To understand how heroin affects the brain, we have to understand how the brain works. The brain has millions of cells that react to chemicals in the body, including the things that we consume. These reactions affect how our body works. The cells in the brain that react to chemicals are called receptors.
Some receptors only react to certain types of chemicals. The receptors that react to heroin are called opioid receptors.
Opioid receptors in the brain affect how we feel pain, pleasure, depression, anxiety and stress. They also affect our appetite, how we breathe and how we sleep. The brain naturally produces chemicals called endorphins that attach to opioid receptors. Endorphins reduce feelings of pain and help regulate bodily functions.
When a person smokes, injects or snorts heroin, the drug immediately enters the bloodstream and travels to the brain. Inside the brain, heroin attaches to opioid receptors and is converted to morphine and another chemical called 6-MAM.
The initial effects of heroin occur when the drug attaches to opioid receptors in the brain. This causes the euphoria of the initial high. It takes less than 20 minutes for the body to convert heroin to morphine and 6-MAM. That’s why most people say the initial high only lasts for between five and 15 minutes.
Morphine and 6-MAM stay in the brain for longer periods of time. These drugs continue to attach to opioid receptors for several hours. They likely cause prolonged effects that are milder than the initial high caused by heroin, according to a 2013 study published in the British Journal of Pharmacology.
When the body feels pleasure, such as when you hug a loved one, a small amount of endorphins attach to the brain’s opioid receptors. But heroin overwhelms the receptors, causing a large surge in happiness. That’s why many people say using heroin feels like extreme happiness or relaxation.
Opioid receptors affect more than happiness. Heroin can temporarily relieve feelings of depression or anxiety. The drug can also relieve pain the same way that prescription opioids relieve pain. High doses of opioids attach to opioid receptors, which prevents the brain from making you feel any type of pain.
The immediate positives associated with heroin aren’t worth the risks. Opioid receptors control important life functions, and heroin disrupts these processes. When the brain is flooded with heroin, opioid receptors in the brain can no longer tell the body how to function properly.
The most common cause of immediate brain damage from heroin use occurs when the drug slows breathing to a dangerously low rate, according to the National Institute on Drug Abuse.
Heroin use can prevent the brain from receiving enough oxygen. Without oxygen, brain cells die. If enough brain cells die, the person dies. Most people who lose their life to heroin overdoses die because they stopped breathing.
People can survive heroin overdoses. The amount of brain damage caused by the overdose depends on how long they were without oxygen. Some people are able to fully recover because they weren’t without oxygen for enough time for brain cells to die.
But people may lose enough brain cells to severely change how their brain works. These people may need life support or assistance from caregivers for the rest of their lives.
The brain remembers situations and circumstances that cause pleasure. These memories subconsciously motivate us to seek pleasure by making us crave things that make us happy.
Heroin disrupts the pleasure and reward system in the brain by overwhelming opioid receptors and causing changes to the way that the brain functions, according to an article in the journal Science & Practice Perspectives.
Because of these changes, people are driven to seek more heroin — even when the drug is causing serious consequences in their lives. Heroin is so addictive because it changes how a person experiences happiness and other emotions.
Heroin disrupts the reward system in the brain. It overwhelms opioid receptors, causing massive amounts of pleasure. The brain notices that heroin makes us feel good, and it remembers the situation that the person was in when he or she used heroin. In short, the brain produces cravings for heroin because it learns over time that the drug causes happiness.
After repeated heroin use, opioid receptors in the brain adapt by becoming less responsive. This is called tolerance. People with a high tolerance to heroin feel less pleasure when using the drug because their opioid receptors have become less sensitive to its effects. Some people with a high tolerance end up taking higher doses of heroin to feel pleasure. As the person continues to use heroin, opioid receptors continuously adapt to the increasing doses. Thus, the person’s tolerance continues to increase.
When opioid receptors adapt to heroin and become less responsive, other changes occur that make the brain rely on the drug to function normally. This is called dependence. Without heroin, the opioid receptors of a dependent person act abnormally. This abnormal brain activity causes heroin withdrawal symptoms.
Each time people use heroin, it reinforces changes in the brain’s reward system that cause cravings. Brain receptors continue to adapt to heroin exposure, making people more dependent on the drug as they continue to use it.
Depending on a variety of genetic and environmental factors, some people develop a disease called heroin addiction because of changes to areas of the brain that affect self-control, motivation and pleasure. Most of the time, these people seek heroin for the sole purpose of avoiding withdrawal.
Without heroin treatmetn, people addicted to the drug may be unable to quit. They are often incapable of reversing the long-term changes that heroin has caused without professional help.
Detoxing from heroin helps the brain recover from adaptations that cause dependence. Once people complete detox and overcome withdrawal, counseling and therapy can help them learn how to control cravings and make healthy decisions.
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