The Neurobiology of Addictive Disorders

Abstract

Addiction is increasingly understood as a neurobiological illness where repetitive substance abuse corrupts the normal circuitry of rewarding and adaptive behaviors causing drug-induced neuroplastic changes. The addictive process can be examined by looking at the biological basis of substance initiation to the progression of substance abuse to dependence to the enduring risk of relapse. Critical neurotransmitters and neurocircuits underlie the pathological changes at each of these stages. Enhanced dopamine transmission in the nucleus accumbens is part of the common pathway for the positively rewarding aspects of drugs of abuse and for initiation of the addictive process. F-Aminobutyric acid,opioid peptides, serotonin, acetylcholine, the endocannabinoids, and glutamate systems also play a role in the initial addictive process. Dopamine also plays a key role in conditioned responses to drugs of abuse, and addiction is now recognized as a disease of pathological learning and memory. In the path from substance abuse to addiction, the neurochemistry shifts from a dopamine-based behavioral system to a predominantly glutamate-based one marked by dysregulated glutamate transmission from the prefrontal cortex to the nucleus accumbens in relation to drug versus biologically oriented stimuli. This is a core part of the executive dysfunction now understood as one of the hallmark features of addiction that also includes impaired decision making and impulse dysregulation.Understanding the neurobiology of the addictive process allows for a theoretical psychopharmacological approach to treating addictive disorders,one that takes into account biological interventions aimed at particular stages of the illness.

Neurobiological Bases of Alcohol Addiction

“…enzymes, receptors, neurotransmitting and message system transporters, reflecting on the synaptic transmission 19,20 . Thanks to numerous researches and studies during the last decades, many of the biochemical, cell and molecular bases of alcohol addiction have become known, revealing that alcoholism as well as other addictions are now to be considered as brain diseases 20 . Various addictive substances also result in changes in various parts of the brain; however, there is a group of brain structures that are affected by all addictive substances, i.e.…”

Addiction, Experimental Models and Neurobiological Mechanisms

“…The ephemeral pleasure derived from substance use is gradually replaced by the sole need to have it, with social and medical consequences that mean suffering for the subject and those around him or her. [1,3] The substances that are used or misused are constantly renewing, which requires health surveillance measures, in particular towards the risk of addiction. This surveillance and monitoring requires detailed knowledge of the physio-pathological mechanisms, of models of the dependency process, and of the means to detect addiction risk.…”

Addiction is a disease: We must change our attitudes toward addicts

“…People use addictive substances because they generate intense brain responses -reward, craving and withdrawal -mediated by neurotransmitters (particularly dopamine) that potently drive behaviour. 4 The use of addictive substances also directly causes difficulty with decision-making and with judging the consequences of one's actions by impairing the function of brain areas responsible for cognition (the prefrontal cortex). Stimuli and stressors in a user's environment reinforce addictive behaviour.…”

“…Over time, continued substance use causes permanent anatomic and chemical changes in the brain. 4 Addiction is a chronic relapsing disease that we must treat as we do other such diseases. We do not expect the hearts of patients with heart failure to behave normally -we understand that their function has been altered by disease.…”