Tuesday, December 6, 2011

Generate Good

Today we're going to contemplate the mystical and powerful realm of DNA, chromosomes and genetics.  

It's well-known that there exists within all of us genetic predispositions.  Usually, these are talked about medically as causing us to have a higher likelihood of heart disease, cancer, high cholesterol, and other health-related problems.  Problems we can't specifically control (except possibly through medications for some).  There are factors we can control, but the ones we can't are the genetic ones.  We get it from our parents and there's nothing we can do about it.

However, there is a growing body of evidence to suggest that certain behaviors have a genetic component.  Alcoholism is one such behavior.  Or is it a disease?  A study in Sweden followed alcohol use in twins who were adopted as children and reared apart. The incidence of alcoholism was slightly higher among people who were exposed to alcoholism only through their adoptive families. However, it was dramatically higher among the twins whose biological fathers were alcoholics, regardless of the presence of alcoholism in their adoptive families.  What caused this?  Was it a genetic abnormality that helped cause the alcoholism?  Or is it possible that the excessive consumption of alcohol altered the genes of the biological parents, which in turn were passed on to the kids?  This is one of those 'which came first' type questions.  I saw a study once that claimed to show there were differences between the brains of homosexuals as compared to the brains of heterosexuals.  The point trying to be made was that people are born gay (an argument I don't see the need to get involved with).  But what if gay behavior caused the brain difference?  What about taking drugs?  Legal and illegal.  If alcohol can do it, surely drugs could.  
What about behaviors that affect brain chemistry like gambling and pornography?  

Can you change your genetics for the worse?  

Obviously, our behavior affects our kids in that we are training them by example.  And that, itself, can be passed on through generations.  But if you can alter your genetics by behavior, what kind of responsibility does that place on us?  

In Exodus 20, while giving the 10 commandments, God says:
I, the Lord your God, am a jealous God who will not tolerate your affection for any other gods.  I lay the sins of the parents upon their children; the entire family is affected—even children in the third and fourth generations of those who reject me.  But I lavish unfailing love for a thousand generations on those who love me and obey my commands.

Later, in the New Testament, the disciples asked Jesus about a man blind from birth.  Was this situation because of the man's sin, or the sin of his parents?  Jesus answered neither, at least in this case.  But the disciples saw a strong connection between sin and effect, even to the children of the sinner.

How could it be fair to punish the children for the sins of the parents?  I like the unfailing love part in Exodus 20, but what is this 'affect' for the entire family and generations to come?
Is it a learned behavior?  Genetics?

And if we can alter our genes for bad, what about for good?
Could it be possible to improve our genetic makeup through good behavior?

We can, at a minimum, recognize the role of example and behavior in affecting generations.  But if there is any validity to this idea of genetic alteration, the stakes have been raised to a whole new level.


  1. Just got this in an email today:

    Ecstasy users' brains show toxic effects
    CBC News
    Posted: Dec 5, 2011 4:00 PM ET

    Ecstasy study, Archives of General Psychiatry

    Given the widespread recreational popularity of Ecstasy and its potential therapeutic use, it is important to find out what a toxic dose is, researchers say. RCMP

    Female Ecstasy users show long-lasting signs of toxicity in their brains, an imaging study shows.

    The neurotransmitter serotonin, a critical signaling molecule, has roles in regulating mood, appetite, sleep, learning and memory.

    In Monday's issue of the Archives of General Psychiatry, U.S. researchers used PET scans to look at levels of certain serotonin receptors in different regions of the brain in 15 women who had used Ecstasy compared with 10 who had never taken it.

    The study is important, said study author Dr. Ronald Cowan, a psychiatry professor at Vanderbilt University in Nashville, because the drug is now being tested as a treatment for post-traumatic stress disorder and anxiety associated with cancer.

    "Our studies suggest that if you use Ecstasy recreationally, the more you use, the more brain changes you get,” Cowan said. Investigators will need to know the dose at which Ecstasy becomes toxic before it is used as a treatment, the study’s authors cautioned.

    In the study, they found Ecstasy use produces chronic serotonin neurotoxicity in humans.

  2. And this:

    The US National Institutes of Health has earmarked nearly half a billion dollars for a plan that it hopes will usher in an era of diagnoses and treatments based on genome sequencing.

    The four-year plan expands its flagship Large-Scale Genome Sequencing Program to focus on medical applications "to begin to explore the front edge of genomics, which will move us into genomic medicine", says Eric Green, director of the NHGRI.

    Green acknowledges that moving sequencing into the clinic is not going to be simple. "WE EXPECT THERE TO BE SURPRISING FINDINGS (I added the caps), we expect some things not to work," he says. "One of the things our institute can do on behalf of all of NIH is to get data on varying overarching sets of issues around applying genomics to medicine."

  3. And this:

    Shoot ’em Up Videos Are Under the Microscope

    Gary Baldwin
    Health Data Management Blogs, December 1, 2011

    The sheer scope of research areas driven by imaging is on grand display here at RSNA 2011. On Nov. 30, for example, I attended a press conference on a controversial topic--the effect of violent video games on players. Researchers from Indiana University School of Medicine in Indianapolis are pushing the frontiers of understanding here. “For the first time, we have found that a sample of randomly assigned young adults showed less activation in certain frontal brain regions following a week of playing violent video games at home,” said Yang Wang, M.D., assistant professor, department of radiology and imaging sciences.

    In the study, two groups of similar males were compared. One group played what researcher Vincent Mathews, M.D., described as a “first person shooter game,” which he declined to identify by brand name, only describing it as a popular game designed for mature audiences. The second group played no games. Both groups underwent functional MRI studies before and after. In essence, the group playing the violent games revealed a decrease in blood flow to the area of the brain associated with cognitive function and emotional control, Mathews said during a press conference. “There is a statistically significant difference in the way the brain functions after playing violent video games,” he said.

  4. I'm not ignoring this topic, but really I'm just kinda chewing on it.

    I think your subsequent posts (particularly the video game one) have possibly introduced multiple subjects into this thread. Maybe not, as they could be related.

    Epigenetics is the term used to describe changes in the genetic code. To me this is both fascinating and fantastical. I can sort of understand how chemical factors could produce changes/mutations in DNA. What I can't wrap my brain around is how behavioral factors are capable of altering the genetic code that is contained in every cell in a person's body.

    I read a study describing how rats from the same litter had a different genetic makeup, with some specific genes either being "activated" or "deactivated", depending on whether or not they received mother rat's affections while they were little baby rats. It's difficult for me to even understand how such a thing is possible, and I'm honestly not sold on it. I need to understand it better. HOW does that happen? How does a gene in my DNA get turned off if my mom doesn't hug me? What if I get a hug later? Gene back on? What about if someone hurts my feelings? Or makes me angry? Or happy? I just have so many questions.

    Regarding the video game experiment, I'm not sure we're even talking about epigenetics there. Blood flow to the brain, and genetic code of DNA, are not synonymous things. The blood flow thing is actually easier for me to grasp than is the DNA thing.

  5. The first comment talks about 'brain changes'. Maybe the person only changes their own brain. Could that affect, or cause a defect in, genes? In the second comment, the director of Genomic Research expects 'surprising findings'. Behavior altered DNA would certainly be one. In the third comment, again brain function was changed for the worse.

    Obviously, theses changes are bad for the individual. I'm just wondering, and I don't think I've ever heard this idea talked about before, if there can be permanent genetic changes as a result.

    To take it into the theological realm, which I tried to do with the Exodus passage and I will now do with Genesis, we know that sin is our primary and fundamental source of all problems, physically, environmentally, emotionally, mentally, and so on. It's well-known that behavior affects physiology. The word 'psychosomatic' describes this relationship. Genetics are part of our physical makeup. Can our behavior 'curse' our future generations with defective genes?

  6. Here's a connection to serotonin levels, a problem referenced in the Ecstasy study.

    Psychologist Philip Hogue suggests that often times risk-taking behavior (such as the abuse of alcohol) is influenced by unbalanced serotonin levels – a neurotransmitter imbalance that could very easily be passed down genetically.

    Is risk-taking behavior the only issue? Of course, that can encompass a lot of problems. Also, it's still not proof that behavior was the initial cause of the predisposition.

  7. Check out this study http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2883563/?tool=pmcentrez

    The conclusion stated: Early age at 1st drink may facilitate the expression of genes associated with vulnerability to alcohol dependence symptoms. This is important to consider, not only from a public health standpoint, but also in future genomic studies of alcohol dependence.

  8. Regarding the psychosomatic comment: I meant to say the way we THINK can affect us physically. But thinking is also a behavior. In fact, we only act according to the way we think. Also, it's in the realm of brain chemistry. Stress is a well-known psychosomatic problem.

  9. Yeah, I'm not disputing the notion that external things, behaviors, thoughts, stresses can affect us on a physical level.

    But to me, there's a pretty big gap between "affect us on a physical level", and "alter the genetic code imprinted in every cell".

  10. Why is there such a big gap for you? Why do you see the genetic code as being so unalterable or indestructible? If it was, we wouldn't have genetic defects to begin with. How do those happen? It may be hard to imagine only because you've never heard it talked about before.

  11. I think the difference for me is temporary change versus permanent change. I'm fully onboard with psychosomatics. You feel stressed or afraid and your mouth gets dry. Your heart starts beating faster. You break out in a sweat. All of this from external factors (or even perceived factors which may not even exist!). I can buy all of that. BUT, there's a big difference between all of those temporary results and actually altering your genetic code! Do you not see that?

    You can burn some incense and it will make your house smell different for a while, but it won't change the floor plan.

  12. Burning incense? Is that a metaphor for something? :) Speaking of which, what about LSD? It's a mind-altering substance. It alters brain chemistry. Could that chemical change your brain to the point of changing your thought processes, behavior, even genetic makeup? Who really knows what's happening?

    Again, I ask why you see genetic code as being so unassailable - though I do think it's a common view that the only thing unchangeable about our physical bodies is the DNA. Why would only that be unchangeable?
    Again, changes DO happen. How?

    Back to LSD - I think it may even be, as with other drugs - especially hallucinogens, a way to open yourself up to spiritual influences. And not necessarily good ones. Many cultures for many years have used drugs in their spiritual ceremonies. There are still so many things we don't understand about physicality and spirituality.
    What's the current status of demon possession?

    You ask: Don't I see that? As though it's somehow obvious. We're not scientists with first-hand proof of either of our views. Just because something hasn't been explored doesn't rule it out. At one time the best science believed the earth was flat, the sun circled the earth, blood letting was good, and so on.

    What IS obvious is that we have a set way of looking at things and to see them from a different perspective is very difficult. For thousands of years, man couldn't have conceived of the earth being one-millionth the size of the sun, or that it was hurtling through space at thousands of miles an hour around the sun. (Exploring the ideas of perspective, bias, and paradigms would make for a great blog post)

    In your example, you described a fight-or-flight response and called it a temporary change. However, repeated stress causes heart problems. Heart problems are know to be inherited. Heart problems are also caused by behavior. Which came first?
    I'm exploring the behavior option.

  13. Well to me, it's pretty obvious that the hairs prickling on the back of your neck when something creeps you out is an entirely different thing than altering the genetic code that "builds us".

    I mean think about this. Your DNA is formed way early in the womb. The very first cells of you that were ever formed contained the instructions detailing how to assemble all the subsequent cells into what you are. It's the blueprint for YOU. It tells your body how to grow, how tall you're going to be, what color hair to have, when to start losing that hair, and whether or not your blood pressure is going to be high all on it's own.

    How can THAT type of stuff be altered by behavior?

    When I go lift weights, it makes me tired, and the next day it makes me sore. Those are the short term effects. If I regularly lift weights over a period of months or years, then it will make my muscles stronger and bigger. But does that mean that my progeny would be "naturally" bigger and stronger than other kids in their class? Absolutely not, that's ludicrous. All of that weight lifting, despite the changes to my muscles, don't do anything to the genetic code that was assembled in my mother's womb.

    And for the record, I haven't ever said that I see DNA as unalterable. I believe that it can be altered by chemical reactions from outside sources. Note that this even includes diet, as food itself contains chemicals. I believe that humanity can theoretically "play God" by identifying THIS gene that dictates THIS trait, and then identifying a chemical that changes the gene to the desired state. I think that's possible.

    What I don't see, however, is how the means of altering that gene could be a hug, a workout, a trauma. How can that alter your DNA? I don't see it.

  14. ‘Magic Mushrooms’ Return to Psychology Labs 40 Years After Leary

    Cancer survivor Lauri Reamer lived in constant dread that her disease would return, until she took a psychedelic drug in a Johns Hopkins University study.

    The 48-year mother of three was given psilocybin, the main ingredient in the “magic mushrooms” of the 1960s, as a remedy to ease anxiety.

    The experience “really cracked me open,” said Reamer, an anesthesiologist at Johns Hopkins in Baltimore before she was diagnosed with leukemia. “It let me be in life again, instead of this place of fear where I had been living.”

    These drugs “diffuse in your brain and some people never see the world the same way again,” said David Nichols, a pharmacologist at Purdue University in West Lafayette, Indiana, in a phone interview.

    On Sept. 29, Griffiths reported in the Journal of Psychopharmacology that use of psilocybin in an earlier study conferred a lasting personality change in some of the 51 participants tested.

    Harvard Project

    Leary did his research in the 1960s at the Harvard Psilocybin Project, running a series of experiments that gave psilocybin to divinity students to gauge their spiritual experiences and to prisoners to see if it would help keep them out of jail after their release.

    1. Excerpt from 'Fool on a Tightrope' by Andrew Palau, son of famous evangelist Luis Palau.

      Since college a broad array of drugs was part of my life. If it was 2 a.m. and we needed some more coke, we went after it. It didn't matter that we had to call shady characters across town to get it. Most of us did drugs—it was our social enhancer.

      But on that night in a Boston club, hopped up on mushrooms and beer, I received a frightful reminder of something that had peeked around at me over the years. The "social additives" that I loved to use and abuse were a gateway into another world, a world that I knew little about—a world that none of us controlled.

      Perhaps now it was time to put the college lifestyle away for good. I wanted success in my job yet I still wanted a good time. I had eased off most of the drugs near the end of my college career but now I felt like it was time to abandon them completely or something bad would happen.

      So, I tried to shelve them. I had to function professionally and, frankly, I was freaked out by the connection between drugs and Satan made clear to me that night in the club. Not only was I conscious of the spiritual pressure of guilt that confirmed there was going to be a time to pay up, I was getting pressure from the other side. As if dealing with God wasn't enough. Now a dark side was making its presence known to me. And I didn't like it.

  15. Your last post illustrates another concern I have. Even terms like "lasting changes" are not synonymous with "altered DNA".

    If we are going to talk about genetic changes, then I want before and after snapshots of the subjects' genome. It shouldn't be acceptable to use before and after behavior/symptoms/characterics and use those as proof of changes in DNA.

  16. I know they're not synonymous, I'm just saying there may be more to this idea than we think. I agree that hard scientific data is what's needed.

  17. Also, what's your take on the Exodus 20 passage?

  18. Well, the first thing I would do is remember what your mom always says, and that is that you have to weigh scripture against the totality of scripture. You can't just lift this one passage out of here and weigh it against itself, on it's own measures.

    That being said, what Exodus 20 makes me think is about Adam and Jesus. One thing that Cain inherited from Adam is a sinful nature. From generation to generation that has been passed down, the sins of our fathers. It's never skipped a generation.

    "But I lavish unfailing love for a thousand generations on those who love me and obey my commands." We know from elsewhere in scripture that this means everyone. Is anyone outside of God's love? No. And the ultimate expression of that love was Jesus.

  19. While I certainly advocate comparing scripture with other scripture, it's also true that a single verse can stand on it's own. If that's not true, show me a verse that is false on it's own unless compared to other scripture. There are instances of hyperbole such as: you must hate your mother and father to follow me, cut off your hand if it causes you to sin, etc. but this passage isn't one of those. That idea CAN be a cop-out on a difficult passage.

    If it's original sin then why stop at the 3rd and 4th generation? Plus He draws a comparison with a second group of people who don't have their sins laid on following generations. Wouldn't original sin affect them too? Even salvation must be individually accessed. You don't get saved because your parents were.

  20. Well I say that you have to view this passage against the totality of scripture, because if you don't, you could come away with a false sense of either security OR hopelessness based on something your ancestors did. Not only that, this passage can even contradict itself when read literally, unless you bring in other scripture.

    Take you and me for example. Do we love God and obey his commands? Yes***. So that means God is going to lavish his unfailing love on the next 1000 generations of our families. Sweet!

    *** - Problem is, neither we nor anyone other than Jesus has ever loved God and obeyed His commands PERFECTLY. Every time. And that means that EVERYONE also falls into the other category as well. At some time or another, every person who has ever lived has rejected God and willfully chosen to disobey His commands. So how can I have both 1000 generations of love coming, but also 4 generations of sin being passed down simultaneously? How does that work? Can you have both at the same time? I think you can, but only in the context of what I described above, ie Adam and Jesus.

  21. You also have a much less spiritual option here regarding interpretation of this passage. It would go like this:

    God's commands are for our good and His glory.

    When we follow them, and teach these things to our children, and children's children, they are blessed and live happy lives, and pass this down.

    When we disobey His commands and live selfish, destructive lives, our families suffer, and our children never learn how to obey God. Thus they lives selfish destructive lives and their families suffer as well. And on the cycle goes.

  22. Yes, your last comment agrees with what I was saying in the original post about the importance of our roles and examples as parents.

    Your previous comment about false sense of security or hopelessness made me think about the 'eternal security' doctrine. I'm involved in a lengthy discussion with Kory about that right now. We've been talking about the tension between God's promises and His warnings - some of which seem to imply that salvation can be lost. I'm going to try to edit those and put them in the Civil War post.

  23. Incidentally, I consider your last comment to contain highly spiritual content.

  24. First, I think I agree with Steve, that sure we can probably find a way to alter DNA through chemicals or isolating specific switches and flipping them (early on in the life stage).

    Second (and I think this is what Steve's getting at, forgive me if I'm wrong, I've read the responses over the course of days), most of this talk is about how what we do can change things like brain pathways, or habits, or similar by use of drugs/actions/etc. I don't think this is changing the DNA. I think it's probably more akin to when I lift weights, I make tiny tears in the muscles, and then they heal and become stronger, wash/rinse/repeat. Same with drugs - they alter your brain, and other organs in the body - sometimes temporarily, other times permanently. But I doubt that's altering the DNA, rather more like running your car engine without oil - you're breaking it down! (at least with the negative examples of changing your body/brain/etc.)

    Third, are there diseases that we can be more susceptible to based on genetics? Sure, but we still have the ability to change our behaviors based on that knowledge to do our best to limit said genetic problems - though some genetic defects are unalterable (or at least not related to our choices) like blindness or being short or whatever.

    Fourth, is it possible there's an "alcholic gene"? or any other gene for some kind of behavior/illness/lifestyle? I think that's the wrong question to ask. (BTW I think it's possible that there may be, but I don't think any of the tests have proven it, Steve says we need before and after pictures of DNA, and I agree, it'd need to be present at birth and then you can show me how it's in all people who have that problem later in life. Case in point the study on homosexuality you cited, correlation doesn't mean cause).

    That being said, I think the right question is: What am I going to choose to do with the genes I have? Just because someone may have an "alcoholic gene" (if it exists) is not an excuse for him to get drunk, out of control, and destroy his life and other people's. This applies to any other "________ gene". The excuse (if it's even possible) that "I was born this way" is complete crap. We only use it when we want to blanket over something we feel bad about doing, or we want to feel validated in doing. If it involves an action in any way shape or form, it involves a choice, regardless of how you were born. You may be born with desires, but you can always over come them if you choose to. I have the desire to eat meat, but if I thought it was wrong, I could overcome that desire, as much as it would suck. Our society just says "If you have any desire, you should just go with it...no rules is the path to freedom."

    Your post awhile back about discipline applies perfectly here...discipline is the only way to enjoy true freedom - not everything in life is good for us.

  25. To start with, Micah, you and Steve should never comment on the same post. Things could any direction, real fast, from brilliance to heresy. Secondly, the fact that you both agree AGAINST me causes me to feel more secure in my position :) JK

    Here's the thing...we don't know exactly everything and every way that DNA gets corrupted. I'm just postulating the idea that behavior can have an effect. If you agree chemicals can in early life, why not in later life. It's possible a person is predisposed to alcoholism because their genetic makeup predisposes them to ANY kind of addictive or OCD behavior. It may be possible that behavior causes the expression of those genes that are then 'flipped' and passed on. No proof, just an idea.

    On the 'born this way' assertion that many gays make: As I said, I think it's a non-starter. We're ALL born sinful. That's not an excuse to sin all we want. You may be born predisposed to alcoholism. As you said, that doesn't justify boozing it up constantly under the excuse of genetics.

  26. Now who's laughing?! (actually I don't think it's funny)

    Regular consumption of sugary beverages linked to increased genetic risk of obesity

    Researchers from Harvard School of Public Health have found that greater consumption of sugar-sweetened beverages (SSBs) is linked with a greater genetic susceptibility to high body mass index (BMI) and increased risk of obesity. The study reinforces the view that environmental and genetic factors may act together to shape obesity risk. The study appears in the New England Journal of Medicine.

    "Our study for the first time provides reproducible evidence from three prospective cohorts to show genetic and dietary factors-sugar-sweetened beverages-may mutually influence their effects on body weight and obesity risk. The findings may motivate further research on interactions between genomic variation and environmental factors regarding human health," said Lu Qi, assistant professor in the Department of Nutrition at HSPH and senior author of the study.

    In the past three decades, consumption of SSBs has increased dramatically worldwide. Although widespread evidence supports a link between SSBs, obesity and chronic diseases such as diabetes, there has been little research on whether environmental factors, such as drinking sugary beverages, influence genetic predisposition to obesity.

    Visit Harvard for the release.

  27. More support, in the area of gene expression it seems:

    From Medical News Today

    'Angry Mom' gene revealed

    From this (research on environment affecting behavior), the researchers analyzed whether the responses were determined by the genetic make-up of the mothers, by looking at the brain's dopaminergic system - the area that helps regulate emotional and behavioral responses to surrounding environments.

    They particularly focused on the DRD2 Taq1A single nucleotide polymorphism (SNP)... (which) controls the synthesis of dopamine, a chemical that regulates behavior in the brain.

    The researchers say previous studies have revealed that people who possess one T allele - known as the "sensitive" gene - for this SNP are more likely to show aggression compared to those without the sensitive gene.

    The study showed that around 50% of the mothers surveyed possessed the T allele.

    The results revealed that mothers who were in possession of the T allele were much more likely to engage in harsh parenting in deteriorating local economic conditions and areas with decline in consumer confidence.

    'Proof' that genes react to environments

    However, the researchers say that mothers without the T allele showed no such changes under worsening economic conditions.

    Additionally, when economic conditions were improving, the researchers found that mothers with the T allele were less likely to engage in harsh parenting compared to mothers without the T allele.

    The researchers say this finding is significant as it shows that the effect of genes on people's behavior could depend on the quality of their environment.

    Irwin Garfinkel, co-author of the study and professor of contemporary urban problems at the Columbia University School of Social Work, says:

    "This finding provides further evidence in favor of the orchid-dandelion hypothesis that humans with sensitive genes, like orchids, wilt or die in poor environments, but flourish in rich environments, whereas dandelions survive in poor and rich environments."


    Research suggests that people at increased risk for developing addiction share many of the same neurobiological signatures of people who have already developed addiction. This similarity is to be expected, as individuals with family members who have struggled with addiction are over-represented in the population of addicted people.

    However, a generation of animal research supports the hypothesis that the addiction process changes the brain in ways that converge with the distinctive neurobiology of the heritable risk for addiction. In other words, the more one uses addictive substances, the more one's brain acquires the profile of someone who has inherited a risk for addiction.

    One such change is a reduction in striatal dopamine release. Dopamine is a key brain chemical messenger involved in reward-related behaviors. Disturbances in dopamine signaling appear to contribute to reward processing that biases people to seek drug-like rewards and to develop drug-taking habits.

    In the current issue of Biological Psychiatry, researchers at McGill University report that individuals at high risk for addiction show the same reduced dopamine response often observed in addicted individuals, identifying a new link between addiction risk and addiction in humans.

    Dr. Marco Leyton and his colleagues recruited young adults, aged 18 to 25, who were classified into three groups: 1) a high-risk group of occasional stimulant users with an extensive family history of substance abuse; 2) a comparison group of occasional stimulant users with no family history; and 3) a second comparison group of individuals with no history of stimulant use and no known risk factors for addiction. Volunteers underwent a positron emission tomography (PET) scan involving the administration of amphetamine, which enabled the researchers to measure their dopamine response.

    The authors found that the high-risk group of non-dependent young adults with extensive family histories of addiction displayed markedly reduced dopamine responses in comparison with both stimulant-naïve subjects and non-dependent users with no family history.

    "This interesting new parallel between addiction risk and addiction may help to focus our attention on reward-related processes that contribute to the development of addiction, perhaps informing prevention strategies," said Dr. John Krystal, Editor of Biological Psychiatry.

    Leyton, a Professor at McGill University, said, "Young adults at risk of addictions have a strikingly disturbed brain dopamine reward system response when they are administered amphetamine. Past drug use seemed to aggravate the dopamine response also but this was not a sufficient explanation. Instead, the disturbance may be a heritable biological marker that could identify those at highest risk."

    This finding suggests that there are common brain mechanisms that promote the use of addictive substances in vulnerable people and in people who have long-standing habitual substance use.

    Better understanding this biology may help to advance our understanding of how people develop addiction problems, as well as providing hints related to biological mechanisms that might be targeted for prevention and treatment.

    Explore further: Cocaine addiction: Phase-specific biology and treatment?

    More information: "Reduced Dopamine Response to Amphetamine in Subjects at Ultra-High Risk for Addiction" by Kevin F. Casey, Chawki Benkelfat, Mariya V. Cherkasova, Glen B. Baker, Alain Dagher, and Marco Leyton , Biological Psychiatry, DOI: 10.1016/j.biopsych.2013.08.033

    Journal reference: Biological Psychiatry search and more info