Neuronal excitation-inhibition (E/I) balance is crucial for proper brain function. Membrane transporters regulate neurotransmitter homeostasis, playing a fundamental role in synaptic signaling and maintaining E/I balance in neural networks. Their function is particularly critical at the extremes of the life cycle, where impairments contribute to neurodevelopmental and neurodegenerative disorders. Understanding the role of neurotransmitter transporters in these processes is essential for uncovering new therapeutic strategies for brain health.