Background: Imprecision of the psychiatric phenotype might partially explain the failure of genetic research to identify genes that contribute to susceptibility of anxiety disorders. Previous research concluded two underlying constructs, worry and rumination, might explain anxiety subsyndromic symptoms in Costa Rican patients with history of mania. The goal of the current study is to explore the presence of latent constructs for quantitative anxiety in a group of subjects with a wide diagnostic phenotype and non-affected individuals. Methods:We conducted an exploratory factor analysis of anxiety trait in 709 subjects. Our sample was comprised by 419 subjects with psychiatric disorders and 290 non-affected individuals. We used principal factors extraction method with squared multiple correlations of the STAI (trait subscale). Results:We found the following preliminary results: a three-factor solution with a good simple structure and statistical adequacy was obtained with a KMO of 0.92 (>0.6) and Bartlett's Test of Sphericity of 5644,44 (p<0.05). The STAI items were grouped into three factors: anxiety-absent, worry and rumination based on the characteristics of the symptoms. Conclusion:Two underlying constructs, worry and rumination may explain anxiety subsyndromic symptoms in Costa Rican subjects. Our proposed underlying structure of subsyndromal anxiety in individuals should be considered as an important factor in defining better phenotypic characterizations on a broader diagnostic concept. Worry and rumination as a phenotypic characterization may assist in genotyping; however, its predictive value on actual illness outcome still requires more research. The Genome-Wide QTL analysis for anxiety trait in the same sample is ongoing.

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