Many patients with personality disorders also suffer from depression. However, little is known about the implications of such comorbidity for psychotherapy.  In this blog post, Fritz Renner, Lotte L.M. Bamelis, Marcus J.H. Huibers, Anne Speckens, and Arnoud Arntz explore these implications with data taken from their larger research program comparing schema therapy to other psychotherapy techniques. Depressed patients with personality disorder recovered less during psychotherapy than did non-depressed patients. However, when controlling for the general severity of symptoms, there were no differences between the groups. These outcomes indicate that patients are less likely to recover from their personality disorder when their overall symptom severity is high. 

Personality disorders and depression often go hand in hand: It is estimated that more than half of the patients with a personality disorder also suffer from depression. This high co-occurrence between personality disorders and depression can have important implications for the treatment of personality disorders and depression. For example, it is possible that treatment of a patient with depression would be complicated for patients who also have personality disorders. In fact, several studies have shown that depressed patients with co-morbid personality disorders indeed have worse treatment outcomes; however, it is notable that other studies do not support this finding. Another important question that has not been investigated in randomized controlled trials so far is whether the presence of depressive disorders complicates the treatment of personality disorders and therefore has a negative impact on treatment outcomes in patients with personality disorders.

We addressed this question empirically by drawing data from a recent large randomized controlled trial on the (cost-)effectiveness of schema therapy for personality disorders (Bamelis, Evers, Spinhoven, & Arntz, 2014). Participants in this study fulfilled the criteria for either cluster-C (92% of participants) and/or for histrionic, narcissistic or paranoid personality disorder. Participants were randomly allocated to receive either 50 sessions of schema therapy (n = 147), treatment-as-usual (duration clinically decided) (n = 135), or (open-ended) clarification-oriented psychotherapy (n = 41). The main results of this study are reported in Bamelis et al. (2014).

Forty-four percent of the patients in this study also met diagnostic criteria for depression. We expected that those with co-occurring depression would recover less often from their personality disorder and show more impairment in psychosocial functioning at the end of the three-year study phase when compared to those with no co-occurring depression. We were also interested in exploring whether these findings would differ between the three treatments.

In line with our hypothesis, personality disorder patients who also met diagnostic criteria for depression recovered less often at the end of the three-year study period when compared with personality disorder patients who did not meet diagnostic criteria for depression. However, when we controlled for the general severity of symptoms the two groups did not differ anymore in their recovery rates. This means that it is not the depression per se that complicates treatment of personality disorders and therefore leads to lower recovery rates but rather the overall severity of symptoms with which personality disorder patients present upon entering treatment. These findings were the same for all three treatments in the study. Another finding was that personality disorder patients with depression had poorer levels of psychosocial functioning before and after treatment compared to those without co-occurring depression and this effect reduced, but remained, when controlling for general symptom severity.

What do these findings mean for clinicians using schema therapy?

These findings suggest that the presence of depression in personality disorder patients is not an obstacle to improve in treatment. However, patients who present with an overall higher general symptom severity upon entering treatment are less likely to recover from their personality disorder. Note that this is true for all treatments under investigation in this study and not only schema therapy. Importantly, patients with personality disorders who are also depressed are likely to experience more psychosocial problems before and after treatment and it is possible that these patients could benefit from treating depression in schema therapy (or other treatments) in addition to treating the underlying personality disorder.

For further reading:

Bamelis, L. L., Evers, S. M., Spinhoven, P., & Arntz, A. (2014). Results of a multicenter randomized controlled trial of the clinical effectiveness of schema therapy for personality disorders. American Journal of Psychiatry, 171(3), 305-322. doi: 10.1176/appi.ajp.2013.12040518

Renner, F., Bamelis, L. L., Huibers, M. J., Speckens, A., & Arntz, A. (2014). The impact of comorbid depression on recovery from personality disorders and improvements in psychosocial functioning: results from a randomized controlled trial. Behavior Resarch and Therapy, 63, 55-62. doi: 10.1016/j.brat.2014.09.006