Table A1.
Overview of FAA stability related studies.
| Study | Study type* | N= | Subjects | EEG Methods | Intervention | Relevant factors |
|---|---|---|---|---|---|---|
| Allen et al., 2004 | 1 | 30 | MDD (females) | 3 to 5 Ax., 8 or 16 weeks apart | Acupuncture (specific and non-specific) | HRSD change score |
| Bruder et al., 2008 | 1 | 18 | MDD and HC | 2 Ax., 12 weeks apart | Fluoxetine treatment | Response (“CGI-I rating much or very much improved”) |
| Debener et al., 2000 | 1 | 15 and 22 | MDD and HC | 2 Ax., 2–4 weeks apart | Several antidepressants | BDI-score |
| Deldin and Chiu, 2005 | 1 | 15 and 18 | MDD and HC | 4 Ax. On 1 day | Cognitive restructuring | Happiness change score |
| Gollan et al., 2014 | 1 | 37 and 35 | MDD and HC | 2 Ax., 16 weeks apart | Behavioral activation | IDS-SR |
| Keune et al., 2011 | 1 | 78 | MDD | 2 Ax., 8 weeks apart (neutral vs. sad state) | Mindfulness | BDI en BDI-Change, gender |
| Spronk et al., 2008 | 1 | 8 | MDD | 2 Ax., pre/post-treatment | rTMS | None that was associated with frontal asymmetry |
| Vuga et al., 2006 | 1 | 49 and 50 | Childhood onset depression and HC | 2 Ax., 1–3.2 years apart | Some cases on ADs (13 of n = 49) | Age, sex, BDI |
| Davidson et al., 2003 | 2 | 41 | HC | 2 Ax., 8 weeks, 4 months | Mindfulness meditation | |
| Hagemann et al., 2002 | 2 | 59 | HC | 4 Ax., all 4 weeks apart | None | |
| Hagemann et al., 2005 | 2 | 59 | HC | 3 Ax., all 5 weeks apart | None | |
| Sutton and Davidson, 1997 | 2 | 46 | HC | 2 Ax., 6 weeks apart | None | No depression scores (only BIS/BAS and PANAS) |
| Tenke et al., 2017 | 2 | 39 | HC | 2 Ax., 5–16 days apart | None | |
| Tomarken et al., 1992 | 2 | 85 | HC | 2 Ax., 3 weeks apart | None | |
| Carvalho et al., 2011 | 3 | 12, 8 and 7 | MDD, remitted and HC | 1 Ax. | None | BDI |
| Feldmann et al., 2018 | 3 | 22, 16 and 34 | MDD, remitted and HC (also other groups, with comorbid anxiety) | 1 Ax. | None | BDI |
| Gotlib et al., 1998 | 3 | 16, 31 and 30 | MDD, remitted and HC | 1 Ax. | None | |
| Grünewald et al., 2018 | 3 | 28 and 31 | MDD and HC | 1 Ax. | None | BDI |
| Nusslock et al., 2018 | 3 | 37 and 69 | MDD and HC | 1 Ax. | None | BDI |
| Study | Relevant analyses | Calculation FAA | Conclusion |
|---|---|---|---|
| Allen et al., 2004 | FAA solely: ICCs. FAA in relation to symptoms: Correlations & multivariate Repeated Measures analysis of variance (HRSD-score) with changing covariates (3 asymmetry measures) | ln[Right] - ln[Left] | Stable across time and independent of depression severity. |
| Bruder et al., 2008 | 1. Interaction Response-Nonresponse-HC * Hemisphere * Site. 2. Interaction Response * Site * Hemisphere * Session. 3. Test-retest correlations. | Interaction of site and hemisphere | Overall stable. 1. No FAA differences between groups. 2. No change of FAA over time. 3. Moderate test-rest correlations of FAA after treatment. |
| Debener et al., 2000 | 1. Cronbachs alpha FAA for internal consistency. 2. Correlation FAA-BDI. 3. Temporal stability through Pearson correlations. | 1. Interaction of session * site * region (posterior-anterior) * Hemisphere 2. ln(right) - ln(left) | Overall: Not a stable measure. 1. Good internal consistency. 2. No correlation with BDI, so state-independent. 3. Unstable temporal stability of frontal regions (not posterior). |
| Deldin and Chiu, 2005 | 1. Interaction Diagnosis * Block * Region * Laterality 2. Correlation FAA-Happiness score | 1. Interaction with region and laterality 2. ln F4 - ln F3 | Overall: no changes between assessments on the same day. 2. No correlation. |
| Gollan et al., 2014 | 1. Rep Measures ANOVA FAA over time. 2. Correlation pre FAA-pre IDS/pre FAA-post IDS/post FAA-pre IDS/post FAA-post IDS | log F4 - log F3 | Overall: FAA = stable, trait-like. 1.No changes in FAA. 2. No significant correlations. |
| Keune et al., 2011 | 1. Cronbachs alpha. 2. ANOVA interaction FAA time 1 * time 2. 3. Correlation FAA-affect scores (to test state). 4. Test-retest reliability with Pearson product moment correlations. 5. Correlation FAA-BDI time 1. 6. Correlation FAA Change-BDI Change. 7. Interactions with gender | subtracting power values in the left hemisphere from the values in the right hemisphere | 1. Stable. 2. Change (in sad condition, not in neutral). 3. No correlation with affect, so stable. 4. Correlates, so reliable. 5. Significant correlation FAA-BDI in sad condition (not in neutral, this was only for other sites). 6. No correlation. 7. No gender interaction effects. |
| Spronk et al., 2008 | Interaction of Time * Hemisphere (left: F3, FC3, F7. Right: F4, FC4, F8) | Interaction of time and hemisphere | No interaction for alpha1, alpha2 and alpha. Alpha seems a trait. |
| Vuga et al., 2006 | 1. Cronbach's alpha. 2. ANOVA with Age, apart for the sexes. 3. ICC 4. ANOVA with group, sex, and FAA at Time 2 as dependent variable, on Time 1 as dependent variable. 5. Same analyses, apart for with and without medication. 6. Regression on FAA Time 2, with FAA Time 1, BDI and BDI-change. | ln(F4) - ln(F3) | Overall: Moderate to high long term stability. 1. Consistent. 2. No influence of Age or Sex. 3. Moderately stable. 4. Stable after p-value correction, without correction there would be differences. 5. Same results with and without medication, so stable. 6. Depressive symptom severity and change in symptoms did not affect EEG asymmetry stability. |
| Davidson et al., 2003 | Group (mindfulness/waitlist) * Time. | ln(F4) – ln(F3), ln(F8) – ln(F7) | Changes in asymmetry were only observed in other electrode pairs, not in F3/4 or F7/8. |
| Hagemann et al., 2002 | Model of LST theory | ln power density F4 − ln power density F3 | 60% trait - 40% state |
| Hagemann et al., 2005 | Model of LST theory | ln F4 − ln F3 | 40–50% state |
| Sutton and Davidson, 1997 | Averaged over 13 asymmetry measures (from 13 homologous electrode pairs): Cronbach's alpha (0.87) and ICC (0.57) | log F4 − log F3 | High to modest test-retest reliability |
| Tenke et al., 2017 | Test-retest correlations | F4 − F3 | Variation in outcome: low in general, but it is correlating. Test-retest correlations differ per research site, but is in general significant for F3-F4: 0.371 (see supplement). |
| Tomarken et al., 1992 | 1. t-tests of asymmetry measures. 2. ICCs and Pearson correlations. 3. Cronbach's alphas | log R minus log L power density | 1. Stable: "…asymmetry measures tended to be associated with nonsignificant shifts in mean values over time". 2. Not very high, buy significant ICCs (0.66 for Avg Ref baseline only, 0.79 for Avg Ref across time). 3. Acceptable-to-excellent Cronbach's alphas. |
| Carvalho et al., 2011 | 1. ANOVA on FAA, with hemisphere and group. 2. Correlation FAA-BDI. | ln[right] − ln[left] | Overall: doubtful, whether cross-sectional data is sufficient to establish trait properties. But there are no indications against FAA having trait properties. 1. No interaction especially between MDD and remitted, but also controls. 2. No correlation. |
| Feldmann et al., 2018 | 1. One-way ANOVAs on FAA between the HC, Mda- and rMDa- . 2. Correlation FAA-BDI | ln[right ROI] − ln[left ROI] | The most relevant results: 1. No differences between MDD and remitted. 2. No correlations. |
| Gotlib et al., 1998 | Regression with 1st predictor “Never vs. Ever depressed” and 2nd predictor “Currently depressed vs. remitted” | log R − log L | Most relevant results: No difference between currently depressed and remitted. FAA seems to be a state independent marker. |
| Grünewald et al., 2018 | Correlation FAA-BDI | ln[right] − ln[left] | Overall no specific conclusion on state or trait, but no correlations were found in the MDD group. |
| Nusslock et al., 2018 | Correlation FAA-BDI | right − left | Overall: "[our results] highlight the trait like quality of reduced relative left frontal EEG activity." 1. No correlation. |
*Type 1: Multiple assessment moments with depressed patients. Type 2: Multiple assessment moments, only healthy controls. Type 3: Cross-sectional study. MDD = major depressive disorder, HC = healthy controls, Ax. = assessment(s), HRSD = Hamilton Rating Scale for Depression, CGI = Clinical Global Impression, BDI = Beck Depression Inventory, IDS-SR = Inventory of Depressive Symptomatology-Self Report, BIS/BAS = Behavioral Avoidance/Inhibition Scales, PANAS = Positive and Negative Affect Scale, ICC = Intraclass Correlation Coefficient, HRSD = Hamilton Rating Scale for Depression, HC = healthy controls, BDI = Beck Depression Inventory, LST theory = latent state-trait theory, Avg Ref = average reference.