10/07/2026
H.pylori is a common coinfection that shows up with Lyme disease. It is never just Lyme disease.
H. pylori is a bacterium that can live in the stomach for years and cause chronic inflammation of the stomach lining. In some people, long-term infection contributes to gastric mucosal atrophy, which can interfere with normal vitamin B12 absorption.
Vitamin B12 is essential for normal brain and nerve function, including DNA synthesis and myelin maintenance. When B12 becomes severely deficient, neurological and psychiatric problems can develop, including irritability, depression, behavioral changes, cognitive problems and, rarely, psychotic symptoms.
In this case, a 16-year-old boy developed a year-long pattern of irritability, apathy, crying, regressive behavior and truancy, along with psychotic symptoms. He also developed neurological abnormalities including ataxia, muscle rigidity, impaired coordination, reduced arm swinging, a masked facial expression and a positive Romberg sign. Endoscopy and biopsy found gastric mucosal atrophy with H. pylori colonization, while testing indicated vitamin B12 malabsorption.
He was diagnosed with a mood disorder with psychotic features associated with B12 deficiency. Treatment included daily 500 mcg intramuscular B12, low-dose risperidone and H. pylori eradication therapy. At the 2-week follow-up, his psychotic symptoms were no longer present and several neurological abnormalities had improved.
H. pylori eradication was confirmed one month later, and his psychiatric symptoms did not recur during the subsequent follow-up. Because this was a single case with several treatments given together, it suggests a possible chain of stomach disease → B12 malabsorption → B12 deficiency → neuropsychiatric symptoms, but does not prove H. pylori directly caused the psychosis.
PMCID: PMC3404901
