In this post, we are referring to the low-dose mineral supplement, Lithium Orotate, and not the high-dose prescription, Lithium Carbonate, which is known to have many side effects. Again, this is not considered medical advice and dosing/exposure will depend on individual needs.
“Lithium is thought to help regulate the neurotransmitter glutamate by keeping the amount of glutamate between brain cells at a stable, healthy level to support healthy brain function. The mineral has been shown to be neuroprotective and to prevent neuronal cell death from free radical stress, effectively protecting neurons from glutamate-induced, NMDA receptor-mediated free radical damage in animals. In effective doses, lithium reduces neurological deficits. [3,4] In animal models, lithium was also found to promote increased cytoprotective B-cell activity.  Research has also found using lithium, in a long-term low-dose support, promotes healthy brain aging.” https://www.orthomolecularproducts.com/assets/1/30/PDN_LithiumOrotate2.pdf
“Interestingly, lithium appears to preserve or increase the volume of brain structures involved in emotional regulation such as the prefrontal cortex, hippocampus and amygdala, possibly reflecting its neuroprotective effects. At a neuronal level, lithium reduces excitatory (dopamine and glutamate) but increases inhibitory (GABA) neurotransmission; however, these broad effects are underpinned by complex neurotransmitter systems that strive to achieve homeostasis by way of compensatory changes. For example, at an intracellular and molecular level, lithium targets second-messenger systems that further modulate neurotransmission. For instance, the effects of lithium on the adenyl cyclase and phospho-inositide pathways, as well as protein kinase C, may serve to dampen excessive excitatory neurotransmission. In addition to these many putative mechanisms, it has also been proposed that the neuroprotective effects of lithium are key to its therapeutic actions. In this regard, lithium has been shown to reduce the oxidative stress that occurs with multiple episodes of mania and depression.”
Potential mechanisms of action of lithium in bipolar disorder. Current understanding