Investigating risk factors for postpartum psychosis in bipolar disorder

Abstract

Risk of postpartum psychosis (PP) is high in bipolar disorder (BD), however, factors influencing this risk are poorly understood. In particular, whether adverse childhood experiences (ACEs), anxiety disorders and a range of within-pregnancy factors increase risk of PP in BD is yet to be examined. Of within-pregnancy factors that have been investigated, most have been assessed retrospectively. Prospective studies examining risk of PP in BD are scarce. The main aims of this thesis were to a) examine the relationship between ACEs, anxiety disorders and the lifetime occurrence of PP in BD and b) investigate potential within-pregnancy risk factors for PP in BD using a prospective follow-up design. ACEs, anxiety disorders and lifetime occurrence of PP were assessed via semi-structured interview and self-report questionnaires in 504 parous women with DSM-IV BD-I. Withinpregnancy potential risk factors (including medication, sleep, obstetric and psychosocial factors) were assessed prospectively in 103 pregnant women with DSM-5 BD (n=84 BD-I/SA-BD; n=19 BD-II/BD-NOS) via semi-structured interview in late pregnancy (baseline); perinatal psychopathology was assessed via interview at 12-weeks postpartum. All data were supplemented by clinician questionnaires and/or psychiatric case-notes. Neither history of ACEs (p-values of 0.06-0.95) nor anxiety disorders (of any type; p=0.47, phobias; p=0.23, panic; p=0.53) were significantly associated with the lifetime occurrence of PP. 21% women in the prospective sample experienced PP within 6 weeks of delivery. In unadjusted analyses, an episode of mania/affective psychosis during pregnancy (p=0.001; OR 11.67, 95% CI 2.61-52.21) and loss of at least one complete night of sleep across labour/delivery (p=<0.01; OR 5.35, 95% CI 1.50-19.11) significantly increased risk of PP. After adjusting for known lifetime correlates of PP, mania/affective psychosis in pregnancy remained a significant predictor of PP (p=<0.01; OR 16.49, 95% CI 2.76-98.48). Further adjustment revealed prophylactic mood stabilising medication in the postpartum period had little influence in moderating risk of PP (p=0.61; OR 0.67 95% CI 0.14-3.16). No significant associations were found between withinpregnancy psychosocial or psychological factors and PP. This prospective study demonstrated that risk of PP is high in women with BD, despite use of prophylactic mood stabilising medication. History of ACEs or anxiety disorders did not influence lifetime risk of PP. Mania/affective psychosis with onset during pregnancy significantly increased risk of PP, over and above associations with known lifetime risk factors. Sleep loss associated with labour may act as a final common pathway in the triggering of PP. If replicated, these findings have clinical implications for managing risk of PP in women with BD. The role of neurobiological and medication related factors in the pathophysiology of PP requires further investigation in larger samples