Adolescence is a period of developing emotional regulation. However, alexithymia has rarely been examined during this period. The objective of this study is to examine the factor structure and internal consistency of the Korean version of the 20-item Toronto Alexithymia Scale (TAS-20K) in normal adolescents in South Korea.
The TAS-20K was administered to a sample of 290 adolescents aged from 12 to 16 years old. Internal reliability, test-retest reliability, and factorial validity were evaluated.
The three factors of the TAS-20K were confirmed by confirmatory factor analysis. The internal consistency, measured using Cronbach's alpha coefficient was acceptable for difficulty in identifying feelings, good for difficulty in describing feelings, and acceptable for externally oriented thinking.
Our study indicates that the TAS-20K is an appropriate instrument to assess alexithymia in Korean adolescents.
The term "alexithymia", which literally meant "no words for feelings," was originally introduced by Sifneos in the 1970s, when he described the emotional deficits among psychosomatic patients.
Many researchers have attempted to develop reliable and valid instruments to measure alexithymia, using varied approaches including self-report scales, observer-rated questionnaires, and projective techniques. Most of these early instruments, however, failed to meet minimal psychometric standards.
The cognitive level of children does not allow them to have the abstraction and self-reflection that is needed to recognize and describe their emotions and associations connected with stressors.
The questionnaire was administered to 310 middle school students. They were a non-clinical sample and 290 (93.5%) of the participants provided complete data. Thus, this study included 290 adolescents (147 boys, 50.7%; 143 girls, 49.3%) ranging in age from 12 to 16 years old (mean, 13.46; SD, 0.89) in Daegu City, which has approximately 2.4 million inhabitants, located in southeastern South Korea. We sent letters to headmasters requesting their school's participation in this study assessing the reliability and validity of the TAS-20K in Korean adolescents. Permission was obtained in advance from the headmasters, teachers, and parents' committees of the school districts in which the study was performed. The study sample was drawn from two middle schools representing different socioeconomic areas of the city. Participants with prior psychiatric diagnosis and treatment have been excluded. The sample size was estimated according to the following general rule: to have at minimum five times as many observations as variables to be analyzed, and preferably a ten-to-one ratio.
To estimate test-retest reliability, 22 randomly selected students were asked to complete the same scale after a 4-week interval. All participants were volunteers who were informed that the aim of the research was to evaluate the reliability and validity of the TAS-20K. Written informed consent was provided by all participants at enrollment.
The TAS-20 is a 20-item self-report instrument with each item rated on a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree); 5 items are inversely rated. Total scores range between 20 and 100, and higher scores mean a higher tendency toward alexithymia. For the English version of the scale, cutoff scores have been established empirically with total scores greater than 60 indicating a presence of alexithymia and scores less than 52 indicating a definite absence of alexithymia.
The reliability and validity of TAS-20K have been well-demonstrated in adults by Lee et al.
To determine how well the original three-factor TAS-20 model fits the Korean data in the adolescent sample, we performed a confirmatory factor analysis (CFA) using LISREL version 8.1.28 To examine the model fit, we evaluated 4 fit indices: the Goodness-of-Fit Index (GFI); the adjusted goodness-of-fit index (AGFI); the root-mean-square residual (RMS); and the Root-Mean-Square Error of Approximation (RMSEA). The following standards were used to evaluate the model fit: GFI 0.85 or greater; AGFI 0.80 or greater; RMS 0.10 or less; and RMSEA 0.08 or less.
To evaluate internal reliability and item-to-scale homogeneity of the TAS-20K in a Korean adolescent sample, we calculated Cronbach's α coefficients and mean inter-item correlations for the total scale and for each factor. A standard of 0.70 or higher was set for α, and an optimal range of 0.20 to 0.40 for the mean interitem r.
The comparisons of the TAS total score and subscale scores between boys and girls were estimated by use of an independent t-test and among the three age-groups by one-way analysis of variance (ANOVA). In order to compare alexithymia across age groups, the sample was divided into three groups: group 1 (12-13 years old), group 2 (14 years old), and group 3 (15-16 years old). The basis for choosing these categories was to create groups of similar sizes, in order to ensure sufficient data for all analyses, stratified by age as in the Finnish adolescent study.
The Bonferroni test was used as a post-hoc test for the ANOVA. The Pearson χ2 test was used to test differences in the rate of alexithymia between groups, and the Pearson χ2 test with Bonferroni correction was used as a post-hoc test. Statistical analysis was performed with SPSS/Windows (Version 14.0).
The fit indices of the standard three-factor model reached acceptable standards, GFI=0.898, AGFI=0.863, RMS=0.072, and RMSEA=0.061 (90% confidence interval, 0.052-0.071). Parameter estimates for the whole sample are presented in
We used the common three-factor solution, which is presented in
As shown in
The mean total score on the TAS-20K was 45.7 (SD: 8.5). The mean score for boys was 46.2 (SD: 8.7) and for girls was 45.1 (SD: 8.2) with no difference between the sexes. There were no significant differences in the mean scores among age-groups.
The mean scores of the three TAS factors were the following: DIF: 11.9 (SD: 4.9); DDF: 11.5 (SD: 3.3); and EOT: 22.3 (SD: 3.6). The differences were not statistically significant between the sexes for the three TAS factors. The differences were statistically significant between age-groups for DIF and EOT factors.
Among 290 middle school students, 5.2% (5.4% of boys and 4.9% of girls; p=0.83) were alexithymic. In the youngest age-group, the rate of alexithymia was 4.1% (boys: 4.4%, and girls: 3.8%), and in the middle and oldest groups, 6.7% (boys: 7.8%, and girls: 5.7%) and 4.5% (boys: 3.9%, and girls: 5.4%), respectively. The difference between the age-groups for the rate of alexithymia was not significant (p=0.66). No significant differences emerged between the sexes in any age-group for the rate of alexithymia. Descriptive statistics of total scores and the three factors of the TAS-20K are presented in
In general, the results of this study support the idea that the TAS-20K has good psychometric properties in adolescent subjects. The estimates of internal reliability for the full scale are comparable to those obtained with the English version of the scale (TAS-20: 0.86, DIF: 0,80, DDF: 0.76, EOT: 0.71).
According to the original authors of the English scale, factor 3 is consistently reported to have low internal consistency, and Cronbach's α coefficients for factor 3 mostly ranged between 0.34 to 0.68 for different language translations.
Although the internal reliability estimates (α=0.61) are below the standard of 0.70 for the DDF factors of the present study, the original author of the English scale sugested that the Cronbach's α coefficient above 0.60 deonstrated adequate reliability for factor 2 (DDF) and 3 (EOT).
The parameter estimates of the factor relationship for girls were higher than for boys, and the estimates related to Factor 3 for girls were low. These results are consistent with the findings of a Finnish adolescent sample and a university student sample in Korea.
The originally established three-factor model for the TAS-20
Although the test-retest reliability was less than 0.70 for the DDF factor (0.65), TAS-20K total scores and DIF and DDF scores of the TAS-20K were stable over a 4-week period.
Adolescence is the period of maturation when emotional, psychological, and social development proceeds. A capacity to be aware of one's own emotions and feelings and to regulate them increases more rapidly during adolescence than in childhood. We hypothesized that the incidence of alexithymia would decrease apace in the process of adolescent development, compatible with the results of a previous study.
This study showed no significant differences among the age-groups in the prevalence of alexithymia. This result is inconsistent with the findings of a previous study.
More cross-cultural studies are needed to evaluate possible changes in alexithymic tendencies over developmental periods. Knowledge of normative alexithymic featu res can be helpful in assessing a given adolescent's development, and especially in assessing an adolescent's age-appropriate capacity to do "psychotherapeutic work" and in providing appropriate treatment including psychotherapy. Because lack of emotional regulation capacity is associated with psychiatric problems,
This study has limitations: it was not intended to measure sociodemographic or depression factors. Both of them have been shown to be associated with alexithymia among adults.
TAS-20 total sores >60 are defined as alexithymic cases. The study used this common cutoff point to calculate the alexithymic rate for adolescents. However, this point has not been validated for adolescents yet. Further studies are needed to label a cufoff point for adolescent-aged subjects.
The results of this study support the use of the TAS-20K for a Korean sample of adolescents. Future research should evaluate the concurrent, convergent, and discriminant validity of alexithymia measures, and to explore the extent to which alexithymia might influence health among Korean adolescents.
We conclude that the TAS-20K is an appropriate method for assessing alexithymia among young people in Korea.
This work was supported by BioMedical Research Institute grant,
Parameter estimates from the results of confirmatory factor analyses of the TAS-20K among non-clinical adolescents aged from 12 to 16 years
TAS-20K: the Korean version of the 20-item Toronto Alexithymia Scale, N: number
Confirmatory factor analysis: parameter estimates for the relationships among the three factors of the TAS-20K and goodness-of-fit indices among non-clinical adolescents aged from 12 to 16 years old
*p<0.05. F1: difficulty in identifying feelings, F2: difficulty in describing feelings, F3: externally oriented thinking a accepted value. N: number TAS-20K: the Korean version of the 20-Item Toronto Alexithymia Scale
Internal consistency (Cronbach's α) and Mean iter-item correlation coefficient (MeanIC) for the TAS-20K and the three factors in the whole sample and in boys and girl and in different age-groups
DIF: difficulty in identifying feelings, DDF: difficulty in describing feelings, EOT: externally-oriented thinking, TAS-20K: the Korean version of the 20-Item Toronto Alexithymia Scale, α: Cronbach's α
Descriptive statistics of the total TAS-20K score and the three factors of TAS-20K for the whole sample and boys and girls and different age-groups
*p<0.05. TAS-20K: the Korean version of Toronto Alexithymia Scale, DIF: difficulty in identifying feelings, DDF: difficulty in describing feelings, EOT: externally-oriented thinking, N: number, SD: standard deviation, NS: not significant