Several studies have suggested the relationship between the month of birth and the occurrence of a mental disorder in adulthood. Also an association has been founded between the month of birth and the presence of specific genetic polymorphisms associated with mental disorders, as is the case with bipolar disorder.
The aim of this study is to explore the relationship between births in different season and bipolar disorder.
For this purpose, a retrospective review of all psychiatric admissions in our hospital between 2002 and 2013 was performed, as well as the date of births and the final diagnostic codes according to ICD 10 for each hospital discharge. Only the first admission was included for each subject to avoid the confounding variable in frequency, caused by readmissions. An ANOVA analysis was used to calculate the differences between the months and the frequency of the diagnosis.
Significant differences that suggest a possible relationship between month of birth and Bipolar Disorder were found.
An important limitation is the large number of cases dismissed for improper coding and the possibility of changing the diagnosis of an individual throughout their lifetime.
Conducting prospective cohort studies to confirm this hypothesis are considered necessary.