Season of birth variations in dimensions of functioning evaluated by the diagnostic interview for borderline patients

In view of recent reports showing that cerebrospinal fluid (CSF) levels of monoamine metabolites exhibit season of birth variations, and that they are also associated with section II (impulse action patterns) of the diagnostic interview for borderline patients (DIB), we analyzed two samples of data to investigate the relationship between the season of birth and the DIB. The first sample comprised 202 patients participating in psychobiological research in Stockholm, and the second sample comprised 130 patients who had committed suicide in Västerbotten in northern Sweden. Those with intermediate score for section II (impulse action patterns) were significantly more likely to have been born during the season October to January in the pooled data, and this tendency persisted in separate analyses for the two samples and for the two diagnostic groups mood disorders and schizophrenia, respectively. Those with high score for section IV (psychosis) were significantly more likely to have been born during February to April in the pooled sample and in the nonschizophrenic group. In the group with schizophrenia, those born during February to April had significantly high scores for section III (affects). These results throw further light on the role of season of birth in suicidology and in psychiatric morbidity.