Substance Use Disorders and Addictions

Keith J. Morgen

• Publisher: SAGE Publications, Inc
• Year: 2016
• ISBN:
  9781483370583
• Edition: 1
• Topic: Sciences sociales
• Subtopic: Sociologie

Based on a decade of research and theory, Substance Use Disorders and Addictions examines co-occurring psychiatric disorders as the norm with substance use disorders and addictions. With more than 20 years of experience in the field as a clinician, a researcher, a program developer, and an instructor, Keith Morgen encourages a holistic approach to working with individuals, using a single case example throughout the text to encourage the sequential application of concepts to co-occurring disorders. With DSM-5 diagnostic criteria, the 2014 ACA code of ethics, and 2016 CACREP standards integrated throughout, readers will benefit from this applied and cutting-edge introduction to the field. "Keith Morgen presents an outstanding updated text on substance use disorders where students will be able to better conceptualize treating the substance use disordered client while adhering to common clinical work flows integrating the DSM-5, the ACA's 2014 code, of ethics and the latest CACREP standards." –Kevin A. Freeman, Mercer University Substance Use Disorders and Addictions is part of the Counseling and Professional Identity Series. To learn more about each text in the series, please visit www.sagepub.com/cpiseries.

Chapter 1 Substance Use Disorder and Addiction: Basic and Brief Psychopharmacological and Neuropsychological Review

Opening Thoughts

Any discussion of substance use disorder and addiction must start in the brain. You are treating a psychological, neurological, and medical condition of the brain. Understanding how the substance(s) can act on the brain and how these actions may influence thought, emotion, and behavior is critical to understanding the substance use disorder and addiction condition. However, I want to emphasize that the information in this chapter in no way represents a complete and thorough coverage of the pertinent psychopharmacological and neuropsychological concepts. That is impossible. There are countless texts devoted entirely to the content here in Chapter 1. Consequently, my goal for this chapter is simple: I want you to learn content from the following pages and (perhaps more important) realize that there are other areas you need to learn more about and have an initial direction and leads to go address that inquiry. So this is where we start.

Central Nervous System

The human brain is built of two cell types: neurons (numbering in the 100 billion range) and an even larger number of glia. Each is addressed below.

Neurons

Neurons communicate via a series of circuits. These circuits are the foundation for all we are, experience, and feel. Thus, our thoughts, emotions, and behaviors are all rooted in neurons. Figure 1.1 displays the four parts of the neuron anatomy (cell body, axon, dendrites, and synapse). The cell body consists of the nucleus and receives all the input information and is consequently the origin of all neurotransmitter and action potential activation. Action potential is when a neuron membrane is depolarized beyond its threshold. The axon is the “sending” component that transmits a signal down the neuron to the synapse. Here, in the synapse, the neurotransmitters are released. This is how neurons speak to one another as the neurotransmitter signals are received by the dendrites on nearby neurons. In brief, neurons serve three functions: inhibition, excitation, and neuromodulation. Inhibition is the process of one neuron releasing an inhibitory neurotransmitter. Excitation is the neuron releasing an excitatory neurotransmitter. Neuromodulation involves one neuron impacting neurotransmission, typically at somewhat of a distance. Many receptors and neurotransmitter systems are involved with substance use disorder and addiction, including dopamine, serotonin, norepinephrine, glutamate, gamma-aminobutyric acid (GABA), acetylcholine, the endogenous opiate system, and the cannabinoid system (Pinel, 2013).

Figure 1.1 Neuron Anatomy

©iStockphoto.com/ttsz

Glia

These are supporting cells of the central nervous system and can outnumber neurons by a margin of 10 to 1. Glia used to be considered the glue of the central nervous system that holds neurons together. However, recent work has uncovered that glia are now known to have substantial influence over various central nervous system processes. Specifically, some glia cells regulate neurotransmission and are involved in the reuptake process for various excitatory neurotransmitters.

Neurotransmitters

Numerous neurotransmitters form the language via which neurons communicate and we live and breathe. At any given moment, all you feel, think, and do can be linked all the way back to these chemicals—neurotransmitters—which are passed between neurons in the synapse. A comprehensive review of the neurotransmitters is beyond the scope of this chapter and text. However, Figure 1.2 provides a brief review of the neurotransmitters involved with the substance use disorder and addiction conditions.

Figure 1.2 Neurotransmitters Relevant to Substance Use Disorders

Source: From “Impacts of Drugs on Neurotransmittion,” by National Institute on Drug Abuse, 2007 (https://www.drugabuse.gov/news-events/nida-notes/2007/10/impacts-drugs-neurotransmission).

Brain Areas Associated With Substance Use and Addiction

The brain is made up of a few areas with strong connections to the addiction process. These areas handle dozens of functions, and substance use or the recovery from substance use can impact functioning within these areas as well as the many thousands of connections, or tracts, between these structures (Pinel, 2013). Some key areas are discussed below.

Brain Stem

The hindbrain is made of the cerebellum, pons, and medulla. Typically, the midbrain, pons, and medulla are all tied together and described as being the brain stem (Pinel, 2013). The brain stem is theorized to handle such functions as motor control, language, attention, fear and pleasure regulation, the regulation of cardiac and respiratory function, regulation of the central nervous system, and the maintenance of consciousness. Figure 1.3 shows the location of the brain stem, cerebellum, pons, and medulla.

Figure 1.3 Anatomy of the Human Brain, Showing Brain Stem and Other Areas

© Can Stock Photo Inc./roxanabalint

Anatomically, the brain stem is the most interior and primitive brain area. Several components of the brain stem are theorized to be involved with substance use disorder and addiction, including the ventral tegmental area (VTA), substantia nigra (SN), and dorsal raphe nucleus (DRN). The VTA is involved in the substance and natural reward circuits of the brain and is critical for cognition and emotion (Pinel, 2013). In addition, the VTA’s neurons project to several other key brain areas relevant to substance use disorders and addiction, such as the prefrontal cortex (PFC). The SN plays a role in reward seeking and learning. The DRN also contributes to learning and memory functions, as well as playing a role in affect (Holtz, 2010).

Basal Ganglia

The basal ganglia sits between the brain stem and cortex and consists of areas relevant to substance use disorder and addiction. The nucleus accumbens (NAc) contributes to the cognitive processes of motivation, pleasure, reward, and reinforcement (Pinel, 2013), as well as playing a role regarding responses to novel stimuli (Holtz, 2010). The amygdala is involved with memory and decision-making and emotional processes; specifically, the consolidation of emotional memories (Pinel, 2013). Figure 1.4 shows the location of the basal ganglia and associated areas within the brain linked with addiction, such as the subthalamic nucleus (Pellouox & Baunez, 2013) and the caudate nucleus (Bohbot, Del Balso, Conrad, Konishi, & Leyton, 2013).

Figure 1.4 Drawing of the Brain Showing the Basal Ganglia and Thalamic Nuclei

© Can Stock Photo Inc./Blambs

Cortex

This is the outermost and most advanced brain area. Pinel (2013) and Holtz (2010) reviewed how the cortex consists of several areas linked with substance use disorders and addiction: the anterior cingulate cortex, dorsolateral prefrontal cortex, orbitofrontal cortex, insular cortex, and the hippocampus. The anterior cingulate cortex is responsible for such functions as reward anticipation, empathy, emotion, impulse control, and emotion. It helps to modulate emotional responses. The dorsolateral prefrontal cortex is involved in executive functions, which include working memory as well as cognitive flexibility and planning. This area is frequently discussed as relevant to problems with attention and motivation. In addition, this area is activated in risky or moral decision-making processes involving a cost/benefit analysis of several potential decisions. The orbitofrontal cortex may be involved with linking affect to reinforcement as well as the decision-making processes. The insular cortex is associated with exposure to substance-related triggers, and this brain area is involved with a host of functions, including the processing of negative emotional experience (Critchley, Wiens, Rotshtein, Öhman, & Dolan, 2004) as well as the integration of sensory input from multiple sources (Taylor, Seminowicz, & Davis, 2009). Finally, the hippocampus plays a critical role in the integration of emotion and memory as well as having an influence on long-term memory (Pinel, 2013). Figure 1.5 displays the general human brain anatomy and the functions associated with these areas. Just about all these areas are in some manner influenced by the addiction process, whether during the active use and/or recovery periods.

Figure 1.5 Human Brain Anatomy, Function Area, and Mind System

Adapted from © Can Stock Photo Inc./eveleen.

Dopamine Pathways

As discussed in Figure 1.2, dopamine plays a pivotal role across most substances discussed in this text. There are four dopamine pathways in the brain, with the first three being involved in the substance use disorder and addiction process: mesolimbic, mesocortical, nigrostriatal, and tuberorinfundibular. Each is briefly discussed below.

The mesolimbic pathway runs between the ventral tegmental area to the nucleus accumbens. However, the dopamine cells of the mesolimbic pathway also project to other areas relevant to substance use disorders and addictions, including the amygdala, bed nucleus of the stria terminalis (BNST), and lateral hypothalamus. The mesocortical pathway extends to the frontal lobes and includes several structures believed to have an important role in the addictive process, such as the dorsolateral prefrontal cortex (Dagher, Owen, Boecker, & Brooks, 1999), the orbitofrontal cortex, and the anterior cingulate (Bush, Luu, & Posner, 2000). For example, the prefrontal cortex facilitates the control of impulsive behavior. Any alteration in this area, such as via substance use, could lead to increased impulsivity and possible substance use. The third dopamine pathway in the brain is the nigrostriatal pathway, which primarily controls movement and may explain some motor deficits in substance-using individuals (Gardner & Ashby, 2000). The fourth pathway, the tuberoinfundibular pathway, does not play a role in substance use and addiction.

Psychopharmacology: Basics

Route of Administration

The specific format in which a substance is administered will have a major impact on four key concepts: (1) the speed in which the substance begins influencing the body, (2) how this substance is distributed throughout the body, (3) the intensity of the effect, and (4) the speed in which any side effects will be experienced. There are a few ways that substances are administered, with most being divided between the enteral or parenteral routes.

Enteral Substance Administration

Substances administered via the enteral route enter into the bloodstream through the gastrointestinal system (Stahl, 2013). This route is most typically administered orally via a liquid or tablet. Another enteral route is sublingual via the blood-rich tissues found under the tongue.

Parenteral Substance Administration

This route entails the injection of the substance directly into the body (Stahl, 2013) and is typically the preferred route if a rapid onset of substance effects is desired. There are a few types of parenteral administration. Subcutaneous administration is the injection of a substance right below the skin surface, with the advantage being slow absorption into the body. This process (called “skin popping” by illegal substance users) thus provides the substance available for absorption over a period of time. Intramuscular administration injects the substance directly into the muscle. Since muscles are blood rich, the intramuscular process administers the substance into the body quicker than the subcutaneous method. The intravenous method injects the substance directly into the vein; thus, this provides a direct and immediate access to the bloodstream (Stahl, 2013).

Other Routes of Administration

Transdermal administration involves the absorption of a substance through the skin surface. Intranasal administration involves “snorting” the substance through the nose, allowing the substance to enter the system through blood-rich sinus tissues. Inhaling administers the substance into the system via passing through the microscopically thin (1/100,000th of an inch) layer between the air and the circulatory system via the blood-rich tissues in the lungs (Stahl, 2013).

Distribution and Transport

DeVane (2004) underscored the case-by-case nature of substance distribution, with the process influenced by countless variables such as gender, age, muscle tissue ratio, or degree of hydration at the time of substance administration. Substances also need to move to a site of action in the body. However, some types of chemicals move more freely than others. For example, water-soluble compounds can mix easily with blood plasma and can thus be easily moved throughout the body. Alcohol is an example of a water-soluble compound. Other compounds must bind with fat molecules in order to move throughout the body. These compounds are called lipid soluble. While a lipid-soluble compound is bound to the fat molecules the compound cannot be eliminated from the body, but it also cannot produce the intended effect. Thus, the compound must detach from the lipid molecules and enter the bloodstream to reach the site of action desired.

Biotransformation

Biotransformation is usually focused in the liver, although other organs, such as the kidneys, might also be involved...