How much can we blame our genes for addictive behavior?

The Oscar-nominated actor Robert Downey Jr., star of countless films including Chaplin, the Iron Man series, Tropic Thunder and Zodiac, started making movies when he was just five years old. He’s also famous for his descent into drug addiction, which he says started even earlier than age five.

Downey has told a number of interviewers that he believes he has an addictive personality, and that he may have passed that personality on to his son, Indio, who recently pled guilty to felony cocaine possession and entered a rehabilitation program. Meanwhile, Downey (the elder) has talked about how his own father introduced him to drugs.

Downey’s stories beg critical questions about how humans handle drugs and addiction:

  • Is addiction inherited, and genetic?

  • Is addiction more a cultural and environmental phenomenon?

  • Is there such a thing as an addictive personality?

Drug rehabilitation, medical and psychological treatments and even the criminal justice system depend heavily on the right answers to those questions.

According to the National Institute on Drug Abuse (one of the National Institutes of Health), illegal drug abuse costs the United States more than $181 billion each year “in health care, productivity loss, crime, incarceration and drug enforcement.” And these costs are based on an assumption that drug addiction, as NIDA puts it, “is a chronic, relapsing brain disease.”

But that doesn’t necessarily make it genetic. Nor does a pattern of heritability for, say, alcoholism, make that disorder entirely genetic. Researchers are looking at addiction as a complex interaction of genes, metabolism, environment and behavior. This has come a long way from the early 20th century, when addiction was seen more as a morality problem, or even since the 1980s, when we witnessed the primitive eggs-on-a-frying pan “this is your brain on drugs” advertisements. Researchers have largely abandoned the search for an overarching “addictive personality,” in which a person shows an archetypal vulnerability for any addiction, be it cigarettes, alcohol, heroin, or gambling.


2019-disneylegend-rdj-1180x600.jpg

If you or someone you know is struggling with addiction, contact us today by calling 732-702-2242.

Case for genes

Of all the people who try alcohol or illegal drugs, only 10 to 20 percent get addicted. No single gene has ever been isolated for people who get hooked on alcohol, drugs or other substances. But a number of studies show that genetics does play some significant role:

  • Identical twin studies have shown a fairly strong concordance (sharing a behavior and genetic trait), but even these show some variability. For example, a Medical College of Virginia twin study on cocaine use showed a 54 concordance rate for identical twins versus 42 percent for fraternal twins, but for cocaine abuse showed a 47 percent concordance for identical twins and only eight percent for fraternal twins.

  • Other studies showed some differences depending on type of substance. A Washington University, St. Louis, review showed that 33 to 71 percent of the variation in nicotine addiction was inherited, while 48 to 66 percent of variation in alcohol addiction was inherited, and 49 percent of variation in gambling addiction was inherited.

  • A search for genes has uncovered a number of genetic clusters that affect behavior and mood, and could be connected with addiction. Genes on no fewer than eight chromosomes have been tagged for some role in chemical dependence.

Related article:  Plant-based meat industry start-up Daring targeting chicken-free ‘chicken’, the world’s favorite protein

Case for the environment

Also taking a step away from the early focus on moral fiber, behavioral scientists have been examining external factors that could lead to addiction:

  • Twin studies, this time looking at identical twins who did not have the exact same upbringing, showed that the twin who had experienced childhood sexual abuse did show a strong tendency toward substance abuse, while the twin who did not have these experiences did not share this addiction.

  • Some researchers have pointed to social structures as a key factor in addiction. Monkey studies have shown that those who were dominated by other monkeys are more likely to take cocaine than more socially powerful monkeys. Others have looked at poverty, and living on the fringes of society as something that prods addiction.

  • Certain behavioral disorders, like anxiety or impulsive behavior, have been suspected of driving addiction. Feeling anxious can fuel the need to consume drugs that alleviate these feelings and other social fears, while teenagers may become addicted because they can’t yet control their emotions effectively.

Case for nature and nurture

  • Many alcohol abuse studies have focused on the gene ALDH2, which controls the conversion of acetaldehyde, a rather toxic metabolite of alcohol. Some variants of ALDH2 don’t convert acetaldehyde into acetate very well, particularly in Asian populations. While some studies show that people with this version of ALDH2 were far less likely to get addicted to alcohol, the heavy-drinking business culture that developed in Japan and other Asian nations in the 1980s and 1990s forced businessmen (mostly men) to drink anyway.

  • While addicts may behave as if they have a disease state (compulsive drug seeking and use, despite harmful consequences), and addiction does change how certain neurotransmitters like dopamine are metabolized, they also can completely recover on their own, at rates up to 80 percent.

  • Epigenetic changes, as we’ve written about in the Genetic Literacy Project, have been shown to also affect who becomes an addict and why. Excessive cocaine and alcohol use can determine how genes that protect against addiction are regulated, while increases in dopamine receptor numbers (and activity) can help prevent addiction.

Was Robert Downey Jr. right?

Recently, a NIDA director estimated that the genetic risk of addiction averages about 50 percent. So, Downey may have passed on a tendency for substance abuse to his son, but it may have just as much been the same way he was influenced by his father as it was through his own DNA.

  1. How much can we blame our genes for addictive behavior?

Habit vs. Addiction: What’s the Difference?

From a mental health point of view, the difference between habit vs. addiction can be as perplexing as it is overwhelming. The line that separates the two can be unclear, and habit-forming and addictive behaviors can overlap in a lot of unexpected ways. Understanding the differences between the two can help us make better decisions and avoid losing control.

What Is a Habit?

A habit can be summed up as a routine or regular behavior that gets harder to give up the longer that behavior goes on. The best examples of habits can be seen in how people start the day. Morning rituals largely consist of a variety of habits, like brushing teeth, taking a shower, making coffee, etc. Over time, the sequence of these behaviors can become consistent for people.

An article in Forbes unpacked the ways people develop positive habits or “rational addictions.” These kinds of healthy habits can only arise, though, when people are more aware of their own behaviors. The article was based in the context of a study that found “as ‘rational addicts,’ people can weigh the costs and benefits of their current behavior taking into consideration its implications for the future, and still choose to engage.” When people know more about how their positive behaviors benefit their lives – and how their negative behaviors do the opposite – they’re much more likely to engage in healthy habits.


At the same time, though, it’s hard to shake habits as we engage with them over and over. Jasmine Bittar of Addiction Center offered tips on how to break bad habits and build new, healthy ones. Centrally, she suggested people exit their comfort zones. Comfort feeds into habits, which is why it’s important for people to try on unfamiliar behaviors to develop healthier, more constructive ones. She recommended four primary goals to develop new habits:

  • Take baby steps to develop new routines.

    • Avoid comfortable or enabling triggers that will tempt you to indulge your habit.

    • Attempt to exchange old behaviors with new, comparable habits.

    • Refrain from self-destructive, self-deprecating thoughts.

In order to understand how habits work, it’s necessary to look at how they affect decision making. Author and New York Times reporter Charles Duhigg, discussed the role of habits within the workplace in an interview with Harvard Business Review. He said, “About 40% to 45% of what we do every day sort of feels like a decision, but it’s actually habit.” This sentiment helps explain the sort of unconscious thought process we go through when making choices. Duhigg went on to say that as habits become more automatic and routine, they become harder to shake later. After people identifying an unhealthy habit, it’s important they “diagnose the cue and the reward.” Then, people can successfully work toward developing new habits.

What Is an Addiction?

Addictions, on the other hand, are much more powerful than habits. In these instances, for the most part, people will make sacrifices to their lives out of an obligation to pursue a substance or practice.

Defining addiction is difficult, but the American Psychiatric Association provides a simple explanation for what brings on certain addictive behaviors. The organization wrote, “People with addiction (severe substance use disorder) have an intense focus on using a certain substance(s), such as alcohol or drugs, to the point that it takes over their life.” As a result, people who are addicted to something experience different modes of thinking and altered brain functions. People who exhibit addictive qualities are sometimes aware of their mental health problem yet continue to engage in risky, problematic behaviors.

Addictions don’t have to be centered on consuming substances, though. Instead, as explored in the International Journal of Preventative Medicine, certain behaviors can be just as addicting. The researchers stated that “behaviorally addicted individuals have certain symptoms and will undergo the same consequences brought about by addiction to alcohol and drugs as well as other obsessive behaviors.”

The National Institute on Drug Abuse looks more thoroughly into the way the brain functions in people who are addicted to something. The organization stated that “surges of dopamine in the reward circuit cause the reinforcement of pleasurable but unhealthy behaviors like taking drugs, leading people to repeat the behavior again and again.” By indulging in the substance or behavior, over time the dopamine that triggers in the brain lessens and lessens. This ultimately reduces the “high” that people get from their addiction, which motivates them to seek out the substance or behavior more and more.

The Significance Between Habit vs. Addiction

Probably the most important distinction between habit vs. addiction is how choice, to an extent, is still possible with habit-forming behaviors. When it comes to addiction, people generally have a harder time making decisions because of their dependence on a substance or behavior. Typically, these factors are linked to the rewards systems in the brain, which helps explain their overarching power in stripping people from the ability to make rational decisions.

The debate between habit vs. addiction has become more intense for mental health experts. Adi Jaffe, Ph.D., of Psychology Today analyzed the ability for people to choose their habits or addictions. Mental health professionals fiercely debate this topic, but he found that both camps are right; habit formation is more choice-based while addictive behaviors can be more neurologically and biologically bound.

“In the end, it comes down to training,” Jaffe said. “If we want to end up with a different set of behaviors, we have to understand the mechanisms and processes that got us there and make a change.” Although this certainly isn’t a definitive end to the debate, it does add a layer of understanding to the difference between addiction vs. habit.

Developmental neuroscientist Marc Lewis, writing for the New York Times, explored how addictions and habits might not be as different as they seem at first. This controversial opinion is comes from the idea that as brain functions change, so do habits. He found that “addiction is brought about by the repeated pursuit of highly attractive goals and corresponding inattention to alternative goals.” This definition frames addictive behaviors as being similar to habit-based ones.

Alternatively, the research Barry J. Everitt, writing for the European Journal of Neuroscience, compared the starker difference between habit vs. addiction. He focused primarily on the treatment side of drug addiction, but he made a point to discuss how habits can lead to acute addictions. He wrote, addiction to drugs is “the endpoint of a series of transitions from initial voluntary, or recreational, drug taking through progressive loss of control over drug use.” In this context, a habit can be seen as the precursor to addiction.

Not all habits will lead to addictive behaviors in the end, but it’s still important to recognize the dependent nature of some substances and practices. It’s not often that people begin with full-blown addictions; instead, addictions develop over the course of time. During the early stages of habit formation, people may still have the power to mold their behaviors and practices.

If you think you’re developing an addiction, or if you think you know someone who is, please contact us at 732-702-2242

Habit vs. Addiction: What’s the Difference?