A Parallel-group, Double-blind, Placebo-controlled Study of Methylphenidate as an Add on Therapy for Mirtazapine in the Treatment of Major Depressive Disorder in Cancer Patients Under Palliative Care

Background

Cancer remains one of the most feared illnesses and the diagnosis of cancer has huge psychological impact on the patients and their care-takers (Knobf, 2007). Depression is one the most common psychiatric sequella (Derogatis et al., 1983)2 and affects the quality of life, compliance to treatment, disease advancement, tolerability to pain and fatigue in cancer patients (Bennett et al., 2004; Sommerset, 2004; Green et al., 2009). However, it is likely that depression is under-recognized and under-treated in cancer patients (Kadan-Lottick et al., 2005).

Depressed feelings manifest in a spectrum ranging from normal sadness to a variety of mood disturbances and clinical presentations. It is challenging to differentiate clinical depression from "normal" emotional distress in cancer patients and the somatic symptoms such as fatigue, loss of appetite or weight, sleep difficulties, poor memory and concentration may mirror the physiological symptoms caused by cancer or its treatment (McDaniel and Musselman, 1995; Masie and Popkin, 1998; Cochinov, 2001; Jesse et al., 2008). This complicates the diagnosis of depression in cancer patients (McDaniel and Musselman, 1995; Masie and Popkin, 1998; Cochinov, 2001; Pasquini and Biond, 2007; Jesse et al., 2008).

Many studies have investigated the prevalence of depression in cancer in the past decades. A previous review by Mc Daniel et al, reported a prevalence of major depression ranging from 4.8% to 9.2% based on studies using standardized diagnostic interviews on cancer outpatients. Prevalence rates were higher in the admitted cancer patients (8% for Major Depression and 15% to 36% for all depressive disorders)(McDaniel and Musselman, 1995). A preliminary systematic review on the prevalence of depression in cancer patients was conducted by the investigator of this study. It showed that major depressive disorder was as high as 10.8% in cancer patients based on structured clinical interview.

In addition to the high prevalence, uncertainty exists with respect to the optimal treatment of depression in cancer. Although a huge number of studies investigated the efficacy of pharmacotherapy for depression in general population, the number of randomized, controlled trials of antidepressants on depression in cancer patient conducted is limited(Challman and Lipsky, 2000; Raison and Miller, 2003). A comprehensive systematic review looking into the effectiveness and tolerability of antidepressant treatment in depressed cancer patients was performed and published by Rodin et al in 2007. Although 7 trials were identified, the authors commented that the number of positive randomized trials was limited and there is a need for more rigorous studies on other newer agents or alternative treatment option (Raison and Miller, 2003). The preliminary systematic review conducted by the investigator of this study also came to the same conclusion.