Investigating d-cycloserine as a potential pharmacological enhancer of an emotional bias learning procedure

Using a daily diary for monitoring intrusive memories of trauma: A translational data synthesis study exploring convergent validity

OBJECTIVE

Intrusive memories are a core feature of posttraumatic stress disorder and have transdiagnostic relevance across mental disorders. Establishing flexible methods to monitor intrusions, including patterns and characteristics, is a key challenge. A daily diary has been developed in experimental settings to provide symptom count data, without the need for retrospective self-report over extended time periods (e.g., 1 week, 1 month). We conducted an exploratory, pre-registered data synthesis investigating convergence between the diary and questionnaire measures of intrusive symptoms long used in clinical practice (Impact of Event Scale, IES, and revised version, IES-R, Intrusion subscale).

RESULTS

Utilising datasets using the daily diary from 11 studies (4 real-world trauma studies, seven analogue trauma studies; total N = 578), we found significant positive associations between the diary and IES/IES-R Intrusion subscale. Exploratory analyses indicated that the magnitude of this association was stronger for the IES (vs. the IES-R), and in individuals with real-world (vs. analogue) trauma.

CONCLUSION

This study provides first evidence of convergent validity of a daily diary for monitoring intrusions with a widely used questionnaire. A diary may be a more flexible methodology to obtain information about intrusions (frequency, characteristics, triggers, content), relative to questionnaires which rely on retrospective reporting of symptoms over extended timeframes. We discuss potential benefits of daily monitoring of intrusions in clinical and research contexts.

Selective attention to emotional stimuli and emotion recognition in patients with major depression: The role of mineralocorticoid and glutamatergic NMDA receptors

BACKGROUND

Mineralocorticoid receptors (MR) are highly expressed in limbic brain areas and prefrontal cortex, which are closely related to selective attention to emotional stimuli and emotion recognition. Patients with major depressive disorder (MDD) show alterations in MR functioning and both cognitive processes. MR stimulation improves cognitive processes in MDD and leads to glutamate release that binds upon N-methyl-D-aspartate receptors (NMDA-R).

AIMS

We examined (1) whether MR stimulation has beneficial effects on selective attention to emotional stimuli and on emotion recognition and (2) whether these advantageous effects can be improved by simultaneous NMDA-R stimulation.

METHODS

We examined 116 MDD patients and 116 healthy controls matched for age (M = 34 years), sex (78% women), and education in the following conditions: no pharmacological stimulation (placebo), MR stimulation (0.4 mg fludrocortisone + placebo), NMDA-R stimulation (placebo + 250 mg D-cycloserine (DCS)), MR + NMDA-R stimulation (fludrocortisone + DCS). An emotional dot probe task and a facial emotion recognition task were used to measure selective attention to emotional stimuli and emotion recognition.

RESULTS

Patients with MDD and healthy individuals did not differ in task performance. MR stimulation had no effect on both cognitive processes in both groups. Across groups, NMDA-R stimulation had no effect on selective attention but showed a small effect on emotion recognition by increasing accuracy to recognize angry faces.

CONCLUSIONS

Relatively young unmedicated MDD patients showed no depression-related cognitive deficits compared with healthy controls. Separate MR and simultaneous MR and NMDA-R stimulation revealed no advantageous effects on cognition, but NMDA-R might be involved in emotion recognition.

Using Cognitive Bias Modification-Appraisal Training to Manipulate Appraisals about the Self and the World in Analog Trauma

Background

Dysfunctional appraisals are a key mechanism in posttraumatic stress disorder (PTSD). Experimental manipulations of appraisals via Cognitive Bias Modification-Appraisal (CBM-App) training targeting cognitions related to the ‘self’ has shown to affect analog trauma symptoms. The present study aimed to conceptually replicate and extend previous findings by comparing a newly developed ‘world’ to the original ‘self’ training, and investigate the moderating role of locus of control (LOC) on intrusions.

Methods

Healthy participants (N = 173) were exposed to distressing films as an analog trauma induction. Next, participants received positive or negative CBM-App, targeting either self- or world-relevant appraisals. Dysfunctional appraisals and LOC were assessed pre- and post-training. During the week after the laboratory session, participants recorded their intrusions and associated distress in a diary. One week later, trauma-relevant symptomatology was assessed.

Results

Positive compared to negative CBM-App induced training-congruent appraisals, independent of the trained cognition (self vs. world). However, there was no effect on analog trauma symptoms and LOC did not moderate the training’s effect.

Conclusions

Our results underline the validity of CBM-App as a method to experimentally manipulate appraisals. However, since we did not fully replicate previous findings further research on mechanisms associated with transfer effects is warranted.

Human perceptual learning is delayed by the N-methyl-D-aspartate receptor partial agonist D-cycloserine

BACKGROUND

The optimisation of learning has long been a focus of scientific research, particularly in relation to improving psychological treatment and recovery of brain function. Previously, partial N-methyl-D-aspartate agonists have been shown to augment reward learning, procedural learning and psychological therapy, but many studies also report no impact of these compounds on the same processes.

AIMS

Here we investigate whether administration of an N-methyl-D-aspartate partial agonist (D-cycloserine) modulates a previously unexplored process - tactile perceptual learning. Further, we use a longitudinal design to investigate whether N-methyl-D-aspartate-related learning effects vary with time, thereby providing a potentially simple explanation for apparent mixed effects in previous research.

METHODS

Thirty-four volunteers were randomised to receive one dose of 250 mg D-cycloserine or placebo 2 h before tactile sensitivity training. Tactile perception was measured using psychophysical methods before and after training, and 24/48 h later.

RESULTS

The placebo group showed immediate within-day tactile perception gains, but no further improvements between-days. In contrast, tactile perception remained at baseline on day one in the D-cycloserine group (no within-day learning), but showed significant overnight gains on day two. Both groups were equivalent in tactile perception by the final testing - indicating N-methyl-D-aspartate effects changed the timing, but not the overall amount of tactile learning.

CONCLUSIONS

In sum, we provide first evidence for modulation of perceptual learning by administration of a partial N-methyl-D-aspartate agonist. Resolving how the effects of such compounds become apparent over time will assist the optimisation of testing schedules, and may help resolve discrepancies across the learning and cognition domains.

Glutamatergic Contribution to Probabilistic Reasoning and Jumping to Conclusions in Schizophrenia: A Double-Blind, Randomized Experimental Trial

BACKGROUND

Impaired probabilistic reasoning and the jumping-to-conclusions reasoning bias are hallmark features of schizophrenia (SCZ), yet the neuropharmacological basis of these deficits remains unclear. Here we tested the hypothesis that glutamatergic neurotransmission specifically contributes to jumping to conclusions and impaired probabilistic reasoning in SCZ.

METHODS

A total of 192 healthy participants received either NMDA receptor agonists/antagonists (D-cycloserine/dextromethorphan), dopamine type 2 receptor agonists/antagonists (bromocriptine/haloperidol), or placebo in a randomized, double-blind, between-subjects design. In addition, we tested 32 healthy control participants matched to 32 psychotic inpatients with SCZ-a state associated with compromised probabilistic reasoning due to reduced glutamatergic neurotransmission. All experiments employed two versions of a probabilistic reasoning (beads) task, which required participants to either sample individual amounts of sensory information to infer correct decisions or provide explicit probability estimates for presented sensory information. Our task instantiations assessed both information sampling and explicit probability estimates in different probabilistic contexts (easy vs. difficult conditions) and changing sensory information through random transitions among easy, difficult, and ambiguous trial types.

RESULTS

Following administration of D-cycloserine, haloperidol, and bromocriptine, healthy participants displayed data-gathering behavior that was normal compared with placebo and was adequate in the context of all employed task conditions and trial level difficulties. However, healthy participants receiving dextromethorphan displayed a jumping-to-conclusions bias, abnormally increased probability estimates, and overweighting of sensory information. These effects were mirrored in patients with SCZ performing the same versions of the beads task.

CONCLUSIONS

Our findings provide novel neuropharmacological evidence linking reduced glutamatergic neurotransmission to impaired information sampling and to disrupted probabilistic reasoning, namely to overweighting of sensory evidence, in patients with SCZ.

Appraisal-based cognitive bias modification in patients with posttraumatic stress disorder: a randomised clinical trial

Background: Negative appraisals of the trauma and its sequelae play a crucial role in the development and maintenance of Posttraumatic Stress Disorder (PTSD). Experimental studies have shown promise in reducing negative appraisal through Cognitive Bias Modification (CBM) training. Objective: To determine whether an online CBM training designed to modify dysfunctional appraisals is successful in reducing appraisal bias in PTSD patients. Method: In this double-blinded 2-arm randomised clinical trial, 107 patients with PTSD were randomly allocated to active (n = 49) or control online CBM training (n = 57). Training comprised the completion of four sessions of online CBM training within one week. Change in bias, as measured by a scenario task and questionnaire (i.e. PostTraumatic Cognition Inventory), was the primary outcome. Secondary outcome included change in PTSD symptoms. Assessments took place prior to training, during training sessions, post-training and at 1- and 6-month follow-up. Results: Intent-to-treat analysis indicated that there was no interaction effect of condition by time. Regardless of training condition, participants showed a small to moderate decline in appraisal bias and PTSD symptoms from pre- to post-training. In both conditions, bias change during training sessions was related to decline in PTSD symptomatology following training. No moderators of outcome were found. Conclusions: There was no evidence that active training was more effective than control training in reducing dysfunctional appraisals. In both conditions, participants showed a decline in dysfunctional appraisals and PTSD symptoms following training. Importantly, bias reduction during training was related to PTSD symptom decline following training. Explanations and future research directions are discussed.