Abstract

Background: Bipolar Disorder (BD) is a major psychiatric illness that continues with recovery, relapses and results in significant morbidity. It has been postulated that birth order may possibly increase the neurodevelopmental risk factors for mental illness. Impact of birth order in Nigeria is peculiar and coupled with the obvious cultural influence and economic hardship, it is apt we study this relationship.
Methods: This was a retrospective study that looked at clinical records of all patients diagnosed with BD between 2019 and 2021. Four hundred and three patients were diagnosed as having BD (Using ICD-10) and had all the required details complete.
Results: The mean age and illness duration for BD were 27.71±5.99 and 5.66±3.54 weeks. Family history of mental illness was 20.1%. Gender and family history of mental illness were significantly associated with birth order, p= 0.036 and 0.030 respectively. BD reduces as birth order increases. Patients from monogamous family had a significant higher duration of illness than polygamous (p=0.023)
Conclusion: BD is most prevalent among the low birth orders and the prevalence decreases as birth order increases. Being a second born is specifically most represented among patients with bipolar disorder.

Key words: Bipolar Disorder, Birth Order, Family History, Mental illness