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Effects of Psychedolic Drugs on the Central Nervous System Back to Course Index

THE BRAIN/CENTRAL NERVOUS SYSTEM

AND PSYCHEDOLIC DRUGS

(Part 3 in a series on the Central Nervous System and Drugs)

 

 

 

Introducing the Human Brain

The human brain is the most complex organ in the body. This three-pound mass of gray and white matter sits at the center of all human activity – you need it to drive a car, to enjoy a meal, to breathe, to create an artistic masterpiece, and to enjoy everyday activities. In brief, the brain regulates your basic body functions; enables you to interpret and respond to everything you experience; and shapes your thoughts, emotions, and behavior.

 The brain is made up of many parts that all work together as a team. Different parts of the brain are responsible for coordinating and performing specific functions. Drugs can alter important brain areas that are necessary for life-sustaining functions and can drive the compulsive drug abuse that marks addiction. Brain areas that are affected by drug abuse include:

 

         The brain stem that controls basic functions critical to life, such as heart rate, breathing, and sleeping;

        The limbic system that contains the brain’s reward circuit – it links together a number of brain structures that control and regulate our ability to feel pleasure. Feeling pleasure motivates us to repeat behaviors such as eating – actions that are critical to our existence. The limbic system is activated when we perform these activities – and also by drugs of abuse. Also, the limbic system is responsible for our perception of other emotions, both positive and negative, which explains the mood-altering properties of many drugs.

The cerebral cortex is divided into areas that control specific functions. Different areas process information from our senses, enabling us to see, feel, hear, and taste. The front part of the cortex, the frontal cortex or forebrain, is the thinking center of the brain; it powers our ability to think, plan, solve problems, and make decisions.

 The Central Nervous System (CNS)

The CNS coordinates the functions of all parts of the body and consists of the brain and the spinal cord, as well as the retina. Together with the Peripheral Nervous System (PNS), it has a fundamental role in the control of behavior. The CNS is contained within the dorsal cavity, with the brain in the cranial cavity and the spinal cord in the spinal cavity.  The brain is protected by the skull, while the spinal cord is protected by the vertebrae, and both are enclosed in the meninges.

The brain receives sensory input from the spinal cord as well as from its own nerves (e.g., olfactory and optic nerves) and devotes most of its volume to processing its various sensory inputs and initiating appropriate and coordinated motor outputs.  Whereas, the spinal cord conducts sensory information from the PNS to the brain and transmits motor information from the brain to our various effectors such as skeletal muscles, cardiac muscle, and various glands.

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions and transmit signals between different parts of the body.  The PNS consists of sensory neurons, clusters of neurons called ganglia, and nerves connecting them to each other and to the CNS.  These regions are all interconnected by means of complex neural pathways.

Neurons send signals to other cells as electrochemical waves travelling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal may be excited, inhibited, or otherwise modulated. Sensory neurons are activated by physical stimuli impinging on them, and send signals that inform the CNS of the state of the body and the external environment. Motor neurons situated either in the CNS or in peripheral ganglia, connect the nervous system to muscles or other effecter organs. Central neurons, which in vertebrates greatly outnumber the other types, make all of their input and output connections with other neurons. The interactions of all these types of neurons form neural circuits that generate an organism’s perception of the world and determine its behavior.

The brain and nervous system are made of billions of nerve cells, called neurons. Neurons have three main parts: cell body, dendrites, and axon. The axon is covered by the myelin sheath. The transfer of information between neurons is called neurotransmission. This is how neurotransmission works:

1. A message travels from the dendrites through the cell body and to the end of the axon.

2. The message causes the chemicals, called neurotransmitters, to be released from the end of the axon into the synapse. The neurotransmitters carry the message with them into the synapse. The synapse is the space between the axon of one neuron and the dendrites of another neuron.

3. The neurotransmitters then travel across the synapse to special places on the dendrites of the next neuron, called receptors. The neurotransmitters fit into the receptors like keys in locks.

4. Once the neurotransmitter has attached to the receptors of the second neuron, the message is passed on.

5. The neurotransmitters are released from the receptors and are either broken down or go back into the axon of the first neuron.

 

At the most basic level, the CNS sends signals from one cell to another or from one part of the body to another part. There are multiple ways that a cell can send signals to other cells. One is by releasing chemicals called hormones into the internal circulation, so that they can diffuse to distant sites. In contrast to this “broadcast” mode of signaling, the nervous system provides “point-to-point” signals where the neurons project their axons to specific target areas and make synaptic connections with specific target cells. Thus, neural signaling is capable of a much higher level of specificity than hormonal signaling. It is also much faster (travel at speeds that exceed 100 meters per second).

At a more integrative level, the primary function of the nervous system is to control the body.  It does this by extracting information from the environment using sensory receptors, sending signals that encode this information into the CNS, processing the information to determine an appropriate response, and sending output signals to muscles or glands to activate the response. The evolution of a complex nervous system has made it possible for various animal species to have advanced perception abilities such as vision, complex social interactions, rapid coordination of organ systems, and integrated processing of concurrent signals. In humans, the sophistication of the nervous system makes it possible to have language, abstract representation of concepts, transmission of culture, and many other features of human society that would not exist without the human brain.

This continuing education course will focus on the area of psychoactive chemicals and the CNS.  The term psychoactive chemical simply means that a chemical has the capability to increase or decrease the speed of electrical impulses along the nervous system.  This is accomplished simply by altering the various bio-chemicals or neurotransmitters at the neuronal gaps or synapses.

This is part 3 in a series of continuing education courses on how drugs affect the Brain/CNS.  This CEU will address psychoactive chemicals. 

 

 

PSYCHOACTIVE CHEMICALS

Psychoactive chemicals are classified by their effects on the CNS.  The classifications of depressants, stimulants, psychedelics/hallucinogens and others (inhalants, prescription drugs, etc.) are commonly used.  Psychoactive chemicals act on the brain by affecting various neurotransmitters (neurotransmitters are brain chemicals that facilitate communication between brain cells).  Many hallucinogens have chemical structures similar to those of natural neurotransmitters (e.g., acetylcholine-serotonin, or catecholamine-like). While the exact mechanisms by which hallucinogens exert their effects remain unclear, research suggests that these drugs work, at least partially, by temporarily interfering with neurotransmitter action or by binding to their receptor sites. Common types of psychoactive drugs/hallucinogens are:

         LSD: LSD is one of the most potent mood-changing chemicals. It was discovered in 1938 and is manufactured from lysergic acid, which is found in ergot, a fungus that grows on rye and other grains.

         Marijuana: Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant (Cannabis sativa).  Other forms include sinsemilla, hashish, and hash oil. All forms are mind-altering (psychoactive) drugs. The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). It is the most popular illicit psychoactive drug.  It magnifies existing personality traits of the user.  Effects often depend on the mind-set of the user and the setting where it is used.

          Peyote: Peyote is a small, spineless cactus in which the principal active ingredient is mescaline. This plant has been used by natives in northern Mexico and the southwestern United States as a part of religious ceremonies. Mescaline can also be produced through chemical synthesis.

          Psilocybin: Psilocybin is obtained from certain types of mushrooms that are indigenous to tropical and subtropical regions of South America, Mexico, and the United States. These mushrooms typically contain less than 0.5 percent psilocybin plus trace amounts of psilocin, another hallucinogenic substance.

          PCP: PCP (phencyclidine) was developed in the 1950s as an intravenous anesthetic. Its use has since been discontinued due to serious adverse effects.

 

PSYCHEDELICS/HALLUCINOGENS (Excerpts were taken from the NIDA website).

Psychedelics/hallucinogens are chemicals that can act as either stimulants or depressants but mostly they distort the perception of the world and create a world in which logic takes a back seat to intensified, confused sensations. The impact of psychedelics on western culture in the 1960s led to semantic drift in the use of the word “psychedelic”, and it is now frequently used to describe anything with abstract decoration of multiple bright colors, similar to those seen in drug-induced hallucinations.  The chemicals in this category represent a diversified group of substances: from psychedelics such as LSD, PCP, and MDMA (Ecstasy) to naturally occurring plants such as marijuana, peyote, and psilocybin (mushrooms).  Many have a long history and have been used for a variety of purposes throughout history. The general effects of psychedelics is that they cause intensified, mixed-up sensations (visual input becomes sound), illusions, delusions, hallucinations, stimulation, and impaired judgment and reasoning.  The very same characteristics that led to the incorporation of hallucinogens into ritualistic or spiritual traditions have also led to their propagation as drugs of abuse. Importantly, and unlike most other drugs, the effects of hallucinogens are highly variable and unreliable, producing different effects in different people at different times. This is mainly due to the significant variations in amount and composition of active compounds, particularly in the hallucinogens derived from plants and mushrooms. Because of their unpredictable nature, the use of hallucinogens can be particularly dangerous. The most common psychoactive drugs are as follows:

 

LSD

LSD is sold in tablets, capsules, and, occasionally, liquid form; thus, it is usually taken orally. LSD is often added to absorbent paper, which is then divided into decorated pieces, each equivalent to one dose. The experiences, often referred to as trips, are typically 10 to 12 hours in duration. LSD is a clear or white, odorless, water-soluble material synthesized from lysergic acid, a compound derived from a rye fungus. LSD is one of the most potent mood-altering drugs known: oral doses as small as 30 micrograms can produce trips that that last up to 12 hours.

LSD is initially produced in crystalline form. The pure crystal can be crushed to powder and mixed with binding agents to produce tablets known as microdots or thin squares of gelatin called window panes; more commonly, it is dissolved, diluted, and applied to paper or other materials. The most common form of LSD is called blotter acid sheets of paper soaked in LSD and perforated into 1/4-inch square (individual dosage units). Variations in manufacturing and the presence of contaminants can produce LSD in colors ranging from clear or white, in its purest form, to tan or even black. Even uncontaminated LSD begins to degrade and discolor soon after it is manufactured, and drug distributors often apply LSD to colored paper, making it difficult for a buyer to determine the drugs purity or age.

 

LSDs effects

The precise mechanism by which LSD alters perceptions is unclear. Researchers suggest that LSD, like hallucinogenic plants, acts on certain groups of serotonin receptors designated the 5-HT2 receptors, and that its effects are most prominent in two brain regions: One is the cerebral cortex, an area involved in mood, cognition, and perception; the other is the locus ceruleus, which receives sensory signals from all areas of the body and has been described as the brains novelty detector for important external stimuli.

LSDs effects typically begin within one-half hour of ingestion. Users refer to LSD and other hallucinogenic experiences as trips and to the acute adverse experiences as bad trips. Although most LSD trips include both pleasant and unpleasant aspects, the drugs effects are unpredictable and may vary with the amount ingested and the users personality, mood, expectations, and surroundings.

Users of LSD may experience some physiological effects, such as increased blood pressure and heart rate, dizziness, loss of appetite, dry mouth, sweating, nausea, numbness, and tremors; but the drugs major effects are emotional and sensory. The users emotions may shift rapidly through a range from fear to euphoria, with transitions so rapid that the user may seem to experience several emotions simultaneously.

LSD also has dramatic effects on the senses. Colors, smells, sounds, and other sensations seem highly intensified. Some sensory perceptions may blend such that a person seems to hear or feel colors and see sounds. They can also cause hallucinations that distort or transform shapes and movements, and may give rise to a perception that time is moving very slowly or that the users body is changing shape. On some trips, users experience sensations that are enjoyable and mentally stimulating and that produce a sense of heightened understanding. Bad trips, however, include terrifying thoughts and nightmarish feelings of anxiety and despair that include fears of insanity, death, or losing control.

LSD users quickly develop a high degree of tolerance for the drugs effects.  After repeated use, they need increasingly larger doses to produce similar effects.  LSD use also produces tolerance for other hallucinogenic drugs such as psilocybin and mescaline, but not to drugs such as marijuana, amphetamines, and PCP, which do not act directly on the serotonin receptors affected by LSD. Tolerance for LSD is short-lived and is lost if the user stops taking the drug for several days.

There is no evidence that LSD produces physical withdrawal symptoms when chronic use is stopped.

Two long-term effect-persistent psychosis and hallucinogen persisting perception disorder (HPPD), more commonly referred to as flashbacks-have been associated with use of LSD. The causes of these effects, which in some users occur after a single experience with the drug, are not known. Another effect of LSD is psychosis which can be described as distortion or disorganization of a persons capacity to recognize reality, think rationally, or communicate with others. Some LSD users experience devastating psychological effects that persist after the trip has ended, producing a long-lasting psychotic-like state. LSD-induced persistent psychosis may include dramatic mood swings from mania to profound depression, vivid visual disturbances, and hallucinations. These effects may last for years and can affect people who have no history or other symptoms of psychological disorder. Some former LSD users report experiences known colloquially as flashbacks. These episodes are spontaneous, repeated, sometimes continuous recurrences of some of the sensory distortions originally produced by LSD. The experience may include hallucinations, but it most commonly consists of visual disturbances such as seeing false motion on the edges of the field of vision, bright or colored flashes, and halos or trails attached to moving objects. These conditions are typically persistent and in some cases remains unchanged for years after individuals have stopped using the drug. Because HPPD symptoms may be mistaken for those of other neurological disorders such as stroke or brain tumors, sufferers may consult a variety of clinicians before the disorder is accurately diagnosed. There is no established treatment for HPPD, although some antidepressant drugs may reduce the symptoms. Also, Psychotherapy may help patients adjust to the confusion associated with visual distraction and to minimize the fear, expressed by some, which they are suffering brain damage or psychiatric disorder.

Most users of LSD voluntarily decrease or stop its use over time. LSD is not considered an addictive drug since it does not produce compulsive drug-seeking behavior. However, LSD does produce tolerance, so some users who take the drug repeatedly must take progressively higher doses to achieve the state of intoxication that they had previously achieved. This is an extremely dangerous practice, given the unpredictability of the drug. In addition, cross-tolerance between LSD and other hallucinogens has been reported.

 Statistics and Trends

In 2009, 779,000 Americans age 12 and older had abused LSD at least once in the year prior to being surveyed. Source: National Survey on Drug Use and Health (Substance Abuse and Mental Health Administration Web Site). The NIDA-funded 2010 Monitoring the Future Study showed that 1.2% of 8th graders, 1.9% of 10th graders, and 2.6% of 12th graders had abused LSD at least once in the year prior to being surveyed. Source: Monitoring the Future External link, please review our disclaimer. (University of Michigan Web Site)

         Marijuana

Marijuana is a green, brown, or gray mixture of dried, shredded leaves, stems, seeds, and flowers of the hemp plant. You may hear marijuana called by street names such as Pot, ganga, weed, grass, 420, boom, Mary Jane, gangster, or chronic. There are more than 200 slang terms for marijuana. Sinsemilla, hashish (“hash”), and hash oil are stronger forms of marijuana. All forms of marijuana are mind-altering. In other words, they change how the brain works. They all contain THC (delta-9-tetrahydrocannabinol), the main active chemical in marijuana. They also contain more than 400 other chemicals. Marijuana’s effects on the user depend on the strength or potency of the THC it contains. THC potency of marijuana has increased since the 1970s but has been about the same since the mid-1980s. Marijuana is the most commonly used illegal drug in the U.S. Short-term effects of marijuana use include:

         Euphoria (for some users; little or no effect for others);

         Problems with learning (attention span is impaired);

         Mild distorted perception (sights, sounds, time, touch);

         Impaired thinking;

         Reduced problem solving skills (primarily math and science);

         Reduced motor coordination; and increased heart rate. Effects can be unpredictable, especially when other drugs are mixed with marijuana;

         Impaired timing, movements, and coordination.

Marijuana is used in many ways. The most common method is smoking where loose marijuana is rolled into a cigarette called a joint or nail. Sometimes marijuana is smoked through a water pipe called a bong. Others smoke blunts (cigars that are hollowed out and filled with the drug). And some users brew it as tea or mix it with food.

 How Long Does Marijuana Stay in the User’s Body?

THC is absorbed by fatty tissues in various organs. The half-life of marijuana is approximately 7 days (half-life is the time required for the body to eliminate one half of the amount of THC stored); consequently, marijuana can be detected for three to four weeks after use. Generally, traces (metabolites) of THC can be detected by standard urine test methods.

 

How Many Teens Smoke Marijuana?

Contrary to popular belief most teenagers have not used marijuana and never will. Among students surveyed in a yearly national survey, only about one in five 10th graders report they are current marijuana users (that is, used marijuana within the past month). Fewer than one in four high school seniors are a current marijuana user.  In 2009, 28.5 million Americans age 12 and older had abused marijuana at least once in the year prior to being surveyed. Source: National Survey on Drug Use and Health (Substance Abuse and Mental Health Administration Web Site). The NIDA-funded 2010 Monitoring the Future Study showed that 13.7% of 8th graders, 27.5% of 10th graders, and 34.8% of 12th graders had abused marijuana at least once in the year prior to being surveyed. Source: Monitoring the FutureExternal link, please review our disclaimer. (University of Michigan Web Site).


Why do Young People Use Marijuana?

There are many reasons why some teens start smoking marijuana. Most smoke marijuana because their friends or siblings use and pressure them to try it. Also, some young people use it because they see older people or family members using it.  Some may think it’s cool to use marijuana because they hear songs about it and see it on TV and in movies. Some may feel they need marijuana and other drugs to help them escape from problems at home, at school, or with friends. No matter how many shirts and caps you see printed with the marijuana leaf, or how many groups sing about it, remember this: You don’t have to use marijuana just because you think everybody else is doing it. Most teens do not use marijuana!


What Happens If You Smoke Marijuana?

 The way the drug affects each person depends on many factors, including:

        Previous experience with the drug;

        Potency (how much THC it has);

        Using other drugs in combination with marijuana.

Some people feel nothing at all when they smoke marijuana. Others may feel relaxed or high. Sometimes marijuana makes users feel thirsty and hungry an effect called “the munchies.” Some users can get bad effects from marijuana. They may suffer sudden feelings of anxiety and have paranoid thoughts. This is more likely to happen when a more potent variety of marijuana is used. These effects are greater when other drugs are mixed with the marijuana.


What Are the Long-term Effects of Marijuana Use?

Findings so far show that regular use of marijuana may play a role in some kinds of cancer and in problems with the respiratory and immune systems. It’s hard to know for sure whether regular marijuana use causes cancer. But it is known that marijuana contains some of the same, and sometimes even more, of the cancer-causing chemicals found in tobacco smoke. Studies show that someone who smokes five joints per day may be taking in as many cancer-causing chemicals as someone who smokes a full pack of cigarettes every day. Also, people who smoke marijuana often develop the same kinds of breathing problems that cigarette smokers have: coughing and wheezing. They tend to have more chest colds than nonusers. They are also at greater risk of getting lung infections like pneumonia. Animal studies have shown that THC can damage the cells and tissues that help protect against disease. When the immune cells are weakened you are more likely to get sick.

 
Marijuana and the Brain

THC affects the nerve cells in the part of the brain where memories are formed. This makes it hard for the user to recall recent events (such as what happened a few minutes ago). Learning is also impaired because of the impairment of their short-term memory. Among a group of long-time, heavy users (6 to 8 joints per day) in Costa Rica, researchers found that the people had great trouble when asked to recall a short list of words (a standard test of memory). People in that study group also found it very hard to focus their attention on the tests given to them.

As people age, they normally lose nerve cells in a region of the brain that is important for remembering events. Chronic exposure to THC may hasten the age-related loss of these nerve cells. In one study, researchers found that rats exposed to THC every day for 8 months (about 1/3 of their lifespan) showed a loss of brain cells comparable to rats that were twice their age. It is not known whether a similar effect occurs in humans. Researchers are still learning about the many ways that marijuana could affect the brain.

 

Peyote

Peyote contains a large spectrum of phenethylamine alkaloids, of which the principal one is mescaline.  The top of the cactus, also referred to as the crown, consists of disc-shaped buttons that are cut above the roots and sometimes dried. When done properly, the top of the root will form a callus and the root will not rot.  The buttons are generally chewed, or boiled in water to produce a psychoactive tea. Peyote is extremely bitter, and most people are nauseated before they feel the onset of the psychoactive effects. The hallucinogenic dose of mescaline is about 0.3 to 0.5 grams, and its effects last about 12 hours. Because the extract is so bitter, some individuals prefer to prepare a tea by boiling the cacti for several hours.

Peyote effects are similar to those of LSD, including increased body temperature and heart rate, uncoordinated movements (ataxia), profound sweating, and flushing. The long-term residual psychological and cognitive effects of mescaline, peyotes principal active ingredient, remain poorly understood. A recent study found no evidence of psychological or cognitive deficits among Native Americans that use peyote regularly in a religious setting. It should be noted, however, that these findings may not correlate to those who repeatedly abuse the drug for recreational purposes. Peyote abusers may also experience flashbacks.

 
Peyote Use

It is difficult to gauge the extent of use of Peyote because most data sources that quantify drug use exclude this drug; however, the Monitoring the Future survey reported in 2008 that 7.8 percent of high school seniors had used hallucinogens other than LSD at least once in their lifetime (includes peyote, psilocybin, and others). Past-year use was reported to be 5.0 percent.

 
Treatment Options

Treatment for alkaloid hallucinogen (such as peyote) intoxication which is mostly symptomatic is often sought as a result of bad trips, during which a patient may, for example, hurt him- or herself. Treatment is usually supportive: provision of a quiet room with little sensory stimulation. Occasionally, benzodiazepines are used to control extreme agitation or seizures.

 

Psilocybin

Mushrooms containing psilocybin are available fresh or dried and are typically taken orally. Psilocybin (4-phosphoryloxy-N, N-dimethyltryptamine) and its biologically active form, psilocin (4-hydroxy-N, N-dimethyltryptamine), cannot be inactivated by cooking or freezing preparations. Thus, they may also be brewed as a tea or added to other foods to mask their bitter flavor. The effects of psilocybin, which appear within 20 minutes of ingestion, last approximately 6 hours.

Psilocybin is obtained from certain types of mushrooms that are indigenous to tropical and subtropical regions of South America, Mexico, and the United States. These mushrooms typically contain less than 0.5 percent psilocybin plus trace amounts of psilocin, another hallucinogenic substance. Mushrooms containing psilocybin are available fresh or dried and are typically taken orally.

The active compounds in psilocybin-containing magic mushrooms have LSD-like properties and produce alterations of autonomic function, motor reflexes, behavior, and perception. The psychological consequences of psilocybin use include hallucinations, an altered perception of time, and an inability to discern fantasy from reality. Panic reactions and psychosis also may occur, particularly if a user ingests a large dose. Long-term effects such as flashbacks, risk of psychiatric illness, impaired memory, and tolerance have been described in case reports. It can also produce muscle relaxation or weakness, ataxia, excessive pupil dilation, nausea, vomiting, and drowsiness. Individuals who abuse psilocybin mushrooms also risk poisoning if one of many existing varieties of poisonous mushrooms is incorrectly identified as a psilocybin mushroom.


 
Treatment Options

Treatment for alkaloid hallucinogen (such as psilocybin) intoxication which is mostly symptomatic is often sought as a result of bad trips, during which a patient may, for example, hurt him- or herself. Treatment is usually supportive: provision of a quiet room with little sensory stimulation. Occasionally, benzodiazepines are used to control extreme agitation or seizures.


 
Psilocybin Use

It is difficult to gauge the extent of use of Psilocybin because most data sources that quantify drug use exclude this drug; however, the Monitoring the Future survey reported in 2008 that 7.8 percent of high school seniors had used hallucinogens other than LSD a group that includes peyote, psilocybin, and others at least once in their lifetime. Past-year use was reported to be 5.0 percent.

 

PCP

PCP (phencyclidine) was developed in the 1950s as an intravenous anesthetic. Its use has since been discontinued due to serious adverse effects.  It is a white crystalline powder that is readily soluble in water or alcohol. It has a distinctive bitter chemical taste. PCP can be mixed easily with dyes and is often sold on the illicit drug market in a variety of tablet, capsule, and colored powder forms that are normally snorted, smoked, or orally ingested. For smoking, PCP is often applied to a leafy material such as mint, parsley, oregano, or marijuana. Depending upon how much and by what route PCP is taken, its effects can last approximately 4 to 6 hours. As noted previously, PCP, LSD, peyote, psilocybin, and LSD are drugs that cause hallucinations, which are profound distortions in a persons perception of reality. Under the influence of hallucinogens, people see images, hear sounds, and feel sensations that seem real but are not. Some hallucinogens also produce rapid, intense emotional swings. LSD, peyote, and psilocybin cause their effects by initially disrupting the interaction of nerve cells and the neurotransmitter serotonin. Distributed throughout the brain and spinal cord, the serotonin system is involved in the control of behavioral, perceptual, and regulatory systems, including mood, hunger, body temperature, sexual behavior, muscle control, and sensory perception. On the other hand, PCP acts mainly through a type of glutamate receptor in the brain that is important for the perception of pain, responses to the environment, and learning and memory.


PCP Effect on the Brain

There have been no controlled research studies on the specific effects of PCP on the human brain, but smaller studies and several case reports have been published documenting some of the effects associated with the use of other hallucinogens. The use of PCP as an approved anesthetic in humans was discontinued in 1965 because patients often became agitated, delusional, and irrational while recovering from its anesthetic effects. PCP is a dissociative drug, meaning that it distorts perceptions of sight and sound and produces feelings of detachment (dissociation) from the environment and self. First introduced as a street drug in the 1960s, PCP quickly gained a reputation as a drug that could cause bad reactions and was not worth the risk. However, some abusers continue to use PCP due to the feelings of strength and power it can induce. Among the adverse psychological effects reported are:

         Symptoms that mimic schizophrenia, such as delusions, hallucinations, paranoia, disordered thinking, and a sensation of distance from ones environment;

         Mood disturbances: Approximately 50 percent of individuals brought to emergency rooms because of PCP-induced problems related to use within the past 48 hours report significant elevations in anxiety symptoms.

People who have abused PCP for long periods of time have reported memory loss, difficulties with speech and thinking, depression, and weight loss. These symptoms can persist up to one year after stopping PCP abuse.


PCP Addiction

PCP is addictive.  Its repeated abuse can lead to craving and compulsive drug seeking behavior, despite severe adverse consequences.


Other Adverse Effects

Unpleasant adverse effects as a result of the use of hallucinogens are not uncommon. These may be due to the large number of psychoactive ingredients in any single source of hallucinogen. At low-to-moderate doses, physiological effects of PCP include a slight increase in breathing rate and a pronounced rise in blood pressure and pulse rate. Breathing becomes shallow; flushing and profuse sweating, generalized numbness of the extremities, and loss of muscular coordination may occur.

At high doses, blood pressure, pulse rate, and respiration drop. This may be accompanied by nausea, vomiting, blurred vision, flicking up and down of the eyes, drooling, loss of balance, and dizziness. PCP abusers are often brought to emergency rooms because of overdose or because of the drugs severe untoward psychological effects. While intoxicated, PCP abusers may become violent or suicidal and are therefore dangerous to themselves and others. High doses of PCP can also cause seizures, coma, and death (though death more often results from accidental injury or suicide during PCP intoxication). Because PCP can also have sedative effects, interactions with other central nervous system depressants, such as alcohol and benzodiazepines, can also lead to coma.

Approximately 50 percent of individuals brought to emergency rooms because of PCP-induced problems related to use within the past 48 hours report significant elevations in anxiety symptoms. People who have abused PCP for long periods of time have reported memory loss, difficulties with speech and thinking, depression, and weight loss. These symptoms can persist up to one year after stopping PCP abuse.


Treatment Options

There is very little published data on treatment outcomes for PCP intoxication. Doctors should consider that acute adverse reactions may be the result of drug synergy with alcohol. Current research efforts to manage a life-threatening PCP overdose are focused on a passive immunization approach through the development of anti-PCP antibodies. There are no specific treatments for PCP abuse and addiction, but inpatient and/or behavioral treatments can be helpful for patients with a variety of addictions, including that to PCP.


How Widespread Is the Abuse

According to the National Survey on Drug Use and Health (NSDUH), there were approximately 1.1 million persons aged 12 or older in 2007 who reported using hallucinogens for the first time within the past 12 months. Also, the Monitoring the Future Survey in 2008, 1.8 percent of high school seniors reported lifetime use of PCP; past-year use was reported by 1.1 percent of seniors; and past-month use was reported by 0.6 percent. Data on PCP use by 8th- and 10th-graders are not available.

 
Physiological effects

At low-to-moderate doses, physiological effects of PCP include a slight increase in breathing rate and a pronounced rise in blood pressure and pulse rate. Breathing becomes shallow; flushing and profuse sweating, generalized numbness of the extremities, and loss of muscular coordination may occur. At high doses, blood pressure, pulse rate, and respiration drop. This may be accompanied by nausea, vomiting, blurred vision, flicking up and down of the eyes, drooling, loss of balance, and dizziness. PCP abusers are often brought to emergency rooms because of overdose or because of the drugs severe untoward psychological effects. While intoxicated, PCP abusers may become violent or suicidal and are therefore dangerous to themselves and others. High doses of PCP can also cause seizures, coma, and death (though death more often results from accidental injury or suicide during PCP intoxication). Because PCP can also have sedative effects, interactions with other central nervous system depressants, such as alcohol and benzodiazepines, can also lead to coma.

 

 

Qs and As (Note: Qs are general in nature and not necessarily directed specifically at Psychedelic drugs)

 

Q-1: How Do drugs Produce Euphoria?

Drugs change the way the brain works by changing the way nerve cells communicate. Nerve cells, called neurons, send messages to each other by releasing chemicals called neurotransmitters. Neurotransmitters work by attaching to key sites on neurons called receptors. Learn more about how neurotransmitters work in the section How Does Your Brain Communicate?

There are many neurotransmitters, but dopamine is one that is directly affected by most stimulants. Dopamine makes people feel good when they do something they enjoy, like eating a piece of chocolate cake or riding a roller coaster. Stimulants cause a buildup of dopamine in the brain, which can make people who abuse stimulants feel intense pleasure and increased energy. They can also make people feel anxious and paranoid. And with repeated use, stimulants can disrupt the functioning of the brains dopamine system, dampening users ability to feel any pleasure at all. Users may try to compensate by taking more and more of the drug to experience the same pleasure.

Q 2: What Are the Short-Term Effects?

In the short term, some drugs especially stimulants can produce joyful feelings, increase wakefulness, and decreases appetite. Users can become more talkative, energetic, or anxious and irritable. Other short-term effects of stimulants can include increased body temperature, heart rate, and blood pressure; dilated pupils; nausea; blurred vision; muscle spasms; and confusion.  Stimulants can also cause the bodys blood vessels to narrow, constricting the flow of blood, which forces the heart to work harder to pump blood through the body. The heart may work so hard that it temporarily loses its natural rhythm. This is called fibrillation and can be very dangerous because it stops the flow of blood through the body.

Q 3: What Are the Long-Term Effects?

As with many types of drugs, repeated abuse can cause addiction. That means that someone repeatedly seeks out and uses the drug despite its harmful effects. Repeated drug use changes the brain in ways that contribute to the drug craving and continued drug seeking and use that characterizes addiction. Other effects of long-term stimulant abuse can include paranoia, aggressiveness, extreme anorexia, thinking problems, visual and auditory hallucinations, delusions, and severe dental problems.

For example, repeated use of cocaine can lead to tolerance of its euphoric effects, causing the user to take higher doses or to use the drug more frequently (e.g., binge use) to get the same effects. Such use can lead to bizarre, erratic behavior. Some cocaine users experience panic attacks or episodes of full-blown paranoid psychosis, in which the individual loses touch with reality and hears sounds that arent there (auditory hallucinations). Different ways of using cocaine can produce different adverse effects. For example, regularly snorting cocaine can lead to hoarseness, loss of the sense of smell, nosebleeds, and a chronically runny nose. Cocaine taken orally can cause reduced blood flow, leading to bowel problems.

Repeated use of methamphetamine can cause violent behavior, mood disturbances, and psychosis, which can include paranoia, auditory hallucinations, and delusions (e.g., the sensation of insects creeping on the skin. The paranoia can result in homicidal and suicidal thoughts. Methamphetamine can increase a persons sex drive and is linked to risky sexual behaviors and the transmission of infectious diseases, such as HIV. However, research also indicates that long-term methamphetamine use may be associated with decreased sexual function, at least in men.

Q 4: Can These Drugs Be Lethal?

Yes, in rare instances, sudden death can occur on the first use of cocaine or unexpectedly thereafter. And, like most drugs, stimulants can be lethal when taken in large doses or mixed with other substances. Stimulant overdoses can lead to heart problems, strokes, hyperthermia (elevated body temperature), and convulsions, which if not treated immediately can result in death. Abuse of both cocaine and alcohol compounds the danger, increasing the risk of overdose.

Q 5: What Are the Differences Between Cocaine and Methamphetamine?

They act in different ways to increase dopamine in the brain. Cocaine works by blocking the dopamine transporter; that is, it doesnt allow dopamine to be recycled back into the neuron after it has done its work. Methamphetamine interferes with this recycling process as well, but it also causes too much dopamine to be released. Another difference is that cocaine disappears from the brain quickly, while methamphetamine has a much longer duration of action. The longer presence in the brain ultimately makes methamphetamine more harmful to brain cells.

Q 6: If a Pregnant Woman Uses Stimulants, Will the Baby Be Hurt?

In the United States between 2006 and 2007, 22.6 percent (or 20,000) of teens ages 15 to 17 used an illicit drug during their pregnancy. Scientists have found that exposure to cocaine during fetal development may lead to subtle but significant deficits later in life, including problems with attention and information processing abilities that are important for success in school. Research is also underway on the effects of methamphetamine use during pregnancy. So far, the data suggest that it may affect fetal growth and contribute to poor quality of movement in infants.

Research in this area is particularly difficult to interpret because it is often hard to single out drugs specific effects among the multiple factors that can all interact to affect maternal, fetal, and child outcomes. These factors include exposure to all drugs of abuse, including nicotine and alcohol; extent of prenatal care; possible neglect or abuse of the child; exposure to violence in the environment; socioeconomic conditions; maternal nutrition; other health conditions; and exposure to sexually transmitted diseases.

Q 7: What Treatments Are Available for Stimulant Abuse?

Several behavioral therapies are effective in treating addiction to stimulants. These approaches are designed to help the person think differently, change their expectations and behaviors, and increase their skills in coping with various stresses in life. One form that is showing positive results in people addicted to either cocaine or methamphetamine is called contingency management, or motivational incentives (MI). These programs reward patients who refrain from using drugs by offering vouchers or prizes. MI may be particularly useful for helping patients to initially stop taking the drug and for helping them to stay in treatment.

Currently, there are no medications approved by the U.S. Food and Drug Administration to treat people who are addicted to stimulants, although that is an active area of research for NIDA.

As with other drugs of abuse, it is possible for individuals to become dependent upon or addicted too many stimulants. Withdrawal symptoms associated with discontinuing stimulant use include fatigue, depression, and disturbance of sleep patterns. Repeated use of some stimulants over a short period can lead to feelings of hostility or paranoia. Further, taking high doses of a stimulant may result in dangerously high body temperature and an irregular heartbeat. There is also the potential for cardiovascular failure or lethal seizures.

Stimulants should be used in combination with other medications only under a physician’s supervision. Patients also should be aware of the dangers associated with mixing stimulants and OTC cold medicines that contain decongestants; combining these substances may cause blood pressure to become dangerously high or lead to irregular heart rhythms.

Q 8: How does the brain communicate?

The brain is a communications center consisting of billions of neurons, or nerve cells. Networks of neurons pass messages back and forth to different structures within the brain, the spinal column, and the peripheral nervous system. These nerve networks coordinate and regulate everything we feel, think, and do.  The brain communicates via:

Neuron to Neuron: Each nerve cell in the brain sends and receives messages in the form of electrical impulses. Once a cell receives and processes a message, it sends it on to other neurons.

Neurotransmitters:  The messages are carried between neurons by chemicals called neurotransmitters. (

Receptors: The neurotransmitter attaches to a specialized site on the receiving cell called a receptor. A neurotransmitter and its receptor operate like a “key and lock,” an exquisitely specific mechanism that ensures that each receptor will forward the appropriate message only after interacting with the right kind of neurotransmitter.

Transporters: Located on the cell that releases the neurotransmitter, transporters recycle these neurotransmitters (i.e., bringing them back into the cell that released them), thereby shutting off the signal between neurons.

To send a message a brain cell releases a chemical (neurotransmitter) into the space separating two cells called the synapse. The neurotransmitter crosses the synapse and attaches to proteins (receptors) on the receiving brain cell. This causes changes in the receiving brain cell and the message is delivered. 

Q 9: How do drugs work in the brain?

Drugs are chemicals. They work in the brain by tapping into the brain’s communication system and interfering with the way nerve cells normally send, receive, and process information. Some drugs, such as marijuana and heroin, can activate neurons because their chemical structure mimics that of a natural neurotransmitter. This similarity in structure “fools” receptors and allows the drugs to lock onto and activate the nerve cells. Although these drugs mimic brain chemicals, they don’t activate nerve cells in the same way as a natural neurotransmitter, and they lead to abnormal messages being transmitted through the network.

Other drugs, such as amphetamine or cocaine, can cause the nerve cells to release abnormally large amounts of natural neurotransmitters or prevent the normal recycling of these brain chemicals. This disruption produces a greatly amplified message, ultimately disrupting communication channels. The difference in effect can be described as the difference between someone whispering into your ear and someone shouting into a microphone.

Q 10: How do drugs work in the brain to produce pleasure?

All drugs of abuse directly or indirectly target the brain’s reward system by flooding the circuit with dopamine. Dopamine is a neurotransmitter present in regions of the brain that regulate movement, emotion, cognition, motivation, and feelings of pleasure. The overstimulation of this system, which rewards our natural behaviors, produces the euphoric effects sought by people who abuse drugs and teaches them to repeat the behavior.

Q 11: How does stimulation of the brain’s pleasure circuit teach us to keep taking drugs?

Our brains are wired to ensure that we will repeat life-sustaining activities by associating those activities with pleasure or reward. Whenever this reward circuit is activated, the brain notes that something important is happening that needs to be remembered, and teaches us to do it again and again, without thinking about it. Because drugs of abuse stimulate the same circuit, we learn to abuse drugs in the same way.

Q 12: Why are drugs more addictive than natural rewards?

When some drugs of abuse are taken, they can release 2 to 10 times the amount of dopamine that natural rewards do. In some cases, this occurs almost immediately (as when drugs are smoked or injected), and the effects can last much longer than those produced by natural rewards. The resulting effects on the brain’s pleasure circuit dwarfs those produced by naturally rewarding behaviors such as eating and sex.16,17 The effect of such a powerful reward strongly motivates people to take drugs again and again. This is why scientists sometimes say that drug abuse is something we learn to do very, very well. 

Q 13: What happens to your brain if you keep taking drugs?

Just as we turn down the volume on a radio that is too loud, the brain adjusts to the overwhelming surges in dopamine (and other neurotransmitters) by producing less dopamine or by reducing the number of receptors that can receive and transmit signals. As a result, dopamine becomes abnormally low, and the ability to experience any pleasure is reduced. This is why the abuser eventually feels flat, lifeless, and depressed, and is unable to enjoy things that previously brought them pleasure. Now, they need to take drugs just to bring their dopamine function back up to normal. And, they must take larger amounts of the drug than they first did to create the dopamine high – an effect known as tolerance.

Q 14: How does long-term drug taking affect brain circuits?

We know that the same sort of mechanisms involved in the development of tolerance can eventually lead to profound changes in neurons and brain circuits, with the potential to severely compromise the long-term health of the brain. For example, glutamate is another neurotransmitter that influences the reward circuit and the ability to learn. When the optimal concentration of glutamate is altered by drug abuse, the brain attempts to compensate for this change, which can cause impairment in cognitive function. Similarly, long-term drug abuse can trigger adaptations in habit or non-conscious memory systems. Conditioning is one example of this type of learning, whereby environmental cues become associated with the drug experience and can trigger uncontrollable cravings if the individual is later exposed to these cues, even without the drug itself being available. This learned “reflex” is extremely robust and can emerge even after many years of abstinence.

Q 15:  What other brain changes occur with abuse?

Chronic exposure to drugs of abuse disrupts the way critical brain structures interact to control behavior – behavior specifically related to drug abuse. Just as continued abuse may lead to tolerance or the need for higher drug dosages to produce an effect, it may also lead to addiction, which can drive an abuser to seek out and take drugs compulsively. Drug addiction erodes a person’s self-control and ability to make sound decisions, while sending intense impulses to take drugs.

 

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