Chaste tree (Vitex agnus-castus) has a long history of use in supporting menstrual health, but its application in PMS—particularly PMS Type D (dominated by depressive symptoms)—is supported by a substantial body of scientific evidence. The primary mechanism of action is believed to be modulation of pituitary hormones, especially by acting as a dopaminergic agonist, which suppresses prolactin secretion. Elevated prolactin has been implicated in the pathogenesis of PMS symptoms, including mood disturbances.

Clinical trials and systematic reviews have demonstrated that chaste tree extract can significantly improve overall PMS symptoms, with particular benefits noted for mood-related complaints such as depression, irritability, and anxiety. For example, a meta-analysis published in Phytomedicine (2019) reviewed several randomized controlled trials and concluded that Vitex agnus-castus is more effective than placebo for reducing PMS symptoms, including psychological symptoms. Another randomized, double-blind study found significant reductions in symptoms like mood swings and depression compared to placebo.

While not all studies focus exclusively on PMS Type D, the consistent improvement in mood-related symptoms supports its use for this subtype. The evidence base, including randomized controlled trials and meta-analyses, justifies a high rating for scientific support, particularly for PMS cases where depressive symptoms predominate.