Born in Liverpool, Brodie was educated at McGill University in Canada and at New York University, where he obtained his PhD in 1935. He worked at the Medical School there from 1943 to 1950 when he moved to the National Institutes of Health at Bethesda, Maryland, where he served as chief of the chemical pharmacology laboratory until 1970.

Brodie worked in a wide variety of fields including chemotherapy, anesthesia, drug metabolism, and neuropharmacology. In 1955 Brodie and his colleagues produced some results that once more raised the possibility of a chemical basis of mental disease. Basically they showed that the tranquilizer reserpine – an alkaloid extracted from the roots of Rauwolfia – can produce a profound fall in the level of serotonin, a naturally occurring monoamine in the brain. The question then arose as to whether the tranquilizing effect of reserpine is due to its reduction of too high a level of serotonin.

It was further shown that some of the actions of serotonin could be neutralized by the presence of the hallucinogen LSD. As the structure of the two molecules are somewhat similar the possibility arose that LSD could monopolize the enzyme that normally breaks down serotonin and thus permit the accumulation of unusually high levels of serotonin. It is perhaps this action that causes the hallucinogenic state and which, it has been argued, mimics the schizophrenic state.

In reality the speculations arising from Brodie's work have turned out to be surprisingly difficult to confirm or reject.