Anxiety Trait as a Potential Endophenotype in First-Degree Relatives of Bipolar Disorder Type I Patients

Background: Early diagnosis in Bipolar Disorder Type I (BDI) is essential for a better outcome. Endophenotypes are an important subtype of biomarkers but to date very few have been discovered in psychiatry. Some previous studies show anxiety-trait as a possible Bipolar Disorder Type I endophenotype, but there is a lack of replication in another populations. Objective: Our study evaluate the presence of anxiety-trait and bipolarity risk in Bipolar Disorder Type I first-degree relatives (FDR). Methods: We evaluated 219 participants (119 healthy controls, 68 healthy FDR and 32 affective unipolar FDR) including socio-demographic data, psychiatric history, Spielberg's State and Trait Anxiety Inventory (STAI), General Health Questionnaire, Beck Depression Scale, and Mood Disorder Questionnaire (MDQ) scores as a measure of bipolarity risk. Results: In our sample, affective unipolar BDI's first degree relatives showed highest scores in STAI anxiety-trait compared to healthy controls and BDI's healthy first degree relatives. STAI-Trait only correlated significantly with bipolarity risk (MDQ) in the unipolar affective first degree relatives subgroup. Conclusion: Unless further investigation is needed, anxiety trait could be a possible BDI's endophenotype candidate since it seems to have high heritability and would confer higher lifetime risk to develop unipolar affective disorder and tendency to bipolarity.