How Do Drugs Affect The Central Nervous System?

Drugs are substances that alter or influence the human body and brain.

They are often prescribed to treat medical conditions such as pain, anxiety, depression, insomnia, and other health problems, and illicit drugs are used illegally for recreational purposes – which can often lead to addiction.

How Do Drugs Affect The Central Nervous System?

Drugs can cause serious harm to the brain and body.

The effects depend on the type of drug taken and the dose – which is why it’s important to always take the right dosage.

This article will discuss drugs and specifically how they can affect the central nervous system in the body.

What Is The Central Nervous System?

The central nervous system (CNS) consists of your brain, spinal cord, and nerves.

It’s a network of neurons that connects everything else in your body.

The CNS controls all voluntary movement, sensation, perception, cognition, emotion, memory, balance, and homeostasis.

In short, anything you do requires the involvement of the central nervous system.

How Does The CNS Work?

Your brain has two parts – the left hemisphere and the right hemisphere.

Each side receives information from different senses and processes this data differently.

For example, if you see something red, your right eye sends signals to your right visual cortex, while your left eye sends signals to your left visual cortex.

These areas process the information and send it to the limbic system where emotions are processed.

The brain also has an area called the hypothalamus, which acts as a control center between the limbic system and the rest of the brain.

It regulates many bodily functions including sleep-wake cycles, hunger/satiety, temperature regulation, sexual function, heart rate, and blood pressure.

The brain also has three main nerve tracts that connect the various regions.

One tract runs through the midbrain, another through the hindbrain, and the third goes through the spinal cord.

These tracts allow the brain to communicate with the rest of the body.

Which Drugs Affect The CNS?

There are several types of drugs that can affect the CNS.

Some are stimulants, some depressants, some hallucinogens, and some sedatives. Here are some examples of each category:

Stimulant Drugs

These drugs increase the activity of the brain by increasing the release of dopamine, norepinephrine, and serotonin.

Examples include caffeine, cocaine, amphetamine, ecstasy, methylphenidate, and methamphetamine.

Depressant Drugs

These drugs decrease the activity of the brain. Depressants slow down the firing of neurons and reduce the release of neurotransmitters.

Examples include alcohol, barbiturates, benzodiazepines, chloral hydrate, dextromethorphan, heroin, ketamine, lorazepam, meprobamate, morphine, phenobarbital, pentobarbital, propofol, thiopental sodium, tricyclic antidepressants, and zopiclone.

Hallucinogen Drugs

Hallucinogenic drugs alter the way we perceive reality. They produce hallucinations or illusions.

Examples include LSD, mescaline, psilocybin mushrooms, salvia divinorum, scopolamine, and tetrahydrocannabinol (THC).

Sedative Drugs

Sedatives calm the brain and reduce anxiety.

They may be prescribed for people who suffer from insomnia, panic attacks, anxiety disorders, depression, and other conditions.

Examples include alprazolam, amitriptyline, clonidine, diazepam, desipramine, fluoxetine, imipramine, isocarboxazid, lithium carbonate, maprotiline, methadone, nortriptyline, oxazepam, paroxetine, propranolol, sertraline, trazodone, valproic acid, venlafaxine, and xylazine.

Neurotoxic Drugs

Neurotoxic drugs cause direct damage to the brain. Some examples include lead, mercury, arsenic, manganese, aluminum, and ethanol.

Psychotropic Drugs

Psychotropic drugs affect the mind by altering brain chemistry.

They are used to treat mental illnesses like depression, schizophrenia, bipolar disorder, obsessive-compulsive disorder, attention deficit hyperactivity disorder, autism spectrum disorder, post-traumatic stress disorder, and others.


An antidepressant works by increasing the levels of serotonin and norepinephrine in the brain.

Serotonin is a neurotransmitter that helps regulate mood, while norepinephrine is a hormone that affects arousal and wakefulness.

Antidepressants also work by blocking certain receptors in the brain.


An anxiolytic reduces anxiety by reducing activity in the amygdala (the part of the brain that controls emotions).

It does this by acting on receptors in the limbic system.


A hypnotic alters consciousness by affecting the thalamus, hypothalamus, and cerebral cortex.

A hypnotic may be used to induce relaxation, reduce pain, reduce insomnia, improve learning ability, enhance sexual performance, and increase appetite.

Drugs have both short-term and long-term effects on the brain. Short-term effects occur within minutes to hours after taking the drug.

Long-term effects take place over days, weeks, months, or even years.

Short-Term Effects Of Drugs On The Brain

  • Stimulation: Increases in alertness, energy, motivation, concentration, and memory.
  • Euphoria: Increased feelings of happiness, joy, excitement, and elation.
  • Anxiety: Decreased feelings of fear, worry, and apprehension.
  • Tolerance: Needing more of the drug to get high; feeling less effect at lower doses.
  • Withdrawal symptoms: Symptoms such as nausea, vomiting, sweating, tremors, diarrhea, stomach cramps, headaches, muscle aches, and cold sweats when you stop using the drug.

Long-Term Effects Of Drugs On The Brain

  • Addiction: Persistent use of a substance despite negative consequences.
  • Dependence: Physical dependence occurs when repeated exposure causes tolerance and withdrawal symptoms. Psychological dependence occurs when an individual develops a strong emotional attachment to a particular substance.
  • Withdrawal: Symptoms of physical and psychological dependence that occur when you suddenly stop using the drug. These symptoms include irritability, restlessness, mood swings, sleep disturbances, and cravings for the drug.

Drug-Related Damage To The Nervous System

Drug-Related Damage To The Nervous System

The brain has many nerve cells called neurons. Neurons connect through synapses.

Synapses are small gaps between two neurons where information passes from one neuron to another.

When a drug enters the body it can damage these connections. This leads to changes in how your brain functions.

Can Drug Addiction Damage Your Brain?

Yes. Over time, drug abuse can sometimes cause permanent damage to the brain.

This damage can lead to problems with thinking, memory, judgment, impulse control, coordination, reasoning, and problem-solving.

Damage To The Brain From Drug Use

Many drugs can cause severe damage to the brain. Some of the consequences of drug abuse are outlined below.


Toxic chemicals produced by the body during the metabolism of drugs build up in the brain and cause cell death.

Degenerative Diseases

Certain diseases, including Alzheimer’s disease, Parkinson’s disease, Huntington’s chorea, and Lou Gehrig’s disease, destroy parts of the brain.

Psychotic Disorders

People who abuse drugs often develop psychotic disorders such as schizophrenia.

Brain Changes Associated With Substance Abuse


Alcoholism causes the brain to shrink, which results in mental problems such as depression, confusion, memory loss, hallucinations, paranoia, and delusions.

Cocaine Addiction

Cocaine addiction causes the brain to grow abnormally large.

It also damages the frontal lobes of the brain. This affects decision-making and judgment.

Heroin Addiction

Heroin addiction causes the brain to swell. This is because heroin increases blood pressure.

As a result, fluid builds up in the brain. Over time this can lead to brain damage.

Methamphetamine Addiction

Methamphetamines increase dopamine levels in the brain.

Dopamine is a neurotransmitter that helps control movement, emotions, and behavior.

Overuse of methamphetamine causes a buildup of dopamine in the brain. This can lead to abnormal movements, insomnia, and anxiety.

Tobacco Addiction

Tobacco addiction causes the brain to shrink. This happens because nicotine constricts blood vessels and lowers blood flow.

In addition, tobacco smoke contains carbon monoxide, which binds to hemoglobin in red blood cells and prevents oxygen from reaching the brain.

Treatment For Drugs And Their Side Effects

There are several treatments available for people addicted to drugs. Treatment includes counseling, medication, or both.

Counseling involves talking about what led you to become addicted and why you want to get help.

Medication may be used to treat withdrawal symptoms.

Medications Used To Treat Drug Addiction


Some antidepressants have been shown to reduce the risk of relapse among recovering alcoholics.

Examples include fluoxetine (Prozac), sertraline (Zoloft), and paroxetine (Paxil).


Antipsychotics are medications used to treat psychiatric conditions such as schizophrenia.

They work by blocking certain receptors on the surface of nerve cells.

Because they block dopamine receptors, antipsychotics are sometimes used to treat cocaine addiction.


These medications are prescribed to relieve anxiety and panic attacks.

They act by binding to benzodiazepine receptors located in the brain.

Benzodiazepines are not addictive but long-term use can lead to tolerance and dependence.

Drug Rehabilitation Programs

Drug rehabilitation programs are designed to provide drug addicts with treatment options.

The goal of these programs is to help addicts overcome their addictions and live healthy lives.

There are many types of rehab centers, each offering different services.

Inpatient Rehab Centers

Inpatient rehab centers offer patients intensive care while they undergo treatment.

Patients stay at an inpatient center for anywhere from 30 days to 90 days.

During this period, patients receive individual therapy sessions, group therapy sessions, family support groups, and other services.

Outpatient Rehab Centers

Outpatient rehab centers allow patients to attend weekly or biweekly counseling sessions.

Aftercare services are provided during weekends and holidays.

Patients who complete outpatient rehab programs often find it easier to maintain sobriety after leaving the program than those who go through inpatient rehab.

Detoxification Centers

Some detox centers specialize in helping individuals withdraw from substances such as heroin, cocaine, and crystal meth.

Detox centers typically offer medical supervision, nutritional supplements, and psychological counseling.


Many drugs can affect the central nervous system. Many of them are legal and some are illegal.

Drug abuse can put you at serious risk of damaging the nervous system due to changes in the brain – but there are many different treatment methods available that can reverse drug-related damage to the CNS.

Tom Anderson