Dr John Frederick Joseph Cade AO (January 18, 1912-November 16, 1980) was an Australian psychiatrist credited with discovering (in 1948) the effects of lithium carbonate as a mood stabilizer in the treatment of bipolar disorder (then known as manic depression). In an age where the standard treatments for psychosis were electroconvulsive therapy and "lobotomy", lithium had the distinction of being the first effective medication available to treat a mental illness.

= Early career = Born in Murtoa, Victoria to a doctor, Dr. Cade was educated at the Scotch College and the University of Melbourne and worked at various mental asylums. Although trained as a psychiatrist, Dr. Cade served in the Australian Imperial Force as a surgeon during World War II. After Singapore fell into Japanese hands, he became a prisoner of war at Changi Prison where he spent three and a half years until the end of the war. During his imprisonment, he reportedly would observe some fellow inmates having strange, vascillating behaviour. He thought perhaps a toxin was affecting their brains and when it was eliminated through their urine, they lost their symptoms.

After the war, Dr. Cade served as the head of the Bundoora Repatriation Hospital in Melbourne. It was at an unused kitchen in Bundoora where he conducted crude experiments which led to the discovery of lithium as a treatment of bipolar disorder. These experiments mostly consisted in injecting urine from mentally ill patients into guinea pigs. These would appear to die faster than when healthy persons' urine was used, leading him to think that perhaps more uric acid was present in these samples. Then, in an effort to increase the water solubility of uric acid, he started to test lithium carbonate.