The Current Evidence Levels for Biofeedback and Neurofeedback Interventions in Treating Depression: A Narrative Review

Table 4

Summary of the studies in EEG power-based neurofeedback.

Article

Sample

Demonstrates efficacy

Outcome measures

Statistical power

Control group

Multiple studies

Randomization

Superior to NT, PLA, or AT

Noninferior to TAU

Inclusion criteria

Treatment procedures

Data analysis

2+ independent studies

Superiority to PLA or AT

Required for level

1

2

2

3

3

4

4

4

4

4

4

5

Major depressive disorder (MDD)

Hashemian, Sadjadi [119] (adolescents, F3 α/θ↓)

Y

C

Y

Y

—

Y

—

—

Y

Y

Y

—

—

Escolano et al. [124] (α-2↑)

Y

Cog

Y

Y

—

—

Y

—

Y

Y

Y

—

—

Lee et al. [45] (F3 β↑ or T4 SMR↑, Pz α↓θ↑)

Y

C, P1

Y

Y

—

—

Y

—

Y

Y

Y

—

—

Wang et al. [112] (P3-P4 20-32 Hz↓)

Y

P1

Y

Y

—

—

Y

—

Y

Y

Y

—

—

EG: sample size of the experimental group; CG: sample size of the control group; NT: no treatment; PLA: placebo intervention; AT: alternative treatment; TAU: treatment as usual; Y: yes (criterion fulfilled); C: clinical outcome measure; P1: well-established subjective test of depression; Cog: cognitive feature of depression; α, β, θ, SMR: EEG frequency bands; ↑: upregulation; ↓: downregulation.