Excitotoxicity, where hyperactivity of certain brain circuits leads to neuron death through excessive calcium and glutamate, can be prevented by lithium.

“The other thing about lithium is that lithium is neuroprotective, that is it can prevent neurons from dying under certain conditions. Why would neurons die? Well, there are a lot of reasons why neurons can die. There can be a physical insult to the neurons. You can get hit really hard in the head, a bullet, God forbid, can enter the skull and kill neurons, there are a lot of reasons why neurons can die. Neuroprotection is a situation in which a neuron is given some sort of chemical or physical resiliency that allows it to suffer an insult and yet bounce back.”