COMMENTS: This article (see the study below) is about dopamine imbalances. Imbalances can be genetic or induced, or both. They take the form of high or low dopamine sensitivity (receptors), or high or low levels of dopamine. A common effect of addiction is having low sensitivity, yet releasing high levels in response to addiction cues. I believe those with porn addiction are in this category.
ARTICLE: (Reuters) – Our need for stimulation and dopamine’s action upon the brain are connected, which explains why people who constantly crave stimulation are in danger of addictive behavior such as drug abuse and gambling.
The urge to actively seek out new experiences is a personality trait that psychologists have known about for years, but up until now scientists have been unable to prove how this urge relates to hormonal activities in the brain.
People with high levels of the hormone dopamine in the brain, and low sensitivity to it, tend to be greater risk takers and may be more prone to addictive behavior, drug abuse and gambling, a study has found.
Scientists from Denmark and Japan said they had proved in research that a need for stimulation is greater on average among those who have more of the gratification hormone, dopamine, in their brains, partly because of their lower sensitivity to it.
The study by Albert Gjedde of Copenhagen University, and published in the Proceedings of the National Academy of Sciences (PNAS) journal on Monday, scanned the brains of healthy volunteers to look at dopamine and dopamine receptor levels.
“People at the higher end of the scale get less effect from the same amount of dopamine as people lower on the scale, until they get so low in dopamine that there is too little…to have an effect,” Gjedde told Reuters in an email.
The findings could help scientists develop ways to prevent or treat addictive behavior, they said, and throw new light on drug approaches to conditions like attention deficit hyperactivity disorder, commonly called ADHD.
The researchers said their findings showed people at the low and high ends of the scale have very different dopamine and dopamine receptor profiles, suggesting it may be better to try to increase or decrease levels of the dopamine itself, rather than to block the receptors.
Drugs like AstraZeneca’s Seroquel and Eli Lilly’s Zyprexa, which belong to a class of drugs known as antipsychotics, work by blocking the action of dopamine in the brain.
They are approved for mental illnesses such as depressions, schizophrenia and bipolar disorder but also increasingly are prescribed for children with ADHD.
THE STUDY: Inverted-U-shaped correlation between dopamine receptor availability in striatum and sensation seeking
Albert Gjeddea,b,c,1, Yoshitaka Kumakurab,d, Paul Cummingc, Jakob Linnetb,c, and Arne Møllerb,c
aDepartment of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen, Denmark 2200;
January 11, 2010
Abstract
Sensation seeking is a core personality trait that declines with age in both men and women, as do also both density and availability of the dopamine D2/3 receptors in striatum and cortical regions. In contrast, novelty seeking at a given age relates inversely to dopamine receptor availability. The simplest explanation of these findings is an inverted-U-shaped correlation between ratings of sensation seeking on the Zuckerman scale and dopamine D2/3 receptor availability. To test the claim of an inverted-U-shaped relation between ratings of the sensation-seeking personality and measures of dopamine receptor availability, we used PET to record [11C]raclopride binding in striatum of 18 healthy men. Here we report that an inverted-U shape significantly matched the receptor availability as a function of the Zuckerman score, with maximum binding potentials observed in the midrange of the scale. The inverted-U shape is consistent with a negative correlation between sensation seeking and the reactivity (“gain”) of dopaminergic neurotransmission to dopamine. The correlation reflects Zuckerman scores that are linearly linked to dopamine receptor densities in the striatum but nonlinearly linked to dopamine concentrations. Higher dopamine occupancy and dopamine concentrations explain the motivation that drives afflicted individuals to seek sensations, in agreement with reduced protection against addictive behavior that is characteristic of individuals with low binding potentials.
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