Acute and continuation therapy in unipolar depression: observations from the run-in phase of a maintenance trial

Is it possible to evaluate true prophylactic efficacy of antidepressants in severely ill patients with recurrent depression? Lessons from a placebo-controlled trial. The fifth trial of the Danish University Antidepressant Group (DUAG-5)

BACKGROUND

We compared citalopram and clomipramine against placebo with respect to recurrence prevention as opposed to relapse prevention in patients with recurrent depression, independently of any acute response to the test drug(s).

METHODS

Patients with recurrent depressive disorder with a current depressive episode of moderate to severe degree were recruited over a period of 6.5 years. After 6-15 months of routine open acute and continuation therapy, and a discontinuation/drug-free period of one month following sustained response (at least 3 consecutive monthly ratings with a HAM-D-17-score below 13), patients were randomised under double-blind conditions, with a follow-up period of 2 years. The major endpoint was recurrence (HAM-D-17-score of 16 or above).

RESULTS

A total of 307 patients were included in the open phase and 174 patients completed at least 6 months of treatment and achieved sustained response. Out of these, only 59 patients (34%) could be randomised to placebo (n=22), citalopram (n=19) or clomipramine (n=22), with protocol violation and/or non-consent being the major reasons for non-randomisation. There were no between-group differences in outcome; almost half of the randomised patients met the criterion for recurrence.

LIMITATIONS

The size of the randomised sample was considerably smaller than the planned size.

CONCLUSIONS

The high risk of drop out prior to randomisation among the eligible patients was presumably caused by an interaction between the study design and the study population. The findings suggest that long-term trial designs interposing a drug-free period prior to randomisation are not feasible and recommendable in severely ill patients.

Longitudinal MRI study of cortical thickness, perfusion, and metabolite levels in major depressive disorder

OBJECTIVE

To determine whether patients with major depressive disorder (MDD) display morphologic, functional, and metabolic brain abnormalities in limbic-cortical regions at a baseline magnetic resonance (MR) scan and whether these changes are normalized in MDD patients in remission at a follow-up scan.

METHOD

A longitudinal 3.0-Tesla (T) magnetic resonance imaging (MRI) study was carried out with cortical thickness measurements with a surface-based approach, perfusion measurements with three-dimensional (3D) pseudo-continuous arterial spin labeling (pCASL), and spectroscopy (1H-MRS) measurements in the anterior cingulate cortex (ACC) with water as an internal reference adjusted for cerebrospinal fluid content. We examined 23 MDD patients and 26 healthy controls. MDD patients underwent a baseline MRI at inclusion and were invited to a follow-up scan when they were in remission or after a 6-month follow-up period.

RESULTS

Major findings were a significantly thinner posterior cingulate cortex in non-remitters than in remitters, a significant decrease in perfusion in the frontal lobes and the ACC in non-remitters compared with healthy controls at baseline and significantly reduced N-acetylaspartate, myo-inositol, and glutamate levels in MDD patients compared with healthy controls at baseline.

CONCLUSION

Using novel MRI techniques, we have found abnormalities in cerebral regions related to cortical-limbic pathways in MDD patients.

The mechanisms of tolerance in antidepressant action

There is increasing awareness that, in some cases, long-term use of antidepressant drugs (AD) may enhance the biochemical vulnerability to depression and worsen its long-term outcome and symptomatic expression, decreasing both the likelihood of subsequent response to pharmacological treatment and the duration of symptom-free periods. A review of literature suggesting potential side effects during long treatment with antidepressant drugs was performed. Studies were identified electronically using the following databases: Medline, Cinahl, PsychInfo, Web of Science and the Cochrane Library. Each database was searched from its inception date to April 2010 using "tolerance", "withdrawal", "sensitization", "antidepressants" and "switching" as key words. Further, a manual search of the psychiatric literature has been performed looking for articles pointing to paradoxical effects of antidepressant medications. Clinical evidence has been found indicating that even though antidepressant drugs are effective in treating depressive episodes, they are less efficacious in recurrent depression and in preventing relapse. In some cases, antidepressants have been described inducing adverse events such as withdrawal symptoms at discontinuation, onset of tolerance and resistance phenomena and switch and cycle acceleration in bipolar patients. Unfavorable long-term outcomes and paradoxical effects (depression inducing and symptomatic worsening) have also been reported. All these phenomena may be explained on the basis of the oppositional model of tolerance. Continued drug treatment may recruit processes that oppose the initial acute effect of a drug. When drug treatment ends, these processes may operate unopposed, at least for some time and increase vulnerability to relapse. Antidepressant drugs are crucial in the treatment of major depressive episodes. However, appraisal and testing of the oppositional model of tolerance may yield important insights as to long-term treatment and achievement of enduring effects.