FAAH and major depressive disorder: Increasing AEA levels by inhibiting fatty acid amide hydrolase (FAAH; EC 3.5.1.99), the main metabolic enzyme degrading this endocannabinoid, was shown to have a great variety of therapeutical applications including chronic pain, refractory anxiety and depression, multiple sclerosis, and cancer without characteristic cannabinoid intoxication symptoms, e.g., catalepsy, reduced body temperature, or stimulated feeding [10,11,12,13].