It has been suggested that acupuncture may achieve treatment effects by modulating the corticostriatal reward/motivation circuitry (within the brain). This area of the brain is often indicated in managing patients with major depressive disorder. (1)
Now, in 2008, Zhang et al. did a meta-analysis on high-quality, randomized, controlled trials. This concluded that acupuncture is safe and effective in treating major depressive disorder and post-stroke depression. (2)
A meta-analysis in 2015 suggested that the combination of an SSRI (selective serotonin reuptake inhibitor, a common antidepressant) + acupuncture had greater therapeutic efficacy than the SSRI therapy alone. (3)
A systematic review in 2017 concluded that acupuncture may act as an alternative therapy to medication for treating depression-related insomnia and could also enhance the benefits of medication, when used together (4).
Just this past November (2018), as systematic review and meta-analysis concluded that acupuncture (along with bright light therapy and massage) may reduce antenatal (during pregnancy, before delivery) depression, but also noted that there needs to be larger, higher-quality trials that include postnatal follow-up, along with maternal and neonatal outcomes. (5) More on postpartum mood support to come!
This just scratches the surface of what acupuncture can do for depression, and higher-quality trails are still needed (and interestingly enough, quite a few are in progress!) to further understand clinical management of depression with acupuncture.
References: PMID: 28802467, (1) PMID: 27693978, (2) PMID: 19632725, (3) PMID: 25704563, (4) PMID: 28286776, (5) PMID: 30423471.