The ubiquity of the SP/NK-1 receptor system in many biological functions and its upregulation under pathological conditions makes this system an important target for several diseases (depression, neural degeneration, alcohol addiction, pain, migraine, inflammatory bowel disease, pruritus, viral infection, bacterial infection, cancer, and emesis [27, 35, 61–65]). This evidence concerns the gene TACR1 and depressive symptom measurement.