There is always hope that someday we will discover a wonder drug that will cure very illness. Well after reading about lithium and bipolar disorder, I have to say, maybe we have been looking to hard. Naturally occurring Lithium, the 3rd element on the periodic table is actually a quite effect treatment for a lot of neurological diseases. Normally lithium is only prescribed for bipolar disorder as it helps control the mania episodes. The list of disorders is helps treat or prevent besides bipolar includes: Huntington’s, Alzheimers, Parkinson’s, ALS, MS, Schozophrenia, and even more. While these are a wide range of diseases, lithium only really affects 3 pathways. By inhibiting NMDA receptors and IP3, lithium prevents Calcium influx into cells and signaling to p38, JNK, and Calpain, which leads to apoptosis. This is why lithium in effective in preventing so many neurodegenerative diseases, it prevents excess apoptosis or cell death. This is also why it helps the mania associated with bipolar. Blocking NMDA receptors helps with glutamate excitotoxicity that causes bipolar. Lithium also inhibits GSK-3, which is important for both inducing apoptosis and preventing the transcription of a lot of neuroprotective proteins like BDNF. Lithium does this by interfering with the Akt/GSK complex that normally activates GSK and by promoting cAMP, which also inhibiting GSK.
Now you may be wondering, if Lithium is so helpful, why don’t we all take it as a supplement? Well that problem with lithium is that it has such a small therapeutic range. Lithium is typically prescribed for bipolar patients around 0.6 mEq/L- 1.2mEq/L. Toxicity occurs above 1.5 mEq/L and has been know to occur in therapeutic ranges. While mild intoxication leads to nausua, vomiting, and diarrhea, severe toxicity which occurs around 2.5 mEq/L, can lead to loss of consciousness, coma, or death. When you compare the dose prescribed to the amount that can lead to death, there isn’t really that much difference. The reason we use it for bipolar patients is because the benefits outweigh the risks. Actually, the majority of studies that found that it prevented the other diseases were conducted on bipolar patients who were prescribed lithium. It presents us with an interesting problem. We know lithium is helpful in preventing a lot of terrible neurological diseases, but we cant take it normally. Maybe someday we will find a way around the side effects and risks of lithium, but until then it remains an interesting ion we can utilize.