10 Addictions psychiatry10.2 Explanations for substance use
10.2 Drug use, dependence and sociocultural explanation
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Written by Resident Doctor Committee · Published
Patterns of illegal drug use
The Crime Survey for England and Wales for the year to March 2025 put past-year illicit drug use at 8.7% of people aged 16 to 59 and 15.1% of those aged 16 to 24, with cannabis the commonest drug.
Household surveys miss people in custody, people without stable housing and others in excluded settings.
Pattern | What defines it | Course |
|---|---|---|
Experimental | Curiosity on a single occasion, with no repeated pattern | Most young people who try a drug stop here |
Situational | Use tied to one kind of setting, such as festivals, parties or clubs, usually with stimulants or hallucinogens | Stops outside that setting |
Recreational | Regular, long-standing use without tolerance or withdrawal | Can progress to dependence |
Dependent | Daily use kept going to relieve withdrawal | Tolerance has removed most of the pleasure |
Why use continues
Positive reinforcement repeats use that felt good, and negative reinforcement repeats use that removes distress or withdrawal.
Identity, relationships, stress and scarce alternative rewards can maintain use without any withdrawal.
Tolerance
Tolerance is a reduced response after repeated use, so larger amounts are needed for an effect once produced by less.
Tolerance is the pharmacological opposite of sensitisation, and it is distinct from dependence and addiction.
Diminished (reverse) tolerance to alcohol arises after abstinence, as acquired tolerance is lost.
Reverse tolerance also arises with alcohol-related brain damage in older drinkers and with impaired hepatic metabolism in liver disease.
Alcohol dependence syndrome and typology
In the Edwards and Gross syndrome, narrowing of the repertoire is a shift from varied drinks and settings to one fixed, stereotyped daily drinking pattern.
Reinstatement is a return to the full dependent pattern within days of drinking again after long abstinence.
Cloninger's type 2 alcoholism is early-onset, male-limited and antisocial, and the person cannot abstain. Type 1 is late-onset and milieu-limited.
ICD-11 hazardous and harmful use
Category | Definition |
|---|---|
Hazardous substance use | Appreciably raised risk to the user or others, with no specific harm yet |
Harmful pattern of use | Damage to health or harm to others has occurred |
The two differ in whether harm has already happened. Both count harm to other people.
Dependence potential
Cannabis has the lowest dependence potential of commonly compared recreational substances, below alcohol, cocaine, heroin and tobacco, in expert scores and in the proportion of users who become dependent.
Cannabis can still cause dependence, psychosis and hyperemesis.
Ketamine and anabolic steroids
Chronic ketamine use causes ulcerative cystitis by toxic injury to the urothelium, leaving an ulcerated, fibrosed, small-capacity bladder.
Anabolic-androgenic steroids are the drugs most associated with non-medical use to build muscle, improve performance and speed recovery.
Steroid users are now a prominent group among people who inject drugs.
'Roid rage', acute emotional instability with aggression, is a recognised psychiatric effect of steroid misuse, for example with nandrolone.
Street names
A substance history needs each slang name matched to the right drug.
Drug | Form and action | Street names |
|---|---|---|
Ketamine | Dissociative anaesthetic, usually snorted as a powder | K, ket, Special K |
Mephedrone | Synthetic cathinone stimulant sold as a white powder | Meow meow, M-cat, drone |
Gamma-hydroxybutyrate (GHB) | Clear liquid taken in millilitre doses; a central depressant acting at gamma-aminobutyric acid type B (GABA-B) receptors | G, GBH, liquid ecstasy |
Methamphetamine | Crystalline, smokable form | Ice, crystal, crystal meth; Tina in chemsex settings |
GHB is chemically unrelated to MDMA, though one of its street names is liquid ecstasy.
Family and social aspects
Co-dependency is a person's psychological reliance on another's addiction, shown by self-sacrificing, rescuing and controlling caretaking.
The co-dependent carer absorbs the dependent person's responsibilities and consequences at the cost of their own needs.
Enabling behaviour is action by those close to the person that shields them from the consequences of use and so sustains it.
Co-dependency describes the carer's own reliance on the addiction, while enabling describes the protective actions that keep use going.
In the National Treatment Outcome Research Study (NTORS), shoplifting was the offence drug-dependent people most often reported on entering treatment.
Culture and criminalisation
Khat is used socially in some Somali, Yemeni and Ethiopian communities and became Class C in the UK in June 2014.
Criminalising khat changed access and consequences, not its stimulant pharmacology.
County lines networks exploit children and vulnerable adults, so assess coercion and safeguarding needs.