Blaming Our Genes: The Heritability of Our Behaviors

This article helps to uncover the question of whether some traits people have are really beyond their control or something they could have picked up throughout their years of development.  When it comes to behavior, genetics plays a significant role, as shown by studies on various traits and disorders. Twin studies and family genetic studies help us understand the heritability of behaviors, indicating how much of a trait is influenced by genetics versus the environment, basically nurture vs. nature. Traits like intelligence and addictive behavior (food addiction, alcohol/drug addictions, sex addiction) both have substantial genetic components, with estimates of heritability ranging from 50% to over 90%, indicating that traits like these are more likely than not to get passed down across generations.  Disorders like schizophrenia, bipolar disorder, and depression also have strong genetic bases, with heritability estimates ranging from 70% to 85%. Similarly, conditions like familial advanced sleep phase syndrome (FASPS), obsessive-compulsive disorder, and autism have clear genetic components contributing to their development. Understanding the genetic basis of these behaviors and disorders can help destigmatize mental illness, improve diagnosis and treatment, and even lead to the development of new therapies.  This article was very interesting to me, but it also freaked me out in a way because of the way that disorders like depression and bipolar disorder can be passed down from generation to generation. I know someone who suffers from depression personally, so I know that the lows are very low and the high can be at times too high. I also know that this person really dislikes the fact that they have this disorder and would be incredibly upset at the fact that will more likely than not pass the trait down. I can't even begin to imagine how it might feel like it's all your fault when your child experiences similar struggles that you face.

Sources

1. https://thereader.mitpress.mit.edu/blaming-our-genes-the-heritability-of-behavior/

2. https://americanaddictioncenters.org/alcohol/hereditary-genetic

Opioid Addiction and Genetic Factors

    Opioid addiction can be categorized as a chronic mental illness that may cause individuals with this disorder to go through periods of relapse and remission throughout their whole life.  This article goes into information about the biological mechanisms of opioid addiction and its receptors.  The opioid epidemic has become a nationwide issue and many suggestions have been made to help treat this illness.  A few medications- methadone, buprenorphine, and naloxone- have been show to have different effects on opioid receptors in the brain.  These medications may help but it is proven that with this the relapse and remission cycle is still highly active with it.  When people try opioids for the first time, for whatever reason that might be, they often experience a euphoric feeling that some individuals want more of.  They want to keep chasing that euphoria or it might alleviate all the pain they have been having so they keep using opioids to the point of losing control over their intake.  What is going on in the brain is that the receptors that are hit with the opioids get adjusted to the drug thus leading to a tolerance build-up.  The tolerance build-up creates a snowball effect because the body will then develop withdrawal symptoms if the individual stops using.  The symptoms can include severe muscle aches, bone pain, tearing, runny nose, diarrhea, abdominal cramping, anxiety, sweating, and agitation.   These symptoms are one of the core parts of opioid addiction and are the main reason for relapse.  Another main part of this article was the genetic susceptibility to addiction.  Twin, family, and adoption studies have proven that there are huge genetic influences on drug addiction proving that addiction is heritable.   It was shown from all these studies that children of addicts had higher rates of psychopathology.  The genetics of parents alone are not the sole cause of addiction as a whole. Actual behavior patterns of an individual such as impulsivity can make a person more likely to develop an addiction.

      It was found that there are molecular mechanisms from opioid-induced tolerance and dependence that play a role in opioid addiction as a whole.  The mechanisms involve the upregulation of cyclic AMP/protein kinase A and cAMP response element-binding signaling.  Along with this mechanism the cravings for drugs, lack of self-control, and strong response to drug-associated stimuli can be associated with cellular and molecular changes of the glutamatergic projection in the prefrontal cortex and the basal ganglia region.  This all means that there are processes in the brain on the cellular level that can be the main driving cause of the burning wildfire which is addiction.  This article goes into more depth about the types of opioid receptors and how this all works.    Many genes have been found that are associated with addiction in the genome.  This article shows information about heroin addiction and how genes can be classified into two systems: the dopaminergic system and the MOR system.  This table gives an organized view of the genes related to opioid addiction.  

      

https://www.mdpi.com/1422-0067/20/17/4294

https://www.sciencedirect.com/topics/medicine-and-dentistry/upregulation

https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/glutamatergic

Can we Blame our Genetics for Overeating?

The decisions in our life like the amount and types of food we consume are controlled by both personal choices and genetic history. The FTO gene is the first gene to be linked to obesity, and one small change in the gene is the difference between low risk and high risk obesity. Individuals who have one high risk copy have a 30% chance to develop obesity, and those who have two high risk copies of the gene have a 70% chance of developing obesity.  A survey of individuals with either one or two copies of the high risk gene revealed that not everyone who was genetically prone to obesity was obese.

The topic of overeating is also a nature vs. nurture case because an individual's risk for obesity is affected by their genetic make up but also the environment in which they live in. Our physiological response to eating or any other habit is associated with a reward system within the brain. It's been established that gene variation can increase a person's chances of being addicted to eating or any other addiction. However not everyone who has this gene variation will get addicted. I agree with this article because an individual's genetic history can make someone more prone to a certain addiction, but the environment in which they are in also plays a significant role.

A Gene Required for Addictive Behavior

Maged1 is a gene that has been previously studied in response to antidepressants and due to its activity in tumors. Since this gene can be altered by chronic cocaine treatment, researchers performed experiments to determine if Maged1 plays a role in cocaine addiction. Many different behaviors (eating, intercourse, etc.) cause rewarding stimuli to release dopamine that activates the “reward system” of the brain. Cocaine blocks the release of dopamine from the synapses which leads to a build-up of dopamine that over stimulates the brain. This build-up eventually leads to changes in the brain that leads to addiction. The mice that lacked the Maged1 gene were unresponsive to cocaine and did not show addictive behavior. Researchers believe that these experiments will help them fully understand drug addiction and new coping mechanisms.

I think that this gene is a very important one to study and experiment with since Maged1 affects numerous “dopamine releasing” behaviors. Not only will the full understanding of this gene be helpful in drug addictions, but it will also be helpful in other issues such as eating disorders. While I am not sure that it will be ethical to alter this gene in fetuses, I think that it will be useful in developing a drug or therapy to combat addiction in adults. There are thousands of people that die everyday due to addictions and I think that the full understanding of the Maged1 gene will be successful in decreasing addiction fatalities.