Surface-based brain morphometry in schizophrenia vs. cannabis-induced psychosis: A controlled comparison.

BACKGROUND & AIM: We examined group differences in cortical thickness and surface-parameters among age and handedness--matched persons with cannabis-induced psychosis (CIP), schizophrenia with heavy cannabis use (SZC), and healthy controls (HC). METHODS: We recruited 31 men with SZC, 28 with CIP, and 30 with HC. We used the Psychiatric Research Interview for Substance and Mental Disorders to differentiate between CIP and SZC. We processed and analyzed T1 MR images using the Surface-based Brain Morphometry (SBM) pipeline of the CAT-12 toolbox within the statistical parametric mapping. After pre-processing, volumes were segmented using surface and thickness estimation for the analysis of the region of interest. We used the projection-based thickness method to assess the cortical thickness and Desikan-Killiany atlas for cortical parcellation. RESULTS: We observed the lowest cortical thickness, depth, and gyrification in the SZC, followed by CIP and the control groups. The differences were predominantly seen in frontal cortices, with limited parietal and temporal regions involvement. After False Discovery Rate (FDR) corrections and post-hoc analysis, SZC had reduced cortical thickness than HC in the middle and inferior frontal, right entorhinal, and left postcentral regions. Cortical thickness of SZC was also significantly lower than CIP in bilateral postcentral and right middle frontal regions. We found negative correlations (after FDR corrections) between the duration of cannabis use and cortical thickness in loci of parietal and occipital cortices. CONCLUSION: Our study suggested cortical structural abnormalities in schizophrenia, in reference to healthy controls and cannabis-induced psychosis, indicating different pathophysiology of SZC and CIP.

Concepts and controversies of malingering: A re-look.

Since time immemorial, humans have tried to feign physical and mental illnesses for various reasons. This led to the development of the concept of illness deception or malingering when one tries to assume a sick role and feigns signs and symptoms to gain external incentives. The conceptual framework of malingering has undergone several changes and there is sufficient evidence to demonstrate that malingering exists. However, the diagnosis of malingering has not yet been established in the mainstream psychiatric nosological systems and still it is present in the appendices as an additional area requiring attention. This is due to the poor construct validity of the diagnosis, problems in defining malingering, problems in assessment by psychological tests and clinical assessment methodology, no well-established guidelines to detect malingering and issues related to labelling/reporting malingering. Because of several controversies in multiple domains of assessment and ethical-social issues, malingering as a distinct entity is grossly neglected. In the upcoming arena of law suits and consumer benefits suits, it is extremely important to have a better understanding of the conceptual issues related to malingering and the controversies related to it. In this review, a brief overview of evolution of concepts and controversies related to malingering is described.