Association between Personality Traits and Obesity indices: Family and Co-twin Analysis

다국어 초록 (Multilingual Abstract)

Personality traits of an individual affect one’s attitude towards life and one’s life style factors determining health status. Since emotional disruption, such as depression and mood disorders, and unhealthy life habits are established risk factors of obesity, investigating the association between personality, life style, and obesity will lead to development of efficient intervention or preventive measure for obesity, according to their personality profiles. To this end, we attempted to explore the associations between Temperament and Character Inventory (TCI)’s seven dimensions and obesity indices: body mass index (BMI), waist circumference, waist hip ratio (WHR), trunk and total body fat percent measured by Dual-energy X-ray absorptiometry (DXA) in Korean twins and their families. Additionally, we aim to discriminate environmental and genetic effect of TCI on obesity using pair-wise analysis of each and combined monozygotic twins (MZ), dizygotic twins (DZ) and sibling pairs adjusted for age and sex. We have expected that estimating non-genetic association between personality traits and obesity will specifically show potential target chains interconnecting personality, life style and obesity.
A total of 3320 individuals (1333 men, 1987 females, 661 families) of the Healthy Twin Study in Korea were involved in this study. This population includes 545 MZ pairs, 122 DZ pairs, and 2695 sibling pairs. Association between TCI and obesity was analyzed adjusting for age, sex, smoking and alcohol consumption history. A random effect model (REM) was applied to adjust familial correlations. For co-twin and sib-pair analyses pair-wise regression models using pairwise-difference values were used.
In conventional regression analyses (REM), among seven domains of TCI, novelty seeking and harm avoidance had the positive association with obesity. Decreased persistence (β =-0.0003), self-directedness (β =-0.0002), cooperativeness (β =-0.0003), and self-transcendence (β =-0.0002) had significant association with WHR and showed paralleled result with other obesity indices. In pair-wise regression model, an association between novelty seeking and persistence, and obesity were further dissected; βW in MZ data showed stronger association than βW in DZ-sibling data and pooled data, indicating that novelty seeking and persistence are associated with obesity and in this association, there are more environmental effects than genetic effect.
The results from this study confirm some of the previous findings. By comparing the βW of different dataset, we could conclude that there is high environmental effect on the association, and that there is more environmental effect on the TCI associated obesity than genetic effect. Suggesting an individual’s personality profiles can be integrated in to personalized intervention of obesity.

목차 (Table of Contents)

• Table of Contents
• I. Introduction --------------------------------- 1
• A. Background Information ---------------- 3
• B. Previous Studies --------------------- 5
• C. Goal ------------------------------- 7
• II. Methods ---------------------------------- 8
• A. Study Population & Measurements ------- 8
• B. Statistical analyses ------------------- 12
• III. Results ----------------------------------- 16
• IV. Discussion -------------------------------- 24
• V. Conclusion -------------------------------- 27
• VI. Reference --------------------------------- 28
• VII. Supplementary Table and Figures ------------ 32
• VIII. Abstract (in Korean) ----------------------- 37