روان رنجوری و درونگرایی: ترکیبی خطرناک برای اختلال تغذیه ای در میان یک نمونه غیر بالینی زنان در مقطع کارشناسی

Recent evidence suggests that people who score low on measures of sociability may be at risk for certain types of psychopathology, including mood and anxiety disorders. In an attempt to extend these findings to other forms of psychopathology, we examined levels of neuroticism and extraversion in relation to eating problems in a non-clinical sample of undergraduate women. The Eysenck Personality Questionnaire (EPQ), Eating Disorders Inventory (EDI), and the Eating Attitudes Test (EAT-26) were completed by 196 first-year undergraduate females. We found that high neuroticism was related to high scores on both of the EDI subscales (Bulimia and Drive for Thinness) as well as high scores on the EAT-26 measure, replicating previous work. In addition, neuroticism served as a moderator such that lower extraversion (i.e., introversion) was related to greater disordered eating, but only for those women who scored high on neuroticism. Thus, a combination of neuroticism and introversion may be a risk-factor for symptoms of eating disorders in a non-clinical sample of university women.

Over the last decade, there has been a dramatic increase in attention paid to eating disorders by researchers, clinicians, and the general public. Given the detrimental effects of eating disorders on an individual's physical and mental health, the study of eating disorders is of critical importance. Prevalence of bulimic behaviors, such as self-induced vomiting or episodes of binge–purge eating, are reportedly as high as 25–35% (Bulik et al., 2000 and Sullivan et al., 1998). The highest rates are found among females aged 15–19, who constitute over 40% of all diagnosed cases (Hoek & van Hoeken, 2003). Research also suggests that as many as 75% of women consider themselves too fat (Scarano & Kalodner-Martin, 1994), 80% have dieted before the age of 18 (Zerbe, 1995), and 35% have engaged in binge eating (Murray, 2003). Among a nationally representative sample of 15,349 grade 9 to 12 students, Forman-Hoffman (2004) found that 1-in-4 female and 1-in-10 male high school students in the U.S. engage in abnormal eating and weight control behaviors. Prevalence rates of clinically-diagnosed eating disorders present more conservative estimates (0.3% anorexia nervosa, 1% bulimia nervosa and binge eating disorder; Hoek & van Hoeken, 2003) than studies examining those who are symptomatic or members of an at-risk population. However, even in “sub-clinical” cases, the accompanying pathology of individuals exhibiting symptoms of eating disorders has been found to resemble the pathology observed in individuals with full-blown eating disorders, bringing into question the utility of standard diagnostic criteria (Garfinkel et al., 1995 and Zaider et al., 2000). Furthermore, given the notion that eating disorders exist along a continuum, early detection of patterns of disordered eating may help in the prevention of more serious syndromes of clinically-diagnosed eating disorders (Forman-Hoffman, 2004). Accordingly, an important purpose of the present study was to examine symptoms, rather than disorders, of eating pathology in a non-clinical population. In identifying at-risk populations, one approach is to distinguish among the various personality traits of individuals who exhibit disordered eating (e.g., Bulik et al., 1995 and Kleifield et al., 1994). For example, Strober (1980) found individuals diagnosed with anorexia nervosa were obsessional, interpersonally insecure, highly dependent, excessively conformist and regimented. Casper (1990) found that individuals with anorexia nervosa (restricting types) scored high in emotional restraint, low on impulsivity, and were extremely conventional compared to a normal population. Kleifield, Sunday, Hurt, and Halmi (1993) noted that individuals with bulimia nervosa exhibited tendencies toward impulsivity and low sociability. Still others have examined interpersonal functioning among individuals with bulimia nervosa and found they were socially dependent and fearful of rejection (Hayaki, Friedman, Whisman, Delinsky, & Brownwell, 2003). The personality dimensions neuroticism and extraversion in relation to eating disorders have received much attention. While neuroticism has long been implicated as a predictor of eating disorders and, in particular, of bulimia nervosa (Cervera et al., 2003, Davis, 1997, Heaven et al., 2001, Kendler et al., 1991, Pearlstein, 2002 and Wade et al., 1995), the extant in literature is less consistent in identifying the role that extraversion (or sociability) may play. Studies of clinical populations have found low levels of extraversion (i.e., introversion) to be related to disordered eating (De Silva & Eysenck, 1987, Feldman & Eysenck, 1986 and Kleifield et al., 1993). Similarly, Bruce, Steiger, Koerner, Israel, and Young (2004) linked bulimia nervosa to social avoidance among a clinical sample of 59 women. Exceptions to these studies are findings by Wade et al. (1995) who reported no relation between extraversion and bulimia nervosa among a clinical sample (N = 58) and a study by Brookings and Wilson (1994) who found extraversion to be positively correlated with EDI-Drive for Thinness and the EAT-26, and to hold no relation to EDI-Bulimia, in a sample of non-clinical participants. Although the results by Brookings and Wilson appear to contradict previous research, it is important to consider that these authors used a different measure of extraversion and neuroticism (i.e., NEO Personality Inventory; Costa & McCrae, 1985) in a non-clinical population. Given the inconsistencies among the clinical samples and the one study of a non-clinical sample, there is a need for further research to clarify the link between extraversion and eating disorders. Furthermore, while low sociability has been linked to bulimia nervosa, we know little concerning the relation between sociability and anorexia nervosa, a distinct type of eating pathology that may have its own unique set of personality correlates. Finally, although previous studies have established independent relations between disordered eating, neuroticism, and extraversion, the present study appears to be the first to examine the interaction of the variables neuroticism and extraversion in eating problems in a non-clinical, university-aged population. Indeed, we sought to extend previous studies, which have examined personality dimensions independently, by looking at the interaction of personality traits in accounting for unique variance. Specifically, we examined whether extraversion and problem eating might be intensified for those individuals who are higher on neuroticism as compared to those who show a disposition towards lower neuroticism. We chose to examine neuroticism as a moderator given Claridge and Davis's (2001) argument that neuroticism acts as an “emotional amplifier” by inflating pre-existing personality traits from adaptive, healthy, behaviors to unhealthy behaviors (p. 396). They argue that neuroticism contributes to the dynamics of abnormal behavior through its role as a moderator. Overall there were three goals of the present study. The first goal was to clarify research on the role extraversion plays in disordered eating in a non-clinical sample. Second, we were interested in identifying whether the personality dimensions extraversion and neuroticism would be similarly connected to both anorexia nervosa and bulimia nervosa given that most studies have linked these personality dimensions to bulimia nervosa alone. Third, we sought to examine whether neuroticism moderates the association between extraversion and disordered eating. To this end, we tested the interaction of personality traits in relation to disordered eating rather than focusing solely on individual personality characteristics. We recruited a group of first year undergraduate women and had them complete the Eysenck Personality Inventory (EPQ) measures of Neuroticism and Extraversion along with the Eating Disorder Inventory (EDI) and the Eating Attitudes Test (EAT-26), which are widely used to index symptoms of eating problems. Based on previous findings we predicted pathological eating would be related uniquely to: (1) high levels of neuroticism, and (2) low levels of extraversion (i.e., introversion). Also, we predicted that the combination of neuroticism and extraversion would account for unique variance in eating problems, above and beyond the individual contributions of each trait.