The correlation between longitudinal changes in hypothalamic–pituitary–adrenal (HPA)-axis activity and changes in neurocognitive function in mixed-state bipolar II disorder

Abstract

Introduction

In this study, we aim to determine 1) the differences in cortisol in patients with bipolar II disorder (BD-II) and control subjects and 2) the correlation between cortisol levels and cognitive function in patients with BD-II during a 24-week follow-up period.

Methods

We recruited a total of 32 BD-II patients and 30 healthy control subjects. The BD-II patients were assessed for clinical severity and serum cortisol level at baseline and at weeks 8, 16, and 24. The Brief Assessment of Cognition in Affective Disorders (BACA) was adopted to evaluate cognitive function at baseline and endpoint (week 24). Meanwhile, we assessed the controls for serum cortisol level and BACA at baseline.

Results

We observed that the BD-II group had a higher serum cortisol level and lower BACA composite scores compared with the healthy controls at baseline. A significant correlation was found between changes in Verbal Fluency, a subset of BACA, and changes in serum cortisol level after the 24-week follow-up, controlling for age, gender, years of education, and clinical severity (P<0.001).

Conclusion

We propose that serum cortisol may be involved in the psychopathological mechanisms of cognitive decline in BD-II.

Keywords:

• bipolar II disorder
• cognitive function
• cortisol level
• correlation

Supplementary materials

Table S1 Correlations between cortisol and all BACA scales at baseline

Table S2 Correlation between levels of cortisol and cognitive testing (BACA) in mixed-state BD-II patients over 24 weeks of follow-up

Acknowledgments

The authors would like to thank Ms Yu-Hsuan Lin and Ms Yi-Chin Wang for their assistance in preparing this manuscript.

This work was supported in part by MOST 103–2622-B-006–006-CC2 (to R-BL), MOST 103–2314-B-075B-006 (to S-YL) from the Taiwan Ministry of Science and Technology; VGHKS104-098 (to S-YL), VGHKS105-122 (to S-YL), and VGHKS107-153 (to S-YL) from Kaohsiung Veterans General Hospital, Taiwan.

Author contributions

H-HL wrote the first draft, S-YL gave conceptual advice and revised the manuscript. S-YL, C-CW, H-LC, and L-JW managed the lab work and statistics. C-HC and TL managed participant recruitment. R-BL supervised this work and edited the manuscript. All authors contributed toward data analysis, drafting and critically revising the paper and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interest in this work.