Deciphering Mental Illness: Neurons vs. Neuroglia

Although more than 60 psychotropic drugs are currently approved for mental illness, their therapeutic index remains modest, with limited efficacy over placebo and substantial adverse effects. Initial concerns that glucagon-like peptide-1 (GLP-1) analogs might produce starvation-related central nervous system (CNS) effects, like those of anorexia nervosa, have been subverted by their largely positive outcomes. Clinical observations of reduced "food noise", altered reward behaviors, and improved mood have prompted trials evaluating these agents for their potential as psychotropics. This serendipitous paradox compels re-evaluation of prevailing psychiatric disease models. The focus on small-molecule neurotransmitters operating at synapses appears insufficient to explain complex psychiatric illness or the effects of larger molecules like GLP-1. Notably, psychiatric disorders, though familial, do not follow Mendelian inheritance and show considerable heterogeneity in symptoms, suggesting that DNA sequence variation alone is inadequate as a unifying explanation. Alan Turing's pre-DNA morphogenesis model, emphasizing chemical gradients and developmental divergence, offers an alternative framework. While Virchow and Cajal established neuron-centered paradigms, later reinforced by neurochemical and monoaminergic discoveries, emerging evidence increasingly implicates neuroglia, particularly astrocytes, in higher mental functions, and their disruption in psychiatric diseases. This nascent and fragmented field warrants integration. Herein, we review astrocyte phylogenetics across vertebrates, their regional specialization within the human brain, and their synthesis of diverse small and large molecules. We propose adopting a model in which neurons and neuroglia act together in syncytial constellations that underlie complex mental functions, mediated by their molecular products. Finally, we outline strategies for drug-development and therapeutics harnessing syncytial constellations and astrocyte-derived molecules.