Taurine regulates intracellular sodium levels. Long term supplemental taurine decreases levels of intracellular sodium. That taurine can affect intracellular sodium levels is clear. What is not clear is the effect of taurine on various sodium-dependent transporters. I have argued than low taurine levels by affecting sodium levels can dysregulate the sodium-dependent multivitamin transporter.
Neurotransmitter sodium symporters, which co-transport a neurotransmitter and sodium, among other molecules transport taurine, GABA, dopamine, serotonin and noradrenaline. Taurine is clearly involved in calcium homeostasis. Taurine could also be involved in sodium homeostasis.
Dysregulation of sodium homeostasis could dysregulate the transport of dopamine, serotonin, noradrenaline and GABA which play large roles in the regulation of mood. Antidepressants, antipsychotics and anioxylitcs target serotonin, dopamine, noradrenaline and GABA. Antidepressants, antipsychotics and anioxylitcs could be called for now in the treatment of mental illness due to dysregulation of sodium homeostasis which dysregulates dopamine, serotonin, noradrenaline and GABA.
Quite frequently individuals with major mental illnesses will take medications that affect dopamine, serotonin, noradrenaline and GABA. Dysregulation of sodium homeostasis could underlie the need by individuals with major mental illnesses to take medications from all three major classes of drugs used to treat mental illness. Supplemental taurine could help with re-regulation of sodium homeostasis. No argument is being made that only dysregulation of sodium homeostasis is the biological basis of major mental illnesses.