After the discoveries of chlorpromazine and another antipsychotic drug, haloperidol, in the 1950s, scientists figured out that these drugs changed the brain’s levels of the chemical messenger dopamine. Since then, the relationship between dopamine and schizophrenia has been hotly pursued by the research community, even though it is not exactly clear how those drugs work to combat symptoms. Thousands of studies have been published describing the link between dopamine and schizophrenia. . . . Dopamine probably does play a role in schizophrenia, but other still unexplored factors might be as or more important. The cause of the disease remains unclear.The same thing could be said about serotonin and antidepressants. The antidepressants that make some depressed people feel better have a measurable impact on Serotonin levels, but we don't understand the relationship between serotonin and depression and don't have a clue what causes depression in the first place.
When you think about how poorly we understand the brain, it is no wonder that we have so much trouble helping people with mental illness.