Telling true from false: cannabis users show increased susceptibility to false memories.

Previous studies on the neurocognitive impact of cannabis use have found working and declarative memory deficits that tend to normalize with abstinence. An unexplored aspect of cognitive function in chronic cannabis users is the ability to distinguish between veridical and illusory memories, a crucial aspect of reality monitoring that relies on adequate memory function and cognitive control. Using functional magnetic resonance imaging, we show that abstinent cannabis users have an increased susceptibility to false memories, failing to identify lure stimuli as events that never occurred. In addition to impaired performance, cannabis users display reduced activation in areas associated with memory processing within the lateral and medial temporal lobe (MTL), and in parietal and frontal brain regions involved in attention and performance monitoring. Furthermore, cannabis consumption was inversely correlated with MTL activity, suggesting that the drug is especially detrimental to the episodic aspects of memory. These findings indicate that cannabis users have an increased susceptibility to memory distortions even when abstinent and drug-free, suggesting a long-lasting compromise of memory and cognitive control mechanisms involved in reality monitoring.

[Dissociation (conversion) - malingering - antisocial personality disorder: differential diagnostic reflection on the basis of a case study]. / Dissoziation (Konversion) - Simulation - Dissozialität: Differentialdiagnostische Überlegungen anhand eines Fallbeispiels.

In this case report we refer to the big challenge of making a diagnosis in a deliberate malingering in the field of mental disorders. We specifically describe the difficulty regarding the differentiation between a conversion disorder and malingering of a serial delinquent. For such a person avoiding criminal persecution is one of the most frequent reason to deceitfully simulate a mental illness. In this field, symptoms of conversion disorders exceed the average; furthermore, a great number of organic-neurological illnesses may appear to be very similar to a conversion disorder or in many cases a neurological disorder can actually be detected in the course of a somatic examination. A further obstacle for the differential diagnosis can be seen in the difficulty to discern it from factitious disorders. However, it is quite possible to discern the deliberate malingering of a mental disorder from a conversion disorder by means of the diligent diagnosis of a competent and experienced doctor/assessor who specialises.

Detecting malingering in traumatic brain injury: Combining response time with performance validity test accuracy.

OBJECTIVE: The present study examined the incremental utility of item-level response time (RT) variables on a traditional performance validity test in distinguishing adults with verified TBI from adults coached to feign neurocognitive impairment. METHOD: Participants were 45 adults with moderate to severe TBI, 45 healthy adults coached to feign neurocognitive impairment (SIM), and 61 healthy adult comparisons providing full effort (HC). All participants completed a computerized version of the Test of Memory Malingering (TOMM-C) in the context of a larger test battery. RT variables examined along with TOMM-C accuracy scores included mean RTs (Trial 1, Trial 2, correct and incorrect trials) and RT variability indices. RESULTS: Several RT indices differed significantly across the groups. In general, SIM produced longer, more variable RTs than HC and TBI. Of the RT indices, average RT for Trial 1 and 2 were the best predictors of group membership; however, classification accuracies were greatly influenced by the groups being compared. Average RT for Trial 1 and 2 showed excellent discrimination of SIM and HC. All RT indices were less successful in discriminating SIM and TBI. Average RT for Trial 1 and 2 added incremental predictive value to TOMM-C accuracy in distinguishing SIM from TBI. CONCLUSION: Findings contribute to a limited body of research examining the incremental utility of combining RT with traditional PVTs in distinguishing feigned and bona fide TBI. Findings support the hypothesis that combining RT with TOMM-C accuracy can improve its diagnostic accuracy. Future research with other groups of clinical interest is recommended.

[A case of pathomimesis]. / Sluchai patomimii.

Pathomimesis (skin artefacts, Munchausen syndrome, artificial dermatitis, etc.) is an artificial deficiency of the skin and it is referred to a group of psychosomatic disorders, evidencing affective and in some cases paranoiac delirium disturbances. A case of this condition is described.

Assessment of malingering in chronic pain patients using neuropsychological tests.

Validity checks into neuropsychological tests have been successful at detecting malingering in litigant patients with mild brain injury in recent years. This study expanded on these findings and examined whether 6 neuropsychological tests could be used to detect malingering in litigant (n = 55) and nonlitigant (n = 53) patients claiming cognitive deficits due to chronic pain. Encouraging findings were found. When patients were matched on age, gender, racial or ethnic background, years of education, and time postinjury, almost one third (29%) of patients in the litigant group failed 2 or more validity checks in these 6 neuropsychological tests versus none (0%) of the patients in the nonlitigant group. This result challenges the validity of some litigant patients who complain of cognitive deficits due to chronic pain. Furthermore, the findings suggest that neuropsychological assessments can be used as part of the assessment of chronic pain complainants. Further investigation of the validity markers in these 6 neuropsychological tests is recommended.

[A case of pathomimia]. / Sluchai patomimii.

The authors describe a case of pathomimesis with simulation of seborrheal pemphigus, when the patient was referred to Group II invalidity.