Maarten J.V. Peters

Heart rate variability in response to affective scenes in posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) is characterized by psychophysiological abnormalities, such as an altered baseline heart rate and either hyper- or hyporeactivity to a wide range of stimuli, implying dysfunctional arousal regulation. Heart rate variability (HRV) has been established as an important marker of arousal regulatory ability. The aim of the present study was to examine HRV in PTSD under different affective conditions and to explore the role of potential moderating factors. To meet this purpose, videos of varying emotional valence were presented to trauma-exposed participants with PTSD (n=26), trauma-exposed participants without PTSD (n=26), as well as non-trauma-exposed controls (n=18) while HRV was recorded. The PTSD group showed lower HRV than non-trauma-exposed controls at baseline (corrected for age) and throughout different affective conditions implying decreased parasympathetic activity and an inflexible response regulation. There was a negative relationship between HRV and self-report of both depression and state dissociation.

Cure or curse? Ambivalent attitudes towards neuroleptic medication in schizophrenia and non-schizophrenia patients

Neuroleptic non-compliance remains a serious challenge for the treatment of psychosis. Non-compliance is predominantly attributed to side effects, lack of illness insight, reduced well-being or poor therapeutic alliance. However, other still neglected factors may also play a role. Further, little is known about whether psychiatric patients without psychosis who are increasingly prescribed neuroleptics differ in terms of medication compliance or about reasons for non-compliance by psychosis patients. As direct questioning is notoriously prone to social desirability biases, we conducted an anonymous survey. After a strict selection process blind to results, 95 psychiatric patients were retained for the final analyses (69 participants with a presumed diagnosis of schizophrenia psychosis, 26 without psychosis). Self-reported neuroleptic non-compliance was more prevalent in psychosis patients than non-psychosis patients. Apart from side effects and illness insight, main reasons for non-compliance in both groups were forgetfulness, distrust in therapist, and no subjective need for treatment. Other notable reasons were stigma and advice of relatives/acquaintances against neuroleptic medication. Gain from illness was a reason for non-compliance in 11-18% of the psychosis patients. Only 9% of all patients reported no side effects and full compliance and at the same time acknowledged that neuroleptics worked well for them. While pills were preferred over depot injections by the majority of patients, depot was judged as an alternative by a substantial subgroup. Although many patients acknowledge the need and benefits of neuroleptic medication, non-compliance was the norm rather than the exception in our samples.

Poor working memory predicts false memories

Two studies investigated whether individual differences in simple span verbal working memory and complex working memory capacity are related to memory accuracy and susceptibility to false memory development. In Study 1, undergraduate students (N=60) were given two simple span working memory tests: forward and backward digit span. They also underwent a memory task that is known to elicit false memories of nonpresented words, the Deese/Roediger-McDermott (DRM) paradigm. Poor simple span working memory (as reflected by suboptimal backward digit span scores) was related to elevated levels of false recognition. Study 2 (N=65) replicated this finding, in that suboptimal backward digit span performance was found to be predictive of false recognition. However, complex working memory capacity (operation span) was not related to false recognition. This pattern suggests that even in a homogenous sample of undergraduates, poor working memory is associated with the susceptibility to recollect words never presented.

The corrective effects of warning on false memories in the DRM paradigm are limited to full attention conditions

Effects of attention control and forewarning on the activation and monitoring of experimentally induced false memories in the Deese/Roediger-McDermott paradigm were investigated in a young adult sample (N=77). We found that reducing the degree of attention during encoding led to a decrease in veridical recall and an increase in non-presented critical lure intrusions. This effect could not be counteracted by a forewarning instruction. However, these findings did not emerge in a (retrieval supportive) recognition task. It seems that divided attention increases false recall when attention control and forewarning have to compete for limited cognitive resources in a generative free recall as opposed to a retrieval supportive recognition task. Forewarning instructions do not always protect young adults against experimentally induced false memories.

Did I say that word or did you? Executive dysfunctions in schizophrenic patients affect memory efficiency, but not source attributions.

Introduction. Schizophrenic patients have difficulties in recognising previously presented verbal information and identifying its sources. The antecedents of these recognition and source misattributions are, however, largely unknown. The current study examined to what extent schizophrenic patients’ lack of memory efficiency, their memory errors, and their source misattributions are related to neurocognitive deficits (i.e., executive dysfunctions). Methods. 23 schizophrenic patients and 20 healthy controls were administered an adapted version of the Deese/Roediger-McDermott (DRM) task from which parameters of memory efficiency, memory errors, source misattributions, and two-high threshold measures were derived. Furthermore, two neurocognitive tasks tapping executive functions were administered: the Wisconsin Card Sorting Test (WCST) and the Behavioural Assessment of the Dysexecutive Syndrome (BADS). Using multiple linear regression analyses, we examined whether these neurocognitive measures predicted various memory parameters. Results. Patients with schizophrenia showed poorer memory efficiency and were more prone to make internal-external source misattributions with high confidence. However, they did not more often falsely recognise critical lure words than controls. Executive dysfunctions predicted memory efficiency, but not source misattribution performance. Conclusion. Our findings provide further evidence that schizophrenic patients’ memory impairments are intimately related to fundamental neurocognitive deficits.

Cognitive underperformance and symptom over-reporting in a mixed psychiatric sample.

The current study examined the prevalence of cognitive underperformance and symptom over-reporting in a mixed sample of psychiatric patients (N = 183). We employed the Amsterdam Short-Term Memory Test (ASTM) to measure cognitive underperformance and the Structured Inventory of Malingered Symptomatology (SIMS) to measure the tendency to over-report symptoms. We also administered neuropsychological tests (e.g., Concept Shifting Task; Reys Verbal Learning Test) and the Symptom Checklist-90 (SCL-90) to the patients. A total of 34% of them failed the ASTM, the SIMS or both tests. ASTM and SIMS scores were significantly, albeit modestly, correlated with each other (r = −.22). As to the links between underperformance, over-reporting, neuropsychological tasks, and the SCL-90, the association between over-reporting on the SIMS and SCL-90 scores was the most robust one. The subsample that only failed on the ASTM performed significantly worse on a compound index of memory performance. Our findings indicate that underperformance and over-reporting are loosely coupled dimensions and that particularly over-reporting is intimately linked to heightened SCL-90 scores.

Enhanced memory performance on an internal-internal source monitoring test following acute psychosocial stress

Research on the effect of acute stress and high levels of glucocorticoids on memory has largely focused on memory tasks involving the medial temporal lobe (e.g., declarative memory). Less is known, however, about the effects of stress and glucocorticoids on more strategic memory processes regulated by the prefrontal cortex (e.g., source monitoring). In the current study, the authors investigated whether exposure to acute psychosocial stress would result in altered source monitoring performance relative to the performance of a nonstressed control group. To this end, the authors assigned nonsmoking, healthy, young men to either a stress (n = 22) or a control (n = 18) condition, after which the men were given an internal source monitoring test. Results show that relative to control participants, stressed participants made fewer source monitoring errors. This study suggests that stress may have differential effects on memory, depending on whether the memory test is regulated by the prefrontal cortex or the medial temporal lobe.

Confusing action and imagination: action source monitoring in individuals with schizotypal traits.

To explore whether schizotypal traits may undermine source monitoring for actions, 67 undergraduate participants (21 men) completed the Schizotypal Personality Scale and were then given a source-monitoring task in which some specific acts had to be performed, whereas others only had to be imagined. Next, participants had to complete an old-new recognition task and ascribe the source, i.e., whether they had performed or only imagined the items (i.e., source monitoring). Participants also completed a working memory capacity task (i.e., Operation Span task). We found that the higher the Schizotypal Personality Scale scores, the poorer recognition and source attribution scores. Relative to participants with low levels of schizotypal traits (i.e., controls), those with higher levels of schizotypal traits more often falsely claimed to have performed actions when in fact they had only imagined them. Although participants high and low in schizotypical traits did not differ in their working memory capacity, poor working memory capacity was related to source misattribution (i.e., increase false alarms). The present findings indicate that schizotypal traits undermine source monitoring for action in a healthy population.

Detecting coached feigning using the test of Memory Malingering (TOMM) and the structured inventory of Malingered Symptomatology (SIMS)

Undergraduate students were administered the Test of Memory Malingering (TOMM) and the Structured Inventory of the Malingered Symptomatology (SIMS) and asked to respond honestly, or instructed to feign cognitive dysfunction due to head injury. Before both instruments were administered, symptom-coached feigners were provided with some information about brain injury, while feigners who received a mix of symptom-coaching and test-coaching were given the same information plus advice on how to defeat symptom validity tests. Results show that, although the accuracy of both instruments appears to be somewhat reduced by a mix of symptom coaching and test coaching, the TOMM and SIMS are relatively resistant to different kinds of coaching.

Visual false memories in post-traumatic stress disorder (PTSD)

There is an ongoing debate whether or not patients with post-traumatic stress disorder (PTSD) are more prone to produce false memories. The present study investigated this question using a visual variant of the Deese-Roediger-McDermott (DRM) paradigm, additionally addressing underlying mechanisms of false memory production (e.g., depression, dissociation, emotional valence, arousal). The visual paradigm was administered to 48 traumatized individuals with (n=20) and without PTSD (n=28) and 28 non-traumatized controls. Groups did not differ with regard to memory performance and memory confidence. False memories were correlated with depression. We recommend that future studies employ trauma-related material to further explore memory aberrations in PTSD.