The happiness hormone: a brief history


Google the word "dopamine" and you will learn that its nicknames are the "happy hormone" and the "pleasure molecule" and that it is among the most important chemicals in our brains. With The Guardian branding it "the Kim Kardashian of neurotransmitters," dopamine has become a true pop-science darling - people across the globe have attempted to boost their mood with dopamine fasts and dopamine dressing.

A century ago, however, newly discovered dopamine was seen as an uninspiring chemical, nothing more than a precursor of noradrenaline

When Casimir Funk, a Polish biochemist and the discoverer of vitamins, first synthesized the dopamine precursor levodopa in 1911, he had no idea how important the molecule would prove to be in pharmacology and neurobiology. Nor did Markus Guggenheim, a Swiss biochemist, who isolated levodopa in 1913 from the seeds of a broad bean, Vicia faba.

Just before World War II, a group of German scientists showed that levodopa is metabolized to dopamine in the body, while another German researcher, Hermann Blaschko, discovered that dopamine is an intermediary in the synthesis of noradrenaline.

The dopamine story picked up pace in the post-war years with the observation that the hormone was present in various tissues and body fluids, although nowhere as abundantly as in the central nervous system.

In 1960, however, the medical community was not yet ready to accept that dopamine was anything but a boring intermediate between levodopa and noradrenaline. At a prestigious London symposium, Carlsson and his two colleagues presented their hypothesis that dopamine may be a neurotransmitter, thus implicating it in Parkinson's disease.

By the late 1960s, levodopa and dopamine were making headlines. A 1969 New York Times article described similar stunning improvements in patients with Parkinson's disease who were treated with levodopa.

The history of dopamine, however, is not only about Parkinson's disease but extends to the treatment of schizophrenia and addiction.

According to a 2015 article in Nature Reviews Neuroscience, a wave of low-quality research followed which led the authors to conclude that we are "addicted to the dopamine theory of addiction." Just about every pleasure under the sun was being attributed to dopamine, from eating delicious foods and playing computer games to sex, music, and hot showers. As recent science shows, however, dopamine is not simply about pleasure - it's about reward prediction, response to stress, memory, learning, and even the functioning of the immune system. Since its first synthesis in the early 20th century, dopamine has often been misunderstood and oversimplified.

Source: Medscape