Comorbid Eating Disorders and Posttraumatic Stress Disorder: Implications for Etiology and Treatment

The comorbidity of eating disorders, particularly those characterized by binge eating and/or purging, and posttraumatic stress disorder (PTSD) has been fairly well established.¹ This association has been more frequently investigated among women. However, a recent investigation in a U.S. nationally representative sample found that 39.81% of women and 66% of men with a lifetime diagnosis of bulimia nervosa (BN) also met criteria for lifetime PTSD. In this study, 26% of women and 24% of men with a lifetime diagnosis of binge eating disorder (BED) met criteria for a diagnosis of lifetime PTSD.²

Childhood sexual abuse is also considered a nonspecific risk factor for eating disorders,³ meaning that it also precedes the onset of other disorders. More recent studies that have investigated multiple types of childhood and adult traumas have found consistent associations with eating disorders.¹ In one of our earlier studies, we found that most women with lifetime anorexia nervosa (AN; 71%), BN (78%), and BED (63%) had been exposed to at least one form of interpersonal trauma, including physical or sexual assault, mugging, kidnapping, or witnessing familial violence.²

Although men are understudied in eating disorders in general, as well as in investigations of comorbid PTSD and disordered eating, evidence suggests that men with eating disorders may have significant trauma histories as well. In Mitchell et al.’s 2012 study, all the men with lifetime histories of BN had experienced interpersonal trauma, as had 68% of men with AN, and 74% of men with BED.²

The Connection between Trauma/PTSD and Disordered Eating

Several potential mechanisms link trauma/PTSD and disordered eating. Exposure to trauma is a criterion for the development of PTSD.⁴ Trauma also may play an etiologic role in the development of depression, eating disorders, substance use disorders, and borderline personality disorder.^4-7 Stressful life events may also play a role in the development of eating disorders.⁸ In addition, PTSD and eating disorders may share biological vulnerabilities, including dysfunction in the hypothalamic-pituitary-adrenal (HPA) axis, which has been associated with chronic stress.⁹ Generally, exposure to trauma may contribute to global psychophysiological dysregulation, increasing risk for development of psychopathology.¹⁰ Binge eating and purging also may be used as forms of self-medication, enabling an individual to cope with symptoms of negative affect.¹¹ The act of binge eating may produce a dissociative-like state of disinhibition,¹² serving as a form of emotional numbing or avoidance. Of note, use of disordered eating to regulate negative affect may be particularly characteristic of individuals high in impulsivity,¹³ a trait that has been associated with PTSD¹⁴ as well as BN.¹⁵

How Body Image Is Affected By Trauma

There also may be direct links between exposure to specific types of trauma and body image. Interpersonal trauma may negatively impact one’s body image, as demonstrated by findings that women with histories of sexual assault have more negative images of their physical selves than do women without sexual assault histories.¹⁶ Sexual abuse may lead women to develop more critical views of themselves, thus leading to body image disturbance.¹⁷ It has been hypothesized that some women with a history of sexual assault wish to be thinner in order to minimize their secondary sex characteristics and to appear less attractive to potential perpetrators.¹⁸ Conversely, although this has been less well studied, victims of sexual assault may engage in binge eating in order to gain weight and thus to appear less attractive or to look stronger, in an attempt to “arm” themselves against potential perpetrators.

Choosing the Best Treatment Approach

To date, no treatments have been developed specifically for clients with comorbid PTSD and eating disorders. However, because PTSD and eating disorders share many common biological and psychological features, it is possible that treatment for one disorder could result in improvement of symptoms for the other. Cognitive behavioral therapies (CBTs), including CBT-Enhanced for Eating Disorders (CBT-E )¹⁹ and Cognitive Processing Therapy for PTSD (CPT 20)²⁰ are recommended for both disorders. CPT has two forms, one that involves a written trauma narrative plus cognitive therapy to challenge and address problematic cognitions about the trauma, one’s self, and the world, and a second form, CPT-C, that uses cognitive therapy without the written trauma account. Both are effective treatments for PTSD.²¹

Clinicians treating patients with these comorbid disorders often must determine which disorder to treat first, or whether to blend treatment approaches and to address both disorders at the same time. The specific approach selected depends in part on the severity of the eating disorder symptoms, which have the potential to be dangerous and even life-threatening.²² In less-urgent situations, case conceptualization, in addition to the patient’s preference, may guide the choice to treat one disorder before the other.

Case formulation may be an especially useful tool for describing interrelationships among PTSD and eating disorder symptoms and associated variables.^{22, 23} Essentially, the patient and clinician diagram the patient’s symptoms as well as contributing factors, to determine the mechanisms that link them. In some, perhaps milder, cases of comorbid disordered eating and PTSD, the eating disorder symptoms may have developed solely as a maladaptive coping mechanism. In this case, treating the PTSD first, while continuing to monitor eating disorder symptoms, could result in remission of the disordered eating symptoms. In addition, CPT involves 12 treatment sessions, and PTSD symptoms may remit quickly.

Sometimes Referral Is Needed

Some of the cognitive exercises in CPT could focus on the impact of the trauma on the patient’s eating disorder symptoms. However, clinicians without specific PTSD expertise may need to refer patients to another professional. In a recent study of women presenting for PTSD treatment, we found that although symptoms common to both PTSD and disordered eating, including impulse regulation, interoceptive awareness, interpersonal distrust, and ineffectiveness, improved following CPT, there were no changes in drive for thinness or bulimia symptoms.²⁴ Thus, symptoms specific to eating disorders may require additional treatment following standard therapy for PTSD.

For patients with more severe eating disorder symptoms that could interfere with PTSD treatment, the eating disorder may need to be treated first. Specifically, nutritional rehabilitation may be necessary so that the patient can engage in psychotherapy.²³ In addition, it may be possible to treat symptoms of both disorders using a blended approach.²⁵ However, future research is needed to determine whether there is greater benefit to a sequential vs. simultaneous approach to treating comorbid eating disorders and PTSD.

Future Research

Eating disorders have high rates of comorbidity with other disorders, including PTSD. To date, there are no established treatments for eating disorders and comorbid PTSD. Both PTSD and eating disorders can be extremely debilitating on their own. It is recommended that clinicians conduct thorough psychiatric evaluations, including assessment for trauma histories for patients with eating disorders, and to attempt to determine what, if any, role trauma may have played in the onset of the patient’s eating disorder. Severity of symptoms and case conceptualization may guide the choice to choose to treat either the PTSD or eating disorder first or whether to treat them simultaneously. Future research is needed to determine the best treatment options for eating disorders with comorbid PTSD and whether a sequential or simultaneous approach offers the greatest benefit.