Principal domains of quantitative anxiety trait in subjects with lifetime history of mania.

Background: High comorbidity rates for anxiety have been documented in subjects with history of mania or hypomania. We explored the presence of latent constructs of quantitative anxiety in subjects who have a history of mania or hypomania.

Methods: We conducted an exploratory factor analysis of anxiety trait in 212 subjects who have a lifetime history of at least one manic/hypomanic syndrome. Participants were originally recruited for a Costa Rican sibling pair genetic study of Bipolar Disorder. We used principal factors extraction method with squared multiple correlations (SAS/SAT Professional software) of the STAI (trait subscale).

Results: A three-factor solution with a good simple structure and statistical adequacy was obtained with a KMO of 0.84 (>0.6) and Bartlett's Test of Sphericity of 2.4668E-162 (p<0.05). Items were grouped into anxiety-absent factor and the anxiety-present symptoms in two additional factors based on the nature of the symptoms, worry and rumination.

Limitations: Comorbid disorders could affect the interaction of anxiety score with manic/hypomanic symptoms. Some statistical parameters (mood status independence, score distribution and correlation between trait score and quantitative mania/hypomania) were not taken into consideration to extract the factors. Because anxiety dimensions were explored on individuals with history of mania or hypomania and not in healthy subjects, comparison of our results with other studies can draw confusing conclusions.

Conclusions: Two underlying constructs, worry and rumination may explain anxiety sub-syndromic symptoms in Costa Rican patients with history of mania or hypomania.