The Brain and Addiction

Even if you are born with an addiction gene, you aren’t born an addict. The reason why scientists  research “addiction genes” is to find biological differences that make someone more or less susceptible or prone to developing an addiction.

An example of this, is recently the Yale School of Public Health identified an addiction gene associated with multiple cases of alcoholism, drug abuse and other addictive behavior. The scientist found a “strong and significant” correlation between a gene known as PKNOX2 (located on chromosome 11) and drug and alcohol addiction among white women with European origin. The women with this gene were almost twice as likely as white men, black women or black men to have two or more addictions.

This isn’t the first time that an addiction gene has been identified. In fact, there isn’t just one single addiction gene. Vulnerability to addiction is the result of many genes interacting, as well as, the influence of social and environmental factors. All of these contribute to the risk of addiction. Someone having an addiction gene, or multiple, will not inevitably make them an addict. But it does mean that they should be careful.

People who are prone because of an addiction gene, may find it harder to quit once they start. It might be why you and your friend can go out for drink every night, but only one of you is unable to stop drinking. Or there may be more severe withdrawal symptoms when trying to quit. Whereas, someone without an addiction gene may have less trouble giving up an addictive substance. Or they may have felt sick from a drug instead of good, which kept them from becoming hooked on it in the first place.

The relationship between addiction and genes is complex with many factors determining whether someone will develop an addiction. However, a good place to look for genetic clues is your family history. Children of addicts are 8 times more likely to develop an addiction. But remember, carrying an addiction gene doesn’t necessarily determine your destiny.

A recent study found a relationship between cocaine addiction and dopamine receptors. According to the National Institute on Drug Abuse (NIDA), the study suggests that people with naturally low levels of dopamine in the brain (or lower receptor availability), possibly due to genetics, are more susceptible to the rewarding effects of cocaine. Thus, making them more prone to cocaine addiction and relapse.

Dopamine receptors play an important role in the brain’s primary reward system. They exist in the outer membrane of brain cells and control motivation, emotion, thought, movement, and more. The dopamine receptors protein allows for the neurotransmitter dopamine to attach to these cells and affect their activity. The majority of the time, dopamine molecules occupy some of these dopamine receptors, while the rest of the receptors remain unoccupied and available until a stimulus (like drug use) increases the level of dopamine. When this increase occurs, the empty receptors help “mop up” the excess dopamine.

“Predisposition seems to play a role in addiction, as does the dopamine system’s rapid and robust reduction in dopamine receptor availability in response to cocaine,” said Dr. Nader, who believes that lower dopamine receptor availability could be a precursor of cocaine addiction and other addictions to drugs.

The study, as presented by NIDA, observed the dopamine receptors of rhesus monkeys before, during and after cocaine use. PET scans were used to reveal the level of dopamine receptors availability prior to initial cocaine exposure. The study found that the monkeys with lower dopamine receptors availability self-administered cocaine at higher rates. Therefore, it suggests that lower dopamine receptors availability increases sensitivity to the rewarding effects of cocaine. There was also a rapid decrease in the level of available dopamine receptors after continuous cocaine use in the monkeys. Which means cocaine addiction could be the cause and effect of damaged dopamine receptors.

Similar human studies have also concluded reduced levels of dopamine receptors availability among cocaine abusers, as well as heroin, nicotine, amphetamine, alcohol, and even the severely obese. However, the human studies could not confirm pre-existing proportions of dopamine receptors availability prior to drug use.

Dr. Nader’s next research will examine the likelihood of relapse between the monkeys whose levels of dopamine receptors availability remain low while abstaining and those whose dopamine receptors recover after discontinuing the use of cocaine.

Most of us have who have known an alcoholic, know the tendency that alcoholics misread emotional cues. One of the most frustrating and difficult aspects of alcoholism is the toll that it takes on relationships. When alcoholics misread emotional cues it often results in alcoholics taking offense when none was intended, or failing to interpret a loved one’s sadness, anger, disappointment, or even joy. And an alcoholics misread emotional cues can lead to further substance abuse followed by more deterioration of relationships and lives. However,

According to Medical New Today, a new study from Boston University School of Medicine found that individuals who have a long history of alcoholism, even those who have abstained (from one month to many years), showed abnormal brain activity when looking at facial expressions of others (a registering of less intensity). The brains of alcoholics, or former, alcoholics misread emotional cues because of an abnormality in their brain function. In this study, which was published in the August 11, 2009 issue of Alcoholism: Clinical and Experimental Research, researchers used functional magnetic resonance imaging (fMRI) to focus on abnormalities in the temporal limbic (the amygdale and hippocampus) part of the brain.

“Since ‘reading facial expressions’ is an important part of social interaction, alcoholics as well as other previously addicted groups, may be suffering from brain abnormalities in parts of the brain that control emotional perception and memory,” said author Marlene Oscar Berman, PhD, a professor of neurology (Neuropsychology) and psychiatry, in regards to the study’s findings about alcoholics misread emotional cues. “Furthermore, these results reveal neural substrates underlying alcoholism-related emotional anomalies and impairments of brain reward circuitry that mediate addictions such as alcoholism.”