The Neurobiology of Addiction

Resolve

I wanted to start this thread in response to "Do Psychologists generally believe that depression can be inherited? " by Freiheit. I wanted to generate an interesting discussion on this and hopefully get some alternative views from other people. These are some excerpts from my Final year essay

Neurobiology of Addiction
Genes that code the enzymes which metabolise alcohol were the subject of a 2006 study on drug abuse and addiction. They found that Mexican Americans had low levels of alcohol metabolic enzymes that subsequently offered little or no protection from alcoholism whereas it was found that Asian populations had the specific alleles for alcohol dehydrogenase and Aldehyde dehydrogenase which because of their metabolic properties offered a certain degree of protection (Trujillo). It was also found that individuals who were found to carry the polymorphic gene CYP2D6 which has been found to be a poor metaboliser of some amphetamines and opiates, had a high degree of genetic protection from developing addictions to these drugs of abuse because this specific gene assists in turning the drugs into a more active morphine congener. What this essentially all means is that the reinforcing effects of the drugs i.e. the pleasure, the high, the anticipatory feelings before the act are all stunted in these individuals. In Western Europe, Spanish populations show the highest rate of the CYP2D6 gene 10%, with most other European countries falling below 5% (Trujillo) and they also were found to have a high frequency of multiple copics of the gene which means they fall into a class known as ultra-rapid metabolisers (Trujillo). This in theory should offer greater protection from the aforementioned drugs of abuse. However recent studies on drug abuse in Europe show that in Spain, of the 49283 who presented for the treatment of problem drug abuse, (3rd highest in Europe) “45.1 % of all clients reported that cocaine was the primary drug, followed by 40.4 % for opioid’s” (EMCDDA). However in light of this paradox we know addiction is a multifaceted, polygenic disorder, involving not only numerous interacting environmental influences but also numerous interacting genes for risk and protection (Trujillo).

Any opinions???

Valmont

The genetic information is new to me, thanks for sharing it. I will have to read up on it soon. When I studied the neurobiology of addiction, the class was primarily focused on the role of the mesolimbic dopamine pathway and Robinson and Berridge's Incentive Salience theory. Although I have only read your excerpt, it seems that the genetic factors do not play a very important role in drug addiction and that they are superseded by other factors. What do you think? Also, what was the title of your essay?

steddyeddy

Im no psychologist but wouldnt trauma affect disposition to alcohol abuse or acloholisim also?

Odysseus

I wouldn't have much time for it, but there is the theory of the A1 gene I think it was Blum et al possibly 1980-1. Here is a bit of info I just searched for Not everyone who tries a drug will become addicted to it. Some researchers are looking into the possibility that some people have a genetic predisposition to using drugs. The Dopamine D2 receptor A1 gene has been found to be more common in alcoholics and cocaine abusers than it is to the general public. Researchers believe this gene is linked to compulsive or feeling-seeking behavior. However, some people in the general public have this gene without developing an addiction. Scientists are still working on finding out the exact meaning behind this gene and genetic causes of drug addiction.

Most psychiatrists seem to focus on the reward pathways connected to the Nucleus Accumbens. I been to a few talks by The Priory Group in the past year and they where very strongly focused on this.

Personally I don't have much time for it, but addiction is such a hugh area there is room for everybody.

Odysseus

steddyeddy wrote: »

Im no psychologist but wouldnt trauma affect disposition to alcohol abuse or acloholisim also?

It can be, but my experience is addiction is very subjective, however, as a psychoanalyst we would focus very strongly on this area, but it would not necessarily equate to PTSD.

Resolve

Valmont wrote: »

The genetic information is new to me, thanks for sharing it. I will have to read up on it soon. When I studied the neurobiology of addiction, the class was primarily focused on the role of the mesolimbic dopamine pathway and Robinson and Berridge's Incentive Salience theory. Although I have only read your excerpt, it seems that the genetic factors do not play a very important role in drug addiction and that they are superseded by other factors. What do you think? Also, what was the title of your essay?

no wouldnt say they are superceded by other factors but interlinking components of addiction ie. environment, gentics, brain abnormalities, learned behaviour etc all contribute to developing addcitive behaviours and these occur in different combinations. as regards brain abnormalities and to respectively add further confusion to the debate....

certain elements necessary for an individual to be classified as addiction prone

The first areas identified were deregulated mesolimbic dopamine pathways which would automatically amplify any intake of substance by flooding the synapses giving more of a high when compared to a regulated mesolimbic pathway. Secondly, functional MRI scans found abnormalities in both the orbitofrontal cortex and the anterior cyngulate gyrus of already addicted individuals. The orbitofrontal cortex is linked to feelings of reward and emotions and hence is linked with the function played by the limbic system. This system is targeted along the stimulant reward pathway and the presence of these abnormalities would increase vulnerability to amphetamine addictions. Also irregularities in the anterior cynagulate gyrus which is responsible for reward anticipation and may be a primary suspect in the intense urges and cravings an already dependant person feels. Another area identified was the bodys potential to up-regulate brain derived neurotrophic factors: which is in plain English means, the brains growth hormone which acts in the hippocampus, creates or increases neurons associated with learning and memory in a process known as neurogenesis and can often lead to increased addiction specific neurological pathways as a result. Put simply, through the causality of administering the substance and the subsequent reward, you learn to become addicted faster than someone who doesn’t have this up-regulation potential.

Odysseus

Resolve wrote: »

no wouldnt say they are superceded by other factors but interlinking components of addiction ie. environment, gentics, brain abnormalities, learned behaviour etc all contribute to developing addcitive behaviours and these occur in different combinations. as regards brain abnormalities and to respectively add further confusion to the debate....

certain elements necessary for an individual to be classified as addiction prone

The first areas identified were deregulated mesolimbic dopamine pathways which would automatically amplify any intake of substance by flooding the synapses giving more of a high when compared to a regulated mesolimbic pathway. Secondly, functional MRI scans found abnormalities in both the orbitofrontal cortex and the anterior cyngulate gyrus of already addicted individuals. The orbitofrontal cortex is linked to feelings of reward and emotions and hence is linked with the function played by the limbic system. This system is targeted along the stimulant reward pathway and the presence of these abnormalities would increase vulnerability to amphetamine addictions. Also irregularities in the anterior cynagulate gyrus which is responsible for reward anticipation and may be a primary suspect in the intense urges and cravings an already dependant person feels. Another area identified was the bodys potential to up-regulate brain derived neurotrophic factors: which is in plain English means, the brains growth hormone which acts in the hippocampus, creates or increases neurons associated with learning and memory in a process known as neurogenesis and can often lead to increased addiction specific neurological pathways as a result. Put simply, through the causality of administering the substance and the subsequent reward, you learn to become addicted faster than someone who doesn’t have this up-regulation potential.

How would you consider the above in relation to the treatment of addict's subjects? In other words in what way would that viewpoint contribute to a treatment programme and it delivery? If that makes sense.

Resolve

Odysseus wrote: »

How would you consider the above in relation to the treatment of addict's subjects? In other words in what way would that viewpoint contribute to a treatment programme and it delivery? If that makes sense.

firstly it wouldnt be something which i would base treatment on! to be honest if someone is born autistic, aspergers particularily, which is basically a prenatal brain abnormality correct me if im wrong, they can learn in much the way the addict can, to achieve their goals hope and dreams much the way you or i could. treatment programs would be probably tailored arounds triggers, recognising avoiding coping etc social interaction techniques, desensitisation... depends on the client and their psychosocial position and what the presenting problem is ie addiction or dependance, Comorbity? is there a dual diagnosis? hence the need for asessments at the beginning of therapy

Hope this answers ur Q?

Odysseus

Resolve wrote: »

firstly it wouldnt be something which i would base treatment on! to be honest if someone is born autistic, aspergers particularily, which is basically a prenatal brain abnormality correct me if im wrong, they can learn in much the way the addict can, to achieve their goals hope and dreams much the way you or i could. treatment programs would be probably tailored arounds triggers, recognising avoiding coping etc social interaction techniques, desensitisation... depends on the client and their psychosocial position and what the presenting problem is ie addiction or dependance, Comorbity? is there a dual diagnosis? hence the need for asessments at the beginning of therapy

Hope this answers ur Q?

Yeah that's fine, I'm always type of curious abouth the implications of such research for the treating practitioner, but I have limited knowledge in the area, think I did one psych biology module during my degree, so very limited.