RELAPSE IN THE LONGITUDINAL TRAJECTORY OF FUNCTIONING IN BIPOLAR DISORDER TYPE I

Abstract

Introduction: Bipolar disorder (BD) is a recurrent and chronic mood disorder. BD type I (BD-I) is associated with high disability, lower quality of life, and excess mortality. Importantly, BD is also associated with severe functional impairment. Staging models suggest BD is a progressive illness and use episode recurrence and functional impairment in euthymia as main proxy measures. Research has identified deficits in functioning in BD compared to healthy controls (HC) and suggest that impairment may be sustained in periods of euthymia and related to episode recurrence. The current research uses data from a larger longitudinal neuroimaging study to investigate psychosocial and subjective cognitive function, as measured by the Functional Assessment Short Test (FAST) and the Cognitive Failures Questionnaire (CFQ), in individuals with BD-I who experienced an episode relapse (BDR) compared to those who did not (BDNR) and healthy controls (HC). Methods: Participants completed up to 3 visits over 2 years, that took place approximately 1 year apart. The final sample consisted of 61 HC, 21 BDR, and 26 BDNR participants. Three analyses were conducted to explore between and within-subject differences: mixed-effects analysis of variance (ANOVA), one-way Kruskal-Wallis tests, and simple linear growth analyses. Missing data precluded using three time points for some analyses, so the mixed-effects ANOVA and one-way Kruskal-Wallis tests used two re-binned timepoints (baseline and follow-up) and the growth curve analysis used all three timepoints. Results: Significant differences were found between the HC group and both BD groups (BDR and BDNR) for both the FAST and CFQ at baseline and follow-up visits. No significant differences were found between the BDR and BDNR groups, neither differences at timepoints nor differences in change across timepoints. The BDNR group demonstrated a significant decrease in CFQ scores over the 3 timepoints. Conclusion and Future Directions: The results suggest that individuals with BD-I experience sustained impairment in psychosocial and subjective cognitive function over time compared to HC, but relapse does not have a significant effect on this impairment. Since the BDNR group demonstrated a decrease in CFQ scores over time, not experiencing relapse may be implicated in the improvement of subjective cognitive functioning. Future studies with longer measurement windows and larger sample sizes could further clarify these findings.