The Neurobiology of Addiction

Brain_Broccoli_by_faiizeThis is the first installment of a five part series on the neurobiology of addiction by Jennifer Fernández, PhD. Follow along on Power Over Addiction or Facebook.


Addiction is a biopsychosocial phenomenon that affects over 20 million people in the United States. The factors that cause addiction are not yet well understood, with some arguing that it is a disease and others suggesting it’s more complicated than that.

But we can identify some predictors for addiction and we do understand the impact it has on the brain.

This five part series will primarily focus on current understanding about the brain structures and neurotransmitters involved in addiction. We’ll also look at the interaction specific drugs have with neurotransmitters in the brain and how this accounts for preferences in drug selection. We’ll start with an overview of addiction theories then dive into the neurocircuitry and neurobiology of addiction. We’ll conclude by looking at the effect of drugs on neurotransmitters in the brain and discuss why one develops a drug of choice.

Theories of addiction

Although we don’t fully understand addiction, there are lots of theories that attempt to explain it. The most popular one is the disease model. It explains that addiction has a biological origin that causes changes in the brain. This model also accounts for the heredity of addiction, or genetic predisposition. Studies of twins who have been separated at birth show that they are likely to develop addictions, despite growing up in different home environments.

You may have also heard addiction described as a hijacker of the reward center of the brain. Brain imaging studies show that overuse of drugs or compulsive behaviors “hijack” the reward system and can lead to changes in the brain that make it difficult to experience pleasure as one did before.

Then there’s the self-medication hypothesis. It posits that people use drugs to help them cope with physical and/or emotional pain. It helps explain why people turn to specific drugs or compulsive behaviors to help them deal with things like depression, chronic pain, trauma, or grief.

But the best way to explain addiction is as a biopsychosocial phenomenon. We know that addiction has a biological component. It causes temporary and permanent changes in the brain and body. We also know there is a psychological component: an inability to cope with distressing emotions. The social component of addiction is related to peer culture, as they influence what you use, how you use it, or how (not) to deal with your emotions.

In the question about nature versus nurture, the answer might just be nature and nurture. Drugs affect us biologically and we may even be genetically predisposed to those effects. Your parents, family, friends, or lovers may have modeled addictive behaviors or inability to cope with emotions in a healthy manner.

The next installment of this series will focus on the neurocircuitry of addiction.

Photo credit: Faiize

 

Zap away cocaine addiction with lasers! or magnets!

brain laserResearchers at the National Institute of Health and UCSF claim to have stopped and started cocaine addiction in rats with the use of laser stimulation to the prefrontal cortex, the brain region where decision making and impulse control take place. “When we turn on a laser light in the prelimbic region of the prefrontal cortex, the compulsive cocaine seeking is gone,” said Antonello Bonci, MD, scientific director of the research program at the NIH’s National Institute on Drug Abuse (NIDA).

Studies with human subjects are already being designed ,according to Billy Chen, the lead researcher. But lasers wouldn’t be used with human participants. Prefrontal cortex stimulation would be achieved through the use of transcranial magnetic stimulation (TMS) which is currently being used as a treatment for depression. It should be noted that the jury is still out on the efficacy of TMS to treat depression, as reported in the journals Current Pharmaceutical Design and Pharmacology and Therapeutics.

This is all very interesting, but addiction is more than biological. People don’t become addicted to a drug because of their neuroanatomy and neurochemical environment. It’s more complex than that. It seems unclear to me what exactly changes in the prefrontal cortex due to this stimulation. Does it make a person (or a rat) more mature and logical in their decision making process? If that’s the case, there may be many uses for this technology! Needless to say, I’m skeptical.

You can read the abstract and view supplemental information about the study in Nature.

Thanks to Jim Wiggins for sharing this article.

Photo credit: Block and Tackle Productions

Circumcision of the brain?

opiate addiction

Photo by Domiriel

Physicians in China performed brain surgeries to treat opiate addiction by destroying the nucleus accumbens, the pleasure center of the brain. The procedure is called stereotactic ablation of the nucleus accumbens, which means brain tissue is burned away. Although the procedure was banned in 2004, surgeries continued in the name of research.

The hope was that by destroying the part of our brain responsible for pleasure associated with drug use (among other things) the desire for using drugs would diminish. Results published in World Neurosurgery last October showed that 5 years after the surgery, 53% of participants had relapsed and were addicted to opiates again. In addition, 21% of participants experienced memory deficits and 18% experienced loss of motivation. These side effects are permanent due to the irreversible nature of the treatment. Read more about this controversial surgery here.

It is clear that addiction has devastating effects, but how far are we willing to go to treat it? Is it fair to ask addicts to potentially sacrifice pleasure and motivation to kick their habit? Some of the participants of this study were as young as 19 years old and had been addicted to heroin for 3 years. Granted, this research was conducted in China, a place where the death penalty is considered a suitable intervention for addiction. Is it ethical to have moral standards influence scientific research? Where do we draw the line?

The Truth About Addiction

addiction

Addiction is not a character flaw and it most definitely is not a choice.

Addiction is a biopsychosocial phenomenon that results in negative consequences and feelings of shame and guilt. Biological, psychological, and social factors culminate into a dependent relationship to a substance or compulsive behavior as a means of coping with distressing emotional, psychological, and environmental states.

More specifically, addiction is characterized by several criteria:

  1. the inability to resist an urge to consume a substance or engage in a behavior that is harmful
  2. an increase in tension or arousal before the act, followed by gratification and relief
  3. a noticeable  increase in amount and frequency of the act in order to achieve the desired effect (e.g. pleasure or escape)
  4. over-investment of resources, such as time and money, to engage in the act
The  emotions associated with addiction are one of the most notable elements. Shame, guilt and powerlessness are hallmarks of addiction and often lead to feelings of self-loathing and isolation. Individuals suffering from addiction are often misunderstood by their families and loved ones, causing them to lie and keep secrets.

This website offers information about addiction, drugs, and compulsive behaviors, including the latest news and research. Resources for people with an addiction and their loved ones can also be found here.

 

Informing yourself can be the first step in gaining power over your addiction.