of a 26-year-old with purported PANDAS showed mild gliosis and increased CD3-, CD4-, and CD25-stained lymphocytes in the basal ganglia 4
- However, this represents a single case and cannot be generalized
Clinical Implications
For clinicians evaluating adult patients with sudden-onset OCD or tics:
- Standard OCD treatment approaches should be utilized, including cognitive-behavioral therapy and selective serotonin reuptake inhibitors 2
- Confirmed streptococcal infections should be treated with appropriate antibiotics regardless of neuropsychiatric symptoms 2
- There is insufficient evidence to support immunomodulatory treatments for adults with suspected post-streptococcal neuropsychiatric symptoms 1
Conclusion
While case reports suggest the possibility of PANDAS-like presentations in adults, the scientific evidence remains insufficient to establish adult PANDAS as a clinical entity. The concept of PANDAS itself remains controversial even in pediatric populations. Clinicians should approach suspected cases with caution and focus on evidence-based treatments for the presenting neuropsychiatric symptoms while appropriately treating any confirmed streptococcal infections.