Uncovering Negative Interpretation Bias in Remitted/Recovered Depression with Laboratory Task

Research has demonstrated that individuals with a history of depression engage in complicated strategies (e.g., thought suppression) that may mask the possible existence of major depression. Increasing the mental strain, such as retrieving a six-digit number, may reveal depressive thinking in previously depressed individuals. This study examined the hypothesis that thought suppression could mask a cognitive vulnerability to depression and illustrated how cognitive tasks disrupt mind control.

This case-control study recruited 255 participants with a convenience sampling method conducted at the Razi Educational and Therapeutic Psychiatric Center (Tehran, Iran) in 2021. Participants were divided into five groups, then they were evaluated by a scrambled sentence test (SST) after random assignment to either mental load or no mental load conditions. The number of negative unscrambled statements was used as an index of negative interpretation bias. After gathering data, analysis of variance (ANOVA) for different group factors and conditions was carried out to test the main hypotheses.

The effect of the intervention provided to each group on the score of the Hamilton Depression Rating Scale (HRDS) was significant (F (4, 208) = 511.77, P < 0.001). A significant correlation (r = 0.36, P < 0.01) was found between depression (HDRS) and negative interpretive bias (SST). Analysis of ANOVA has revealed a significant effect on the group (F (4, 412) = 14.94, P < 0.001). The effect of the mental load was not significant (F (4, 412) = 0.09, P = 0.75), but the group × load interaction was significant (F (4, 412) = 5.03, P < 0.001). Post hoc test was used to draw multiple comparisons between the five groups.

The results revealed that people who are vulnerable to depressive disorders are predominantly engaged in thought suppression, which can conceal their depressogenic thinking until cognitive requests consume their mind control efforts.