Dysfunction of the prefrontal cortex in addiction

Dysfunction of the prefrontal cortex in addiction: neuroimaging findings and clinical implications
R Z Goldstein & Nora D Volkow, 2011
http://www.nature.com/nrn/journal/v12/n11/full/nrn3119.html


Abstract

 

The loss of control over drug intake that occurs in addiction was initially believed to result from disruption of subcortical reward circuits. However, imaging studies in addictive behaviours have identified a key involvement of the prefrontal cortex (PFC) both through its regulation of limbic reward regions and its involvement in higher-order executive function (for example, self-control, salience attribution and awareness). This Review focuses on functional neuroimaging studies conducted in the past decade that have expanded our understanding of the involvement of the PFC in drug addiction. Disruption of the PFC in addiction underlies not only compulsive drug taking but also accounts for the disadvantageous behaviours that are associated with addiction and the erosion of free will.

Addiction, reward sensitivity and expectation sensitivity

Addiction: Decreased reward sensitivity and increased expectation sensitivity conspire to overwhelm the brain's control circuit
Nora D Volkow et al., 2010
http://europepmc.org/articles/PMC2948245?pdf=render

Abstract

Based on brain imaging findings, we present a model according to which addiction emerges as an imbalance in the information processing and integration among various brain circuits and functions. The dysfunctions reflect (a) decreased sensitivity of reward circuits, (b) enhanced sensitivity of memory circuits to conditioned expectations to drugs and drug cues, stress reactivity, and (c) negative mood, and a weakened control circuit. Although initial experimentation with a drug of abuse is largely a voluntary behavior, continued drug use can eventually impair neuronal circuits in the brain that are involved in free will, turning drug use into an automatic compulsive behavior. The ability of addictive drugs to co-opt neuro transmitter signals between neurons (including dopamine, glutamate, and GABA) modifies the function of different neuronal circuits, which begin to falter at different stages of an addiction trajectory. Upon exposure to the drug, drug cues or stress this results in unrestrained hyperactivation of the motivation/drive circuit that results in the compulsive drug intake that characterizes addiction.

Tabakabhängigkeit:

Tabakabhängigkeit ist die häufigste psychische Störung.

Ralf Schneider, SF, 2011

Versüchtelung ganzer Gesellschaften?:

"In den letzten Jahren scheinen immer mehr Menschen alle möglichen Verhaltensweisen in einem solchen Extrem zu betreiben (von Extremspotarten wie Bungee-Springen und free-climbing über rauschhaftes Einkaufen bis hin zu süchtigem Arbeiten und Börsen-Zocken), dass man von einer zunehmenden "Versüchtelung" der Gesellschaft sprechen kann. Besonders die medialen Abhängigkeiten (TV, Computer, Internet, Handys) scheinen zuzunehmen."

... und an anderer Stelle:

"Die generelle Tendenz, mit sich, den anderen und der Welt süchtig umzugehen, verbreitet sich. Man kann von einer langsamen Versüchtelung immer größerer Teile der Bevölkerung ausgehen. Der süchtige Umgang wird mehr und mehr das Normale."

Werner Gross, Hinter jeder Sucht... & Sucht ohne Drogen, 2002 & 2003

Sucht:

Sucht - ob mit oder ohne Drogen - kann definiert werden als unabweisbares Verlangen nach einem bestimmten Gefühls-, Erlebnis- und Bewusstseinszustand. Das Ziel von süchtigen Verhalten ist entweder, Lustgefühle herbeizuführen und/oder Unlustgefühle (Unruhe, Trauer, Wut etc.) zu vermeiden.

Werner Gross, Hinter jeder..., 2002