Category Archives: Addiction Research

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.

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

Researchers stop stress-related relapse in rats

stressWe all deal with stress and have to learn methods to reduce and manage the stressors that life throws at us. But for someone with an addiction, day to day stressors can have a disastrous impact. Stress can trigger relapse, especially early in the recovery phase of addiction when new coping skills are being introduced and a person experiments with various strategies to find those best suited to their lifestyle needs.

Past research has focused on the psychological and emotional mechanisms involved in stress-induced relapse and there has been some speculation about the brain structures and neurotransmitters involved, but now researchers from Brown University and the University of Pennsylvania have found that by blocking kappa opioid receptors in the ventral tegmental area (VTA), rats under stress do not relapse on cocaine.

The VTA is the brain structure responsible for rewarding the fulfillment of basic needs, like hunger, sleep, and love. It contains dopamine releasing neurons that communicate with other brain structures, like the nucleus accumbens and the pre-frontal cortex when a basic need is met. It’s also involved in the rewarding release of dopamine when one uses a drug. GABA is an inhibitory neurotransmitter that slows down the release of dopamine in the VTA of a healthy brain.

Kappa opioid receptors are released in the VTA during stress and interrupt GABA’s process. By blocking those receptors in rats, researchers found they were able to resist relapsing on cocaine after five minutes of stressful exercise. “If we understand how kappa opioid receptor antagonists are interfering with the reinstatement of drug seeking we can target that process,” Kauer said. “We’re at the point of coming to understand the processes and possible therapeutic targets. Remarkably, this has worked.”

This is exciting news in the field of addiction as we are learning more and more about the neurobiological underpinnings of this devastating disorder. Researchers are especially excited about the potential to develop prescription drugs to help prevent relapse, and although this prospect may help people overcome their addiction, it is important to remember that addiction is more than just neurobiological processes. People overcoming addiction also need to learn emotional regulation and healthy alternatives to fulfill unmet needs in their lifestyles.

You can read more about this study here.

Photo credit: bottled_void

Is internet addiction real?

If internet use interferes with one’s life and ability to function, internet addiction or compulsive internet use may be a concern.

Internet Addiction

Although there is debate in the academic world about the authenticity of internet addiction there is no dispute that, for some people, excessive internet use can cause distress, strife, and disruption in their ability to function. Internet addiction is somewhat of a misnomer and compulsive internet use seems to capture the nature of the disorder more accurately. It’s compulsive because use of the internet acts as a substitute for an unmet lifestyle need. For example, someone who suffers from depression or anxiety may turn to the fantasy world of the internet to escape those uncomfortable emotions. Obviously this is also true of drug addictions, and although a recent study shows differences in the brain anatomy of excessive internet users, the results are inconclusive.

The Center for Internet Addictions proposes  the following diagnostic criteria for internet addiction for users who have experienced four or more of the following symptoms in the last month:

  • Feeling preoccupied with the Internet or online services and thinking about it while off line
  • Feeling a need to spend more and more time online to achieve satisfaction
  • Inability to control online use
  • Feeling restless or irritable when attempting to cut down or stop online use
  • Going online to escape problems or relieve feelings such as helplessness, guilt, anxiety or depression
  • Lying to family members or friends to conceal how often and how long you stay online
  • Risking the loss of a significant relationship, job, or educational or career opportunity because of online use
  • Continuing use even after spending too much money on online fees
  • Going through withdrawal when offline, displaying symptoms such as increased depression, moodiness, or irritability
  • Staying online longer than originally intended

Compulsive internet use can take on several forms:

  • cybersex & pornography
  • online relationships
  • gaming
  • compulsive shopping

Regardless of the biological underpinnings of excessive internet use, it is clear that people experience distress and disruption to their lives when they compulsively turn to the internet for relief. If you think your internet usage is compulsive, contact a mental health professional for an evaluation. It is highly likely that you are using the internet to cope with an underlying issue.

Photo credit: Federico Morando