Yoga Exercises on Executive Functions among Individuals with Schizophrenia

The current study aimed to determine the effect of yoga exercises on executive functions among individuals with schizophrenia. Deficits in cognitive abilities are widely recognized as a core feature of schizophrenia. Among the cognitive impairments, executive functions have a more effective role in limiting the ability of patients to maintain and relearn the skills required to operate in the real world. Studies indicated that practicing yoga could improve abstraction and mental flexibility, spatial processing, working memory, spatial memory, emotion processing, attention and recall. Besides, it could reduce reaction times and increase accuracy in executive function tasks in various settings. Accordingly, in the present study, the researchers provided a yoga intervention program to patients with schizophrenia, assuming that by practicing this course, the study subjects could improve their executive functions.

This was a quasi–experimental study with a pretest–posttest and a control group design. It was conducted on 24 patients with schizophrenia (adult females) in Isfahan City, Iran. The study participants were randomly assigned into two groups of experimental and control. The experimental group underwent a 20–week yoga training. Wisconsin software was used to evaluate the executive functions of studied samples. A repeated–measures Analysis of Variance (ANOVA) was applied to analyze the collected data.

According to the repeated–measures ANOVA results of the preservative variable, the interaction between time and group (F44,2 =3.417, p=0.042, h=0.134) was significant at the error level of 5%. The Bonferroni post–hoc test data revealed that the mean score in the intervention group was significantly higher in pretest than the posttest (p=0.001) and follow–up (p=0.049) phases; however, there was no significant difference between the results of posttest and follow–up (p=0.624) in this group. These results highlight the effectiveness of the intervention on reducing the preservative variable immediately after the intervention as well as its stability after the intervention. In the “correct answers” variable, the interaction between the experimental group and the time scale (F44, 2=5.171, p=0.010, h=0.190) was significant at the error level of 5%. The Bonferroni post–hoc test data in the intervention group indicated that the mean number of correct answers in the pretest was significantly less than that of the posttest (p=0.003) and follow–up (p=0.008) in the study participants. Furthermore, there was no significant difference (p=0.001) between the mean score of correct answers in posttest and follow–up stages in them. Therefore, the intervention effectively increased the number of correct answers and this effect continued after the completion of intervention. In the incorrect answer variable, the interaction between the experimental group and the time scale (F44, 2=5.329, p=0.008, h=0.195) was significant at the error level of 5%. The Bonferroni post–hoc test findings manifested that in the intervention group, the mean frequency of incorrect answers in the pretest was significantly less than that of the posttest (p=0.001) and follow–up (p=0.007) stages. Besides, there was no significant difference between the mean frequency of correct answers in posttest and follow–up stages (p=0.001). Therefore, the intervention was effective in reducing the frequency of correct answers; this effectiveness remained stable after the interruption of intervention. Regarding the required time of attempt completion, the interaction between the experimental group and the time scale (F 44.2=6.140, p=0.004, h=0.218) was significant at the error level of 5%. The Bonferroni post–hoc test results in the intervention group revealed a significantly higher mean time in the pretest than the posttest (p<0.001) and follow–up (p<0.001) phases. In addition, there was no significant difference (p=0.001) between the meantime in the posttest and follow–up stages.

Following 20 weeks of yoga practice, the study participants in the yoga intervention group revealed significantly improved performance in executive functions. Yoga has been supported to have immediate psychological effects, including decreased anxiety, depression, and stress, as well as positive modifications in perceived executive functioning. Studies suggested that yoga has an immediate quieting effect on the sympathetic nervous system; hypothalamic and pituitary-adrenal axis responses to stress. The provided 20–week yoga intervention may have resulted in improved psychological states, which led to enhanced cognitive performance in the executive function tasks of the test group. Eventually, yoga exercises could improve cognitive abilities by affecting the structural and functional properties of the brain.