Managing the Patient with Co-Morbid Depression and an Anxiety Disorder

Depression and anxiety disorders frequently co-occur. This type of co-morbidity is associated with higher severity, suicidality, chronicity and treatment resistance. However, available treatment guidelines mainly focus on treatment for singular disorders. The current paper describes diagnostic and treatment issues relevant for adequately addressing patients with depression and an anxiety disorder, using information from both guidelines and a search of recent literature.

Apart from differential diagnosis, the diagnostic evaluation should include a thorough assessment of the symptoms of both disorders, preferably by using a structured clinical interview, and an assessment of depression severity in terms of suicidality, psychotic symptoms and impairment. Treatment should first address the primary disorder in terms of severity and risk. As a rule, severe depression should be treated before the anxiety disorder, using antidepressant medication or combined treatment (plus psychotherapy). In less severe pathology, the primary focus may be determined by examining the temporal pattern and the subjective burden of each disorder as experienced by the patient.

Treatment is often sequential. Treatment of the primary disorder may or may not relieve the co-morbid disorder as well. If the primary disorder is an anxiety disorder, co-morbid depression generally implies earlier use of an antidepressant. Co-morbid mild depression may also react favourably to psychotherapeutic treatment of the anxiety disorder. Recent literature on concurrent treatment of both depression and anxiety shows that modern antidepressants such as sertraline, paroxetine, fluoxetine, venlafaxine, nefazodone and bupropion have demonstrated efficacy in relieving both depressive and anxiety symptoms compared with placebo. Head-to-head comparisons, although relatively scarce, tend to show superiority over tricyclic antidepressants. Venlafaxine was found to be more effective than fluoxetine in some studies. However, these results should be interpreted with caution because studies vary considerably in terms of patient selection, assessment of anxiety and primary outcome measures. Only one randomized controlled trial compared atypical antipsychotics with placebo. Psychotherapy was generally shown to have a beneficial effect on the co-morbid conditions, and available evidence appears to favour combined treatment. The results should be interpreted with caution because the number of studies on this issue was relatively small, with considerable clinical and methodological heterogeneity.