John Frederick Joseph Cade AO (18 January 1912 – 16 November 1980) was an Australian psychiatrist who in 1948 discovered the effects of lithium carbonate as a mood stabilizer in the treatment of bipolar disorder, then known as manic depression. At a time when 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.