The effect of hydrocortisone on fear information processing as a predictor of clinical changes following brief cognitive-behavioral therapy in spider-fearfuls
Final Report Abstract
Meta-analytical data suggest that anxiety disorders are most effectively treated by exposure therapy. However, as it has frequently been reported that a subgroup of patients do not achieve clinically significant symptom improvement, more research is needed to identify key mechanisms for an effective treatment outcome and strategies to optimize the effects of exposure therapy. Recently, it has been shown that a single session of exposure-based cognitive behavioral therapy (CBT) rapidly influences automatic threat processing (measured using cognitive bias reaction time tasks) which, in turn, is predictive of psychotherapeutic changes at 4-week follow-up. Building upon these findings, the question remains whether additional treatment ingredients might (i) boost these early changes in emotional information processing and (ii) whether these predict a more pronounced symptom improvement. Here, a promising approach constitutes the administration of cognitive enhancer substances such as hydrocortisone or d-cycloserine (DCS). The current project focused on DCS - an antibiotic assumed to influence key neural processes which may contribute to a more pronounced symptom reduction when combined with exposure-based CBT. As part of a DFG-funded 8-months postdoctoral research fellowship, the current project aimed to investigate (i) the effects of probing glutamatergic function using an acute dose of DCS on performance in emotional cognitive tasks one day after brief CBT and (ii) whether pharmacological effects on threat vigilance predict changes in clinical symptoms after four weeks, compared to placebo. 40 spider-fearful healthy adults were randomised to a group receiving a single dose of 250 mg DCS versus placebo while performing a single session of CBT at drug peak level in a double-blind between-groups design. Self-report clinical measures (Spider Anxiety Screening, Fear of Spiders Questionnaire) were assessed immediately before (baseline) and after CBT treatment (post-treatment) as well as one day and four weeks after treatment (1-day follow-up, 4-week follow-up). Further, spider-fearfuls completed the behavioral approach task (BAT) and two fear information processing tasks, i.e., the Extrinsic Affective Simon Task (EAST) and the Approach-Avoidance Task (AAT), at baseline, 1-day follow-up and 4-week follow-up. After exclusion of statistical outliers, the final study sample consisted of 35 participants (DCS group: n = 18; placebo group: n = 17). 45.45% of participants fulfilled the criteria of a diagnosis of a specific phobia according to DSM-IV. Findings revealed that a brief CBT treatment was effective in causing recovery as evidenced by improvements in clinical and behavioral measures from baseline to 4-week follow-up (p’s < .001). This improvement was also reflected in the AAT data (p < .001), but not in the EAST data (p = .46). However, there was no significant augmentation effect of DCS on clinical, behavioral and cognitive outcome measures across time points. Further, no predictive value of early changes in attentional bias after brief CBT was revealed for clinical symptom change, controlling for respective baseline values. The findings of the current study illustrate the effectiveness of a very brief psychological intervention in the treatment of clinical and sub-clinical spider phobia. However, the cognitive enhancer DCS did not improve clinical, behavioral or fear information processing outcome measures as compared to placebo. Overall, no predictive value of early changes in fear information processing was revealed for clinical symptom change. Future research is needed to elucidate which factors modulate the efficacy of DCS administration in tandem with exposure-based CBT on clinical symptom improvement. This may inform future studies into the identification of key mechanisms underlying effective treatment outcome.
