By | August 3, 2007 9 Comments

MAO A gene interacts with testosterone to predict sociopathy

Genetic studies of our population estimate that about 50 percent of the differences in trait sociopathy between individuals are due to small differences in our genes. These small individual differences in our genes are called polymorphisms (poly=many, morph=forms), for many forms of the same gene. It is clear that polymorphisms interact with environmental factors during childhood and adolescence to produce sociopathy. It is also clear that the set of traits that we call sociopathy involves many polymorphisms.

There is accumulating evidence that a functional VNTR polymorphism in the promoter region of the monoamine oxidase A (MAO A) gene may give some men a predisposition to sociopathy. Four independent studies have found that this polymorphism interacts with childhood stress to predict sociopathy. VNTR stands for variable number of tandem repeats (the differences between us are due to differences in the numbers of these tandem repeats), the promoter is the part of the gene that regulates its activity. The mutation related to sociopathy makes it less likely that the MAO A gene will be expressed, resulting in lower levels of MAO A. MAO A is an enzyme that breaks down dopamine and other monoamine neurotransmitters such as serotonin and norepinephrine that are critical in emotional responses and impulse control.

There is one Dutch family where a rare MAO A stop-codon polymorphism leads to very low levels of MAO A. All the affected men in this family suffer from mild intellectual impairment and sociopathy. They have very poor impulse control, having committed rape, extreme violence and arson. Follow this link to page 1035 of the article to read the details of their poor impulse control and aggression.

Scientists have used genetic engineering to produce mice that lack the MAO A gene. These mice exhibit increased aggression. High testosterone also increases aggression in male mice.

Previously in “Would somebody please tell me why he did this!”, I discussed the observation that many studies have found testosterone levels to be higher in sociopaths. Increased testosterone levels have also been observed in teens and children at risk for sociopathy. In males, stress can actually increase testosterone levels. This may be one pathway whereby childhood stress leads to antisocial personality disorder (ASPD).

Dr. Rickard Sjoberg from Uppsala University in Sweden, in collaboration with NIH researchers, published a paper in April that is the first to tie together genes and testosterone in the development of sociopathy. Their paper A Non-Additive Interaction of a Functional MAO-A VNTR and Testosterone Predicts Antisocial Behavior (Neuropsychopharmacology, 2007), describes research on 140 Finnish unrelated male criminal alcoholics and controls. In this group of men, high testosterone levels were related to the diagnosis of ASPD, and to aggression, replicating other work.

They also examined low and high expressing MAO A genotypes in their subjects. The low expressing genotype was found in 19/45 controls and 32/95 criminals. Thus, many controls and not all criminals had the low expressing MAO A genotype. However, when they re-examined the relationship between testosterone and aggression and testosterone and ASPD, they found that high testosterone levels were only associated with ASPD and aggression in individuals with the low expressing MAO A genotype.

High testosterone levels in those with the low expressing MAO A genotype were also associated with low levels of MHPG, a byproduct of the breakdown of norepinephrine. These authors also mention that smoking decreases MHPG levels and they factored that in when they did their statistics. This is very interesting given that prenatal smoking increases the risk of sociopathy.

The low expressing MAO A genotype is generally found in about 30 percent of men and so is common. Interestingly, it is found in only 9 percent of women. Also of importance to gender differences in the rate of sociopathy is that this gene is found on the X chromosome. Women have two X chromosomes and men only have one. Therefore, men are more likely to be affected by mutations in genes that are found on the X chromosome. Interestingly, there are studies suggesting that the genetic transmission of ASPD is highest when the affected biologic parent is the mother. This is consistent with the idea that mothers who have two low expressing MAO A genes are passing them on to all of their sons.

Fathers do not contribute an X chromosome to their son’s genetic make-up. Therefore, this particular polymorphism cannot be responsible for the genetic transmission of sociopathy or alcoholism from father to son.

There are other genetic polymorphisms that have been found in higher frequency in sociopaths. Until now I have not been convinced enough of their importance to share the findings with you. The take home message is that the gene-environment interactions that produce sociopathy occur on multiple levels and are very complex. In any case, children who may carry genetic risk require special parenting and protection from the stress caused by a sociopathic and/or addicted parent.

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i believe my son is a sociopath. he is 20 and has been troubled since his early years, everyone of the symptons rings true. He totally does not think anything is wrong with him, can I can get him diagnosed? How do I do this? His father is a narcissist and we divorced when my son was 7. I also have 2 daughters and my son starting acting out i tried to get treatment for him, he was diagnosed with adhd his father would not agree to medications and treatment and took him under his care, my son has gone downhill fast and his trouble is getting worse, he dropped out of school, cant keep a job and is currently under investigation for rape. My question is was this passed down by me or his father or both. My one daughter has adhd as well, what are her risks and do they have a chance of passing this to their children. This has been hell, any comments or advise would be greatly appreciated.


Probably in jail now due to no early intervention nor awareness.

be it not possible at young age to give more female hormones to level out the testosterone? be so mike been so given testosterone for feminine looking nearly and no interest in sex. be so he grew himself hairs on his body afters. before this i had more body hairs than himself.

be so when i meet of himself he had naught body hair and be so lack of testosterone he be so have of himself.


super chic

@ lori… I don’t know the answer to your question, but I just wanted to let you know that I am here, very sorry to read about what you are going through, I hope you will check back, there are many people on this site that have a child who is a sociopath, you can get a lot of support here!!!


I am so glad I read this blog. I posted a question recently on another thread about the effects of anabolic steroids on the brain function of a sociopath. When I read this article, lightbulbs went off in my mind like fireworks because so many things made sense. I am not well versed in technical terms regarding brain function, but as I read these words they made complete sense to me.

My ex s-path grew up in an extremely abusive environment and the article pointed out that this type of upbringing could lead to decreased levels of MAO A. This paired with his obvious levels of testosterone, plus the pure testosterone he pumps into his body via a needle would help to explain, according to the findings in the article, his sociopathy. Of course there are so many other variables to this as well as any other story, but everything I have observed about my ex and his past fits the findings here to a TEE.

Another lightbulb was the part of the article about the family members who all showed s-path traits. My ex is one of nine children. Not a single sibling from the entire family has ever had a successful long lasting relationship. Not a single one! Coincidence? Every one of the nine siblings also has poor impulse control, i.e. drug abuse, pathological lying, multiple sex partners, inability to hold a job long term, and the list goes on. Again, it is staggering to me that every single one of them share many of the same s-path characteristics. I am by no means diagnosing an entire family, but I found it fascinating to make the correlation between the information in the article and my ex s-paths own life, both familial and individual. This kind of answered my question about the steroid use. I guess the rest of my questions may go foreveer unanswered, but just when I find myself doubting myself and thinking, “maybe it isn’t him, maybe it really is me”, I find a blog like this one and I am once again reminded that, “No, it really is HIM!”

Ox Drover

Dear Waking up,

If you don’t take home one single lesson from this blog but the o ne about “IT IS HIM, NOT ME” then you can heal, and you can recover!

Obviously your X had the double whammy, BADDDD ENVIRONMENT AND BAD GENES! Your child can have a good parent, and that is worth a lot! So keep on reading and keep on learning! Be the best parent you can be and leave the rest to God! ((((Hugs)))) and God bless.


Yes, leave the rest to God…
I hate to admit this but I have been pretty angry with God lately. I look at this however as a step up from briefly questioning the very existence of God, but grief plays some cruel tricks on our minds. I do believe with all my heart that it was God Herself who led me to “stumble” upon LF. Just when I think all hope is gone God shows himself in the most unlikely ways. I know I have just contradicted myself with the whole love/hate relationship comment, but my emotions and daily disposition change with the wind as well. I do feel that Im making progress, and like I said, just when things seem bleakest something happens and I find strength to keep going. Thanks for the support.

Ox Drover

I’ve raised and bred several species of animals in my life, and genetics, plays a big part in their over all temperment, so why, since we are also mammals, shouldn’t it at least play a gernal part in ours?

Training and environment also plays a significant part in what kind of person we become, as well as an animal.

Yesterday I went to get a heifer caught up to go to the butcher tomorrow afternoon. She is from a very gentle cow, but she has never been handled or “messed with” and so therefore does not trust people. She does trust her family (small herd) so when she saw us driving the herd (which we rarely do any more) she got spooked and took off through a fence to escape. I “fooled” her though, by taking one of her aunts who is VERY gentle (a former show heifer) and will follow me like a dog for treats of a slice of bread. So she saw her aunt getting something and with the strong herd instinct that cattle have, she rushed over to be with her aunts and sibs. Bingo! I had her caught in a secure facility from which she couldn’t escape, and by using a little cow-pychology, one or two at a time, I released the rest of the herd retaining the “chosen one.”

Since I had a purpose, and feel no remorse or guilt about this, it must mean I am a cow’s version of a “psychopath” where she is concerned. However, I do my best to make sure she doesn’t suffer undue or unneccessary stress or injury either psychological or physical as it makes the meat tough.

Her mother and her aunts are half sisters, out of cows who were also half sisters, and so on for several generations, so my cattle have a well known genetic package that has been CULLED for “bad attitudes” for for 10-15 generationsn by me, and for probably that many generations by the previous owner of those genetics. Bulls have been chosen not only on their physical perfection or the size of their arse, but on the TEMPERMENT of not only themselves but the temperment of both their parents.

But even while my heifer that goes to the butcher tomorrow is from a long line of gentle cattle from a breed that is considered gentle compared to other breeds, she is “wild” because I never gave her a loving environment up close so she could get to know me and trust me.

I think you can take most critters and if they are treated badly enough, or scarry enough, they will become fighters just to survive (not all, but most will, I think) But you aren’t going to have much luck “taming” a calf born from a breeding herd of the Spanish fighting cattle, and “taming” a tiger so that it is truly trustworthy isn’t going to be very successful at all, there are just some things that are bred so deeply in the the animal or species that it will take generations of domestication and highly selective breeding to take that aggression out of the animal.

This heifer has gentle genetics, but didn’t have an environment that made her want to have contact with humans, or have humans tell her which direction to go. But, she was born and bred to produce high quality beef, not more baby calves, so I didn’t spend a great deal of time training her to lead or to Love me and trust me.

My P-son was born out of a “herd” filled with psychopaths on both side of his parents, me and my x husband. and I know for a fact that both sides of my family of origin had a significant number of psychoplaths, going back for generations. So it isn’t unlikely he got a HIGH dose of genetic material as well as some environmental component that “turned on” his psychopathic aggression at puberty.I have NO idea what it was that “triggered” it. Or if, or when, it could have been stopped, or if it actually could have been stopped.


So what does the following mean? >> “levels of MAO A. MAO A is an enzyme that breaks down dopamine and other monoamine neurotransmitters such as serotonin and norepinephrine that are critical in emotional responses and impulse control.”< Does this mean that there are low levels of the neurotransmitters or that there are higher levels in some areas or what, exactly? Thanks ahead of time amd please let me know specifics.


The thing about the testosterone is interesting, as when I met my wife she has an unusually large sexual appetite more than ive ever seen in a woman, she also told me she had higher levels of testosterone then most women and a doctor put her on blood pressure medication designed for men with a side effect of lower testosterone.

Add in her mother is just like her, and she had a rough childhood, with some chemical imbalance in her, and I guess that’s why im here today.

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