The present investigation was prompted by research indicating that anxious and nonanxious depressed patients show significantly different response and remission rates and patterns with established pharmacotherapies [1
], thereby providing support for the view that anxious depression may be a meaningful subtype of MDD [2
] that may benefit from either additional or different therapeutic tactics. Based on the transdiagnostic nature of CT we predicted that, while anxious depressed patients would present with greater illness severity, they would not evidence significantly poorer outcomes with CT for MDD relative to their nonanxious depressed counterparts.
We tested our predictions using data from a large trial of CT for recurrent MDD (n = 523) and employed definitions of anxious depression and treatment outcome comparable to that in extant work [2
]. Anxious depressed patients constituted approximately one half of our sample (50.4%) and, consistent with previous findings, a number of indices of pretreatment illness severity were more evident among anxious depressed than nonanxious depressed patients [4
]. As expected, we observed large improvements in measures tapping both depressive and anxiety symptoms in both subtypes, providing support for the hypothesis that CT for MDD is flexible enough to address both depressive and anxiety symptoms simultaneously. Interestingly, the rate of improvement in anxiety symptoms was greater in anxious depressed than nonanxious depressed patients. This finding may simply reflect that there is more room for improvement among anxious depressed patients, but may also suggest that strategies such as restructuring faulty threat appraisals and reducing avoidance are an important focus of CT in this group of depressed patients. Examination of session content is required to address this hypothesis.
Consistent with previous reports relating anxious depression to poorer pharmacotherapy outcomes [2
], anxious depressed patients were less likely to achieve response and remission status as determined by clinician HRSD17
ratings. However, other findings suggested that these between-group differences do not indicate that CT should be viewed as an ineffective treatment for anxious depressed patients. Specifically, it appears that because the anxious depression subgroup presented with more severe symptomatology (HRSD17
mean ± SD: 22.7 ± 3.7 vs. 18.1 ± 2.8), it was simply more difficult to reach the cutoff scores for response (HRSD17
= 12 plus absence of DSM-IV MDE) and especially remission (HRSD17
= 7) within a 12- to 14-week protocol. Indeed, a comparison between the two subtypes regarding their speed of improvement in depressive symptoms as determined by clinicians (i.e. HRSD17
) suggested that the anxious depressed patients actually experienced a greater rate of improvement on the HRSD17
than nonanxious depressed patients. Also important to note here is that anxious and nonanxious depressed patients showed comparable attrition rates, suggesting that, unlike what Fava et al. [2
] documented for pharmacotherapy, the ability of patients to ‘tolerate’ a full course of CT may not vary as a function of severity of anxiety symptoms.
Corroboration of the hypothesis that anxious depressed patients do not evidence significantly poorer CT outcomes than nonanxious depressed patients also comes from self-report data. Specifically, although anxious depressed patients required more time than nonanxious depressed patients to achieve the QIDS-SR response cutoff, the subtypes did not evidence significantly different response and remission rates using QIDS-SR definitions, nor did they show a differential rate of improvement on the QIDS-SR and BDI. Interestingly, the two subtypes did not significantly differ with respect to stable remission rates either. Because stable remission has been associated with decreased risk of relapse and recurrence [24
], this finding may imply that anxious depressed patients treated with CT are not at an increased risk of poorer long-term outcomes. It will be possible to test this hypothesis when the follow-up phase of this study is complete.
Several study limitations deserve mention. First, we investigated potential group differences in the context of a standardized ‘open’ trial of CT. The absence of a credible treatment comparator or placebo makes it difficult to ascertain that response and remission patterns are due to the specific components of CT rather than nonspecific factors associated with clinical care and ongoing assessment. Thus, the present findings may not be specific to CT, but representative of therapeutic change occurring with care in general. Second, because we excluded patients with comorbid substance dependency or primary obsessive-compulsive disorder and patients unable to discontinue antidepressants or benzodiazepines, we may have inadvertently excluded persons with the highest levels of anxiety symptoms. Third, the omission of measures that tap anxiety psychopathology more broadly (i.e. cognitive, somatic and behavioral avoidance features) also limits us with respect to making inferences regarding improvements in anxiety psychopathology that occur with CT of MDD. Fourth, since anxious depressed patients presented with greater illness severity, more episodes, more anxiety disorders, less education, and were more likely to be non-Caucasian, it is possible that one or more of these characteristics did, in part or in combination, influence differences in outcomes where they were observed in this sample. Last, the study did not include a combined CT plus pharmacotherapy strategy, which is often used in clinical practice; thus, the data do not allow comment on this strategy.
Taken together, our findings provide only limited support for the hypothesis that anxious depressed patients constitute a group resistant to established treatments. We note that the clinician ratings, in particular, provide some support for this hypothesis. Overall, our findings suggest that, at least with CT, in spite of presenting with greater illness severity, patients with anxious depression report decreases in symptoms that are not significantly poorer than that observed in their nonanxious counterparts. Instead, they may simply need additional time and/or sessions to achieve remission during acute phase treatment. We believe this is an important hypothesis that warrants further testing, calling for studies that manipulate the dose of acute phase CT. Indeed, findings consistent with this hypothesis would support an emphasis on training therapists to personalize CT to the patient's presenting symptoms – an idea at the very essence of what the first-generation CT therapists called a ‘functional analysis’ [27
] as well as contemporary conceptualizations of the sequential model of treatment for depression [28
] – instead of developing complex modular variants of basic CT for MDD. An additional important avenue of future research is testing whether anxious depression is a moderator of between-group differences in randomized controlled trials comparing CT to antidepressant medications or their combination. A recent report further suggests that it may be important to measure and include in the analyses patient preferences for treatment, because receiving the preferred treatment has been associated with improved outcomes both for CT and pharmacotherapy [29
]. Results of such efforts can ultimately best guide recommendations for appropriate treatment modalities for anxious depressed patients.