Intimate partner violence (IPV) is a problem of major public health importance that is related to substance problems among women (Wekerle & Wall, 2002
). Among IPV-exposed women, 7% - 44% report drug and alcohol problems severe enough to be diagnosed with substance abuse or dependence (Golding, 1999
). Further, IPV-exposed women are more likely than women who are not exposed to IPV to report heavy or binge drinking (Bonomi et al., 2006
; Lemon, Verhoek-Oftedahl, & Donnelly, 2002
) and to abuse or be dependent on drugs and/or alcohol (McCauley et al., 1995
; Tolman & Rosen, 2001
Despite the high rates of substance misuse among IPV-exposed women, little research has examined factors that may increase the risk of drug and alcohol problems in this population. Yet the identification of such factors could inform treatment and prevention efforts. One potential factor is posttraumatic stress. IPV is related to high levels of posttraumatic stress (Coker, Weston, Creson, Justice, & Blakeney, 2005
). In fact, 31% - 84% of IPV-exposed women report posttraumatic stress symptoms severe enough to be diagnosed with posttraumatic stress disorder (PTSD) (Golding, 1999
Significant relationships between posttraumatic stress and substance problems are well documented across a wide range of populations (Breslau, Davis, & Schultz, 2003
; Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995
; Schnurr & Spiro, 1999
). In particular, IPV-exposed women are more likely to suffer from PTSD than women who have not been exposed, thus, IPV-exposed women may be especially vulnerable to drug and alcohol problems (Salomon, Bassuk, & Huntington, 2002
; Tolman & Rosen, 2001
). This hypothesis has not been thoroughly investigated. It has been shown that among low income and homeless single mothers, more than half of whom experienced IPV, PTSD was associated with drug and alcohol use (Salomon et al., 2002
). Among IPV-exposed women, trauma-related symptoms including PTSD symptoms were related to heavy episodic alcohol use (Kaysen et al., 2007
). Finally, among community-based IPV-exposed women, those who used drugs reported higher rates of PTSD and PTSD symptom severity than those who reported no drug use (Sullivan & Holt, 2008
). Therefore, IPV-exposed women may be vulnerable to substance misuse partially due to IPV-related posttraumatic stress. Yet, we know of no tests of this hypothesis.
Additionally, examining IPV by type (i.e., physical, sexual, and psychological IPV) as it relates to posttraumatic stress and substance use may prove important. While each type of IPV has demonstrated a relationship to posttraumatic stress or substance use in at least one study, there have been no consistent trends across studies (Basile, Arias, Desai, & Thompson, 2004
; Coker, Davis, et al., 2002
; Coker, Smith, et al., 2002
; Heru, Stuart, Rainey, Eyre, & Recupero, 2006
; Houry, Kemball, Rhodes, & Kaslow, 2006
; Smith, Thornton, DeVellis, Earp, & Coker, 2002
; Testa & Leonard, 2001
). Therefore, it is unclear whether any particular type of IPV places women at risk for IPV-related posttraumatic stress and drug and alcohol problems. One possible explanation for the inconsistencies found in prior work lies in methodological choices.
Most studies assess either the severity of PTSD symptoms or full criteria for the disorder
. An examination of posttraumatic stress measured in the aforementioned ways provides invaluable information for treatment of PTSD and its correlates as well as for the design of future research. However, it also may be useful to examine posttraumatic stress by measuring symptom severity as well as the range of impairment in functioning experienced and whether or not an event qualifies as traumatic, but not adhere to full criteria to be diagnosed with the disorder (American Psychiatric Association, 1994
). Given that many IPV-exposed women experience a range of PTSD symptoms but do not meet full criteria for PTSD, this measure of posttraumatic stress may help to further elucidate the relationships among IPV, posttraumatic stress, and substance problems and inform the development of substance use interventions for women who experience a range of posttraumatic stress.
The majority of studies examining the relationship between posttraumatic stress and substance use do so without a focus on the referent traumatic event for which PTSD is assessed (e.g., Najavits, Sonn, Walsh, & Weiss, 2004
; Testa, Livingston, & Hoffman, 2007
) despite the documented importance of the event in moderating relationships between trauma exposure and PTSD (Ozer, Best, Lipsey, & Weiss, 2003
). Ozer and colleagues meta-analysis found that interpersonal trauma was more strongly related to PTSD than other traumatic events including natural disasters and combat. IPV is uniquely different from many other traumatic events in several ways. Exposure to IPV often is chronic rather than acute. Also, unlike other referent traumatic events where there is no identified perpetrator (e.g., natural disaster) or the perpetrator is not intimately known to the victim (e.g., enemy in combat), IPV is perpetrated within an intimate relationship by someone who likely is a source of stress and
positive experiences and resources. Moreover, women who were victims of violence by intimate partners appear more likely to suffer from PTSD than women who were victims of violence by people with whom they were not intimate (Dansky, Byrne, & Brady, 1999
). This body of literature suggests that IPV-related posttraumatic stress deserves particular attention in research.
The question arises then as to how IPV-posttraumatic stress could be related to substance problems among those with IPV. In line with tension reduction theory (Conger, 1956
) and the self-medication hypothesis (Khantzian, 1997
), IPV-exposed women may use substances to manage negative affect and, in particular, may select a drug of choice because of its effect on specific symptoms. Thus, it is not negative life events such as IPV per se that contribute to substance use and problems. Rather, it is negative affect resulting from IPV, such as posttraumatic stress that is related to substance problems. Although we know of no direct tests of this hypothesis among IPV-exposed women, there is evidence that posttraumatic stress partially mediated the relationship between other types of interpersonal violence (childhood sexual and physical abuse) and drug and alcohol use (Epstein, Saunders, Kilpatrick, & Resnick, 1998
; Zlotnick et al., 2006
). One study of women who were sexually assaulted as adults (not specific to IPV), however, found that lifetime PTSD symptoms did not mediate the relationship between women’s sexual victimization and subsequent heavy drinking (Testa et al., 2007
). Because IPV-related PTSD may be experienced differently than PTSD related to other traumatic events (for example, because of the chronic exposure to the referent traumatic event of IPV), it is necessary to test for mediation specifically among IPV-exposed women.
This study extends previous work on the relationships among IPV, posttraumatic stress, and substance use in several ways. First, we evaluated the relationships among types of IPV, IPV-related posttraumatic stress, and substance problems. Second, we examined these relationships utilizing a latent measure of posttraumatic stress. Third, we tested whether IPV-related posttraumatic stress mediated the relationships between types of IPV and substance problems. In order to examine the unique contributions of types of IPV and IPV-related posttraumatic stress to substance problems, we controlled for childhood trauma and past IPV, which are related to PTSD and substance problems (Coker, Davis, et al., 2002
; Coker et al., 2005
; Seedat, Stein, & Forde, 2005
; Widom, 1999
; Widom, Marmorstein, & White, 2006
). Based on existing research and theory, it was predicted that physical, sexual, and psychological IPV would be positively related to drug and alcohol problems through their relationship with IPV-posttraumatic stress.