P1: MRM/SPH P2: MRM/RKP QC: MRM Journal of Psychopathology and Behavioral Assessment (JOBA) PP099-298982-03 March 13, 2001 10:23 Style file version Nov. 07, 2000 Journal of Psychopathology and Behavioral Assessment, Vol. 23, No. 1, 2001 Psychopathic Personality Traits and Somatization: Sex Differences and the Mediating Role of Negative Emotionality Scott O. Lilienfeld1,2 and Tanya H. Hess1 Although a number of investigations have provided evidence for an association between antisocial per- sonality disorder and somatization disorder, the variables underlying this association remain unknown. We examined the relations among measures of primary and secondary psychopathy, somatization, and negative emotionality (NE) in 150 undergraduates. Somatization was positively and significantly cor- related with measures of secondary, but not primary, psychopathy, and the relations between secondary psychopathy indices and somatization tended to be significantly stronger in females than in males. Some support was found for the hypothesis that the association between secondary psychopathy and somatization is mediated by NE, but not for the hypothesis that low levels of behavioral inhibition lead to somatization. Although the present findings are consistent with the possibility that somatization is a sex-differentiated manifestation of secondary psychopathic traits, replication of these findings in clinical samples will be necessary. KEY WORDS: psychopathy; antisocial personality disorder; somatization disorder; sex differences; negative emotionality. The phenomenon of “comorbidity,” or diagnostic mer syndrome is characterized by a chronic history of covariation, represents one of the foremost challenges antisocial and criminal behavior, whereas the latter is to contemporary psychopathology researchers (Caron & characterized by a chronic history of unexplained physi- Rutter, 1991; Frances et al., 1992). Such covariation is cal complaints (American Psychiatric Association, 1994; particularly rampant among Axis II disorders (Grove & Kirmayer, Robbins, & Paris, 1994). The covariation be- Tellegen, 1991) and is also prevalent between Axis I and tween ASPD and SD is superficially puzzling because Axis II disorders (Lilienfeld, Waldman, & Israel, 1994). these conditions share few, if any, overt diagnostic fea- Although the application of the term and concept of co- tures. A sizeable body of evidence suggests that ASPD morbidity to psychopathological syndromes is contro- and SD covary within both individuals and families (see versial (Lilienfeld et al., 1994; Spitzer, 1994), there is Cloninger, 1978; Lilienfeld, 1992, for reviews). a general consensus that a better understanding of the In a sample of 250 psychiatric patients, for example, covariation among diagnostic syndromes can provide Lilienfeld, VanValkenberg, Akiskal, and Larntz (1986) valuable leads for research on shared etiological factors found that ASPD and SD were significantly associated 3 (Maser & Cloninger, 1990). within individuals (rq = .55). Moreover, a significantly Of the comorbidities consistently reported in the psy- higher proportion of probands with SD than without chopathological literature, one of the most enigmatic has SD reported having a first-degree relative with ASPD been the association between antisocial personality dis- (rq = .63). More recently, Frick, Kuper, Silverthorn, and order (ASPD) and somatization disorder (SD). The for- Cotter (1995) found moderate and statistically significant 1Emory University, Atlanta, Georgia. 3 2To whom correspondence should be addressed at Department of Yule’s Q (rq) is an index of the magnitude of the association between Psychology, Room 206, Emory University, Atlanta, Georgia 30322; categories that is unaffected by the base rates of the disorders in question e-mail: [email protected]. (Fienberg, 1980). 11 0882-2689/01/0300-0011$19.50/0 C 2001 Plenum Publishing Corporation P1: MRM/SPH P2: MRM/RKP QC: MRM Journal of Psychopathology and Behavioral Assessment (JOBA) PP099-298982-03 March 13, 2001 10:23 Style file version Nov. 07, 2000 12 Lilienfeld and Hess correlations between dimensional measures of ASPD and Several authors (e.g., Goodwin & Guze, 1996; SD in a sample of 90 mothers of clinically referred chil- Lilienfeld, 1992) have further conjectured that ASPD dren. Although Boyd et al. (1984) found no covariation and SD are sex-differentiated manifestations of a shared between ASPD and SD in their analyses of the Epi- personality diathesis, although the precise nature of this demiological Catchment Area data, the low rates of SD diathesis remains to be determined. According to this in these data (approximately .1%) render these nega- hypothesis, males possessing this diathesis are likely to tive results difficult to interpret (see Cloninger & Guze, exhibit ASPD features, whereas females possessing this 1975; Cloninger, Reich, & Guze, 1975; Guze, Woodruff, diathesis are likely to exhibit SD features. This “sex dif- & Clayton, 1971, Liskow, Othmer, Penick, DeSouza, & ferentiation hypothesis” is consistent with data indicating Gabrielli, 1986, Robins, 1966; Spalt, 1980; Zoccolillo & that ASPD is more common in males than in females, Cloninger, 1986, for further data suggesting significant whereas SD is more common in females than in males levels of covariation between SD and ASPD, antisocial (American Psychiatric Association, 1994). This hypoth- behavior, or both, across individuals). In addition, both esis is also consistent with findings demonstrating that ASPD and SD are associated with an early age of on- males tend to exhibit higher levels of overt aggression set, chronic course, substance abuse, marital and famil- than females do (Maccoby & Jacklin, 1974), although ial discord, high rates of abuse and neglect of children, sex differences in “relational” (i.e., interpersonal) aggres- and poor response to psychotherapy and pharmacotherapy sion are less pronounced and perhaps even reversed in (Cloninger, 1978; Goodwin & Guze, 1996; Zoccolillo & direction (Eagly & Steffen, 1985; Werner & Crick, 1999). Cloninger, 1986). These similarities provide suggestive, Thus, one potential interpretation of this literature is that but by no means conclusive, evidence of shared etiologi- the personality diathesis underlying ASPD and SD tends cal origins for ASPD and SD. to be channeled into different phenotypes in males and Several authors (e.g., Carothers, 1975; Gorenstein females depending partly on levels of overt aggression. & Newman, 1980; Lilienfeld, 1992) have posited that Nevertheless, there is at present little direct evidence in the psychopathological correlates of SD extend beyond support of the sex differentiation hypothesis of ASPD and ASPD to psychopathic personality (psychopathy). Al- SD (but see Hamburger, Lilienfeld, & Hogben, 1996, for though measures of psychopathy tend to correlate mod- data suggesting that histrionic personality disorder and erately with measures of ASPD (Lilienfeld, 1994), the ASPD may represent sex-differentiated manifestations of former syndrome, unlike ASPD, is traditionally concep- psychopathic personality traits). The sex differentiation tualized as a constellation of covarying personality traits. hypothesis is not inconsistent with the previously noted These traits, which were first delineated systematically covariation between ASPD and SD (e.g., Lilienfeld et al., by Cleckley (1941/1982; see also Lykken, 1957; McCord 1986), because biological sex may serve primarily to shift & McCord, 1964), include guiltlessness, callousness, dis- slightly the phenotypic manifestation of the diathesis un- honesty, egocentricity, risk taking, poor impulse control, derlying ASPD and SD. As a consequence, males possess- and superficial charm. ing high levels of this diathesis may be somewhat more A number of authors have argued that ASPD is con- likely to exhibit ASPD features than SD features, and vice- siderably more etiologically heterogeneous than is psy- versa for females possessing high levels of this diathesis. chopathy and incorporates both “primary” (Cleckley) psy- The mechanisms underlying the association between chopathy as well as a m´elange of other conditions (e.g., ASPD and SD remain largely or entirely unknown. “neurotic psychopathy,” “dyssocial psychopathy”) that Lilienfeld (1992) reviewed several theoretical models that place individuals at heightened risk for antisocial behavior have been invoked to account for the ASPD–SD link. (Hare, Hart, & Harpur, 1991; Lykken, 1995). These latter Among these explanations are the behavioral disinhibition antisocial conditions are sometimes collectively referred model and the negative emotionality (NE) model. Accord- to as “secondary” psychopathy. Indeed, factor analyses of ing to the behavioral disinhibition model, both primary psychopathy measures have typically revealed two sepa- psychopaths (including some individuals with ASPD) and rable dimensions, one corresponding to the core affective individuals with SD are characterized by an underac- and personality deficits described by Cleckley, and the tive behavioral inhibition system (BIS) (Gorenstein & other corresponding to overt antisocial behavior (Harpur, Newman, 1980). Gray (1982) proposed that the BIS, a psy- Hare, & Hakstian, 1989). There is little evidence, however, chobiological system coursing through the septum, hip- bearing on the association between primary psychopathy pocampus, and orbitofrontal cortex, mediates sensitivity and SD, because virtually all controlled studies of the di- to conditioned signals of