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October 2, 2025 57 mins

Dopamine. Serotonin. Endorphins. We have all heard these terms. And these are not just scientific curiosities. Few are those who have never wondered if their brain chemicals are "just off balance".

So how accurate are the popular theories about these mythic molecules?

To guide us through the topic, I'm joined by Judy Grisel—an ex-addict and a world-leading neuroscientist of addiction.

We will discuss all the main elements of brain chemistry by using drugs and addictions as a window into the topic. Towards the end, we also search for ways to better help those who struggle with addiction.

As always, we finish with my guest's reflection on humanity.

DIG DEEPER

This episode is part 4 of this autumn's brain science series. See more

at ⁠⁠OnHumans.Substack.com⁠/brain⁠⁠

Judy Grisel’s book is Never Enough: The Neuroscience and Experience of Addiction

Want to support the show? Join the club at Patreon.com/OnHumans.


FACT-CHECKING

No major mistakes have been found so far.
As a minor note, the SSRI study we mention in healthy volunteers primarily assessed cognitive processing (reinforcement learning/sensitivity) rather than self-reported “emotional flattening”; however, general blunting of emotional responses in healthy participants has been reported by earlier researchers.

If you spot an error in this or other episodes, please reach out on Substack or via email.


KEYWORDS

Names mentioned: Kent Berridge | Mark Lewis | Barbara Sahakian | Trevor Robbins

Technical concepts: dopamine | wanting vs liking | serotonin (5/HT) | serotonin receptor 2A | selective serotonin uptake inhibitors SSRIs | GABA vs glutamate | endorphins | endocannabinoids | alcohol | cocaine | MDMA | psychedelics | behavioral addictions (e.g. porn) | runner's high | cannabis / THC | neurogenesis & pruning | brain plasticity | SSRIs | MDMA (SERT reversal) | emotional blunting | opponent-process theory (A→B) | addiction as disease vs learned state | meaning, motivation, recovery


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