Is transcranial direct current stimulation, alone or in combination with antidepressant medications or psychotherapies, effective in treating major depressive disorder? A systematic review and meta-analysis

Table 2 Study characteristics for each trial

First author (year)	Treatment strategy	Location		Electrode size (cm²)	Number of electrodes	Current (mA)	Session duration (min)	Session number (n)	Total charge	N	Age (mean)	Female ratio	Baseline score
First author (year)	Treatment strategy	Anode	Cathode/reference	Electrode size (cm²)	Number of electrodes	Current (mA)	Session duration (min)	Session number (n)	Total charge	N	Age (mean)	Female ratio	Active	Sham
Boggio (2008) ¹ [49]	mono	F3	RSA	35	2	2	20	10	11.4	31	49.4	0.70	21.1 ± 4.4	21.9 ± 4.8
Loo (2010)¹ [12]	mono	F3	F8^a	35	2	1	20	5	2.9	40	45.6	0.55	18.3 ± 5.75	17.25 ± 4.7
Blumberger (2012)¹ [52]	mono	F3	F4	35	2	2	20	15	17.1	24	47.3	0.83	24.9 ± 3.1	24.1 ± 2.9
Loo (2018)² [32]	mono	F3	F8^b	35	2	2.5	30	20	17.1	84	46.7	0.50	29.05 ± 5.01	27.69 ± 5.56
Bennabi (2015) ¹ [36]	+med	F3	FP2	35	2	2	30	10	42.9	23	61.8	0.65	22.7 ± 5.3	24.2 ± 5.6
Brunoni (2013) ² [31]	+med	F3	F4	25	2	2	30	10	24	60	41.0	0.68	30.73 ± 6.72	30.50 ± 6.81
Pavlova (2018) ¹ [51]	+med	F3	F8^a	17.5	2	0.5	20 30	10	5.7 8.6	69	37.6	0.63	17.8 ± 3.7³ 16.3 ± 3.1⁴	16.6 ± 2.5
Brunoni (2014) ¹ [16]	+psych*	F3	F4	25	2	2	30	10	24	37	43.8	0.30	25.6 ± 5.8	27 ± 5.7
Segrave (2014) ² [50]	+psych*	F3	F8^a	35	2	2	24	5	6.9	18	40.4	0.33	27 ± 5.57	27.11 ± 4.68
Welch (2018) ¹ [37]	+psych^#	F3	F4	25	2	2	30	12	28.8	14	53.2	0.86	20.9 ± 13.7	32.2 ± 11.44
Nord (2019) ¹ [38]	+psych^#	F3	ID	35	1	1	20	8	4.6	39	35.6	0.51	21.95 ± 3.20	21.05 ± 3.27
Mayur (2018) ² [39]	+ECT	F3	F8^b	25	2	2	30	10	24	16	45.0	0.38	29.5 ± 10.16	32.38 ± 6.44

¹Baseline score was assessed by HDRS
²Baseline score was assessed by MADRS
³Duration of stimulation = 20 min
⁴Duration of stimulation = 30 min
Treatment strategy: mono, tDCS monotherapy; +med, tDCS +medication therapy; +psych, tDCS +psychotherapy therapy (*cognitive control therapy; ^#cognitive behavioural therapy); +ECT, tDCS +ECT therapy
Location: F3- left DLPFC, F4- right DLPFC, F8-lateral contralateral orbit(a)/lateral right frontal(b)/, FP2-contralateral supraorbital area, RSA: right supraorbital area, ID: ipsilateral deltoid. Electrode locations were reported according to the International 10/20 system
Total charge defined as the amount of charge received by the subject during all tDCS sessions, which equals (current intensity × stimulation duration × number of sessions)/electrode size [43]
N represents sample size that applied to data analysis

ISSN: 1741-7015