Detecting malingering mental illness in forensics: Known-Group Comparison and Simulation Design with MMPI-2, SIMS and NIM

Abstract

BackgroundCriminal defendants may often exaggerate psychiatric symptoms either to appear non-accountable for their actions or to mitigate their imprisonment. Several psychometric tests have been proposed to detect malingering. These instruments are often validated by Simulation Design (SD) protocols, where normal participants are explicitly requested to either simulate a mental disorder or respond honestly. However, the real scenarios (clinical or forensic) are often very challenging because of the presence of genuine patients, so that tests accuracy frequently differs from that one obtained in well-controlled experimental settings. Here we assessed the effectiveness in criminal defendants of three well-known malingering-detecting tests (MMPI-2, SIMS and NIM) by using both Known-Group Comparison (KGC) and Simulation Design (SD) protocols.MethodsThe study involved 151 male inmates. Participants to the KGC protocol were all characterized by a positive psychiatric history. They were considered as genuine patients (KGC_Controls) if they had some psychiatric disorders already before imprisonment and scored above the cutoff of SCL-90-R, a commonly used test for mental illness, and as suspected malingerers (KGC_SM) if they were diagnosed as psychiatric patients only after imprisonment and scored below the SCL-90-R cutoff. Participants to SD protocol had no history of psychiatric disease and scored below the SCL-90-R cutoff. They were randomly assigned to either group: Controls (requested to answer honestly, SD_Controls) and simulated malingerers (requested to feign a psychiatric disease, SD_SM). All participants were then submitted to MMPI-2, NIM and SIMS.ResultsResults showed that while MMPI-2, SIMS and NIM were all effective in discriminating malingerers in the SD, SIMS only significantly discriminated between KGC_Controls and KGC_SM in the Known-Group Comparison. Receiver Operating Characteristic (ROC) curves analysis confirmed the better sensitivity of SIMS with respect to the other tests but raised some issues on SIMS specificity.DiscussionResults support the sensitivity of SIMS for the detection of malingering in forensic populations. However, some specificity issues emerged suggesting that further research and a good forensic practice should keep into account multiple measures of malingering, including psychometric data, clinical and social history and current clinical situation. These methodological constraints must be kept in mind during detection of malingering in criminal defendants reporting psychiatric symptoms.

Malingering of Psychotic Symptoms in Psychiatric Settings: Theoretical Aspects and Clinical Considerations

“…While auditory hallucinations (AH) are considered “classic” psychotic symptoms, they are also associated with bereavement, trauma, and intense emotions, borderline personality disorder, insomnia, traumatic brain injury (TBI), and organic brain lesions [ 36 – 38 ]. De Marchi and Balboni [ 39 ] outlined some characteristics of AH that are consistent with established psychotic conditions. For example, a single sensory mode is common in the manifestation of a psychotic disorder, while multiple and/or simultaneous modes may be considered signs of malingering [ 40 ].…”

Detecting symptom exaggeration and minimization using translated versions of the MMPI-2 and MMPI-2-RF: A systematic review and preliminary meta-analysis.

“…Regarding study design, 15 of the 20 studies that examined the MMPI-2 utilized a simulation design, though one of these studies used both a simulation design and known-group comparison (De Marchi & Balboni, 2018). Nine of the 15 simulation studies included a clinical control group (i.e., simulators were compared to genuine psychiatric patients).…”