Marc Lewis is a cognitive neuroscientist and professor emeritus of developmental psychology, at the University of Toronto from 1989 to 2010, now blogging, writing, and speaking on the science, experience, and treatment of addiction. He is the author or co-author of over 50 scientific journal articles on developmental psychology, emotion, and neuroscience. He now contributes regularly to The Guardian and other popular publications.


The harm done by addicts to themselves and those around them has riveted public attention. It has become essential to explain addiction in professionally sanctioned terms, and to that end doctors, psychiatrists, medical researchers and treatment providers have come to define it as a chronic brain disease.

Yet the idea that addiction is a disease doesn’t square with how the brain actually works. Nor does it square with the experience addicts have of their own struggles. Lewis has marshalled the data on brain change and interviewed hundreds of addicts. In his writings and talks he shows that the neural changes accompanying addiction also accompany normal learning and development. Yet these changes are accelerated (and preserved as habits) when learning is driven by intense motivation, as it is in love, religion, war, and racism, as well as in addiction.

The brain changes that go with addiction don’t indicate a diseased brain. They indicate plasticity in response to strong attractions, in a brain that keeps developing. The implications for recovery are vital. Treatment succeeds when the assumption of helplessness is replaced by tools for empowerment, insight, and continuing growth.


Presentation at TEDx–Radboud University
May 29, 2013

Conversation with the Dalai Lama at the Mind & Life “Dialogue,” Craving,
Desire, and Addiction, Dharamsala
October 28, 2013

Presentation hosted by Johann Hari at the Festival of Dangerous Ideas, Sydney Opera House
September 6, 2015

Nobel Conference on Addiction, Gustavus Adolphus College
October 7, 2015

Presentation at the Royal Institution, London
July 14, 2016

Public debate, David Winston Turner Endowment Fund, Melbourne
October 21, 2016


Why the disease model of addiction does far more harm than good. Scientific American, 9 February, 2018

Brain change in addiction as learning, not disease. New England Journal of Medicine, 18 October, 2018

To book Marc Lewis PH.D., contact Rob Firing at