Source: Abnormal Psychology, University of Florida
Difficulty: Intermediate | Prerequisites: Introductory familiarity with the DSM (Diagnostic and Statistical Manual of Mental Disorders) and basic neuroscience terms (central nervous system, neurotransmitters). Earlier chapters on anxiety or mood disorders provide useful context for understanding comorbidity.
Substance use disorders sit at the intersection of biology, psychology, and social context. This chapter defines what counts as a substance use disorder, walks through how the diagnostic criteria evolved from DSM-IV to DSM-5, and then surveys the five major substance classes covered in the course: depressants, stimulants, opioids, hallucinogens, and cannabis. You should already be comfortable with the general structure of DSM diagnoses and the idea that mental disorders exist on a spectrum of severity. The material here connects directly to later discussions of treatment approaches and to the comorbidity patterns you will see across mood, anxiety, and personality disorders.
A substance use disorder is a pattern of chronic difficulty resisting alcohol or drugs that causes real harm to a person's life. The DSM-5 merged the older categories of "substance abuse" and "substance dependence" into one unified diagnosis with 11 criteria grouped under four domains: impaired control, social impairment, risky use, and pharmacological indicators (tolerance and withdrawal). At least two criteria must be present over a 12-month period for a diagnosis.
Substance use disorder (SUD)
A disorder involving chronic difficulties in resisting the desire to drink alcohol or take drugs, resulting in clinically significant impairment or distress. Think of it as the umbrella diagnosis that replaced the older abuse/dependence split.
Substance
Any natural or synthesised product that has psychoactive effects.
Substance intoxication
Behavioural and psychological changes that occur as a direct result of a substance's physiological effects on the central nervous system. In simple terms, this is the state of being "under the influence."
Substance withdrawal
Psychological and behavioural symptoms that emerge when a person who has been using a substance heavily for a prolonged period stops or sharply reduces use. Withdrawal symptoms are typically the opposite of intoxication effects.
Substance abuse (DSM-IV)
A diagnostic category for recurrent substance use that leads to significant harmful consequences across four areas: failing obligations, hazardous use, legal problems, and continued use despite social or legal trouble. Think of it as the "harmful pattern" diagnosis, now folded into the broader SUD category.
Substance dependence (DSM-IV)
The condition most people think of as "drug addiction," characterised by tolerance, withdrawal, compulsive use, and inability to stop despite harm. This category was merged with substance abuse in DSM-5.
Tolerance
Diminished effects from the same dose, requiring increasingly larger amounts to achieve intoxication. In simple terms, the body adapts, so you need more to feel the same thing.
Physiological dependence
A state in which the body has adapted to the presence of a substance so that withdrawal symptoms appear when use stops. Not required for a DSM-IV diagnosis of dependence.
Psychological dependence
Compulsive use of a substance despite disruptions in everyday functioning, driven by craving rather than physical withdrawal.
Craving
An intense desire or urge to use a substance. Added as a criterion in DSM-5 (replacing the legal-problems criterion from DSM-IV).
Blackout (alcohol-induced amnesia)
Amnesia for events that occurred while intoxicated, experienced once the person is sober again. This is a memory gap, not a loss of consciousness.
Delirium tremens (DTs)
The most severe stage of alcohol withdrawal, involving auditory, visual, and tactile hallucinations, terrifying delusions, fever, and irregular heart rate. Fatal in roughly 10% of cases.
Behavioural and psychological changes caused by a substance's physiological effects on the CNS
Onset is soon after ingestion; severity scales with the amount consumed
Intoxication declines as the substance clears from the body, but symptoms may linger for hours or days after the substance is no longer detectable
Specific symptoms depend on the substance, the dose, tolerance, the context, and the user's expectations
Acute (short-term) intoxication is clinically distinct from chronic intoxication
Psychological and behavioural symptoms that appear when heavy, prolonged use is stopped or sharply reduced
Withdrawal symptoms are typically the opposite of the intoxication effects for that substance
Must cause significant distress or impairment in everyday functioning to qualify diagnostically
Diagnosed when recurrent use leads to significant harmful consequences in at least one of four categories within 12 months:
Failure to fulfil major obligations at home, work, or school (showing up late, poor performance, using at work)
Repeated use in physically hazardous situations (e.g. driving)
Recurrent legal problems related to the substance (DUI, possession)
Continued use despite ongoing social or legal problems caused by the substance
This is what most people think of as "addiction." Key features:
Tolerance: the same dose produces diminished effects, so the person needs more
A person may have a very high blood level of the substance without being aware of its effects
Risk of developing tolerance varies: highest for alcohol, opioids, stimulants, and nicotine; lower for cannabis and PCP
Withdrawal: psychologically dependent users experience severe withdrawal symptoms
Sometimes the substance must be tapered gradually to prevent dangerous symptoms
Users may keep taking the substance specifically to avoid withdrawal
Physiological dependence was not required for a DSM-IV diagnosis of substance dependence; compulsive use despite life disruption was sufficient
A dependence diagnosis preempted an abuse diagnosis (a person could have abuse without dependence, but not both simultaneously)
The DSM-5 merged the separate categories of substance abuse and substance dependence into a single diagnosis: substance use disorder.
Why the change:
Clinicians found it difficult to reliably differentiate abuse from dependence
The legal-problems criterion from DSM-IV was dropped because it was very rare in adults
A craving criterion was added in its place
Research showed 9-10% prevalence under both the old and new systems, so DSM-IV criteria can still be used for discussion purposes
What DSM-5 recognises:
10 substance classes where substance use disorders can occur
Five of those classes are covered in this chapter: depressants, stimulants, opioids, hallucinogens, and cannabis
Severity is graded by the number of criteria met: 2-3 = mild, 4-5 = moderate, 6+ = severe
At least 2 of these 11 criteria must be present over a 12-month period for a diagnosis.
Substance taken in larger amounts or over a longer period than originally intended
Craving: an intense desire or urge to use the substance
Persistent desire to cut down or control use
A great deal of time spent obtaining, using, or recovering from the substance
Failure to fulfil major role obligations at home, work, or school
Important social, work, or recreational activities given up or reduced because of substance use
Continued use despite persistent or recurring social or relationship problems caused or worsened by the substance
Recurrent substance use in physically dangerous situations (driving, operating machinery)
Continued use despite awareness of ongoing physical or psychological problems likely caused or worsened by the substance
Tolerance: needing increased amounts for the desired effect, or experiencing diminished effect at the same dose
Withdrawal: characteristic withdrawal symptoms for the substance, and/or taking the same or a similar substance to relieve withdrawal symptoms
"Substance abuse and substance dependence are the same thing." They were separate diagnoses in DSM-IV. Abuse referred to harmful patterns of use; dependence referred to what most people call addiction (tolerance, withdrawal, compulsive use). The DSM-5 merged them, but understanding the historical distinction matters for exam questions.
"You need physical withdrawal symptoms to be diagnosed with a substance use disorder." Physiological dependence (tolerance and withdrawal) was not required even under DSM-IV. Compulsive use despite life disruption was enough. Under DSM-5, any two of the 11 criteria suffice.
"Tolerance is the same as dependence." Tolerance is one feature of dependence (needing more to feel the same effect), but dependence involves a broader pattern of compulsive use and loss of control. A person can develop tolerance without meeting criteria for a full disorder.
"The DSM-5 still uses the legal-problems criterion." It does not. That criterion was dropped because legal consequences were very rare in adult populations. Craving replaced it.
Know the 11 DSM-5 criteria and which domain each belongs to (impaired control, social impairment, risky use, pharmacological). This is very likely to appear as a matching or classification question.
Be able to explain why DSM-5 merged abuse and dependence (low reliability of the abuse diagnosis, difficulty differentiating the two in practice).
Understand the difference between tolerance and withdrawal, and that neither is required for a DSM-5 diagnosis.
The shift from "legal problems" to "craving" is a commonly tested DSM-IV-to-DSM-5 change.
Know that DSM-5 uses a severity spectrum (mild, moderate, severe) based on criterion count, rather than a binary abuse-or-dependence split.
True or False: Under DSM-5, a person must show tolerance and withdrawal to be diagnosed with a substance use disorder. (False, any 2 of 11 criteria suffice.)
True or False: DSM-5 still includes legal problems as a diagnostic criterion. (False, it was replaced by craving.)
Fill in the blank: The four DSM-5 criterion domains are impaired control, social impairment, risky use, and ______. (Pharmacological criteria.)
True or False: Under DSM-IV, a person could receive both an abuse and a dependence diagnosis simultaneously. (False, dependence preempted abuse.)
Fill in the blank: In DSM-5, a substance use disorder is graded as mild (2-3 criteria), moderate (4-5), or ______ (6+). (Severe.)
Q: A patient needs increasingly larger doses of a substance to achieve the same effect. Which DSM-5 criterion does this illustrate, and which domain does it fall under?
A: This illustrates tolerance (Criterion 10), which falls under the pharmacological criteria domain.
Q: What was the primary reason the DSM-5 combined the categories of substance abuse and substance dependence?
A: Clinicians had difficulty reliably differentiating the two, and the diagnosis of substance abuse showed low inter-rater reliability.
Q: Under DSM-5, how many criteria must be present, and over what time period, for a substance use disorder diagnosis?
A: At least 2 of 11 criteria must be present over a 12-month period.
Q: Name the four domains of the DSM-5 substance use disorder criteria and give one example criterion from each.
A: Impaired control (e.g. craving), social impairment (e.g. failure to meet role obligations), risky use (e.g. use in dangerous situations), pharmacological criteria (e.g. tolerance).
Q: A person uses a substance compulsively and it severely damages their work and relationships, but they show no signs of tolerance or withdrawal. Could they be diagnosed with a substance use disorder under DSM-5?
A: Yes. Physiological dependence (tolerance and withdrawal) is not required. If at least two criteria from any domain are met over 12 months, the diagnosis applies.
This material connects to mood disorders (Chapter 6) because substance use disorders frequently co-occur with depression and bipolar disorder, and substance-induced mood changes can complicate differential diagnosis. It also links to anxiety disorders (Chapter 5), since withdrawal symptoms often include significant anxiety, and many people use substances to self-medicate anxiety. Later chapters on treatment will draw directly on the DSM-5 criteria covered here, as severity grading (mild, moderate, severe) guides treatment intensity.
Substance use disorder, SUD, substance abuse, substance dependence, drug addiction, tolerance, withdrawal, craving, intoxication, DSM-5 criteria, DSM-IV vs DSM-5, impaired control, social impairment, risky use, pharmacological criteria, psychoactive substance, physiological dependence, psychological dependence, blackout, delirium tremens, DTs, abnormal psychology, University of Florida, Chapter 14