Purpose. – Borrelia burgdorferi (Bb) infection can affect the central nervous system and possibly lead to psychiatric disorders. We compared clinical and demographic variables in Bb seropositive and seronegative psychiatric patients and healthy controls.

Method. – Nine hundred and twenty-six consecutive psychiatric patients were screened for antibodies to Bb and compared with 884 simultaneously recruited healthy subjects.

Results. – Contrary to healthy controls, seropositive psychiatric patients were significantly younger than seronegative ones. None of the studied psychiatric diagnostic categories exhibited stronger association with seropositivity. There were no differences between seropositive and seronegative psychiatric patients in hospitalization length, proportion of previously hospitalized patients and proportion of subjects with family history of psychiatric disorders.

Conclusion. – These findings elaborate on potential association between Bb infection and psychiatric morbidity, but fail to identify any specific clinical ‘signature' of Bb infection.