Table 3: Considerations about types of control groups in studies of mind-body therapies.

Control groupsProsCons

Usual care control(i) Ethical
(i) Variability in usual care for depression according to the individual
(ii) Attrition

Wait-list control(i) Ethical
(ii) Enhance recruitment and retention
(i) Expectation bias
(ii) Does not allow for blinding of participants to hypothesis
(iii) Extends study time
(iv) Waiting too long for intervention may lead to attrition
(v) No control for non-specific treatment effects

Active control(i) Ethical
(ii) Enhance recruitment and retention
(iii) May allow for blinding of participants to hypothesis
(iv) Control for threats to internal validity
(i) Must exactly parallel treatment group in time and attention
(ii) May become an intervention in and of itself
(iii) May be more difficult to detect treatment effect