Origin
Most of the evidence supporting that "addiction" is a brain disease comes from studies conducted in the 1980s and 1990s with laboratory animals that were administered large amounts of amphetamine intravenously, sometimes even directly into the brain. These studies investigated the short- and long-term effects of amphetamines on neuronal structure and function. A
consistent finding is that a single large dose of amphetamine in non-tolerant animals causes extensive damage to dopamine neurons. This
neurotoxicity can be prevented if increasing doses of amphetamine are used over several days to the animal. In other words,
tolerance is a protective factor for the brain;
Brain damage: Dopamine Theory
From there, the theory of dopamine was created, which is the theoretical basis defended by NIDA, Nora Volkow and a whole dome of people. This theory comes to tell us, briefly, what NIDA puts on its website:
In other words, according to them, there is irreversible damage to the dopamine D2 receptors;
One of the
most rigorous studies on the subject investigated it in abstinent people and the results obtained indicated that no differences could be found between the abstinent people and the control group.
Nora Volkow, the director of NIDA, weighed in on this, reaffirming that addiction was a chronic disease, but that proving it required current techniques to be more sensitive.