To our knowledge, this is the first prospective investigation of the course of MDD in an ED sample, derived from the largest and longest prospective, naturalistic longitudinal follow-up of women with EDs. Consistent with previous reports of MDD in ED samples (Brewerton et al. 1995
; Godart et al. 2004
; Fernandez-Aranda et al. 2007
; Herzog & Eddy, 2007
), we found that 59% of the 246 patients recruited had one or more episodes of depression, a prevalence much greater than the 15% or so that would be expected in the general population.
With regard to MDD recovery and relapse, patients who fared the worst had more severe baseline depressive symptoms, and better psychological functioning suggested a higher chance of recovery. Our findings are consistent with previous studies of depression that have linked more severe depressive symptoms to poorer treatment outcomes (Kirsch et al. 2008
Rates of MDD recovery varied by ED diagnosis at study entry, with patients diagnosed as ANR having a lower chance of recovery from MDD than those diagnosed with ANBP or BN. However, participants with ANR who did recover from MDD were less likely to have had an MDD relapse compared to individuals who had fully recovered from their ED. Likewise, participants were more likely to have a depressive relapse if they were closer to their ideal body weight. This finding is consistent with previous studies that indicate that recovered or weight-restored AN participants continue to experience increased or persistent depressive symptomatology in comparison to healthy controls (Pollice et al. 1997
; Holtkamp et al. 2005
; Wagner et al. 2006
These findings were striking, as it is generally thought that recovery from one condition may facilitate recovery from a comorbid condition. There may, however, be other factors in play with regard to patients with EDs. For example, recovering from an ED and/or attaining a healthier weight may mobilize control issues within the patient, which may in turn precipitate feelings of depression. Recovery from an ED may be associated with a loss of identity and routine, and fuel a fear of weight gain. Beresin et al. (1989)
interviewed women who had recovered from AN who reported that with their recovery, they initially felt a loss of self-respect (for “giving in” to getting well) and that they were losing their ‘specialness’. Such feelings may lead to depressive symptoms, particularly if the ED is chronic.
Lifetime alcohol and drug abuse were relatively uncommon in the sample as a whole (17% and 14%, respectively; ), and rates did not change significantly in the recovered and relapsed samples. We do not have information on whether the history of alcohol or substance abuse represented current or past abuse in these subjects, but the findings suggest that a lifetime history of these did not significantly impact on recovery or relapse from MDD. Consistent with recent reports (Steffen et al. 2006
), our primary and sensitivity analyses revealed antidepressant treatment did not significantly impact either recovery from or relapse to MDD. This may reflect the increasingly questionable efficacy of antidepressants in general (Moncrieff et al. 2004
), or a finding specific to an ED population in which greater comorbidity may lead to poorer outcomes. It is also possible that participants may not have been compliant in taking the medication, or that the medications may not have been absorbed due to purging behaviors.
Limitations of this study warrant acknowledgement. The ED diagnostic subgroups in our study were small, and ideally this study should be replicated in a larger sample with all diagnostic subgroups. Our study also lacked a control group of participants without EDs, and thus we cannot attribute effects observed specifically to the presence of an eating disorder, nor rule out the confounding effect of time in this longitudinal study.
This study was initiated in 1987 and we used RDC criteria for MDD because of the consideration regarding its stability over time. The DSM is now used for research and clinical work on MDD, and diagnostic instruments have been modified for the updated criteria. During the study period, selective serotonin reuptake inhibitors (SSRIs), particularly fluoxetine, were the most commonly prescribed medications for depression, and thus it may be difficult to generalize these findings to the larger range of antidepressants currently available. It was difficult to determine whether any improvements seen among ED subjects were due to either anti-depressants or to psychotherapy, since most patients received both, and only 9 patients (6%) received antidepressants alone at some point in the course of the study. Also, data were available only for treatment received, and not the specific reason for treatment. Finally, because there was no accepted therapy for AN or BN at the time, we did not gather details about psychotherapy administered. It is possible that cognitive behavioral therapy (often the initial treatment of choice for BN now) may have had an impact on MDD symptoms.
In conclusion, our findings support an overlap between EDs and MDD, and suggest that the presence and type of ED may affect recovery from MDD and relapse to MDD. While these findings may suggest a relationship between EDs and MDD, they do not demonstrate any specific causal link. Antidepressants do not seem to significantly impact MDD recovery or relapse in this population, which may have implications for the development of treatment strategies in individuals with comorbid MDD and EDs.