DCM 2101 · CNS Pharmacology
Drug Abuse: Definitions, Risk Factors and Clinical Assessment
Substance-related problems are common in clinical practice and may present in any department: trauma, emergency care, medical wards, mental health, antenatal care, outpatient clinics and community health. A patient may arrive with seizures, confusion, depression, injuries, gastrointestinal bleeding, pneumonia, sexual risk, violence, poor treatment adherence or social collapse—and the underlying contributor may be harmful substance use. This lesson explains the language, biology and biopsychosocial factors behind drug abuse. The aim is not to label or shame a person. It is to help the clinical learner recognise risk early, speak safely and respectfully, assess urgency, and connect the patient to appropriate care.Learning objectives
- Define drug, psychoactive substance, drug use, misuse, hazardous use, harmful use, dependence and substance use disorder.
- Explain why the older term drug abuse should be used carefully in modern clinical communication.
- Describe the neurobiology of reward, tolerance, dependence, withdrawal and craving.
- Classify psychoactive substances by their main CNS effect without glamorising their use.
- Identify individual, family, peer, school, community and structural risk factors.
- Identify protective factors and principles of prevention.
- Take a brief, non-judgemental substance-use history and identify urgent red flags.
1. What do we mean by “drug abuse”?
A drug is any substance capable of changing a biological function. Many drugs are beneficial when prescribed correctly: for example antibiotics, anaesthetics, antiepileptic medicines and opioid analgesics. A psychoactive substance is a substance that changes mental processes such as perception, consciousness, mood, cognition or behaviour. Alcohol, nicotine, cannabis, sedatives, opioids, stimulants and some medicines can all be psychoactive.Important language point: “Drug abuse” is still used in many teaching curricula and public discussions, but it can sound blaming and is not a precise diagnosis. Prefer substance use, hazardous substance use, harmful substance use, substance dependence or substance use disorder when documenting and speaking with patients. Use person-first language: say “a person with an opioid use disorder,” not “an addict.”
| Term | Meaning | Clinical example |
|---|---|---|
| Use | Consumption of a substance. Use alone does not automatically mean disorder, but it may still be unsafe in some circumstances. | Taking a prescribed sedative exactly as directed after surgery. |
| Misuse | Using a medicine in a way that differs from its prescription or intended purpose. | Taking another person’s tramadol, doubling a prescribed dose, or using a sedative to sleep after alcohol use. |
| Hazardous / risky use | A pattern that increases the probability of future harm, even when harm is not yet clearly established. | Drinking alcohol before driving, or recurrent intoxication in a person with epilepsy. |
| Harmful use | Use that has already caused physical or mental health damage. | Alcohol-associated gastritis, cannabis-associated panic symptoms, or injection-related infection. |
| Dependence | A physiological and behavioural adaptation marked by strong desire to use, impaired control, tolerance and/or withdrawal. | A person develops tremor and anxiety when alcohol is stopped and drinks to relieve the symptoms. |
| Substance use disorder (SUD) | A clinically significant pattern of problematic use with impaired control, social impairment, hazardous use and pharmacological features such as tolerance or withdrawal. | Repeated opioid use despite overdoses, family conflict and failure at work, with persistent craving and inability to cut down. |
| Intoxication | Reversible, acute behavioural and physiological effects while a substance is active in the body. | Slurred speech, unsteady gait and impaired judgement after alcohol. |
| Withdrawal | A syndrome that follows reducing or stopping a substance after physiological adaptation. | Seizures and delirium after abrupt cessation of heavy alcohol use; diarrhoea, pain and yawning after opioid cessation. |
Why the definition matters
Clinical decisions depend on the pattern, not only the name of the substance. A patient can have serious acute intoxication without dependence; another can have dependence without being intoxicated during the clinic visit. A prescribed medicine can be medically appropriate, harmful, misused or associated with dependence depending on indication, dose, duration, monitoring, co-use with other substances and the patient’s circumstances.2. How substance use becomes a health problem
Substance use is not explained by “weak character.” It develops through an interaction of brain biology, genetics, mental health, trauma, family environment, peer influence, opportunity, culture, poverty, marketing and drug availability. The same substance may have very different effects in different people and situations.The reward pathway
Many psychoactive substances, through different mechanisms, increase dopamine signalling in the mesolimbic reward pathway. This pathway includes dopaminergic neurons in the ventral tegmental area and targets such as the nucleus accumbens, limbic structures and frontal cortex. Dopamine is not simply the “pleasure chemical”; it helps assign salience, motivates learning and reinforces behaviours linked with reward.
Initial reinforcement
A substance may reduce anxiety, relieve pain, produce stimulation, sedation, euphoria or social disinhibition. The brain learns to repeat the action because it is followed by an immediate reward or relief.
Conditioning and cues
Places, friends, emotions, music, money, stress and even particular times of day become cues linked to use. Later, these cues can trigger craving before the substance is taken.
Tolerance
Repeated exposure may cause reduced response. The person uses more to obtain the same effect, increasing toxicity and financial/social harm. Tolerance to one effect does not guarantee tolerance to respiratory depression, overdose or accidents.
Dependence and withdrawal
The body adapts to ongoing exposure. When the substance is removed, symptoms may occur because the adapted brain and body are temporarily unbalanced. Using again may relieve withdrawal, reinforcing continued use.
Clinical insight
Negative reinforcement is powerful
Early use may be driven by seeking pleasure (positive reinforcement). With progression, use may be driven mainly by avoiding withdrawal, distress, insomnia, pain or dysphoria (negative reinforcement). This helps explain why telling a dependent person simply to “stop” is rarely enough. Effective care combines medical assessment, psychological support, social intervention and relapse prevention.3. Broad classification of psychoactive substances
The next lesson examines major drugs and management in detail. For this introduction, classify substances by their predominant CNS effect. A single substance can produce more than one effect, and effects change with dose, route, combinations and patient factors.| Group | Examples | Typical CNS effect | Important clinical concern |
|---|---|---|---|
| Depressants / sedatives | Alcohol, benzodiazepines, barbiturates, some sleeping medicines | Reduced anxiety, sedation, impaired coordination and slowed reaction time. | Respiratory depression, falls, road traffic injury, dangerous withdrawal and greater overdose risk when combined with opioids. |
| Opioids | Morphine, codeine, tramadol, heroin, fentanyl and related medicines | Analgesia, sedation and euphoria through opioid receptors. | Respiratory depression, coma and death in overdose; constipation; dependence and severe withdrawal discomfort. |
| Stimulants | Caffeine, nicotine, amphetamines, cocaine and related substances | Increased alertness, energy, sympathetic activity and sometimes euphoria. | Agitation, arrhythmia, hypertension, hyperthermia, psychosis, seizures and cardiovascular events. |
| Cannabinoids | Cannabis products and synthetic cannabinoids | Altered perception, relaxation, impaired memory/coordination; effects can be unpredictable. | Accidents, panic, impaired learning, psychotic symptoms in vulnerable people and dangerous effects with synthetic products. |
| Hallucinogens / dissociatives | LSD-like substances, ketamine, phencyclidine and some plant products | Marked perceptual change, altered reality testing or detachment from surroundings. | Accidental injury, panic, severe agitation, psychosis and risky behaviour. |
| Inhalants | Solvents, glues, petrol and aerosols | Rapid intoxication with dizziness, disinhibition and CNS depression. | Hypoxia, aspiration, burns, arrhythmias and sudden death; strong safeguarding concerns in children and adolescents. |
| New psychoactive substances | Unregulated synthetic stimulants, cannabinoids and other rapidly changing products | Variable and often unpredictable. | Unknown purity, adulterants, delayed recognition and severe toxicity not detected by routine testing. |
4. Risk factors: the biopsychosocial model
A risk factor is a feature associated with higher likelihood of harmful use or substance use disorder; it is not proof that a person will develop a disorder. Risk factors accumulate and interact. A good clinician asks not only “what substance?” but also “what function is this substance serving in this person’s life?”A. Individual and biological factors
- Age and neurodevelopment: adolescence and young adulthood are periods of high vulnerability. The reward system is highly responsive while judgement, impulse control and long-term planning continue to mature. Early initiation is associated with greater later risk.
- Genetic and family predisposition: heritability contributes to vulnerability, but genes do not act alone. A family history should prompt supportive screening, not fatalism or blame.
- Temperament and impulsivity: novelty seeking, poor impulse control, sensation seeking and difficulty regulating emotion may increase risk when combined with access and stress.
- Chronic pain or disability: people may self-medicate pain, insomnia or functional limitation. Prescribed opioids and sedatives require careful risk–benefit review and monitoring.
- Previous exposure: early nicotine, alcohol or cannabis use may increase later risk through learning, social exposure and neurodevelopmental effects.
- Pregnancy: pregnancy does not prevent substance use disorder. It requires confidential, compassionate assessment because abrupt cessation of some substances can be harmful and both maternal and fetal risks must be managed by trained clinicians.
B. Mental health and trauma factors
- Depression, anxiety, PTSD and grief: substances may be used to numb distress, sleep or escape intrusive memories. They commonly worsen mood, sleep and functioning over time.
- Psychotic and bipolar disorders: substance use can trigger, mimic or worsen symptoms; stimulant and cannabis exposure may be particularly important in a vulnerable person.
- Attention and behavioural disorders: untreated symptoms, academic difficulty and impulsivity may increase risk. Assessment should distinguish prescribed therapeutic use from non-medical misuse.
- Adverse childhood experiences: abuse, neglect, household violence, parental substance problems, bereavement and displacement increase risk through chronic stress, disrupted attachment and limited coping resources.
- Suicidality: intoxication lowers inhibition and increases impulsive self-harm risk. Always assess suicidal thoughts, plans and immediate safety when mental distress and substance use coexist.
C. Family and relationship factors
Factors that increase risk
- Parental or caregiver substance use that is normalised or poorly supervised.
- Family conflict, violence, separation, neglect or inconsistent discipline.
- Low emotional connection, poor communication or absence of safe adult support.
- Economic stress that increases conflict, hopelessness or unsafe work patterns.
Protective family factors
- Warm, consistent caregiving and clear boundaries.
- Open discussion of substances without humiliation or threats.
- Adults who model healthy coping and seek care early.
- Practical support for school, work, healthcare and safe recreation.
D. Peer, school and workplace factors
- Peer pressure and social norms: friends can create direct pressure, make a substance available, or create the false belief that “everyone is doing it.” Peer influence can also be protective when friends support healthy goals.
- School disengagement: poor attendance, learning difficulty, bullying, exclusion and lack of future opportunity can increase risk. School connectedness and achievement are protective.
- Workplace exposure: occupational stress, long shifts, isolation, injury, access to medicines, transport work and workplace cultures that normalise alcohol or stimulant use may contribute.
- Leisure and boredom: lack of safe recreation and positive identity-building activities can leave young people more vulnerable to risky peer environments.
E. Community, economic and structural factors
- Availability and price: easy access, informal sale, poor regulation, low price and aggressive marketing increase exposure.
- Poverty, unemployment and inequality: financial stress, hopelessness, unstable housing and lack of opportunity can increase risk; they also make recovery harder.
- Conflict, displacement and disasters: trauma, separation from family, disrupted health services and loss of livelihood increase vulnerability.
- Stigma and barriers to treatment: fear of arrest, rejection, violence, cost, distance, confidentiality concerns and lack of youth-friendly services delay help-seeking.
- Media and digital influence: online content can normalise intoxication, promote products or spread misinformation. Critical media literacy is increasingly important.
5. Protective factors: what reduces risk?
Prevention is more than warning young people about drugs. Effective prevention strengthens the conditions that make healthy choices possible.| Level | Protective factors and practical examples |
|---|---|
| Individual | Emotional regulation, coping skills, accurate knowledge, problem-solving, refusal skills, treatment of pain and mental illness, positive identity and hope for the future. |
| Family | Secure attachment, supervision appropriate to age, respectful communication, stable routines and early help for conflict or caregiver substance problems. |
| School / workplace | Belonging, anti-bullying systems, academic/work support, clear substance policies, safe recreation, counselling and confidential referral routes. |
| Community | Youth-friendly services, mental-health care, safe housing, livelihood opportunities, faith/community support, sports/arts and protection from violence. |
| Policy | Age limits, drink-driving enforcement, regulation of marketing and supply, access to essential medicines without diversion, and evidence-based treatment rather than punishment alone. |
6. Recognising possible harmful substance use
No single sign proves substance use. Look for a pattern, ask directly and consider alternative diagnoses. Symptoms may be due to infection, delirium, head injury, metabolic disease, medication adverse effects, mental illness or interpersonal violence.
Physical clues
- Unexplained injuries, falls, burns or road traffic incidents.
- Altered pupils, tremor, sweating, slurred speech, unsteady gait, sedation or marked agitation.
- Sleep disturbance, appetite/weight change, recurrent gastritis, liver disease, needle marks, skin infections or sexual-health risk.
- Repeated presentations with vague symptoms, pain requests or medication loss.
Behavioural and social clues
- Decline in work/school performance, absenteeism or financial difficulty.
- Relationship conflict, secrecy, legal problems or social withdrawal.
- Using alone, using in dangerous situations, escalating amount or inability to cut down.
- Continuing despite clear harm, repeatedly seeking early prescriptions, or spending much time obtaining/using/recovering.
Mental-health clues
- Anxiety, depressed mood, irritability, panic, paranoia, hallucinations or cognitive impairment.
- Suicidal thinking, self-neglect or violent behaviour—especially during intoxication or withdrawal.
- Symptoms that appear after starting, escalating or stopping a substance.
7. A respectful clinical assessment
Use a private setting whenever possible. Start with a normalising, non-accusatory introduction: “I ask all my patients about alcohol, tobacco, medicines and other substances because they can affect sleep, mood, pain and treatment. Would it be okay to ask you a few questions?”Key history questions
- What substances? Include alcohol, tobacco/nicotine, cannabis, non-prescribed medicines, prescribed medicines, inhalants, stimulants, opioids and traditional/herbal products.
- How much, how often and by which route? Ask about smoking, drinking, swallowing, snorting, injecting or other routes; route changes overdose and infection risk.
- When was the last use? This helps identify current intoxication or possible withdrawal.
- Why does the person use? Explore pain, sleep, stress, peer belonging, grief, trauma, work demands and mental symptoms.
- What harms have occurred? Ask about blackouts, injuries, school/work, family, finances, legal problems, infections, pregnancy and driving.
- Any dependence features? Craving, failed attempts to stop, tolerance, withdrawal, morning use or using to avoid withdrawal.
- Any high-risk combinations? Alcohol with sedatives or opioids, multiple stimulants, or medicines taken without prescription can be life-threatening.
- Safety and mental health? Screen for suicidal thoughts, psychosis, violence, abuse, safeguarding concerns and child-care responsibilities.
Urgent red flags: reduced consciousness, slow or abnormal breathing, cyanosis, seizures, severe agitation, hyperthermia, chest pain, severe hypertension, arrhythmia, delirium, hallucinations with dangerous behaviour, suspected overdose, suicidal intent, trauma, pregnancy with acute substance-related illness, or a child exposed to substances. Stabilise airway, breathing and circulation, check glucose and seek emergency/senior help immediately.
8. Prevention and early intervention
| Level of prevention | Goal | Examples |
|---|---|---|
| Primary prevention | Prevent initiation or delay onset. | Family and school programmes, life skills, mental-health promotion, safe recreation, regulation of availability and accurate public education. |
| Secondary prevention | Identify risky use early and stop progression. | Routine screening, brief intervention, motivational conversation, treatment of depression/anxiety and referral before severe dependence develops. |
| Tertiary prevention | Reduce complications, disability and relapse in established disorder. | Withdrawal management, relapse prevention, treatment of infections/mental illness, rehabilitation, family work, harm reduction and social reintegration. |
9. Exam and OSCE application
- Differentiate intoxication, withdrawal, tolerance and dependence; they are not interchangeable.
- Ask every patient about prescribed drugs, over-the-counter products, herbal remedies and non-prescribed substances—not only “illegal drugs.”
- Use person-first, non-stigmatising language and protect privacy, especially for adolescents, pregnant people and patients with mental illness.
- Always consider other causes of altered behaviour or consciousness; do not assume intoxication.
- Never miss emergency signs of overdose, dangerous withdrawal, trauma, suicidality or violence.
- Risk factors increase probability but do not determine destiny. Identify strengths and protective factors as well as problems.
Knowledge Check Summary
Vital facts to remember
- “Drug abuse” is an older, imprecise term; use clear clinical language such as hazardous use, harmful use, dependence or substance use disorder.
- Substance use disorders arise from interacting biological, psychological, social and structural factors—not moral failure.
- Reward learning, cues, tolerance, withdrawal and craving help explain progression and relapse.
- Adolescence, trauma, mental illness, family conflict, peer exposure, drug availability and poverty are important risk factors.
- Supportive relationships, school/work connectedness, coping skills, early screening and accessible healthcare are protective.
- Use a private, non-judgemental history and identify intoxication, withdrawal, overdose and mental-health red flags urgently.
