Can a streptococcal (strep) infection lead to Obsessive-Compulsive Disorder (OCD)?

Streptococcal Infection and OCD: The PANDAS Connection

Yes, streptococcal infections can trigger obsessive-compulsive disorder (OCD) in certain individuals through a proposed autoimmune mechanism, though this relationship remains a hypothesis requiring further research to establish definitive causality. 1

Understanding PANDAS and PANS

Streptococcal infections have been linked to neuropsychiatric symptoms through a condition called Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections (PANDAS). This condition is characterized by:

• Sudden onset of OCD and/or tic disorders
• Pre-pubertal symptom onset
• Episodic course of symptoms
• Temporal association with Group A Streptococcus (GAS) infections
• Associated neurological abnormalities 1, 2

The proposed mechanism involves an autoimmune response where antibodies produced against streptococcal bacteria cross-react with brain tissue, particularly affecting the basal ganglia, similar to what occurs in Sydenham chorea (a manifestation of rheumatic fever) 1.

Research has evolved to recognize a broader condition called Pediatric Acute-onset Neuropsychiatric Syndrome (PANS), which includes sudden-onset OCD triggered by various infections and other insults, not just streptococcal infections 1.

Evidence Strength and Limitations

The evidence linking streptococcal infections to OCD has several important limitations:

• The American Heart Association states that "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

• Systematic reviews indicate that "rigorously conducted research regarding treatments for PANDAS is scarce, and published studies have a high risk of bias." 3

• While primarily described in children, there are limited case reports of adult-onset OCD following streptococcal infections 4, 5

Clinical Presentation

The clinical presentation of PANDAS/PANS typically includes:

• Abrupt, dramatic onset of OCD symptoms (unlike typical gradual onset)
• Multiple comorbidities including separation anxiety (86-92%), school issues (75-81%), sleep disruptions (71%), tics (60-65%), and urinary symptoms (42-81%) 6
• Males are affected approximately twice as often as females 6
• Average age of onset around 7 years, though cases have been reported in young adults 4, 6

Diagnostic Approach

When evaluating a patient with sudden-onset OCD:

1. Document the temporal relationship between streptococcal infection and OCD symptom onset/exacerbations
2. Look for evidence of recent streptococcal infection (throat culture, rapid antigen detection test, or elevated antistreptolysin-O titers)
3. Rule out other causes of acute neuropsychiatric symptoms
4. Note that proper specimen collection technique is crucial for accurate testing results 7

Management Considerations

The American Heart Association 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

Standard OCD treatment approaches should be utilized:

• Cognitive-behavioral therapy
• Selective serotonin reuptake inhibitors
• Treatment of confirmed streptococcal infections with appropriate antibiotics 7, 3

Important Clinical Pitfalls

1. Overdiagnosis: Not all cases of OCD with concurrent streptococcal infection represent PANDAS. The temporal relationship and sudden symptom onset are critical diagnostic features.

2. Undertreatment of streptococcal infections: Confirmed streptococcal pharyngitis should be treated with appropriate antibiotics to prevent complications, regardless of neuropsychiatric symptoms 7.

3. Inappropriate use of immunomodulatory therapies: Current evidence does not support routine use of plasma exchange or intravenous immunoglobulin for PANDAS 1.

4. Failure to consider PANDAS in adults: While primarily described in children, case reports suggest streptococcal-triggered OCD can occur in adults 4, 5.

5. Overlooking standard OCD treatments: Even in suspected PANDAS cases, evidence-based OCD treatments should not be delayed while investigating infectious triggers.