Biology Behind: Addiction!

Greetings everybody, 

I bet you are all thinking 'wow Biobunch has not done one of these Biology Behind posts for a while' and you are so right I haven't! But I got to thinking have you ever wondered why you cannot help but come back to Biobunch every Friday? I'm afraid it may be because you are addicted to the website, have no fear though! because I am going to help you understand the biology behind your Biobunch addiction. 

There are many ways of thinking of addiction however, a great scientist once broke it down into three distinct stages, with each stage exploiting certain sections of your wonderful brain anatomy in order to make you feel the way you do. 

Stage 1: The Bingeing/Intoxication stage 
Characteristics of this stage include overstimulation of our brains reward system, eventually this leads to loss of control over the thing that we are craving, and ends in bingeing. There are three parts of our brain exploited during this system. 

Basal ganglia: Involved in processing rewards and the formation of habits

Nucleus accumbens: The section of our brain that receives dopamine released from the ventral segmental area. The nucleus accumbens helps to control our satiety, inhibition and inner desires.

Ventral Tegmental Area: Otherwise known as one of our brains primitive structure, and is located near the top of our brain stem. It is also our dopamine factory, and produces all the brains dopamine (responsible for giving us that feel good feeling). 

Stage 2: Withdrawal symptoms and the 'negative moods'
Habitual exposure to the addictive substance or behaviour eventually leads to a reduction in the number of dopamine receptors present in the Nucleus accumbens. 

Nucleus accumbens: The reduction in the number of dopamine receptors present on the surface, places a demand on the brain to engage with more of the addictive behaviour or substance, just to reach a similar level of feel good feeling. 

Amygdala: Changes within this structure triggered by addiction have been twinned to the emotions and behaviour suffered by people going through withdrawal such as irritability, anxiety and stress.

Stage 3: Anticipation
People that have become dependent on a behaviour or substance carry around these uncontrollable cravings to repeat this addiction.

Frontal cortex: Circuitry thought to be messed up by drug misuse. This structure is made of two parts that play a role in addiction: The prefrontal cortex is important for thoughts and actions and the orbitofrontal cortex plays a part in controlling behaviour.

Hippocampus: This structure aids in fixing our desires whether they or not they have negative consequences. They do this through the consolidation of our memory.

The exploitation of our reward system:

As previously mentioned the Ventral Tegmental Area of the brain is responsible for the production and release of dopamine when stimulated. Dopamine is linked to the feeling of pleasure and euphoric experiences. However, the release of dopamine can be inhibited or controlled by the GABA neuron that is also present in this area. Check out the diagram of the reward system below:

Addictive substances such as alcohol, amphetamines and cocaine wreak havoc on our brain reward system by affecting the release and inhibition of dopamine by imitating neurotransmitters. Check out some of the examples listed below:

Alcohol, Opioids and Cannabis: These substances suppress the inhibitory action of the GABA neurons, allowing for unregulated release of dopamine.

Amphetamines and Nicotine: These drugs directly activate the release of dopamine into the brain.

Cocaine: This drug works by blocking the process through which dopamine is removed from synapses (a gap between two neurons), this ensures a continued state of euphoria.

The genetic link between our metabolism and addiction risk:

There are many social and psychological factors that are thought to increase the risk of some individuals to addiction, however, we are looking more at biology so I am going to bring you into the world of genetics! Yay! Some of the strongest genetic risk factors for developing an addiction such as alcoholism are those linked to our bodies metabolism.

Genes encoding for the metabolism of alcohol as seen in the above picture plays a role in the development of addiction. Acetaldehyde is toxic to the body and is quickly converted into acetate. However, the gene ALDH2 causes the toxic acetaldehyde to linger and build up in our system, this causes the onset of hangover like symptoms (nausea, temperature). The presence of this gene makes even light drinking semi- unbearable,  those individuals expressing this gene variant are nine times less likely to suffer from alcoholism, as a cause of this. Interestingly, genes encoding for slow alcohol metabolism (such as the ALDH2) are found most commonly in the Asian population. 

Interestingly, where the presence of that gene variant reduced the risk of developing an addiction it is the opposite for those predisposed to cigarette addiction. The presence of a gene called CHRNA5 more than doubles your risk of becoming addicted to nicotine. Smokers often remember their first smoke as being an un-pleasureable experience due to a heavy nauseous feeling. CHRNA5 expression in individuals was found to reduce this initial negative effect, even though the mechanism of how this happens remains unclear it may be linked to the CHRNA5 coding for a section of the acetylcholine receptor (receptor involved in pleasurable experiences) in our brains.

The long road to recovery:

OK, I know what your thinking, addiction really messes with our brain so, how can we possibly recover from that? It's most definitely an uphill battle for recovery from addiction as many of the changes are long lasting. HOWEVER! what should we always remember when it comes to our anatomy? Your body is amazing. That includes your brain, given the time a majority of the physical damage can be undone. 
Brains of people who suffered from alcohol abuse disorders often shrink, given time and sobriety the brain can regain some of its original mass.
Additionally, functional recovery also gets underway. It may not be able to restore all the damaged pathways but it begins to find alternative routes avoiding damaged parts of our brain, much like how the voice on your GPS screams out 'Rerouting' or 'Calculating alternative route' when you miss that turn on the road. AMAZING #teambrain

Alright guys, that marks the end of the post! I think what we have learned here is that you may be addicted to Biobunch but that is OK! because I think that addiction is completely healthy. In fact, I would recommend you continue your weekly dose, however feel free to increase your dose as required there are 90 posts on this blog. Have you read all of them? If so which was your favourite, be totally honest. Till then, as always have an awesome weekend.

Over and out.

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