Harmonizing categorical and dimensional measures of manic episodes in bipolar disorder

Authors

  • IC Akwue
  • LN Lacbawan
  • GW Hawariat
  • EK Besançon
  • A Freifeld
  • L Kassem
  • FJ McMahon

Abstract

Bipolar disorder (BD) is a severe mood disorder characterized by recurring depressive, manic, and mixed episodes. Two instruments, the Mood Disorder Questionnaire (MDQ) and the Diagnostic Interview for Genetic Studies (DIGS), can be utilized to identify and evaluate manic symptoms in BD. This study aims to develop a dimensional measure of manic episodes using either the MDQ or DIGS data. Such a measure could enhance the efficiency of collecting phenotypic data, provide quantitative assessments of mania when only MDQ or DIGS data are available, and capture genetic information from relatives with subclinical manic symptoms. Data from 88 participants in the Amish-Mennonite Bipolar Genetics (AMBiGen) study who completed both MDQ and DIGS were analyzed. Two harmonization methods were tested: 1) manually matching items from the mania section of the DIGS with similar MDQ questions, then DIGS-based scores were calculated and correlated with actual scores from the MDQ; 2) conducting a Canonical Correlation Analysis (CCA) to identify optimal linear combinations of DIGS and MDQ items maximizing correlations between the instruments. Both methods demonstrated significant phenotypic correlations between DIGS and MDQ measures. Scores derived from the manual matching method showed a high correlation with actual MDQ scores (R = 0.85, p<0.0001). CCA detected two canonical variables significantly correlated between DIGS and MDQ, explaining 38% of the variance. The first canonical variable correlated most strongly with increased self-confidence and energy (adj. canonical correlation = 0.83, p=0.0002), while the second correlated with irritability and argumentativeness (adj. canonical correlation = 0.75, p = 0.0151).

Scientific Focus Area: Clinical Research

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