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Links to Criminal Behavior

Using DNA from an inmate population, Dr. Todd Armstrong is studying the link between genes, childhood adversity and criminal behavior.

A team of researchers at Sam Houston State University are studying the effects of genes and environmental adversity on criminal behavior among inmates incarcerated in a correctional facility located in a large city in the southern United States.

In the first study of its kind in North America, Dr. Todd Armstrong—along with Drs. David Gangitano and Brian Boutwell—at the College of Criminal Justice are studying the link between specific genetic markers and self-reported childhood adversity in an incarcerated sample. The study is based on data that includes DNA samples, surveys, and criminal records of approximately 100 inmates incarcerated on a variety of charges, including violent crimes, drug offenses, property crimes, disorderly conduct and weapons offenses.

“To date, this is the first sample from an incarcerated population in North America that has been genotyped,” said Dr. Armstrong, principal investigator on the research. “While there are studies that show genetic variation is linked to anti-social behavior more generally, the extent to which the genes explain variation in criminal activity within an incarcerated sample has not yet been tested."

Preliminary results from the data show two interesting findings. In the first, the gene for Monoamine oxidase A (MAO-A), which degrades neurotransmitters, interacted with 5-HTT, the serotonin transporter gene to predict variation in criminal activity. In the second, a marker in the MAO-A gene predicted more serious offenses among inmates with parents who were involved in criminal activity. The same marker predicted less serious offenses for inmates who suffered child abuse.

The DNA samples will provide a wealth of information on the links among genes, environment and criminal behavior. Dr. Armstrong and his team will initially target those genes that have been linked to anti-social or aggressive behavior in prior research, but many more markers can be investigated in the future.

“We see this as a beginning for us, not an end,” said Dr. Armstrong. “We are going to try to make the most of our current data collection, but we’re beginning to plan an additional study that would allow us to relate genetic variation to treatment outcomes. Ultimately, it may be possible to match people with a treatment modality. Our hope is that through this we will be able to improve the success of rehabilitative and drug treatments.”

The study began in the summer of 2010 when DNA samples were collected from volunteer inmates using cheek swabs. Those swabs were analyzed by the DNA Lab at Sam Houston State University’s Forensic Science Program as part of a capstone research project for four students from the Master of Forensic Science Program, including Shahida Flores, Kristina Scott, Mary Symonds and Jessica Motl.

"There have been a few published studies that link certain genetic markers (e.g., testosterone receptors) and aggression,” said Dr. David Gangitano, a DNA expert in the Forensic Science Department. “In the brain, serotonin, a pharmacological target of antidepressants, also plays an important role in aggressive behavior. Dopamine targets the pleasure center….This field is very interesting and important because if you find the differences in the genetic markers associated to neurotransmitters, you may be able to predict a potential predisposition to aggressive behavior. Some of these markers, like the case of MAO-A, have already been used to reduce sentences in court.”

In the future, the inmate samples will be compared against a control group made up of university students to identify the differences in genetic makeup. Much of the research is now possible due to a new DNA sequencer that can speed the process of sample analysis.

“This opportunity is invaluable to work together on criminal profiles,” said Dr. Gangitano. “Our collaboration has created a place for a new discipline at SHSU – Behavioral Genetics.”

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