Moderating effect of avoidance on the relationship between depression and suicidal ideation across different types of...

Suicidal ideation following trauma exposure is frequently associated with depressive and post-traumatic stress disorder (PTSD) symptoms; however, the interactive effects of depression and distinct PTSD symptom clusters on suicidal ideation remain poorly understood.

To examine whether specific PTSD symptom clusters - namely intrusion, avoidance and hyperarousal - moderate the association between depressive symptoms and suicidal ideation, and whether these effects vary across different trauma types.

Medical records of 127 psychiatric out-patients with a history of at least one traumatic event were analysed. All participants had completed the Hamilton Rating Scale for Depression, the Impact of Event Scale-Revised, and the suicidal ideation item of the Beck Depression Inventory II. Trauma types were categorised into early versus late, single versus multiple, and interpersonal versus non-interpersonal.

Hierarchical regression analyses identified a significant moderating effect of avoidance symptoms on the relationship between depression and suicidal ideation (β = 0.19, P = 0.012), whereas intrusion and hyperarousal symptoms did not show such effects. Specifically, higher levels of avoidance were associated with a stronger positive relationship between depression and suicidal ideation. This moderating effect was observed only among individuals with late (β = 0.28, P = 0.002), single (β = 0.29, P = 0.002) or non-interpersonal trauma (β = 0.34, P = 0.018); it was not evident among those with early, multiple or interpersonal trauma.

These findings underscore the relevance of targeting avoidance symptoms to mitigate suicidal ideation, particularly in individuals with late-onset, single-incident or non-interpersonal trauma exposure. Exposure-based therapeutic interventions may offer particular benefit for reducing suicidal ideation among trauma-exposed individuals with depressive symptoms.