Enduring effects of early-life adversity on reward processes: A systematic review and meta-analysis of animal studies

Two-thirds of individuals experience adversity during childhood such as neglect, abuse or highly-stressful events. Early-life adversity (ELA) increases the life-long risk of developing mood and substance use disorders. Reward-related deficits has emerged as a key endophenotype of such psychiatric disorders. Animal models are invaluable for studying how ELA leads to reward deficits. However, the existing literature is heterogenous with difficult to reconcile findings. To create an overview, we conducted a systematic review containing multiple meta-analyses regarding the effects of ELA on reward processes overall and on specific aspects of reward processing in animal models. A comprehensive search identified 120 studies. Most studies omitted key details resulting in unclear risk of bias. Overall meta-analysis showed that ELA significantly reduced reward behaviors (SMD: -0.42 [-0.60; -0.24]). The magnitude of ELA effects significantly increased with longer exposure. When reward domains were analyzed separately, ELA only significantly dampened reward responsiveness (SMD: -0.525[-0.786; -0.264]) and social reward processing (SMD: -0.374 [-0.663; -0.084]), suggesting that ELA might lead to deficits in specific reward domains.

Clobazam and diazepam in anxiety

The anxiolytic effects of clobazam, diazepam, and placebo were compared in a 4-wk double-blind study of 159 anxious outpatients, primarily from family practice. Clobazam (30 to 80 mg/day) and diazepam (15 to 40 mg/day) were found to induce similar side effect, primarily sedation, and although both active drugs induced greater clinical improvement than placebo, clobazam induced the largest degree of improvement in most aspects. It was speculated that the relatively high daily dosage of diazepam may have been contributed to these results.