For example, liraglutide, a GLP-1 receptor agonist, improved cognitive function in n = 19 patients with major depressive disorder (MDD) or bipolar disorder in a pilot randomised controlled trial (RCT) [16], whilst a systematic review and meta-analysis reported a pooled reduction in depressive symptoms with GLP-1 receptor agonists compared to other antidiabetic therapies [17]. This evidence concerns the gene GLP1R and major depressive disorder.