The essential trace element lithium is well known for its antidepressant activity, or more precise: a deficiency of it leads to dysbalance of neurotransmitters and therefore to depression and many other mental illnesses. Like the alkali metals potassium and sodium it seems to be essential for nerve conduction and the normal functioning of the nervous system.
Rubidium, which is also an alkali metal, seems to exert a similar function. Since a study from 1969, Rubidium is known to improve mood disorders.1 Many studies in humans with the salt rubidium chloride were conducted since then, but unfortunately, this research is still widely unknown.
It has proven therapeutic efficacy in depression, manic-depressive illness and anxiety.2 3 4 5 6 7
Interestingly, these studies found no immediate or long-term side effects of rubidium intake – contrary to antidepressants, which have huge side effects. This is because rubidium is not a drug, but an essential trace element and as long as its is in balance with its antagonists, it has no negative effects.
Some studies suggest that lithium and rubidium are antagonists. While rubidium seems to increase the general level of alertness, activity and affect, lithium reduce hyperactive behavior and excessive affect.8 The toxicity of high doses of rubidium is linked to potassium deficiency, so potassium also seems to be an antagonist.9
Due to their chemical similarity, the alkali metals do not only exert similar functions in the nervous system, but are also antagonists, and a dysbalance of these elements caused by rubidium deficiency, leads to metal illness.
1 https://link.springer.com/chapter/10.1007/978-3-642-76646-6_30
2 https://psycnet.apa.org/record/1989-16617-001
3 https://www.ncbi.nlm.nih.gov/pubmed/8926857
4 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1436619/
5 https://europepmc.org/abstract/med/8412574
6 https://www.researchgate.net/publication/18483051_Rubidium_Biochemical_Behavioral_and_Metabolic_Studies_in_Humans
7 https://link.springer.com/chapter/10.1007%2F978-3-642-76646-6_32
https://www.nature.com/articles/223321a0
9 https://link.springer.com/chapter/10.1007/978-3-642-76646-6_30