TABLE 3.

Results on depression studies.

References	Results on depression
	Decrease of symptoms
Van der Wal and Kok (21)	- In 26 of 31 studies. - Average effect size for humorous therapies was 41% lower than for non-humorous therapies.
Zhao et al. (22)	- In 9 of 10 studies. - Laughter and humor interventions (p = 0.001). - Laughter interventions alone (p < 0.0001) (6 studies). - Humor interventions alone (p = 0.34) (3 studies).
Deutsch (29)	- Significant for the non-depressed group (p < 0.05) on the BDI-II. - Not significant for the depressed group (p > 0.05) on the BDI-II.
Cai et al. (17)	- Measured on BDI (Chinese version) (p < 0.005).
Gelkopf et al. (26)	- Measured on BPRS total score (p < 0.001). - Measured on sub-score BPRS: Anxiety-depression (p < 0.001).
Panichelli et al. (25)	- Decrease on the Hamilton Depression Scale (p < 0.001). - Negative correlation for the CGI-2 (p < 0.001).
Falkenberg et al. (16)	- No significant long-term improvement on BDI (p = 0.17). - Significant improvement on cheerfulness STCI-S (p = 0.03) and STCI-T (p = 0.05). - Significant decreases on seriousness STCI-S (p = 0.03) and STCI-T (p = 0.05). - Significant decrease on bad mood STCI-S (p = 0.03), not on STCI-T (p = 0.12). - Significant improvement on mood after 6 of the 7 meetings measured with the VAS (varying between p = 0.01 and p = 0.05). Only the last meeting the improvement was not significant (p = 0.10).

BDI, beck depression scale; BPRS, Brief Psychiatric Rating Scale; CGI-2, clinical global impressions scales for global improvement; STCI-S and T, State and Trait Cheerfulness Inventory; VAS, Visual Analog Scale, measuring expectations and effectiveness of the humor training on their mood as perceived by the participants.