Neurocognitive Functions Related to Parietal Lobe in Patients with Schizophrenia and Methamphetamine Induced Psychotic Disorder and Healthy Individuals: A Comparative Study.

Background: There are some inconsistent findings about neurocognitive functions in schizophrenia and methamphetamine induced psychosis (MIP). This study aimed to compare these two disorders in terms of neurocognitive functions related to parietal lobe. Methods: This was a cross-sectional study in which 30 patients with schizophrenia, 30 patients with MIP, and 32 healthy individuals were compared. The two groups of patients were selected through convenience sampling from among patients hospitalized in Shahid Beheshti hospital in Kerman, Iran and healthy individuals were selected via convenience sampling from among the employees of Kerman University of Medical Sciences. The three groups were administered clock-drawing test (CDT), Rey-Osterrieth complex figure (ROCF) copying test, and interlocking finger test (IFT) and their demographic and clinical data were collected. The one-way analysis of variance (ANOVA) was used to investigate the differences between the groups. Multivariate analysis of covariance was also used to examine the effects of confounding factors. Besides, follow-up pairwise comparisons were performed after adjustment for multiple testing. Findings: The group with schizophrenia had significantly more impairment than the group with MIP with reference to the results of IFT and the ROCF test. However, the scores of patients with MIP on these two tests were not different from those of the normal controls. With regard to the CDT, the only significant difference was observed between the group with schizophrenia and controls. Conclusion: On the condition that the results are replicated in other studies, some parietal lobe neurocognitive tests might be used when it is difficult to differentially diagnose schizophrenia and MIP.