The neurogenic hypothesis of depression states that adult hippocampal neurogenesis is disrupted by stress and depression and is recovered by chronic treatments with antidepressants. Indeed, chronic antidepressant treatments increased newborn neurons in the adult dentate gyrus in many early studies. However, conflicting findings appeared over time. Thus, our motivation to write this unbiased systematic review and meta-analysis was to answer the following question: can antidepressants reliably promote neurogenesis in adult hippocampus? A meta-analysis was performed on studies in naive rodents. Results indicated that increased neurogenesis is a more nuanced, compound-dependent action of antidepressants than a yes-or-no event. This nuanced notion can lead to a new understanding of the concepts of neurogenic-dependent and neurogenic-independent effects of antidepressants, which would be better described as effects "more-dependent" or "less-dependent" on hippocampal neurogenesis. Further studies are on the way to investigate the strength of the causal relationship between adult hippocampal neurogenesis and behavioural effects of antidepressants.

中文翻译：

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抗抑郁药会促进成年海马的神经发生吗？对幼稚啮齿动物的系统评价和荟萃分析。

抑郁症的神经源性假设指出，成年海马神经发生因压力和抑郁而中断，并通过抗抑郁药的长期治疗而恢复。实际上，在许多早期研究中，慢性抗抑郁药治疗增加了成人齿状回中的新生神经元。但是，随着时间的流逝，发现的结果相互矛盾。因此，我们撰写此公正的系统评价和荟萃分析的动机是回答以下问题：抗抑郁药能否可靠地促进成年海马的神经发生？对幼稚啮齿动物的研究进行了荟萃分析。结果表明，与“是或否”事件相比，增加的神经发生作用是抗抑郁药更为细微的，化合物依赖性的作用。这种细微差别的观念可以导致人们对抗抑郁药的神经源性和神经源性非依赖性作用的概念有了新的认识，将其更好地描述为对海马神经发生的“依赖性更大”或“依赖性较小”。进一步的研究正在调查成年海马神经发生与抗抑郁药的行为作用之间因果关系的强度。