Verbal aggression is one of the most common forms of emotional abuse. The fraction of 31.3% of Korean women report to have had parental verbal violence history,¹ while 65.3% of Korean children aged between 9 and 12 in protective care report to have experienced emotional abuse.² In the U.S., the prevalence of emotional abuse during childhood is 14% in men and 10% in women adults.³ However, the effects of exposure to verbal aggression on its victims have been commonly overlooked regardless of their seriousness and harmfulness. Young adults with a history of verbal abuse (VA) are susceptible to display various psychiatric symptoms, including depression, anxiety and dissociation;^4,5 VA can also cause children to display negative cognitive styles including self-criticism and hopelessness, which are related to psychopathology.^6,7 The effects of VA on mental health are comparable to those of other types of abuse, sexual or physical, which are more commonly considered to be severe,⁴ and these harmful effects are persistent regardless of whether the abuse was perpetrated by parents or peers.⁸ Additionally, VA is thought to cause scars on the brain; reduction of fractional anisotropy of white matter tracts in sufferers, including corpus callosum, arcuate fasciculus, cingulum bundle, has been reported.^8,9

The harmful effects of VA, compared to physical and sexual abuses, are frequently ignored by those individuals who significantly influence children.¹⁰ Also, in middle and high school, many adolescents, nearly two out of three, routinely use profane words without the awareness of their severity.¹¹ To reduce the victims' vulnerability to psychiatric disorders, it is important to develop appropriate measurements and to educate VA's seriousness to the general population, especially children, young adolescents, and even young adults. However, since there is no reliable scale with which to evaluate specific experiences of VA in Korea, developing appropriate measurements of VA experiences can be the first step to recognize the victims.

The verbal abuse questionnaire (VAQ) covers various domains of VA and is a useful tool for detecting a history of VA and measuring the severity of VA experiences. Also, the VAQ is widely applicable regardless of whom the perpetuator is in any specific case. Previous studies have shown that it has adequate internal consistency for both parental VA and peer VA.^4,8 Therefore, we considered that this scale can be easily and widely applied to various populations, thus developed a Korean version of the verbal abuse questionnaire (K-VAQ). This study was conducted to verify the psychometric properties of the K-VAQ and to evaluate its utility for application to the Korean population.

In our study, the K-VAQ showed adequate psychometric properties when used to measure the participants' parental VA experiences. The internal consistency of the K-VAQ (Cronbach's alpha=0.93) showed an acceptable value, similar to previous studies using the original version of the VAQ (Cronbach's alpha=0.98 for maternal and Cronbach's alpha=0.94 for paternal). Also, the item-total item correlation coefficients were within the optimal range (r>0.3).²²

In the exploratory factor analysis, two factors were originally extracted, accounting for 55.34% (eigenvalue: 8.30) and 9.80% (eigenvalue: 1.47) of the total variance, respectively. These results are consistent with the study conducted by Teicher et al.^4,23 However, unlike the results of the original study,^4,23 item 4 was additionally identified as one of the factors in the factor 2 category, along with items 1, 2, and 15. These four items in the factor 2 category consisted of 'raised voices' (items 1, 2, and 15) and 'blame' (item 4). However, we found that some items in factor 1 also included a similar content. For example, item 12 in the factor 1 category implies 'a raised voice' ('scream at you for no apparent reason'). The content of item 9 ('blame you for things you didn't do') was similar to that of item 4 ('blame you for things'). This suggests that the K-VAQ is not clearly classified into two factors. Alternatively, we found a single factor that accounted for 55.34% of the total variance. All factor loadings for each item exceeded 0.05, indicating that all items of the K-VAQ can be classified as a single factor.

To determine the dimensions of the K-VAQ scale, both one-factor and two-factor models were verified using structural equation modelling (SEM). This concluded that the single-factor model is more suitable than the two-factor model. The original version of the VAQ also used the total score of all questions to screen for the presence of a history of VA. This also did not categorize into two subscales. Therefore, our analysis support that the single-factor model can be useful to evaluate VA.

The convergent validity of the K-VAQ was confirmed with significant results from the correlation analysis between the K-VAQ and the LEC-K, a general scale used to evaluate traumatic life events.14 Although the LEC-K did not contain those items that were directly associated with verbal abuse, our results imply the existence of common characteristics in both measures. To substantiate, existing evidences show that verbal abuse leads to elevated psychiatric symptoms, similar to those from physical abuse or catastrophic natural disasters (e.g., earthquake, war).⁸ In this sense, our result shows a possibility that verbal abuse could be a form of psychological trauma that has detrimental impacts on one's mental health. Likewise, concurrent validity was proven by the significant correlations between the K-VAQ and the K-IES-R. Recent studies noted that there were significant relationships between emotional abuse and symptoms of PTSD. Emotionally abusive experiences can significantly predict PTSD symptoms in adolescents of child protective services²⁴ and in general adults.²⁵ Nurses of the psychiatric department who were verbal abused by patients also reported elevated PTSD symptoms as measured by the IES-R.²⁶ Our results are in line with such previous studies by demonstrating that verbally abusive experiences in university students are significantly associated with PTSD symptoms as measured by the K-IES-R.

Moreover, we evaluated the validity of original VAQ's cut-off score. To measure the appropriate cutoff score of the K-VAQ, we conducted a cluster analysis. In the previous research, a cutoff point of 40 was utilized, representing the top 10% of scores in randomly selected participants. This cutoff point showed face validity.⁴ The upper 10% criterion was not applied to our study because our data was acquired from a yearly health examination conducted by a university. A large number of students marked zero on the K-VAQ measure (n=2194), and 77% of our subjects (n=4487) were classified into the minimal trauma experience group. Therefore, a cluster analysis was appropriate to confirm the cutoff point in our data. Within our subjects, there were eight who had K-VAQ scores between 40 and 42; they reported similar ratings on the K-IES-R [mean (SD)=18.13 (20)] and similar frequency of K-IES-R scores that exceeded the cut-off point (38%) to those of the group which reported K-VAQ scores of 43 or above [the K-IES-R mean (SD) score=18.99 (17.82), frequency of K-IES-R scores above the cut-off score=36.4%]. Hence, including these eight subjects in the highly verbally abused group did not disrupt the characteristics of the group; the highly verbally abused group showed significant differences in PTSD symptoms compared to moderately verbally abused group. In sum, previous criteria using VAQ scores of 40 or above^8,9 can be acceptable to find those who had strong verbal abuse experiences that threaten their mental health. Further studies may maintain a connection to the previous studies using this cutoff score. Another potential area for research is of determining whether there are potential mental health problems in subjects who have K-VAQ scores of 20 or above.

There are several limitations to this study. First, the study was performed with university students from a top-ranked university in Korea. Most of the participants were young, male and highly educated. Our subjects might have been raised in a good environment, including high level of social and economic status (SES). Given that childhood maltreatment are influenced by low SES,²⁷ future studies are warranted to include participants with various SES. Among the participants, 37.7% (2194/5814) reported no verbal abuse experience in their lifetime. We are interested in investigating whether this statistics would reflect the representativeness of the general population in a future study. Second, our anonymized data were extracted from a yearly health examination; the degree of test-retest reliability was not evaluated here. Further study is needed to measure the longitudinal stability of the K-VAQ scale and to generalize this scale to various age ranges.

Despite these limitations, this study suggests that the K-VAQ has good psychometric properties. As our sample size was quite large and young adults were suitable subjects, given that VA from parents or peers mainly occurred during their childhoods, our results are likely to be reliable. The K-VAQ can be widely administered to measure the severity of various types of VA and can be used as a screening tool for the presence of VA. This scale can be useful for teachers, clinicians, health care workers, psychologists, or anyone in close contact with young students.