How Does Addiction Work? The Brain Under the Influence

The Role of Glutamate in Addiction

The Importance of Glutamate in Learning and Memory

Glutamate is an important chemical in the brain that helps with learning and memory. It allows your brain to strengthen or weaken connections between brain cells, depending on your experiences. This ability to change and adapt is what helps us form memories and learn new things.

How Changes in Glutamate Function Contribute to Addiction

Glutamate plays a significant role in how addiction is formed.⁵ If you repeatedly use a substance, the glutamate signaling in your brain changes. This affects how the brain processes rewards and forms habits, making substance use more automatic over time. Your brain starts to “learn” that using the substance is important, embedding it into your memory as a strong habit. 

These changes can weaken the brain’s ability to control impulses and make decisions while also strengthening the memories and triggers associated with substance use. This makes it much harder to resist cravings, even when you know the harmful effects. As glutamate continues to drive the learning and memory related to substance use, it deepens the addiction. Understanding this process helps explain why overcoming addiction is such a challenge.

Changes in Brain Anatomy and Function

To better understand this condition, we need to understand the relationship between addiction and the brain.

The Impact of Addiction on Brain Structure

Chronic substance use can lead to fundamental changes in the brain’s structure. Over time, addiction damages essential areas of the brain⁶ that control decision-making, memory, and behavior. The brain’s reward system also gets altered as it becomes more focused on the addictive drug or behavior. 

At the same time, the parts of the brain that help control impulses and emotions become weaker, making it harder to resist cravings. This is how the brain becomes wired to prioritize drug use over other important activities and responsibilities. 

Changes in Dopamine Receptors and Transporters

There’s a deep connection between dopamine and addiction. Repeatedly flooding your brain with dopamine eventually changes how your brain responds to substances you use and activities you do. Because of the artificially high levels of dopamine, your brain may start making fewer dopamine receptors,⁷ or the transporters that recycle dopamine may become less efficient. This means you’ll need more of the substance to feel the same high, increasing your tolerance and causing a stronger pull toward addiction. It also makes it much harder to feel good at all when you’re not using substances, further increasing your motivation to use.

Recognizing the Signs of Addiction

Behavioral Signs of Drug Use or Intoxication

Recognizing the behavioral signs of drug use can help you identify when you or someone you love needs help:

1. Mood and behavioral changes: Mood swings, irritability, aggression, as well as becoming more secretive or withdrawn can signal substance use. 
2. Neglect of responsibilities: Ignoring work, school, or family obligations is a red flag. This might include missing deadlines, frequent absences, or a drop in performance.
3. Unusual social patterns: You might isolate yourself from friends and family or start spending more time with a new social group that uses substances.
4. Physical signs: Red or glassy eyes, slurred speech, and unsteady movements can indicate intoxication. Changes in sleep patterns, such as oversleeping or being unable to sleep, are also common.
5. Financial problems: Frequently borrowing money, unexplained financial difficulties, or stealing to fund drug use are all warning signs.

Sometimes it’s hard to see these changes in ourselves as addictive behaviors become normalized over time. If any of your loved ones bring up concerns, it’s a good idea to take them seriously. “If you find yourself shifting your priorities, increasingly isolated or feeling irritable when not engaged in a behavior, it may be time to get help in breaking the pattern of behavior,”⁸ say experts at the Mayo Foundation. Spotting these changes can empower you to intervene early and get the support you need. 

Physical Signs of Drug Use or Intoxication

Physical signs of drug use or intoxication can vary depending on the substance, but often include noticeable changes in appearance and behavior:

1. Bloodshot or glazed eyes: Red, glassy, or dilated pupils are common signs of intoxication.
2. Sudden weight changes: Rapid weight loss or gain can result from changes in appetite caused by drug use.
3. Poor hygiene and neglect of appearance: The mood, sleep, and schedule instability caused by substance use often causes a decline in personal grooming. Signs might include unkempt hair, dirty clothes, or body odor.
4. Changes in vital signs: Irregular heartbeat, fluctuations in blood pressure, or sweating can signal drug use.
5. Tremors or shaking: Involuntary shaking or trembling, especially in the hands, is often associated with intoxication or withdrawal.
6. Nausea or vomiting: Frequent nausea, vomiting, or other gastrointestinal issues can be related to drug use.

These physical signs can indicate that someone may need medical help or intervention. “Making sure you know the risks and harms associated with alcohol or drug use⁹ can help you stay safe and reduce harm,” says the Victoria Department of Health. 

Seeking Help and Treatment

The Importance of Early Intervention

Addiction is progressive, meaning its intensity and consequences tend to get worse over time. That’s why early intervention is crucial—catching addiction earlier can prevent problems from getting worse and improve your chances of successful recovery. 

The longer addiction goes untreated, the more deeply it takes hold, leading to more disruptive physical, psychological, and social consequences. Early intervention nips patterns in the bud before they become even more engrained, making treatment more manageable and effective. And the sooner you start your recovery process, the more you reduce your risk of overdose and other life-threatening complications. 

Treatment Options for Addiction

Comprehensive addiction treatment usually involves a combination of talk therapy (both individual and group) and complementary therapies. For some people, it may also include medication.

Therapy

Therapy helps you understand and change your behaviors related to substance use. Which therapy is best for you will depend on your condition and which approach resonates best with your goals and values. Addiction treatment professionals use a range of modalities to treat symptoms of addiction and address its root causes. These might include:

• Evidence-based therapies like CBT, motivational interviewing, and contingency management
• Complementary therapies such as energy medicine, experiential therapy (like sports or outdoor activities), massage, and mindfulness meditation 
• Group therapies like psychoeducational, skill building, interpersonal process, or relapse prevention groups 

Medication

Medication is often used in addiction treatment to help manage withdrawal symptoms and cravings. Medications like methadone or buprenorphine, for example, are often used in opioid addiction treatment. If you have a co-occurring mental health disorder that requires medication, a medication review might also be part of your treatment plan. 

Support Groups

Support groups are communities of peers who share experiences, learn together, and motivate each other through challenges. These might be 12-Step groups like Alcoholics Anonymous (AA) or Narcotics Anonymous (NA), or non-12-Step groups like SMART Recovery. These groups can be a vital part of long-term recovery, offering ongoing accountability and support. 

Addiction is isolating. “Anxiety is heightened. Depression is heightened. Sense of loneliness is heightened, which often leads to unhealthy coping in a lot of different ways,” says Jeff Stuhmer, a Licensed Mental Health Counselor and Substance Use Disorder professional. Support groups—whether in-person or online—provide a much-needed sense of community and shared experience. “It’s about community,” says Stuhmer. “We need each other.”¹⁰

The Recovery Process

Recovery happens in stages, along what addiction treatment specialists call a continuum of care: 

• Detox: If you’re physically addicted to alcohol or opioids, or otherwise need a supervised withdrawal process, you’ll need to complete treatment at a medical detox center before starting rehab.
• Inpatient rehab: Intensive rehab in a residential setting allows you to dive into your recovery process while focusing entirely on yourself.  
• Outpatient rehab: Intensive outpatient programs (IOPs) and partial hospitalization programs (PHPs) allow you to attend an intensive program while living at home. Some people choose to attend these in lieu of, or as a stepped-down transition from, residential rehab.
• Sober living: Sober living facilities allow you to put your recovery skills to the test outside of residential rehab, while still living in a substance-free, recovery-focused environment. 
• Continuing care: Ideally, you’ll start planning for life after rehab in earlier stages of recovery. Your continuing care plan is personal to you and may include ongoing therapy, support groups, and lifestyle changes that support a healthy life in long-term sobriety. 

People may not move through this process in a linear way, or may not complete every stage. But research generally shows that the more time you spend in treatment and actively working toward recovery, the better your outcomes will be.¹¹

The Science Behind Addiction in Prevention and Education

Substance use disorders are highly treatable,¹² thanks to plenty of effective behavioral and pharmaceutical therapies that have been developed in recent decades. But there’s a treatment gap. That is, not enough people get the life-changing care they need. According to the American Psychological Association,

More than 40 million people in the United States—16 percent of all Americans over age 12—suffer from nicotine, alcohol or drug addiction. Only about 10 percent of those people receive treatment.

This gap is largely due to the stigma that still surrounds this health condition, which can be addressed by raising awareness and understanding of what it truly entails. 

The Role of Education in Preventing Addiction

Education plays a major in preventing addiction¹³ by demystifying the factors that cause it and equipping people with the knowledge to make informed choices. Understanding the mechanisms of addiction—how substances alter brain chemistry, reinforce compulsive behaviors, and impact mental health—can increase self-awareness and reduce the risk of developing addiction. 

When people are educated about how addiction works, they’re better prepared to recognize early warning signs, avoid risky behaviors, and ask for help when they need it. This empowers individuals and communities to reduce stigma and build supportive environments where prevention strategies can thrive. When we make addiction science more accessible, we lay the foundation for healthier choices and more resilient people.

How Understanding Addiction Can Inform Prevention Strategies 

“Drugs change the brain¹⁴ in ways that make quitting hard, even for those who want to,” says NIDA. “Fortunately, researchers know more than ever about how drugs affect the brain and have found treatments that can help people recover from drug addiction and lead productive lives.” Understanding how addiction works can help us create more effective approaches to treating and preventing it, instead of shaming people who are struggling. If you’re struggling with addiction, effective treatment is available.

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