Tryptophan metabolic pathway crosstalk and composite subtypes of major depressive disorder through the microbiota-gut-brain axis
Major depressive disorder (MDD) is a common and disabling mental illness affecting approximately 332 million people worldwide, with an adult prevalence rate of 5.7%. Although the hypothesis of monoamine neurotransmitter deficiency plays a fundamental role, it cannot fully explain treatment-resistant depression (TRD), w...