Understanding addiction
How Do Drugs Affect the Brain?
Every drug of abuse changes how the brain works — and understanding those changes helps you know what to expect during treatment and recovery.
About this guide
Drugs and the brain
Misusing substances causes problems because of what drugs do to the brain. Even occasional drug or alcohol use can contribute to long-term physical and mental health complications, so understanding how drugs influence the brain matters when you are anticipating treatment and sustained recovery.
Recreational drugs are classified by their effects on the brain, and most fit into three main categories: stimulants, depressants, and hallucinogens. Some drugs are hard to categorize because their effects cross categories, and the categories include legal as well as illegal drugs — many legal substances are highly addictive.
Ambrosia treats substance use disorders at every level of care at our Florida facilities, starting with medically supervised detox when it is needed.
Stimulants
Stimulants speed up the activity of the brain and central nervous system — which is why they are called "uppers" or "speed." They include cocaine, crack, methamphetamine, caffeine, nicotine, and prescription drugs like Adderall, Concerta, and Ritalin, which are prescribed for ADHD and narcolepsy.
Stimulants make you feel energized and alert by artificially increasing dopamine, a neurotransmitter the brain normally releases to help you take action and focus. In the short term that means increased heart rate, elevated body temperature, high blood pressure, and a burst of energy and alertness. With abuse, side effects can include weight loss, sweating, twitching, paranoia, racing thoughts, impulsivity, anxiety, and agitation.
Depressants
Depressants do the opposite: they slow down the brain and central nervous system. The category includes alcohol, opioids like heroin and oxycodone, benzodiazepines like Xanax and Valium, barbiturates, and sleeping pills. Alcohol is one of the most commonly used depressants in the US — according to the National Institute on Drug Abuse, alcohol use disorder is the most common substance use disorder in the United States.
Depressants increase the neurotransmitter GABA, which promotes sleep and reduces anxiety. Under the influence, that feels like relaxation, drowsiness, decreased heart rate, slowed breathing, and delayed reaction time. Side effects include lowered inhibitions, impaired judgment, loss of coordination, blackouts and memory loss, and loss of consciousness.
Opioids are sometimes treated as their own category given the opioid crisis, but in terms of effects on the brain and central nervous system, opioids and other depressants work essentially the same way — and alcohol and opioids both produce severe withdrawal symptoms that make quitting without help dangerous.
Hallucinogens
Hallucinogens — including ketamine, LSD, PCP, mescaline, and DMT — alter your sense of reality by changing how the brain processes sensory information. They interfere with the neurotransmitters serotonin and glutamate, which are involved in mood, sensory input, appetite, muscle control, and pain perception.
Short- and long-term effects can include an altered sense of time, increased heart rate, panic and paranoia, lack of coordination, sleep disturbances, flashbacks, and psychosis — seeing things that are not there, hearing voices, disorganized thinking.
Substances that cross categories
Some substances do not fit neatly into one category because they affect the brain in ways that span more than one:
- Marijuana
- MDMA (molly or ecstasy)
- Kratom
- Synthetic cathinones (bath salts)
- Synthetic cannabinoids
Can the brain recover?
Yes — you can recover from the effects drugs have on the brain and body, but you have to give yourself time. When you stop using, withdrawal symptoms appear as your system adjusts; their severity depends on the substance, how long you used, and how much.
Treatment helps you detox safely, and inpatient rehab helps you understand the underlying issues at the root of the addiction while you build the skills for lifelong sobriety. Peer support and outpatient services then help you stay sober as you rebuild your life in long-term recovery.
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