Effectiveness of Transcranial direct current stimulation on executive functions and amelioration of symptoms of individuals with Major Depression Disorder

The purpose of present study was to investigate the effect of Transcranial direct current stimulation (tDCS) on improvement of executive functions including working memory, cognitive flexibility, and inhibitory control and amelioration of depression symptoms.

The research method was quasi-experimental with pre-test, post-test and followed-up with control group and the statistical population consisted of 33 women with Major Depression Disorder (MDD) who were referred to Outpatient Counseling Centers in districts 1 and 2 affiliated with Education Department in Sari city in 2018. Using convenience sampling method, 20 individuals were selected and were randomly assigned into control and experimental groups. The experimental group received 10 sessions of tDCS for 20 minutes, twice a week. The computerized version of Wisconsin Card Sorting Test (WCST, Heaton & et al. 1993, N-back Krichner 1958, Go-Nogo Test Hoffman 1984, and Beck Depression Test 1996 were used for assessment. Data were analyzed using descriptive indices and mixed analysis of variance with repeated measures.

The results showed that Transcranial direct current stimulation reduced Beck rating scale (F= 38.68, P= 0.001), errors of WCST (F= 9.82, P= 0.006), it’s total time (F= 8.24, P= 0.010), N–back time (F= 28.09, P= 0.001), and reaction time of go stage (F= 4.32, P= 0.05) also increased Go-Nogo accuracy in the go stage (F= 11.66, P= 0.003), nogo stage (F= 15.53, P= 0.001), and the changes remained untill follow-up session. Although, there wasn't any significant differences in cluster of WCST (F= 1.53, P= 0.232).

Transcranial direct current stimulation ameliorates cognitive areas, depressive symptoms, and executive functions. Thus, it can be used as an effective intervention in the treatment of Major Depression Disorder.