Psychopharmacology and drug effects on brain function

¶ … psychopharmacology, the goal is to use drugs to improve brain function. This takes place via very specific actions within the brain. The drug may be administered in one of several ways, and its metabolism will vary based on many factors, making psychopharmacology a complicated medical issue. In addition, some people abuse substances known to have a psychopharmalogical effect. Both the appropriate and inappropriate use of these drugs can have a profound effect on both mind and body.

While researchers have described many uses for these medications, they are not yet "magic bullets" that can be aimed precisely, giving only the desired effect, doing that well, and causing no side effects (Hamilton & Timmons, 1994). Sometimes the side effects can be managed well, but sometimes a medication will help solve another (say, depression) and yet cause or aggravate another (for example, anxiety) (Hamilton & Timmons, 1994).

One author suggests that one think about the interaction of brain, environment and behavior as a triangle, with each side having an effect on the other two (Hamilton & Timmons, 1994). For instance, some drugs may have an immediate effect on behavior; a long-range effect on neurons; and the person's changed behavior may change his or her personal environment. It is important to keep all these ongoing interactions in mind to talk about pharmacology accurately.

In addition, drugs can have physical as well as behavioral or emotional effects. For instance, amphetamines will raise blood pressure, cause the pupils of the eyes to dilate, and relax smooth muscles of the intestines (Murray, 1998). They also depress appetite. The entire person must be considered when thinking about psychotropic medications.

Psychotropic drugs and the brain

The human nervous system has very specific cells that allow the nervous system to communicate within themselves. "Interneurons" exist only in the brain and spinal cord and receive signals from the rest of the body from sensory neurons as well as from other interneurons. There may be as many as 100 billion interneurons, with up to 1,000 synapses where other neurons can communicate with them (Kimball, 2003). There are many different kinds of interneurons.

Most neurons communicate by releasing neurotransmitters to another cell. The part of the cell that sends the message is called an axon. It does not directly touch another cell's synapses, but sends out a neurotransmitter. Different synapses are configured to receive different neurotransmitters (Hamilton & Timmons, 1994). The space between the axon of one cell and the synapse of the next is sometimes called the synaptic cleft, and the goal of many psychotropic drugs is to affect this process in one of several ways.

Some synapses act to reduce the effect of neurotransmitters, so the action between cells is actually far more complex than one cell sending a "message" to another. Some set off chain events, where a neurotransmitter causes a change to happen at another point so another neurotransmitter can be received (Kimball, 2003). Some neurotransmitters facilitate messages in muscles, or other parts of the body, so medications that affect neurotransmitter function can have body-wide effects. Other neurotransmitters, such as dopamine and serotonin, are found only in the brain. To complicate things further, some chemicals called peptides may serve as neurotransmitters, and some also act as hormones. The brain is a complex chemical soup and it is not easy to change those chemicals in highly controlled ways with no negative side effects (Kimball, 2003).

Once a neurotransmitter has been used, it has to be deactivated. Some are simply transported away, but some are broken down by enzymes. At any point in all of these complex operations, a psychoactive drug can alter action and change behavior, emotion, or even thought.

Central Nervous System Stimulants

CNS stimulants include both legal and illegal drugs. Amphetamines and amphetamine-like drugs can be prescribed (Murray, 1998). Cocaine, made from coca leaves, has very narrow medical uses and is frequently available as an illegal street drug. Other stimulants include caffeine and nicotine, and substances containing them can be legally purchased in any store selling tobacco products, coffee, etc.

Methamphetamine is a powder with a bitter taste but no odor (Murray, 1998). When produced illegally, it is often white to yellowish. As an illegal drug it is sometimes called crystal meth or speed. Legally it is sold in pill or capsule form. Illegally, it can be sold in capsules or in chunks. In addition to taking it orally, it can be used intravenously or even smoked. Once a person has become dependent on methamphetamine, it can be a difficult habit to break, with frequent relapses (Murray, 1998).

Amphetamines affect the brain in two ways. First, it stimulates (hence the name "stimulant") the areas of the brain involved in wakefulness and mood, which can create a sense of heightened alertness and well being; and second, it depresses appetite. It produces heightened alertness by releasing stored energy, one reason why using high amounts can be dangerous (Murray, 1998). Abuse of amphetamines can stimulate the brain so much that they cause delusions or even hallucinations.

Cocaine comes from the leaves of the coca plant, which is raised by some groups of people in the Andes Mountains of South America. It is legitimately used as a local anesthetic in such drugs as Novocain, but it is also widely abused as a street drug.

Hallucinogenic Drugs

Hallucinogenic, or psychedelic drugs, are drugs that disrupt perception, particularly sight and sound. They frequently come from naturally occurring plants and have no medicinal qualities. Common hallucinogenic drugs include mescaline, peyote, which comes from a specific cactus plant, and lysergic acid diethylamide (LSD), an easily made synthetic chemical. Some of these drugs are used in native religious ceremonies. For instance, some Native Americans use peyote, a dried cactus flower, in religious rites.

Other psychedelic drugs include dimethoxymethylamphetamine (DOM or "STP") and methylenedioxymethamphetamine (MDMA or "ecstasy"). Their structure resembles that of serotonin, and it is believed that they bind to serotonin receptors in the brain. Phencyclidine, or PCP, sometimes called "angel dust" on the street, is a drug legitimately used by veterinarians (Kimball, 2003). It can have powerful effects on the brain, causing the person to have a greatly exaggerated sense of his or her abilities. PCP can cause a temporary psychotic break. It is sometimes dusted on marijuana to make the marijuana seem more potent.

Marijuana is another naturally occurring drug, related to the hemp plant. Its active ingredient is delta-9-tetrahydrocannabinolm or THC, and is believed to bind to synapses in several parts of the brain (Kimball, 2003). It has several effects on the brain. It can make the user drowsy, acting as a sedative. It can decrease sensation of pain, and if used in large amounts, distort perception somewhat like a hallucinogenic. Unlike sedatives and opioids, however, marijuana use does not result in addiction or increased physical need for the drug (Kimball, 2003). Where the body removes many drugs from the body rapidly, THC leaves the body very slowly, allowing the user to get the desired high with less product, if used closely enough together. Nevertheless, psychological addiction to marijuana is possible. Because of its tendency to distort perception, driving can be particularly hazardous while under the influence of marijuana, as judgment regarding both time and distance are impaired.

Unlike stimulants, TCH tends to encourage appetite rather than suppressing appetite. It may also lower the internal pressure in some kinds of glaucoma, a disease where pressure builds up in the eyeball, eventuality causing blindness if not controlled. Significant controversy currently exists over whether people with cancer or HIV / AIDS should be allowed to use marijuana as an appetite stimulant. Since it also has some ability to control pain, it might hold potential for such use.

Drug abuse issues

While researchers have learned a great deal about what drugs are addictive and why, drug abuse continues as a serious societal problem. The War on Drugs has not eliminated drug abuse and a variety of illegal drugs are easily available in most places of the United States today. In response to this problem, a wide variety of treatments have been devised to help people free themselves from drug addiction.

Efforts at treating drug addiction face multiple problems. There seems to be no quick way for most people to free themselves from drugs (Smart. 1996), but few people can afford stays of several months in treatment centers. Usually the person leaves the treatment program and returns to the circumstances that led him or her to substance abuse to begin with. Drug abusers tend to have drug abusers for friends, and no one wants to be friendless. Poverty and lack of jobs seem to contribute to drug abuse, but those problems are still present when the person returns home. The result is that many people relapse and may have to go through drug treatment programs several times before successfully ending their drug dependency. Youth programs have not been any more successful than those for adults (Smart. 1996).

Pharmacology and Psychological Disorders

The last twenty years have shown a dramatic increase in the numbers of drugs used to treat psychological and psychiatric conditions such as schizophrenia, bipolar disorder, attention deficit hyperactivity disorder and depression.

One of the older classes of drugs for this purpose are tranquilizers. They work like sedatives in that they decrease anxiety, but they do not trigger sleep. They are grouped into two sets: major and minor. The major tranquilizers, such as haloperidol (Haldol) and chlorpromazine, are used for severe psychiatric disorders such as schizophrenia, a devastating condition. They bind to receptors for dopamine and force increased neuron activity (Kimball, 2003).

Minor tranquilizers include Librium, Xanax, Halcion, and Valium. They are benzodiazepines, and bind to GABA receptors, and increase the action of GABA on synapses. These are also the synapses that respond to both alcohol and barbiturates, so these tranquilizers can be quite dangerous if combined with alcohol (Kimball, 2003). Such combinations can result in death by depressing respiration.

Antidepressants work by increasing the amount of serotonin available in the brain. There are several kinds. One breaks down neurotransmitters so they can be recycled into new ones for re use. These are called "MAO inhibitors," and while they have a place in treatment, often other antidepressants may be tried first (Kimball, 2003).

Tricyclics and tetracylics block the reuptake, or absorption, of neurotransmitters, allowing them to be used longer. Some of them include imipramine (Tofranil), desipramine (Norpramine), and mirtazapine (Remeron) (Kimball, 2003). These were once widely used but now selective serotonin reuptake inhibitors (SSRIs) are often the first choice. They inhibit the reuptake of serotonin only, while tricyclics inhibit both serotonin and noradrenaline. Commonly used SSRIs include fluoxetine (Prozac), sertraline (Zoloft), fluvoxamine (Luvox) and paroxetine (Paxil). They all increase the amount of serotonin rapidly, but often do not begin to relieve symptoms of depression for a week or more. The reasons for this are not clear (Kimball, 2003). Different SSRIs have been found to help other conditions in addition to depression, including anxiety disorders and obsessive compulsive disorder.

Bupropion, marketed as Wellbutrin, doesn't fit into any of the categories listed above. It blocks the reuptake of dopamine instead of serotonin, as well as noradrenaline. Effective as an antidepressant, it may also help some other conditions, such as attention deficit hyperactivity disorder, a condition most typically treated with stimulants.

Other Neurochemical Conditions

Mention should be made of the disease Parkinson's Disease (PD). PD is a degenerative disease of the disease marked by increasing loss of control over body muscles. It may start as a slight tremor in the hand, but eventually may make it impossible for the person to walk. People with PD have reduced levels of dopamine in crucial parts of their brain. It is typically treated with Levodopa, which the brain can convert into dopamine (Hines, 2000). Often another drug has to be added to convey the Levodopa into the brain so it can do its job. It is an imperfect solution and can alleviate some but not all of the symptoms of PD, and sometimes the amount of relief given is completely inadequate. We do not yet have good pharmaceutical treatment for PD, which a long-term and worsening disease.

PD can be difficult to diagnose because some psychotropic drugs can mimic this disease. However, when those drugs have been stopped, if the symptoms remain, the person already had PD and the drugs used only made it worse (Hines, 2000).

Herbal Medicines and Psychology

There are literally hundreds of different drugs that can alter behavior (Hamilton & Timmons, 1994), and many of them have their origins in folk medicine. Opiates were first derived from the opium poppy, and the synthetic variations of opiates were developed based on knowledge first gained from studying opiates. Cocaine is a naturally occurring drug, and studying it has triggered more research in similar medications. Many drugs used today are simply medicines first found in herbs but refined in pharmaceutical labs for strength conformity and to remove impurities (Hamilton & Timmons, 1994). Some herbal remedies are being studied today for possible psychological benefit, including ginseng, gingko and St. John's Wort, which has been shown to help mild to moderate depression.