What Causes Addiction? Root Causes and Risk Factors

Addiction is a brain disease associated with compulsive, uncontrolled substance use that continues even with obvious harmful consequences, and its scope includes behaviours like gambling, gaming, or using social media. It usually starts as experimental use, and continued involvement changes brain chemistry until the person can't stop even if they want to. 

In Canada, 16.7% of people aged 15 and older have met the criteria for alcohol use disorder at some point in their lives, according to Statistics Canada's 2022 Mental Health and Access to Care Survey¹. 

So what causes addiction? We will explore the causes, prevention, and how to help a person struggling with addiction.

Key Takeaways

• Addiction is a chronic disease of the brain that affects people from all walks of life.
• Addiction is caused by an interplay of risks and has no single cause.
• Knowing the possible causes of addiction can equip you to respond appropriately when you face moments that may tempt you into drug use.
• The most effective treatments for addictions are those designed to meet the patient's specific needs.

Types of Substance Abuse

The Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR) indicates that most psychoactive substances have the potential for abuse and addiction. The table below lists the substance-related disorders in the DSM-5-TR and shows where the diagnostic rules for each class differ.

Substance class	Common examples	Use disorder diagnosis	Recognized withdrawal syndrome
Alcohol	Beer, wine, spirits	Yes	Yes
Caffeine	Coffee, energy drinks, caffeine pills	No (listed for further study)	Yes
Cannabis	Dried flower, edibles, vapes, concentrates	Yes	Yes
Hallucinogens (including PCP-type drugs)	LSD, psilocybin, DMT, mescaline, PCP, ketamine	Yes	No
Inhalants	Solvents, glue, aerosol sprays	Yes	No
Opioids	Heroin, fentanyl, oxycodone, hydromorphone	Yes	Yes
Sedatives, hypnotics, anxiolytics	Benzodiazepines, barbiturates, carbamates	Yes	Yes
Stimulants	Cocaine, methamphetamine, prescription amphetamines	Yes	Yes
Tobacco	Cigarettes, cigars, vapes, nicotine pens	Yes	Yes

Hallucinogens such as ketamine can produce a use disorder with no recognized withdrawal, and withdrawal weighs far more heavily in opioid misuse, where stopping abruptly can push people straight back to using. Among behavioural addictions, the DSM-5-TR lists gambling disorder and includes Internet gaming disorder among conditions that need further study.

If you or a loved one is struggling with a substance-related disorder, the Canadian Centre for Addictions can help. Call us today at 1-855-499-9446.

Which Substances Are More Addictive?

The addictive potential of substances comes from their ability to stimulate the brain's reward system. The more addictive substances are quick-acting, flood the brain with large amounts of dopamine, and cause severe withdrawal symptoms. Some of the more addictive substances are:

• Opioids (heroin, morphine, fentanyl, oxycodone, hydromorphone)
• Cocaine
• Nicotine
• Barbiturates (phenobarbital, pentobarbital, secobarbital, amobarbital)
• Methamphetamines

Addiction Risk Factors

Addiction can affect people from all backgrounds, and it is not necessarily the result of poor choices or the absence of willpower, a belief that ranks among the most persistent myths about addiction. Smoked or injected drugs reach the brain within seconds, producing a rush that fades in minutes and pushes people to use again, which makes them more addictive than the same drugs swallowed ².

Who is More Prone to Addiction?

Young people are more vulnerable because their brains are still maturing. Statistics Canada found that 8.5% of Canadians aged 15 to 24 met the criteria for a substance use disorder in the previous 12 months, more than double the 3.8% rate across everyone aged 15 and older ¹.

Possible Complications

Addiction to opioids and other substances comes with the risk of overdose, coma, and death. In Canada, 2,787 apparent opioid toxicity deaths were recorded in the first six months of 2025 alone, and 57% of them involved fentanyl ³. Snorting drugs can damage nasal cartilage, injecting can injure skin and muscle, and addictive substances raise the risk of stroke and other cardiovascular complications. Anxiety, depression, and social isolation may follow, and addiction can strain the addict's relationships, finances, and legal standing.

Causes of Addiction

There's no single reason a person becomes addicted, but examining possible causes can offer insight into why someone has become addicted to a substance.

Genetics

A person's genetic composition may be one of the main reasons they become hooked on a substance. The U.S. National Institute on Drug Abuse (NIDA) estimates that genes, together with the way the environment switches them on and off, account for 40% to 60% of a person's risk of addiction ². 

So is addiction genetic? Partly, because inherited biology raises or lowers the odds without deciding the outcome.

Twin studies reviewed by Francesca Ducci and David Goldman put heritability at 0.39 for hallucinogens and 0.72 for cocaine, the lowest and highest values among the addictive disorders they compared ⁴. 

Heritability describes variation across a population, so a value of 0.72 gives no individual a 72% chance of addiction. Some inherited variants lower risk, and changes in the ADH1B and ALDH2 genes alter how the body breaks down alcohol and cause facial flushing after a drink. No single "addiction gene" exists. 

A 2023 analysis of more than one million people found 19 genetic markers tied to a shared addiction risk across alcohol, tobacco, cannabis, and opioids, including PDE4B, a gene involved in regulating dopamine ⁵. If you have a parent or sibling with a substance use disorder, you may have a higher chance of the same disorder.

Addictive Personality

People who ask what an addictive personality is usually mean someone who moves from one compulsion to the next. The DSM-5-TR has no diagnosis by that name, but a review by Erica Birkley and Gregory Smith links several measurable traits to addiction, including urgency (acting rashly under strong emotion) and sensation seeking ⁶. People with these traits may avoid drugs entirely and still form a behavioural addiction.

Mental Health

There is a close link between addictions and mental health conditions. NIDA reports that around one in four people with a serious mental illness also has a substance use disorder ⁷. Individuals with untreated depression, anxiety, bipolar disorder, or schizophrenia are likely to self-medicate with drugs or alcohol, which relieves symptoms for a time and worsens them long-term.

Family History

Growing up in a family where one or more members have struggled with addiction makes you more likely to form a substance use disorder. Seeing addiction-influenced conflict in childhood can present drug use as one of the ways to cope with problems, and the trauma of watching a parent struggle does not necessarily deter children from turning to substances later.

Biological Influences

Gender and metabolic rate may play a role. In Canada, 4.6% of men met the criteria for a substance use disorder in the past 12 months, compared with 3.0% of women ¹. People with faster metabolism may break down drugs quickly, so the effects wear off sooner, and they take more.

Environmental Influences

Young people without adequate parental influence are more likely to experiment with drugs and alcohol, and peer pressure and a desire to fit in can push teens toward addiction. Residents of poorer neighbourhoods may also have easier access to drugs.

Changes in Brain's Reward Circuit

All addictive substances affect the brain's reward circuitry. The first use delivers a powerful, abnormal surge of dopamine, and with continued use the brain adapts, and the reward circuit changes physically. The link between dopamine and addiction shows on brain scans, where people with a history of cocaine use disorder still had lower levels of D2 dopamine receptors four months after stopping ². These changes make the brain seek the drug reflexively.

Chronic Stress

Stress responses motivate us toward solving problems, but too much stress can trigger anxiety and depression. Research on stress and addiction identifies chronic stress as a well-known risk for both the onset of addiction and relapse ⁸. People who lack healthy coping skills may turn to drugs to manage it.

Adverse Childhood Experiences or PTSD

Adverse childhood experiences (ACEs) or trauma may play a role in the onset of addiction. ACEs can include:

• Sexual or physical abuse
• Neglect
• Bullying
• Parental divorce
• Racial or ethnic discrimination.

A study of 8,613 adults found that each ACE increased the likelihood of early drug use two- to four-fold, and people with five or more ACEs were seven to ten times more likely to report illicit drug use problems and addiction ⁹.

Diagnosing Addiction

Blood tests and laboratory screenings can detect the presence of drugs, but they only indicate recent use. A doctor will ask about the frequency and pattern of use, and check if the drug impairs the patient's ability to function. The DSM-5-TR lists 11 criteria for diagnosing substance use disorder:

• Regularly consuming larger amounts of the substance than planned or for a longer period than intended.
• Attempting to stop or reduce substance use and failing.
• Spending a lot of time obtaining, using, or recovering from substance use.
• Craving the substance or expressing an intense desire to use it.
• Failing to fulfil obligations at home, work, or school due to substance use.
• Continued use of the substance even with adverse emotional, social, or personal consequences.
• Giving up important work, recreational, or social activities to use the drug.
• Using the substance in places or circumstances that could lead to harm or injury.
• Continued use of the substance with awareness of a physical or psychological problem it may have caused or aggravated.
• Needing more of the substance to get the same effects (tolerance).
• Withdrawal symptoms in response to not using or trying to reduce the amount of substance used.

Fulfilling two or three of these criteria indicates a mild substance use disorder, four to five a moderate one, and six or more a severe one.

Treating Addiction

The right addiction treatment depends on the individual's addiction severity and the substance of choice, and the most effective treatments are customized to meet the patient's unique needs.

Detoxification

Detoxification is a supervised first step that lets people rid their system of drugs and recover from withdrawal symptoms safely.

Inpatient Rehab

Inpatient rehab is a residential treatment for patients with severe addiction or co-occurring mental health problems, with round-the-clock monitoring and support away from the triggers of daily life.

Therapy/Counselling

Individual counselling and group meetings with a licensed expert use therapies such as CBT, DBT, and Motivational Enhancement Therapy to change the thought patterns behind the addiction.

Sober Living Homes and Support Groups

Sober living homes help people move from inpatient treatment back to everyday life, and support groups like Alcoholics Anonymous (AA) and Narcotics Anonymous (NA) use the famous 12-step programs to provide ongoing peer accountability.

Tips on Preventing Addiction

Addiction can affect anyone, and there is no guaranteed way to prevent it, but you can take steps to lower your chances.

Addiction Education

Learning what causes substance abuse makes you more aware of the risks. Educating teens about the dangers of drug abuse equips them to respond better when they face moments that may tempt them.

Build a Reliable Support Network

Surround yourself with positive people and avoid those who would pressure you into trying substances. Have a ready excuse to give when people offer you drugs.

Treat Existing Mental Illness

Mental illness and addiction are strongly linked, so get professional help for depression, anxiety, or post-traumatic stress disorder before symptoms push you toward self-medicating.

Maintain Proper Work-life Balance

Find healthier ways to de-stress, know when to take a break, and spend time with family. Practising self-care keeps your mind and body healthy and makes it far less likely you'd turn to drugs.

Acting Early Keeps Addiction From Taking Hold

Addictions ruin lives, and knowing why they happen can help keep you and your loved ones safe. If you or a loved one is already struggling with a substance use disorder, contact a professional who will devise a treatment plan that offers the best chance at lasting recovery.

Ready to Take the First Step?

Addiction doesn't get better on its own. Call us today for a free, confidential consultation and find out which program is right for your needs.

Call 1-855-499-9446

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