Milan Valyear has a Master’s degree in psychology from Wilfrid Laurier University and is currently a doctoral candidate at the Center for Studies in Behavioral Neurobiology at Concordia. He studies addiction in the lab of Dr. Nadia Chaudhri and is particularly interested in the neural systems that control how cues in the environment trigger relapse. Using cutting-edge neuroscience tools, he is able to silence specific neural pathways when rats are presented with alcohol cues and observe how they respond.
Blog post
Defining your discipline
June 19, 2018
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As a graduate student studying addiction in rats, I often find it difficult to define my discipline in exact parameters because of the different ways addiction can be characterized depending on the lens through which it is being viewed. Perhaps my first year psychology professor said it best when he advised, “beware that as you aim to shape your discipline, you too will be shaped by your discipline.”
Three definitions of addiction
Clinicians use a set of criteria outlined in the Diagnostic and Statistical Manual of Mental Disorders1 (DSM) to diagnose a variety of psychological conditions. The DSM, however, does not have a set of criteria for addiction. Instead, Substance Use Disorder can be diagnosed as mild, moderate, or severe depending on the expression of 11 criteria grouped into four categories: impaired control, social impairment, risky use, and pharmacological criteria. The relevant criteria for diagnosis are further specified for 10 different substance classes. These criteria are intricate and complicated, but we can observe similar behaviours in rats and use those behaviours to study addiction in the lab. While the constellation of clinical criteria used to diagnose substance use disorders is incredibly useful, it does not seem to adequately define my field of study.
Alternatively, neuroscientists that study addiction have divided the condition into three broad stages: 1) Binge/Intoxication 2) Withdrawal/Negative Affect 3) Preoccupation/Anticipation.2 It is thought that people with substance use disorders cycle through these stages and relapse during the preoccupation/anticipation stage. Initially substance use in the binge/intoxication stage may be controlled by euphoria. However, through many cycles of these stages, substance use may transition to being controlled by the alleviation of dysphoria in the withdrawal/negative affect stage. This dysphoria experienced in the second stage is partly counteracted by the resumption of substance use which maintains the disorder.
For some neuroscientists it is the maintenance of substance use that best characterizes addiction.3 They study the changes in the brain that occur once substance use has become stable, unrelenting, and controlled by dysphoria. Other neuroscientists focus on the acquisition of substance use. How does substance use transition from infrequent to regular?
Some pioneering studies on the acquisition of cocaine use were conducted at Concordia University where researchers allowed rats to press a lever to receive an infusion of cocaine. The majority of rats initially lever-pressed infrequently and irregularly but soon learned to perform stable, regularly-paced lever-presses earning them many infusions of cocaine.4 Although the majority of rats exhibit stable lever-pressing, only a smaller subpopulation display addiction-like behaviours similar to those in the DSM.5 The transition from sampling a substance infrequently to consuming it regularly must precede any cycles through the aforementioned stages of addiction. This initial transition might qualify as a definition of addiction on its own, but it misses some key features that are described in the stages of addiction.
Starting points for meaningful improvements
Only three definitions of addiction are discussed here, but many more exist. The clinical definition of addiction is calculated, descriptive, and designed for diagnosis. The maintenance definition focuses on the dysphoric processes that gain control over substance use. The acquisition definition describes the shift from sampling a substance to using it regularly. While each definition is unique, any definition could serve as a starting point to make meaningful improvements for people suffering from substance use disorders. A clinician could refine the diagnostic criteria or subcategorize different types of disorders to ensure appropriate treatments are prescribed. A neuroscientist studying the maintenance of substance use could develop therapeutic interventions to make quitting more manageable. Alternatively, a neuroscientist studying the acquisition of substance use might discover a method to prevent substance use disorders from developing in the first place.
I might subscribe to the maintenance definition of addiction in my research because it is specific and relates to my subfield. However, it is perhaps best to accept that no definition of a complex field will encompass every nuance. In order to progress in my research and impact my discipline I must also allow a place for other definitions of addiction to live. I aim to shape my discipline, and I allow it to shape me.
1. American Psychiatric Association. Diagnostic and statistical manual of mental disorders. (2013).
2. Koob, G. F. & Volkow, N. D. Neurocircuitry of Addiction. Neuropsychopharmacology 35, 217–238 (2010).
3. Wise, R. A. & Koob, G. F. The development and maintenance of drug addiction. Neuropsychopharmacology 39, 254–62 (2014).
4. Bozarth, M. A. & Wise, R. A. Toxicity associated with long-term intravenous heroin and cocaine self- administration in the rat. J. Am. Med. Assoc. 254, 81–83 (1985).
5. Deroche-Gamonet, V., Belin, D. & Piazza, P. V. Evidence for addiction-like behavior in the rat. Science (80-. ). 305, 1014–7 (2004).
About the author
