What Is Addiction?

Published: February 2026 | Last Updated: February 2026 | Reading Time: 8 min

Defining Addiction

The American Society of Addiction Medicine (ASAM) defines addiction as "a treatable, chronic medical disease involving complex interactions among brain circuits, genetics, the environment, and an individual's life experiences. People with addiction use substances or engage in behaviors that become compulsive and often continue despite harmful consequences."

Key Characteristics

Addiction is defined by several core features: - Loss of control — inability to consistently limit use despite intentions to do so - Compulsion — powerful urges or cravings that drive behavior - Continued use despite consequences — persistence of the behavior despite physical, psychological, or social harm - Tolerance — needing increasing amounts to achieve the same effect - Withdrawal — physical or psychological symptoms when the substance or behavior is discontinued

How Addiction Changes the Brain

The Reward System

The brain's reward system evolved to reinforce survival behaviors — eating, social bonding, and reproduction — by releasing dopamine, which creates feelings of pleasure and motivation. Addictive substances hijack this system by producing dopamine surges 2-10 times larger than natural rewards, overwhelming the brain's normal signaling.

Neuroadaptation

In response to repeated overstimulation, the brain adapts by reducing dopamine receptor density, decreasing natural dopamine production, and strengthening habit circuits while weakening decision-making circuits. These changes explain why individuals with addiction experience diminished pleasure from normal activities (anhedonia), intense cravings, and impaired decision-making.

Prefrontal Cortex Impairment

Addiction compromises the prefrontal cortex — the brain region responsible for judgment, impulse control, and weighing consequences. This explains why individuals with addiction continue using despite knowing the harm: the brain's control center is functionally impaired by the disease itself.

What Causes Addiction?

Genetic Factors (40-60%)

Twin and family studies consistently demonstrate that genetics account for approximately 40-60% of addiction vulnerability. Specific genetic variations affect dopamine receptor sensitivity, drug metabolism, stress response, and impulse control.

Environmental Factors

• Adverse childhood experiences — trauma, abuse, neglect
• Early substance exposure — using substances before age 15 significantly increases lifetime addiction risk
• Peer influence and social environment
• Availability and access to substances
• Chronic stress and socioeconomic factors

Developmental Factors

The adolescent brain is particularly vulnerable to addiction because the reward system is fully active while the prefrontal cortex (impulse control) is not fully developed until approximately age 25. Early substance use during this period significantly increases addiction risk.

Mental Health Conditions

Depression, anxiety, PTSD, ADHD, and other mental health disorders increase addiction vulnerability through self-medication, shared neurological pathways, and common genetic risk factors.

Addiction vs. Physical Dependence

Physical dependence — characterized by tolerance and withdrawal — can occur without addiction. For example, a patient taking prescribed opioids after surgery may develop physical dependence but not the compulsive, out-of-control use that defines addiction. Addiction involves behavioral and psychological components beyond physical dependence.

The Disease Model

Why Addiction Is a Disease

The disease model of addiction, supported by the American Medical Association, the American Psychiatric Association, and the National Institute on Drug Abuse, is based on observable changes in brain structure and function, genetic heritability comparable to other diseases, predictable progression without treatment, and response to medical treatment.

Addiction Is Not a Moral Failing

The disease model does not eliminate personal responsibility but recognizes that addiction fundamentally alters the brain's decision-making and impulse control systems. Understanding addiction as a disease reduces stigma, improves treatment-seeking, and promotes evidence-based approaches to recovery.

Treatment Options

Behavioral Therapies

CBT, motivational interviewing, contingency management, and family therapy address the psychological and behavioral aspects of addiction.

Medication-Assisted Treatment (MAT)

FDA-approved medications exist for opioid, alcohol, and nicotine use disorders. MAT combined with behavioral therapy produces the best outcomes for these conditions.

Levels of Care

Treatment is available across a continuum from outpatient therapy to intensive outpatient programs (IOP) to partial hospitalization to residential treatment. The appropriate level depends on severity, co-occurring conditions, and individual circumstances.

FAQ

Is addiction a choice? The initial decision to use a substance involves choice, but addiction is not simply a matter of willpower. Repeated substance use changes brain structure and function in ways that impair the ability to make free choices about continued use. Addiction is best understood as a disease that begins with a behavior.

Can addiction be cured? Addiction is a chronic condition that can be effectively managed but not cured in the traditional sense. Like diabetes or hypertension, it requires ongoing management. Many individuals achieve long-term recovery and live fulfilling, substance-free lives.

Why do some people become addicted while others do not? Individual vulnerability to addiction results from the interaction of genetic factors, environmental influences, developmental stage, and mental health status. No single factor determines whether someone will develop an addiction.

Is addiction hereditary? Genetic factors account for approximately 40-60% of addiction risk. However, having a genetic predisposition does not guarantee addiction — environmental factors and individual choices also play significant roles.

References

• ASAM. (2019). Definition of Addiction. American Society of Addiction Medicine.
• Volkow, N. D., et al. (2016). Neurobiologic advances from the brain disease model of addiction. New England Journal of Medicine, 374(4), 363-371.
• NIDA. (2022). Drugs, Brains, and Behavior: The Science of Addiction.

Written by the Valley Spring Recovery Center Editorial Team

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