Cognitive therapy and interpersonal psychotherapy reduce suicidal ideation independent from their effect on depression

BACKGROUND: Clinical guidelines suggest that psychological interventions specifically aimed at reducing suicidality may be beneficial. We examined the impact of two depression treatments, cognitive therapy (CT) and interpersonal psychotherapy (IPT) on suicidal ideation (SI) and explored the temporal associations between depression and SI over the course of therapy. METHODS: Ninety‐one adult (18–65) depressed outpatients from a large randomized controlled trial who were treated with CT (n = 37) and IPT (n = 54) and scored at least ≥1 on the Beck Depression Inventory II (BDI‐II) suicide item were included. Linear (two‐level) mixed effects models were used to evaluate the impact of depression treatments on SI. Mixed‐effects time‐lagged models were applied to examine temporal relations between the change in depressive symptoms and the change in SI. RESULTS: SI decreased significantly during treatment and there were no differential effects between the two intervention groups (B = −0.007, p = .35). Depressive symptoms at the previous session did not predict higher levels of SI at the current session (B = 0.016, p = .16). However, SI measured at the previous session significantly predicted depressive symptoms at the current session (B = 2.06, p < .001). CONCLUSIONS: Both depression treatments seemed to have a direct association with SI. The temporal association between SI and depression was unidirectional with SI predicting future depressive symptoms during treatment. Our findings suggest that it may be most beneficial to treat SI first.