Do depression treatments reduce suicidal ideation? The effects of CBT, IPT, pharmacotherapy, and placebo on suicidality

Abstract

Background

Many well-researched treatments for depression exist. However, there is not yet enough evidence on whether these therapies, designed for the treatment of depression, are also effective for reducing suicidal ideation. This research provides valuable information for researchers, clinicians, and suicide prevention policy makers.

Methods

Analysis was conducted on the Treatment for Depression Research Collaborative (TDCRP) sample, which included CBT, IPT, medication, and placebo treatment groups. Participants were included in the analysis if they reported suicidal ideation on the HRSD or BDI (score of ≥1).

Results

Multivariate linear regression indicated that both IPT (b=.41, p<.05) and medication (b =.47, p<.05) yielded a significant reduction in suicide symptoms compared to placebo on the HRSD. Multivariate linear regression indicated that after adjustment for change in depression these treatment effects were no longer significant. Moderate Cohen׳s d effect sizes from baseline to post-test differences in suicide score by treatment group are reported.

Limitations

These analyses were completed on a single suicide item from each of the measures. Moreover, the TDCRP excluded participants with moderate to severe suicidal ideation.

Conclusions

This study demonstrates the specific effectiveness of IPT and medications in reducing suicidal ideation (relative to placebo), albeit largely as a consequence of their more general effects on depression. This adds to the growing body of evidence that depression treatments, specifically IPT and medication, can also reduce suicidal ideation and serves to further our understanding of the complex relationship between depression and suicide.

Introduction

Suicide continues to be a persistent public health problem across the world. Over one million people die from suicide every year and rates have increased by 60% in some countries over the last 45 years (WHO, 2013). Suicide mostly occurs within the context of mental illness: ninety percent of those who died by suicide have a diagnosis of a mental disorder within the last year and 60% of those who die by suicide specifically have had a previous diagnosis of depression. Suicidal behavior runs the gamut from mild ideation (feeling life is not worth living) to moderate ideation (thoughts of ending one׳s life) to acts of self-harm (with questionable intent to die) to actual suicide attempts. Although depression and suicidal ideation co-occur in 47–69% of depressed patients, (Asnis et al., 1993, Bronisch and Wittchen, 1994, Sokero et al., 2003), it is not yet clear whether depression treatments directly decrease suicidal ideation.

Through previous randomized-controlled-trials and meta-analyses, it has been established that cognitive behavioral therapy (CBT; Churchill et al., 2002; Butler et al., 2006), interpersonal therapy (IPT; Cuijpers et al., 2011,2003), behavioral activation therapy (Ekers et al., 2008), problem-solving therapy (Malouff et al., 2007), supportive counseling (Cuijpers et al., 2012b), and possibly psychodynamic therapy (Driessen et al., 2010) effectively treat depression. These psychotherapies are utilized daily alongside pharmacotherapy by psychologists and psychiatrists to treat depression and suicidal symptoms associated with depression. Evidence-based psychotherapies like these are also included in treatment guidelines for suicidality, however, there is limited evidence as to whether these treatments reduce suicidal ideation. Clinicians most often use depression treatments to treat patients with suicidal ideation, as guidelines suggest. However, it is not yet clear whether this is the best course of action for reducing suicidal ideation.

Although the evidence for using antidepressant medication for suicide prevention is insufficient with many trials excluding participants with moderate to severe suicidal ideation, there is evidence that lithium can reduce suicidal behavior in bipolar and unipolar depression (Baldessarini and Tondo, 2010). It is also unclear whether psychotherapy for depression reduces suicidal ideation. A recent meta-analysis examining the effects of cognitive behavior therapy, or a closely related treatment for depression on suicidal ideation showed that there is insufficient research to establish if psychotherapy for depression also has a significant effect on suicidal ideation (Cuijpers et al., 2012a). This meta-analysis did, however, find a significant reduction in hopelessness, a known correlate of suicidality. Additional research is needed that specifically addresses the effects of psychotherapy on fatal and non-fatal suicidal behavior.

Trials on web-based CBT (iCBT) and in-person IPT not included in the aforementioned meta-analysis highlight the additional potential benefits of these two types of psychotherapies in treating suicidal ideation and depression while also highlighting the need for further investigation. One iCBT observational study found reduced suicidal ideation among a community sample. However, participants also could have been receiving other treatments, making the outcomes of the study difficult to generalize (Watts et al., 2012). Another recent web-based CBT trial implemented in suicide call centers showed a decrease in suicidal ideation post-treatment, but saw no differences between CBT and general call center procedures (Christensen et al., 2013).

Only two studies have examined the effect of IPT on suicidal ideation, one in a geriatric population and one in an adolescent population. A small observational study of 12 geriatric patients found decreased suicidal ideation across the course of treatment with IPT (Heisel et al., 2009). The second trial looked at school-based IPT for adolescent depression compared with treatment as usual and found significant reductions of suicidal ideation using IPT (Tang et al., 2009). This suggests that IPT could be a valuable treatment for suicidal ideation associated with depression, however, more and better-powered randomized-controlled trials examining this in both adolescent and adult populations are needed. To the best of our knowledge, no other studies have directly examined the effects of these psychotherapies for depression on suicidal ideation, leaving the field with inconclusive evidence in this regard.

In addition to the lack of empirical evidence that depression treatments reduce suicidal ideation, there is continued debate on the mutual dependence between depression and suicide. Some researchers suggest that suicidal ideation and depression might be related but are independent constructs for various reasons (Oquendo and Currier, 2009). Although suicidal ideation is a symptom of depression, a majority of patients with major depressive disorder (MDD) do not exhibit suicidal ideation, signifying a lack of diagnostic specificity (Oquendo and Currier, 2009, Bolton et al., 2008). Research has also shown that suicidal ideation tends to be recurrent across episodes (Williams et al., 2006), which implies that it may be a specific cognitive bias that is limited to a subset of individuals with depression (Oquendo and Currier, 2009). Because of both the lack of diagnostic specificity and clouded relationship between depression and suicide, the evidence for the effectiveness of depression treatments cannot be generalized to effects on suicidality without further examination of the direct effects of depression treatments on suicidal ideation.

Given the ambiguity concerning whether depression treatments can reduce suicidal ideation, we examined both the relationship between suicidal ideation and depression and the effects of evidence-based depression treatments such as CBT, IPT, and antidepressants on suicidal ideation in both the short-term and long-term follow-ups using data from the National Institute of Mental Health׳s (NIMH) Treatment for Depression Collaborative Research Program (TDCRP). We hypothesized that these treatments have a beneficial effect on the severity of suicidal ideation and that depression and suicidal ideation are related constructs.