Spanish and French psychologists conducted a randomized controlled trial - a format in which participants are randomly assigned to groups in order to fairly compare effects. They investigated how two different meditations affect depressive symptoms and related psychological characteristics. The work was published in the journal Mindfulness.
The trial involved 147 adults recruited in France through social media, university campuses and the researchers' professional contacts. People with a diagnosis of depression or another mental disorder, those taking psychotropic medications, and experienced meditators were not included in the sample. The mean age in the groups was about 49, 46 and 44 years, and most participants were women.
Participants were randomly assigned to three groups of 49 people each: one learned focused-attention meditation (holding attention on a chosen object, for example the breath, returning to it each time the mind wanders), another learned self-inquiry meditation (examining one's own thoughts and beliefs with questions about their origin and influence on emotions and behavior). The third group was a control group and waited its turn. The program lasted four weeks: five online meetings of 60 minutes each and 20 minutes of independent practice five days a week.
Before the start and immediately after the end of the course, participants filled out questionnaires. Depressive symptoms, dysfunctional attitudes (rigid negative beliefs about oneself), identity threat (the feeling that one's "self" is being devalued), cognitive decentering (the ability to look at thoughts and emotions from the outside, not taking them at face value), as well as connectedness to nature and to humanity were assessed.
Both meditations led to a greater reduction in depressive symptoms and feelings of identity threat than waiting - a moderate effect. Both increased cognitive decentering. No reliable differences between the practices were found on these measures. Contrary to the authors' expectations, dysfunctional attitudes decreased only in the focused-attention group.
On connectedness to humanity and nature, the meditations overall did not differ from the control. But in preliminary analyses, only those who practiced self-inquiry showed increases in both types of connectedness.
Preliminary analyses of mechanisms showed: in the focused-attention group, the increase in decentering fully explained the reduction in depressive symptoms and partially explained the decrease in dysfunctional attitudes. In the self-inquiry group, the increase in connectedness to humanity partially explained the reduction in identity threat. Unexpectedly, here an increase in connectedness to nature was accompanied by a smaller reduction in identity threat, and none of the measured processes explained the reduction in depressive symptoms. These analyses were conducted separately within groups, so the mechanisms cannot be directly compared statistically.
The authors note limitations: the control group knew it was not receiving treatment, all data are based on self-reports, participants did not have a depression diagnosis, and mean scores were low, in the non-clinical range. Both programs were led by the same instructor - the first author of the work. Twenty people dropped out of the waiting group versus four to five in each meditation group, the study was not preregistered, there are no follow-up results, and the sample was mostly female and initially interested in meditation.
"Attention and deconstruction practices provide comparable benefits for depression-related outcomes but act through partially different mechanisms. Cognitive decentering played a central role in attention meditation, whereas deconstructive practice showed preliminary associations with connectedness, which requires cautious interpretation," the researchers conclude.