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How Do Prescription Drugs Affect the Brain?

Prescription drugs, although therapeutic when taken appropriately, often have psychoactive properties and therefore can be misused and abused. They are federally controlled substances for this reason and can only be obtained legally with a prescription from a doctor. Before such a prescription is given, doctors weigh the potential health benefits and dangers of their use by a patient.1 One risk is that of misusing or abusing a prescription drug for its desirable effects, such as a feeling of well-being. As is true with many illicit drugs, chronic abuse of many types of prescription medications can result in changes in neurochemistry, which can lead to dependence and addiction. When abused, prescriptions drugs can be just as dangerous as illegal street drugs.1 Around 54 million people reported non-medical (recreational) use of a prescription drug.2

The types of prescription drugs that are frequently abused fall into a number of different categories and have varying effects on the brain, depending on the substance in question.1 This article summarizes several different types of oft-abused prescription drugs, their corresponding effects on the brain, and various treatment options.

Prescription Drug Types

Prescription drugs are commonly available in pill or tablet form, which are intended to be taken orally. In some cases, those who misuse or abuse them may attempt a more immediate method of administration, such as crushing and snorting the pills or dissolving them in water and injecting them.

Some of the more commonly abused categories of prescription drugs are:3-6

  • Opioids: These are used to relieve pain via their interaction with opioid receptors throughout the brain. Common examples include Vicodin, Percocet, OxyContin, and fentanyl.
  • Sedative, Hypnotics, and Anxiolytics: The various medications in this broad category of drugs are used to manage anxiety, panic, seizures, or to aid in sleep; they do this by increasing inhibitory brain signaling throughout the central nervous system (CNS). They can be further subcategorized into the benzodiazepines—such as Valium, Xanax, and Klonopin, the barbiturates—such as phenobarbital, and non-benzodiazepine sleep aids—such as Ambien and Lunesta.
  • Stimulants: These are used to treat attention deficit hyperactive disorder (ADHD) and some sleep-related disorders and include the amphetamines—such as Adderall and Dexedrine, and methylphenidate—such as Ritalin and Concerta; they act to increase the activity of certain brain neurotransmitters, primarily dopamine and norepinephrine, to achieve their CNS-stimulating effects.

Opioid Effects

Prescription opioids activate opioid receptors in the brain and, in doing so, decrease the perception of pain signaling. This receptor interaction is also associated with a release of dopamine in the brain’s mesolimbic reward center, which can result in feelings of euphoria, elation, or pleasure.8, 9  When dopamine is released, other areas of the brain react, creating a memory and associating it with the pleasurable circumstances in which it occured.9  Due in part to these rewarding effects, many people—even those who begin taking these drugs according to a prescription—may begin to misuse them and, eventually, find themselves progressing towards addiction.

Some potential short-term, neurological effects of opioids include:14

  • Mood changes.
  • Depression.
  • Drowsiness.
  • Impaired memory, judgment, and attention.

The neurological manifestations of long-term opioid abuse include:9,14

  • Tolerance: This is characterized by the need to take more of the opioid to achieve the same effects.
  • Drug dependence: This is characterized by the need to take opioids to avoid the emergence of withdrawal symptoms, such as depression, insomnia, anxiety, restlessness, and irritability.
  • Addiction: This is characterized by prolonged, habitual use of opioids regardless of the adverse consequences a user experiences.

It can be difficult to quit abusing opioids once significant physiological dependence has developed, due to the distressing withdrawal symptoms associated with stopping or dramatically reducing use. Formal detox and substance abuse treatment are two beneficial ways to quit opioid use comfortably and safely.

Effects of Sedatives, Hypnotics, and Anxiolytics

Barbiturates, benzodiazepines, and sleep medications fall into a category of drugs called sedatives, hypnotics, or anxiolytics or, more broadly, CNS depressants. These drugs decrease neural excitation by potentiating the effects of an inhibitory neurotransmitter known as gamma-aminobutyric acid (GABA) and, through these GABA-mediated effects, help to increase relaxation, relieve anxiety, and manage certain sleep conditions like insomnia.4 Within the therapeutic range, this is safe, but abusing prescription depressants can result in dangerously high levels of GABA activity.4

The neurological effects of prescription depressants include:4,14

  • Mood swings.
  • Inappropriate aggressive or sexual behavior.
  • Memory and attention problems.
  • Disorientation.
  • Impaired coordination.
  • Drowsiness or stupor.
  • Coma.

Much like chronic opioid abuse, long-term abuse of prescription depressants can lead to the development of severe physical dependence. Withdrawal symptoms associated with benzodiazepines and barbiturates, such as seizures or delirium, can be fatal.14 Professional detox services can minimize the risk of life-threatening complications and help you to stabilize throughout the acute withdrawal period.

Prescription Stimulant Side Effects

Common prescription stimulants, such as amphetamines and methylphenidate, have molecular structures that are similar to certain brain chemical messengers, such as dopamine and norepinephrine. Prescription stimulants increase the effects of these neurotransmitters.6 The overstimulation of the receptors on the postsynaptic neuron (the neuron that receives a message) causes a disruption of the dopaminergic system. This occurs either by blocking the reabsorption of dopamine back into the presynaptic neuron (neuron that sends a message) or by increasing the amount of dopamine released into the synapse.11 The high or euphoric rush a user experiences from stimulants is largely due to the excessive amounts of dopamine released in the synapse.11 

Stimulants can increase the dopamine in the brain very quickly, and this changes the normal communication between brain cells, producing a high while also increasing the risk for dangerous side effects.6

Neurological effects of stimulants include:6,11 

  • Paranioa.
  • Anger.
  • Agitation.
  • Seizures.
  • Reduced sleep.
  • Lack of interest in eating. 

In addition to the effects of active stimulant abuse, the abrupt discontinuation of psychoactive stimulants following long-term use often results in discomfort and cravings.11

Unlike opioids and CNS depressants, stimulants can actually cause a person to become sensitized to some of their effects, as opposed to building a tolerance. This means that after repeated stimulant abuse, a previously harmless dose can more easily result in severe consequences, such as a seizure.11

From Substance Abuse to Addiction

Chronic prescription drug abuse causes complex neurological changes, also called neuroadaptations. These adaptations alter the functioning of certain brain cell functions and are simply the body’s way of compensating for the negative effects of drugs.11 Eventually, and with repeated use, the user needs more and more of the drug to get the same drug-induced effects, also known as tolerance. In their attempts to overcome tolerance, a user may hasten the development of physiological dependence, which means that the body has adapted to the presence of the drug and requires it to function normally.11 The user has entered the territory of addiction when they are unable to control their use regardless of detrimental consequences.

Some signs and symptoms associated with prescription drug addiction are as follows:11,13,14

  • Cravings: This refers to conditioned cues and triggers that stimulate arousal and a strong desire for the drug.
  • Tolerance: This happens when one needs increased amounts of a drug to produce the desired effects or experiences a diminished effect when using a previous dose.
  • Withdrawal: This refers to the various unpleasant effects resulting from abruptly stopping drug use.
  • Social and behavioral problems: These can include inability to fulfill obligations or home, school, or work, interpersonal problems, loss of custody of child, and erratic, anxious, or moody behavior.
  • Physical and psychological problems: These may include poor hygiene, malnutrition, cardiac problems, psychosis, a lack of interest in social activities, and depression and suicidal thoughts.

Addiction Treatment Options

Although prescription drug addiction is a serious health issue and relapse rates are high, formal addiction treatment can help address the underlying issues driving substance abuse and addiction. There are many different addiction treatment options that vary in intensity and setting, such as inpatient, outpatient, luxury, executive, and holistic rehab.

Because of their effects on the brain, some of these types of drugs may benefit from a medical detox prior to entering a substance abuse treatment program; this is because withdrawal from certain types of drugs can be deadly. Professional detox can ensure comfort and safety throughout the withdrawal process. Then once someone is stabilized they can transition into a drug addiction treatment program. Once that is completed, various aftercare or ongoing support measures can help people to stay clean and sober in the long run. These measures may include 12-step groups, non-12-step support groups, individual therapy, and group counseling.

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