The role of tonic immobility and behavioural control in intrusion development

Background: Tonic immobility (TI; involuntary motor inhibition during threat) has been implicated in the onset of posttraumatic stress disorder (PTSD) in previous studies, using cross-sectional designs and (retrospectively measured) TI. Only one study examined spontaneous TI responses in a more controlled setting,using experimental trauma (a ‘trauma film’). TI during the ‘trauma film’ was indeed associated with increased frequency of intrusive memories of the film (Hagenaars & Putman, 2011). Interestingly, high attentional control(the ability to focus and switch attention) buffered against this effect. Reduced controllability was indeed proposed to stimulate PTSD development. In experiments, behavioural control was related to reduced stress when anticipating threat. However, findings are less consistent or scarce for the impact period and postthreat period.  Objective: Replicate the TI x Controlinteraction1 (but with behavioural control) for the impact and post-threat period.  Method: Sixty-four participants watched an experimental trauma (negative pictures) while being allowed to close their eyes or not. Spontaneous TI was measured after picture viewing; intrusions were recorded in a diary in the subsequent week. Informative hypotheses were tested with Bayesian analyses. Results: TI predicted intrusion development. Moderation (TI x Control) and non-moderation (main effect of TI only) were both adequate models, with no preference for either.  Conclusions: We replicated earlier cross-sectional findings regarding TIusing a longitudinal trauma-analogue design. The role of behavioural control may be complicated and/or indirec

Predicting Outcome in an Intensive Outpatient PTSD Treatment Program Using Daily Measures

It is useful to investigate factors that could predict treatment outcomes for PTSD. The current study aims to investigate the relationship between daily measured PTSD symptoms during an intensive six-day treatment program and overall post-treatment outcomes. The treatment program combines eye movement desensitization with reprocessing and prolonged exposure, as well as physical activity and psychoeducation. It was expected that for the entire duration of treatment, as well as the first half of the treatment, a greater decline in daily PTSD symptoms would be a predictor for a greater decline in PTSD symptoms at a four-week follow-up. Data from 109 PTSD-patients (87.2% female, mean age = 36.9, SD = 11.5) were used. PTSD symptoms were measured with the CAPS-5 and the self-reported PTSD checklist for DSM-5 (PCL-5). Daily PTSD symptoms were measured with an abbreviated version of the PCL-5 (8-item PCL). Latent growth curve models were used to describe changes in daily PTSD symptoms and predict treatment outcome. Results show that a greater decline in daily PTSD symptoms measured by the 8-item PCL predicts better treatment outcome (CAPS-5 and PCL-5), but that a patient’s PTSD symptoms on the first day of treatment has no predictive effect. A decline in PTSD symptoms only during the first half of treatment was also found to predict treatment outcomes. Future research should be focused on replicating the results of the current study

A Step-By-Step Guide on Preregistration and Effective Data Sharing for Psychopathology Research

Data analysis in psychopathology research typically entails multiple stages of data preprocessing (e.g., coding of physiological measures), statistical decisions (e.g., inclusion of covariates), and reporting (e.g., selecting which variables best answer the research questions). The complexity and lack of transparency of these procedures have resulted in two troubling trends: the central hypotheses and analytical approaches are often selected after observing the data, and the research data are often not properly indexed. These practices are particularly problematic for (experimental) psychopathology research because the data are often hard to gather due to the target populations (e.g., individuals with mental disorders), and because the standard methodological approaches are challenging and time consuming (e.g., longitudinal studies). Here, we present a workflow that covers study preregistration, data anonymization, and the easy sharing of data and experimental material with the rest of the research community. This workflow is tailored to both original studies and secondary statistical analyses of archival data sets. In order to facilitate the implementation of the described workflow, we have developed a free and open-source software program. We argue that this workflow will result in more transparent and easily shareable psychopathology research, eventually increasing and replicability reproducibility in our research field

Safety behaviors toward innocuous stimuli can maintain or increase threat beliefs

Safety behaviors can prevent or minimize a feared outcome. However, in relatively safe situations, they may be less adaptive, presumably because people will misattribute safety to these behaviors. This research aimed to investigate whether safety behaviors in safe situations can lead to increased threat beliefs. In Study 1, we aimed to replicate a fear conditioning study (N = 68 students) in which the experimental, but not the control group, received the opportunity to perform safety behavior to an innocuous stimulus. From before to after the availability of the safety behavior, threat beliefs persisted in the experimental group, while they decreased in the control group. In Study 2, we examined whether threat beliefs had actually increased for some individuals in the experimental group, using a multi-dataset latent class analysis on data from Study 1 and two earlier studies (N = 213). Results showed that about a quarter of individuals who performed safety behavior toward the innocuous stimulus showed increased threat expectancy to this cue, while virtually nobody in the control group exhibited an increase. Taken together, safety behavior in relatively safe situations may have maladaptive effects as it generally maintains and sometimes even increases threat beliefs

Robust and Efficient Designs for the Michaelis-Menten Model

For the Michaelis-Menten model, we determine designs that maximize the minimum of the D-efficiencies over a certain interval for the nonlinear parameter. The best two point designs can be found explicitly, and a characterization is given when these designs are optimal within the class of all designs. In most cases of practical interest, the determined designs are highly efficient and robust with respect to misspecification of the nonlinear parameter. The results are illustrated and applied in an example of a hormone receptor assay