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Breaking Down Addiction Into Its Constituent Parts: Neuroscience, Incentive Salience, Environment, and Habits

Dr. Daniel H. Lende

Daniel Lende is an associate professor from the department of anthropology at The University of South Florida. He was trained in medical, psychological, and biological anthropology and public health at Emory University in Georgia. His research interests revolve around substance use and abuse, behavioral health, stress, cancer, post-traumatic stress disorder, embodiment, interventions in behavioral health, and risk-factor epidemiology. He has done fieldwork research in both Colombia and the United States. Dr. Lende and Dr. Downey (the other author of our class book) started Neuroanthropology, which is one of The Public Library of Science (PLOS) Blogs.

Addiction and Neuroanthropology

“Addiction and Neuroanthropology” by Daniel H. Lende is a multifaceted explanation of the neural and cultural processes intertwined in drug seeking behavior and addiction. A difference between Colombian ideologies of addiction and North American ideologies is that in Columbia, the problem of addiction doesn’t revolve around pleasure. In Columbia, addiction defies their basic social value, which is protecting family, friends, and the community. In this context, addiction is problematic because drug seeking and using surpasses basic social values. In the United States, however, pleasure is one of the main concerns about addiction. It is viewed as a disease that develops due to one’s biology and self-control. Lende uses both a combination of previous neuroscientific evidence in conjunction with his ethnographic fieldwork to explain how addiction is not a problem of pleasure or the self, but a neuroanthropological conglomerate of a host of factors.

Lende states that addiction is composed of two parts, the compulsive desire for a drug and the drug habit that is formed. Addiction, according to the Diagnostic and Statistical Manual (DSM) consists of four parts. The first criteria are that addiction involves the experiencing of tolerance and withdrawal. The second discusses how addiction also involves continued drug use despite their impact on health and one’s social life. The third further explains addiction as the persistent desire to use drugs after multiple failed attempts at controlling use. Lastly, the fourth criteria are about how drug use interferes with daily life and roles and obligations are neglected.

So, what drives the actual behaviors associated with addiction? The 1993 theory of addiction proposed by Robinson and Berridge claims that incentive salience is the reason for addiction. This theory led to widespread belief that the mesolimbic dopaminergic pathway was singlehandedly responsible. Lende proposes that this view of addiction is problematic and desire and involvement, or the cultural aspects of drug use, are a couple of the components missing from this explanation.

Neuroscience and Addiction

Previous studies have shown us that addiction involves many interconnected brain areas such as emotion, memory, and choice. Addiction encompasses the basal brain, which is involved in body regulation and activation, limbic circuits associated with emotions and environmental processing, and frontal cortices, which are associated with executive functions such as control, planning, and organization. The neuroscientific aspect of the pursuit of drugs and the repeated use of drugs involves two parts of the mesolimbic pathway, the ventral and dorsal striatum and the ventral tegmental area.

Incentive Salience and Addiction

Reward theory states that environmental stimuli shape animal responses. Berridge and Robinson believe that there are three facets to the reward process. The first is liking, or the hedonic impact, learning, or making predictive associations, and lastly, wanting, or incentive salience. Incentive salience is a type of “wanting” that involves goals, expectations, and future outcomes. Salience, however, is still not the complete picture because desire and involvement are both biological and cultural. Incentive salience is mediated by both the nucleus accumbens and the ventral pallidum. Furthermore, individual experiences, the presence of cues, social contexts, and environmental influences all produce different patterns of firing resulting in differences in salience signaling.

An example that provides a better understanding of the behavioral side of the explanation is adolescent drug use. Students with problems in their home life and academic problems at school see few options for fun, success, or a sense of involvement in either of these settings. When rewards from school and family are absent, these two contexts become irrelevant and lose their incentive salience, therefore, students seek other options and other realms where rewards are provided and incentive salience is present. As Berridge et al. (2009) would sum it up, incentive salience is about a subjective sense of “this matters,” rather than conscious desire. Incentive salience is about the motivation of drug seeking rather than the appreciation of wanting or desiring drugs.

Neuroscience and The Formation of Habits

Habits, as defined by Graybiel (2008), are “learned, repetitive, sequential, context-triggered behaviors performed not in relation to a current or future goal but rather in relation to a pervious goal and the antecedent behavior that most successfully led to achieving that goal.” Habits are a product of both behaviors and neurobiology.

Neurologically, learning about the rewards associated with drug use activates the ventral striatum. As drug use becomes persistent and repetitive, a neural activation shift takes place from the ventral striatum to the dorsal striatum, where activation here serves to maintain drug seeking and drug using habits. Due to this shift, the ventral striatum, which serves to evaluate outcomes and consequence of behaviors, no longer serves its function and behaviors are mechanically produced. Despite increased tolerance, habits mediated by the dorsal striatum become resistant to change regardless of the rewards reaped by that behavior.

An example of this is extinction training in lab rats. Rats trained to press a lever that delivers drugs exhibit neurobiologically mediated behaviors associated with the dorsal striatum. When placed in a different context where lever pressing does not yield drugs, rats continuously lever press although no drugs are administered. Only when the dorsal striatum or nucleus accumbens are lesioned do rat lever pressing behaviors cease.

Behavior and The Formation of Habits

This neurological explanation leads people to believe that addicts find little pleasure in continued drug use. However, behaviorally, drug use may still be a rewarding activity. The social interactions associated with drug use are rewarding despite the blunting of the pharmalogical effects of the drug. Once addiction sets in, oftentimes familial relationships and community involvement decreases and strong social bonds develop between drug users. Even without the same extent of high, the social networks formed with drug users become a major source of social interaction. Additionally, stress increases dorsal striatum activation which further reinforces habitual behaviors.

Summary

Drug use has more incentive salience than other areas of one’s life and becomes habitual. Increased drug use is reinforced because of social bonds between drug users, the neurological rewards associated with the high of the drug, and the activation of habit solidifying brain regions. The more involvement in drug social groups, the more incentive salience signaling increases and drug users seek drugs out even more. This complicated picture of drug use shows how addiction is both neurological and anthropological.

Similar Research

This chapter reminds me of our very first readings that discussed nerves, synapses, neurotransmitters, and different regions of the brain. It also reminds me of the second week’s readings about the encultured brain. Addiction is a perfect example of how the brain is encultured. This chapter shows how a neurological structure could influence behaviors and how an individual’s environment and behaviors also serve to reinforce neural activation patters and solidify these behaviors. This reading also reminded me of articles written by Dr. Gilbert Quintero, a cultural anthropologist who researches the social, cultural, and political economic aspects of drug use. Like Lende, Quintero has also studied young adult populations in the United States.

Towards the end of the chapter Lende touches on the idea of cultural models and how they play a role in the addiction process. If you all don’t already know, Dr. Bill Dressler, here in our very own anthropology department, conducts a lot of research on cultural models. His research focuses on how cultural consonance or discordance with salient cultural models may produce health benefits or may prove to be detrimental to one’s health. Next week’s reading on depression and anxiety discusses this concept further. People who are not culturally consonant with salient cultural models of a “good life” develop higher levels of anxiety than those who are culturally consonant. This relates to Dr. Lende’s argument because as we learned, higher levels of stress increase activation in the dorsal striatum. And as we know, the dorsal striatum serves to maintain and further perpetuate habits. Therefore, stress and anxiety associated with alienation from the community and family, coupled with societies’ negative view of addiction and the addict’s discordant lifestyle with salient cultural models, serve to dig a drug addict deeper into his or her drug pattern.

What I Liked or Didn’t Like

I liked how this chapter began by showing the contrasting ideologies behind addiction in Columbia and the United States. I also liked how the discussion progressed to an explanation of previous beliefs about drug use, addiction, and drug addicts. I believe that Lende’s approach of providing the reader with broader preconceived notions about addiction and his “busting” of these myths is an effective way to draw the reader in and provide alternate explanations. He talks about how historically, people have either taken a strictly neurological approach to addiction or a strictly behavioral approach to addiction. Then, he mends these two arguments by explaining how both are intertwined and are required for an accurate and holistic explanation of addiction.

What I thought was lacking was the organization of the chapter. I felt like there were certain areas that could be more condensed and straight to the point. I also felt that information that should have been presented together was scattered around which made it a little more difficult to grasp. This disorganization made the reader fetch for information and have to piece it all together for a comprehensive understanding. Similarly, I felt that a summary at the end of each section with the key take away points would have been beneficial to understanding how each component of the argument ties into the argument as a whole.

 

Questions for Pondering

  1. If the nucleus accumbens and the dorsal striatum are responsible for forming habitual drug seeking behaviors in addicts, why don’t we just lesion those brain areas?
  2. Why do you think that current drug rehab programs so often fail to change addictive behaviors?
  3. Using what Lende has shared with us, how could we use this knowledge to develop a more effective treatment process?
  4. Some children with negative home lives do not turn to drugs while others do. What do you think determines whether a child turns to drugs or not?
  5. Nature or nurture? Which do you think takes precedent in the context of addiction? Why?