A Comparison Study of Working Memory Deficits between Patients with Methamphetamine-Associated Psychosis and Patients with Schizophrenia.

Background: Both patients with methamphetamine-associated psychosis (MAP) and patients with schizophrenia suffer from obvious cognitive deficits in working memory, and this affects the functional prognosis of patients.

Aim: This study is to investigate the difference of working memory deficits between patients with MAP and patients with schizophrenia, especially the difference of central executive system function, and the relevance of working memory deficits and clinical characteristics.

Methods: Twenty-eight male patients with MAP and twenty-eight patients with schizophrenia were recruited. The working memory of subjects was evaluated with the n-back task edited and adapted from English language materials. The positive syndrome scale of PANSS and CGI were employed to assess psychotic symptoms and the severity of patients.

Results: According to the results of repeated measure variance analysis, it was found that both the between-group variable (group) and within-group variable (n) had significant main effects, and the interaction between the between-group variable and the within-group variable was also significant. After Z-transformation, mean (sd) working memory scores of patients with MAP and schizophrenia were 0.91 (0.77) and -0.91 (2.11) respectively, and the difference between these two groups were statistically significant (F=19.253, p<0.001). The relevance between working memory deficits and clinical characteristics was low in both the patients with MAP and patients with schizophrenia.

Conclusion: Patients with MAP were better at regulating, updating, executing and controlling active information than patients with schizophrenia.