Key points are not available for this paper at this time.
BACKGROUND: It is unclear whether pro-dopaminergic drugs reduce anhedonia in major depressive disorder (MDD) and further, if so, to what extent this is the case. METHODS: With lived experienced experts we co-produced two living systematic reviews of randomised controlled trials (RCTs) investigating the relative efficacy of pro-dopaminergic interventions in reducing symptoms of anhedonia in people with MDD (versus placebo) and in relevant non-human animal models (versus vehicle control/no intervention). Multiple electronic databases were searched until June 9, 2024. The primary outcomes were subjective anhedonia symptoms in humans and sucrose preference test (a measure of reward sensitivity and proxy for anhedonia) in animals. We evaluated other important domains and clinical aspects closely related to anhedonia, such as reward/reinforcement tasks, anxiety symptoms, acceptability, tolerability, and adverse events. We performed pairwise meta-analyses separately for human and non-human studies. We also estimated the relative effects of pro-dopaminergic versus non-dopaminergic antidepressants in human studies on anhedonia and overall depressive symptoms using a series of random-effects network meta-analyses of both aggregate and patient-level data. A multidisciplinary panel of international experts (including people with lived experience) then interpreted the overall results and produced a list of recommendations via a triangulation process. This study is part of GALENOS (Global Alliance for Living Evidence in aNxiety, depressiOn, and pSychosis). PROSPERO registration: CRD42023451821. FINDINGS: Pro-dopaminergic interventions were associated with a small reduction of anhedonia symptoms (6 RCTs, n = 2076; SMD -0.24, 95% CI -0.46 to -0.03) in people with MDD and increased sucrose preference in animal models (27 RCTs; SMD 1.34, 0.88 to 1.79). We did not find data about reward/reinforcement tasks in humans. Evidence was rated as low to moderate. In the network meta-analysis, some antidepressants with a non-dopaminergic mechanism of action showed reduction in anhedonia symptoms, which was larger than pro-dopaminergic drugs and probably independent of overall depression improvement. INTERPRETATION: Our findings provide some support for the role of dopamine in anhedonia. However, the precise neurobiological mechanisms of anhedonia in major depression are still poorly understood and we posit that they may be possibly related to altogether different or more general effects of antidepressants on these symptoms. Therefore, data on reward, including reward-related learning and memory, are needed to properly examine the relationship between dopamine modulation and anhedonia. FUNDING: Wellcome (GALENOS project).
Ostinelli et al. (Wed,) studied this question.