حساسیت پردازش حسی در اختلال اضطراب اجتماعی: رابطه برای آسیب رساندن به اجتناب و انواع تشخیصی

Abstract Sensory-processing sensitivity is assumed to be a heritable vulnerability factor for shyness. The present study is the first to examine sensory-processing sensitivity among individuals with social anxiety disorder. The results showed that the construct is separate from social anxiety, but it is highly correlated with harm avoidance and agoraphobic avoidance. Individuals with a generalized subtype of social anxiety disorder reported higher levels of sensory-processing sensitivity than individuals with a non-generalized subtype. These preliminary findings suggest that sensory-processing sensitivity is uniquely associated with the generalized subtype of social anxiety disorder. Recommendations for future research are discussed.

1. Introduction Social anxiety disorder (SAD) is defined as “a marked and persistent fear of one or more social or performance situations in which the person is exposed to unfamiliar people or to possible scrutiny by others” (APA, 1994, p. 416). Results from the National Comorbidity Survey-Replication indicate that the lifetime prevalence rate of SAD is 12.1% (Kessler, Berglund, Demler, Jin, & Walters, 2005). If untreated, the disorder typically follows a chronic, unremitting course, leading to substantial impairments in vocational and social functioning (e.g., Stein & Kean, 2001; Stein, Torgrud, & Walker, 2000). SAD often begins in the mid-teens, but can also occur in early childhood and can manifest itself early on as childhood shyness (Hayward, Killen, Kraemer, & Taylor, 1998; Mick & Telch, 1998; Neal, Edelmann, & Glachan, 2002; Neal & Edelmann, 2003; Rosenbaum, Biederman, Hirshfeld, Bolduc, & Chaloff, 1991; Rosenbaum, Biederman, Pollack, & Hirshfeld, 1994; Schwartz, Snidman, & Kagan, 1999). Childhood shyness (also known as behavioral inhibition) refers to a person's degree of wariness and timidity when encountering novel people, objects, or events (Kagan, 2001) and related constructs have been discussed by others (e.g., Cloninger, 1987a, Cloninger, 1987b and Eysenck, 1981; Gray & McNaughton, 1996). Similarly, SAD and adult shyness are greatly overlapping (Chavira, Stein, & Malcarne, 2002; Heiser, Turner, & Beidel, 2003). Shyness is a stable and highly heritable personality trait (e.g., Daniels & Plomin, 1985). A number of family studies (e.g., Fyer, Mannuzza, Chapman, Liebowitz, & Klein, 1993; Lieb et al., 2000), twin studies (Skre, Onstad, Torgersen, Lygren, & Kringlen, 1993), and high-risk studies (Mancini, van Ameringen, Szatmariu, Fugere, & Boyle, 1996) suggest that SAD is genetically transmitted, especially the generalized subtype of SAD (Mannuzza et al., 1995 and Stein et al., 1998). For example, a direct-interview family study estimated the relative risks for generalized SAD to be 10-fold greater among first-degree relatives of probands with generalized SAD than among first-degree relatives of non-anxious controls (Stein et al., 1998). In contrast, the relative risks for developing SAD were not significantly different among first-degree relatives of probands with non-generalized SAD and non-anxious controls. Moreover, Mannuzza et al. (1995) reported that patients with generalized SAD had a significantly earlier age of onset of the disorder than patients with non-generalized SAD. These findings suggest that the generalized subtype begins at an earlier age and is more heritable than the non-generalized subtype of SAD. However, some researchers (e.g., Stein, Chartier, Lizak, & Jang, 2001) pointed out that it is unlikely that SAD itself, at the level of an Axis I disorder, is genetically transmitted. Instead, it is more likely that one or more temperamental risk factors for SAD are transmitted. One of these possible temperamental risk factors is sensory-processing sensitivity (Aron & Aron, 1997; Aron, Aron, & Davies, 2005). This construct, which can be reliably measured with the 27-item Highly Sensitive Person Scale (HSPS; Aron & Aron, 1997), is conceptualized as a unidimensional personality trait that manifests itself in the form of avoidance of overstimulation. It has been proposed that sensory-processing sensitivity can lead to shyness when negative affect is triggered through an adverse childhood experience (Aron et al., 2005). In other words, sensory-processing sensitivity might be a heritable vulnerability factor for shyness under certain environmental conditions. A conceptually related temperamental trait is harm avoidance of Cloninger's psychobiological model of temperament (Cloninger, 1987a and Cloninger, 1987b).1 Harm avoidance measures the tendency towards behavioral inhibition to avoid punishment, novel stimuli, and non-reward. The 100-item Tridimensional Personality Questionnaire (TPQ; Cloninger, 1987a and Cloninger, 1987b) was designed to measure harm avoidance and two other personality traits—novelty seeing and reward dependence. Several studies have reported greater harm avoidance in individuals with SAD when compared to controls (Chatterjee, Sunitha, Velayudhan, & Khanna, 1997; Marteinsdottir, Tillfors, Furmark, Anderberg, & Ekselius, 2003; Stein et al., 2001). The current study is the first to examine sensory-processing sensitivity in a sample of individuals with SAD. The objectives of the study were to: (1) provide preliminary psychometric data of the HSPS in a SAD sample by comparing the scale to a measure of social anxiety and the TPQ subscales and (2) compare the diagnostic subgroups in the HSPS. We expected that HSPS shows significant correlations with social anxiety and the Harm Avoidance subscale of the TPQ. Moreover, we expected that participants with generalized SAD show greater scores in the HSPS than individuals with non-generalized SAD.

3. Results 3.1. Psychometric data The 27-item HSPS scale showed adequate internal consistency, Cronbach's α = .87; unequal-length Spearman Brown: .86. The score ranged between 5 and 27 with a mean of 16.98 (S.D.: 5.81), median of 17, mode of 17, a skewness of −.098 (S.E.: .26) and a kurtosis of −.87 (S.E.: .51). These data suggest that the scores are normally distributed. A principal component analysis of the measure identified 9 factors with Eigenvalues of greater than 1, explaining 65.83% of the total variance. The Eigenvalues of these factors were 6.47, 2.11, 1.76, 1.44, 1.32, 1.27, 1.21, 1.14 and 1.06. A Scree plot favored a 1-factor solution; the first factor accounted for 23.96% of the explained variance. These results are consistent with the studies by Aron and Aron (1997). 3.2. Covariation between the HSPS with the SPAI and TPQ Table 1 depicts the correlations between the HSPS, the difference score of the SPAI (SPAI-Difference), the agoraphobia subscale of the SPAI (SPAI-Agoraphobia), and TPQ subscales Novelty Seeking, Reward Dependence, and Harm Avoidance. The results showed that the HSPS was poorly correlated with the SPAI-Difference scale, r = .08, p = .48, but highly correlated with the SPAI-Agoraphobia subscale, r = .44, p < .0001. Fig. 1 shows a clear linear relationship between these two scales. In addition, the HSPS shows the predicted positive correlation with HA, r = .52, p = .002 ( Fig. 2). Table 1. Intercorrelations between self-report scales SPAI-Difference SPAI-Agoraphobia NS RD HA HSPS SPAI-Difference .44** .03 −.21 .29 .08 SPAI-Agoraphobia −.08 .02 .41* .44** NS .11 −.04 −.04 RD −.07 .12 HA .52** Total mean (standard deviation) 106.46 (30.46) 21.63 (13.98) 13.31 (4.71) 17.09 (3.76) 23.25 (4.38) 16.98 (5.81) Note: The table shows means and standard deviations (bottom row) and product–moment correlations. SPAI-Difference, Social Phobia and Anxiety Inventory, difference score; SPAI-Agoraphobia, Social Phobia and Anxiety Inventory, agoraphobia subscale score; NS, Novelty Seeking scale of the Tridimensional Personality Questionnaire (TPQ); RD, Reward Dependence scale of the TPQ; HA, Harm Avoidance scale of the TPQ; HSPS, Highly Sensitive Person Scale. The analyses were based on 89 participants for the SPAI and HSPS scales and between 32 and 36 participants for the correlations with the TPQ scales. * Correlation is significant at p < .05 (two-tailed). ** Correlation is significant at p < .01 (two-tailed). Table options Scatter plot and regression of the covariation between the agoraphobia subscale ... Fig. 1. Scatter plot and regression of the covariation between the agoraphobia subscale of the Social Phobia and Anxiety Inventory (SPAI-Agoraphobia) and the Highly Sensitive Person Scale, r = .44, p < .0001. Figure options Scatter plot and regression line of the covariation between Harm Avoidance ... Fig. 2. Scatter plot and regression line of the covariation between Harm Avoidance subscale of the Tridimensional Personality Questionnaire and the Highly Sensitive Person Scale, r = .52, p < .0001. Figure options 3.3. Differences Between Diagnostic Subtypes In order to retain the maximum amount of participants for the statistical analyses, we performed two separate multivariate tests employing a General Linear Model. Table 2 displays the means, standard deviations, and results of the of univariate follow-up tests of this analysis. Table 2. Comparison between social phobia subtypes in self-report measures Generalized subtype Non-generalized subtype F-value HSPS 17.99 (5.66) 13.68 (5.11) 9.98** SPAI Difference 114.75 (25.71) 81.36 (31.07) 25.01** Agoraphobia 24.06 (13.08) 14.05 (14.46) 9.18** TPQ Harm Avoidance 24.21 (3.38) 18.00 (4.32) 17.07*** Novelty Seeking 13.62 (4.96) 12.71 (1.89) .22 Reward Dependence 17.38 (3.98) 18.14 (2.97) .23 Note: The table shows means (standard deviations) and results of statistical tests. HSPS, Highly Sensitive Person Scale; SPAI, Social Phobia and Anxiety Inventory; TPQ, Tridimensional Personality Inventory. The group comparisons in the SPAI and HSPS scales were based on 22 individuals with generalized social phobia and 66 individuals with non-generalized social phobia. The TPQ analyses were based on 29 individuals with generalized social phobia and 7 individuals with non-generalized social phobia. ** p < .01 (two-tailed). *** p < .001 (two-tailed). Table options The first test compared generalized and non-generalized SAD in the SPAI-Difference subscale, SPAI-Agoraphobia subscale, and the HSPS (one of the 89 participants was excluded from the analysis because of missing data). The results showed a significant multivariate group effect, F (3, 84) = 15.38, p < .0001, partial η2 = .35. The univariate follow-up tests revealed that generalized SAD had higher scores in the SPAI-Difference subscale, F (1, 86) =25.01, p < .001, partial η2 = .23, the SPAI-Agoraphobia subscale, 2F (1, 86) = 9.18, p = .003, partial η2 = .098, and the HSPS, F (1, 86) = 9.98, p = .002, partial η2 = .10. The second test compared generalized and non-generalized SAD in the three subscales of the TPQ (2 of the 38 participants were excluded due to missing data). The results revealed a significant multivariate group effect, F (3, 32) = 5.85, p = .003, partial η2 = .35. Univariate follow-up tests showed that the only difference between the TPQ subscales was in the Harm Avoidance scores. The generalized subtype had higher scores than the non-generalized subtype, F (1, 34) = 17.07, p < .0001, partial η2 = .33. No group difference was observed for the other two TPQ subscales (F < .23, p > .6, η2 < .008).