Addictions fall into two broad categories: substance addictions, which involve drugs or alcohol, and behavioral addictions, which involve compulsive activities like gambling or gaming. Within those categories, clinicians recognize more than a dozen specific types, each with distinct patterns of use, withdrawal, and long-term effects on the brain.
How Addiction Is Classified
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5) groups addictions under the heading “Substance-Related and Addictive Disorders.” To be diagnosed, a person needs to meet at least 2 out of 11 criteria within a 12-month period. Those criteria include things like using more than intended, failed attempts to cut back, cravings, neglecting responsibilities, and continuing use despite harm. The more criteria you meet, the more severe the disorder: 2 to 3 is mild, 4 to 5 is moderate, and 6 or more is severe.
An important earlier change was dropping the old distinction between “substance abuse” and “substance dependence.” Those two separate diagnoses created confusion and left some people in a gap where they clearly had a problem but didn’t technically qualify for either label. The current system treats addiction as a single disorder on a spectrum of severity.
Substance Addictions
The DSM-5 recognizes ten classes of substances that can lead to a use disorder. Each one affects the brain’s reward system differently, but all share the core pattern of escalating use, loss of control, and continued use despite consequences.
- Alcohol. One of the most common substance use disorders worldwide, with genetic factors accounting for roughly 48 to 66% of a person’s risk. Alcohol withdrawal can be physically dangerous, producing seizures in severe cases.
- Tobacco. Formerly called “nicotine dependence,” now labeled tobacco use disorder. Heritability estimates range from 33 to 71%, and the dopamine-producing capacity of key brain areas can take about three months of abstinence to normalize.
- Cannabis. Twin studies estimate that 51 to 59% of the variation in cannabis addiction risk is heritable. Cannabis use disorder has become more recognized as higher-potency products have become widely available.
- Opioids. This class includes heroin and prescription painkillers like hydrocodone, morphine, and codeine. Heritability estimates vary widely, from 23 to 54% depending on the study. Dopamine transporter levels in the brain can take 6 to 12 months of abstinence to recover.
- Stimulants. Cocaine, amphetamines, and methamphetamine are grouped together because they all work by flooding the brain with dopamine. Heritability for cocaine use disorders ranges from 42 to 79%. Notably, stimulant withdrawal doesn’t produce the dramatic physical symptoms seen with alcohol or opioids, but cravings can be severe.
- Hallucinogens. This covers both classic hallucinogens (like LSD and psilocybin) and PCP-type drugs. Use disorders in this category are less common but still recognized.
- Sedatives, hypnotics, and anxiolytics. This includes benzodiazepines, sleep medications, and similar drugs. Physical dependence develops quickly, and withdrawal can be medically serious.
- Inhalants. Volatile substances like solvents, aerosols, and gases. Inhalant use disorder is most common among adolescents.
- Caffeine. Caffeine use disorder was added to the DSM-5 as a condition for further study, meaning it’s recognized as a potential problem but doesn’t yet have a full diagnostic category.
Behavioral Addictions
Not all addictions involve substances. Behavioral addictions follow the same core loop: a rewarding activity triggers dopamine release, the brain adapts, and over time you need more of the activity to get the same effect while losing the ability to stop.
Gambling disorder is the only behavioral addiction formally included alongside substance use disorders in the DSM-5. Twin studies put its heritability at about 49%, remarkably similar to many substance addictions. It involves the same loss of control, preoccupation, and continued gambling despite financial or personal harm.
Gaming disorder was recognized by the World Health Organization in 2019 as part of its International Classification of Diseases (ICD-11). To qualify, a person must show impaired control over gaming, increasing priority given to gaming over other activities, and continuation despite negative consequences, all for at least 12 months. This isn’t about playing a lot of video games. It’s about gaming taking over to the point where personal relationships, work, or school are seriously affected.
Compulsive Behaviors That Aren’t Officially Addictions
Several patterns of compulsive behavior look and feel a lot like addiction but haven’t been classified that way, either because the research isn’t definitive or because they fit better under a different diagnostic heading.
Compulsive sexual behavior disorder is listed in the ICD-11 as an impulse control disorder, not an addiction. The WHO took a conservative position: while the behavior shares surface features with addiction (loss of control, escalation, continued engagement despite harm), there isn’t enough evidence yet to confirm the underlying brain processes are equivalent to those in substance or gambling disorders.
Food addiction is another widely discussed concept. Certain hyperpalatable foods, especially those high in sugar, fat, and salt, can trigger cravings and a loss of control that mirrors drug-seeking behavior. Researchers developed the Yale Food Addiction Scale specifically to measure this, adapting the same criteria used for substance use disorders: impaired control, tolerance, and withdrawal symptoms. Still, food addiction is not recognized as a formal diagnosis in the DSM-5, which means it’s assessed and treated inconsistently across clinical settings.
Shopping, social media use, pornography, and exercise are other behaviors sometimes described as addictions in popular culture. While each can become compulsive and damaging, none currently have formal diagnostic standing. That doesn’t mean the suffering isn’t real. It means the clinical framework is still catching up.
Physical Dependence Is Not the Same as Addiction
One of the most misunderstood aspects of addiction is the difference between physical dependence and the disorder itself. Physical dependence means your body has adapted to a substance, so you experience withdrawal symptoms when you stop. This happens with many medications that aren’t addictive at all, including certain antidepressants and blood pressure drugs. People who taper off these medications may feel withdrawal, but they don’t crave the drug or compulsively seek it out afterward.
Addiction, by contrast, is defined by loss of control over intense urges to use, even when use is causing clear harm. You can have addiction without physical dependence: cocaine, for example, doesn’t cause the visible withdrawal symptoms (vomiting, sweating, shaking) that alcohol and heroin do, but cravings can be overwhelming and relapse rates are high. And you can have physical dependence without addiction, as with a patient on long-term pain medication who experiences withdrawal but has no compulsive drug-seeking behavior.
Why Some People Are More Vulnerable
Genetics play a substantial role across every type of addiction studied. Twin research consistently shows that roughly 40 to 60% of the variation in addiction risk is heritable, though the numbers shift depending on the substance. Alcohol sits around 48 to 66%, cocaine between 42 and 79%, and gambling at about 49%.
But genes aren’t destiny. Environmental factors matter enormously, especially early in life. During adolescence, shared environment (family, peers, neighborhood) contributes the most to whether someone starts using a substance. As people move into adulthood, genetic influences become more dominant, explaining up to 75% of individual differences. In other words, your environment largely determines whether you’re exposed to a substance in the first place, but your biology has more influence over whether casual use escalates into a disorder.
Chronic drug use progressively rewires the brain’s reward and decision-making circuits. Drug-related cues become deeply embedded in the brain’s emotional memory systems, which is why a person in recovery can experience intense cravings triggered by a place, a song, or even a mood that they associate with past use. The prefrontal cortex, responsible for impulse control and long-term planning, becomes less effective at overriding those urges.
How the Brain Recovers
The brain does recover with sustained abstinence, but the timeline varies by substance and the type of recovery involved. Structural changes in brain tissue tend to improve first, sometimes within weeks. Neurochemical recovery, where receptor levels and signaling capacity return to normal, takes longer.
For alcohol, certain brain chemicals begin normalizing within the first three months of abstinence, while other receptor systems take six months or more. For opioids like heroin, dopamine transporter levels in the brain’s reward center can take 6 to 12 months to approach normal. For nicotine, dopamine production capacity normalizes around three months. Methamphetamine recovery follows a more complicated path, with some brain markers actually worsening in the first few weeks before starting to improve.
Functional recovery, meaning improvements in decision-making, impulse control, and emotional regulation, generally takes the longest. This helps explain why the early months of recovery feel so difficult: the brain is still physically rebuilding its capacity to manage cravings and make sound decisions. It also underscores why sustained support during that window matters so much.