DOING YOUR OWN RESEARCH

DOING YOUR OWN RESEARCH

If reading this book has raised your level of interest and you want more specific information, or you want the straight story about a new develop­ment, there is no substitute for doing your own research.

Reading both scholarly review articles and original research papers is much easier than most people believe. In fact, one of the first steps in writing this book was gathering such research. Much of the library work for the first edition was done by two college students, neither of whom had any previous experience using a medical library. Should you decide to investigate for yourself, here are some suggestions about where to begin.

Public libraries are not likely to have the sorts of journals and books you will need. Because there is such a vast amount of medical literature pub­lished, most universities with a medical school have a separate library just to house all this information. Find a medical library at a nearby medical school. If for some reason you cannot get to a medical school, check to sec if there is a college or university biology department nearby and use the

library they use.

Next, go to the library and make friends with the reference librarian, because you will need his or her help until you are familiar with the library and the search mechanisms. The most efficient way of searching the literature is to use MEDLINE or PubMed, databases of the National Library of Medicine, a US government institution that allows you  

search almost all the published medical literature on any subject you can think of related to health. You can search by author, title, subject, key­word, institution, and many other descriptors.

In most cases you will find far more information than you need. A good place to start is with reviews. Reviews are documents that consoli­date and summarize the research and literature available in a given area, and they are usually written in less technical language. Reading several recent reviews about the topic you are researching will help you form a base of knowledge about the subject. Practice using MEDLINE by start­ing out with simple concepts; for example, search for marijuana articles. There are hundreds of them, and many of the titles will be so technical that they might seem indecipherable. So tell the computer to select mari­juana review articles. This will reduce the number markedly.

If you have read Buzzed, then you know that one of the active ingredi­ents in marijuana is THC. Try searching for THC and you will get more articles. Refine your search by asking for reviews of THC and you will get articles different from those you did when you searched for marijuana in general. Play with the database and have fun. Search for all kinds of com­binations of keywords, like THC and learning, or THC and adolescent. You will soon have an idea of the enormous amount of information there is about just this chemical. Understand, though, that no one study tells the whole story.

As a final note, we caution you not to accept everything you read as directly applicable to the human condition. Often scientists employ very high levels of a chemical to test for toxic effects in animals, and sometimes the chemical levels they use in/on animals are hundreds or thousands of times higher than a human would ever use, taking into account the weight of the human compared to the animal. Consequently, some of the toxic effects seen in animals may not apply to humans. On the other hand, ani­mal experiments cannot reveal many subtle effects of chemicals, particu­larly psychological ones, and thus animal studies almost certainly miss some important effects that humans will experience. So, as you read a sci­entific paper, remember that it is just a small part of the literature about a drug, and while the data may be true, it is important to understand that data in the context of everything else known about the drug.

HOW ALCOHOL MOVES THROUGH THE BODY

HOW ALCOHOL MOVES THROUGH THE BODY

The amount of alcohol a person consumes at any given time will influence how it moves through the body, but it's important to standardize the amount that we're talking about first, because beer, wine, and spirits con­tain significantly different concentrations of ethanol. A standard drink is often classified as the amount of alcohol consumed in one twelve-ounce beer, one four-ounce glass of wine, or a mixed drink containing one ounce of hard liquor.

GETTING IN

Ethanol is a relatively small molecule that is easily and quickly absorbed into the body. Once a drink is swallowed, it enters the stomach and small intestine, where a high concentration of small blood vessels gives the alcohol ready access to the blood. About 20 percent of a given dose of alcohol is absorbed through the stomach,  most of the remaining 80 percent is absorbed through the small intestine. Once they enter the bloodstream, the alcohol molecules are carried throughout the body and into direct contact with the cells of virtually all the organs.

Often a person who goes out for a drink in the early evening before dinner reports, "The alcohol went straight to my head." Actually, the alco­hol went very rapidly throughout the whole body, and shortly after it was absorbed it became fairly evenly distributed. This process is called equili­bration. But because a substantial proportion of the blood that the heart pumps at any given time goes to the brain, and because the fatty material of the brain absorbs alcohol (which dissolves in both fat and water) very well, that is where the effects are first and predominantly felt. In fact, before equilibration, alcohol's concentration in the brain is actually higher than its concentration in the blood. Since it is alcohol's effects on the brain that lead to intoxication, soon after drinking a person may be more impaired than her blood alcohol level would indicate. So, there is some truth in the statement, "That drink went right to my head."

Indeed, the presence or absence of food in the stomach is perhaps the most powerful influence on the absorption of alcohol. When someone drinks on an empty stomach, the blood absorbs the alcohol very rapidly, reaching a peak concentration in about one hour. By contrast, the same amount of alcohol consumed with a meal would not be completely absorbed for nearly two hours. The food dilutes the alcohol and slows the

emptying of the stomach into the small intestine, where alcohol is very rapidly absorbed. Peak blood alcohol concentration could be as much as three times greater in someone with an empty stomach than in someone who has just eaten a large meal.

The concentration of alcohol in the beverage consumed also signifi­cantly influences its absorption—in general, the higher the concentration, the faster it will be absorbed. So, relatively diluted solutions of alcohol, such as beer, enter the bloodstream more slowly than more highly con­centrated solutions, such as mixed drinks or shots. More rapid absorption usually means higher peak blood alcohol concentrations, so a person who drinks shots might have a higher blood alcohol level than a person who drinks the same amount of alcohol in the form of beer or wine. While you can prove this principle in tightly controlled scientific studies using sub­jects who have completely empty stomachs when they ingest only the dose of alcohol they receive from the researcher, this effect is pretty minimal when people are drinking recreationally, perhaps two to three drinks an hour. Furthermore, people rarely drink under such carefully controlled conditions, and so the safest assumption is that the most important deter­minant of what your blood alcohol concentration is going to be is the amount of alcohol you consume in an hour and whether you have just eaten—not the type of alcohol you consume.

The rapid absorption of high concentrations of alcohol can suppress the centers of the brain that control breathing and cause a person to pass out or even die. People who get into this kind of extreme medical emergency sometimes do so by accepting a challenge to drink a certain amount of alcohol in a short period of time, by playing drinking games that result in the rapid consumption of multiple drinks, or by taking something like Jell-O shots, which get a lot of highly concentrated alcohol into the body in a short time. Often, young people who cannot legally buy alcohol "drink up" before going out to a mall or to a school dance. Some people do a lot of drinking before leaving for an event where alcohol is not permitted. (Col­lege students, most of whom are underage and must therefore conceal their drinking, refer to this as "pregaming.") Given the rapid accumulation of alcohol in the brain, under these circumstances the drinker may be very impaired in terms of her ability to drive or think clearly, though her blood alcohol level would not suggest this degree of impairment.

A person's body type also determines alcohol distribution. A particu­larly muscular or obese person may seem to be "really holding his booze" because he has more fat and muscle to absorb the alcohol. A heavy person

             would register a lower alcohol level in the blood than a lean individual

after an identical dose. However, the extra weight also slows the elimina­tion of alcohol, so he would retain it longer.

In pregnant women, alcohol is freely distributed to the fetus. In fact, because of the large blood supply to the uterus and developing fetus, sonic studies actually indicate that the tissues of the fetus may achieve a higher alcohol concentration than those of the mother. Later in this chapter, we will discuss the effects of alcohol on the fetus, and the lasting effects that prenatal exposure has on the child later in life. For now, it is important to recognize that when alcohol is distributed in the body, it does not dis­criminate between the tissues of the mother and those of the fetus.

GETTING OUT

The roadside Breathalyzer test is actually an excellent way of estimating the amount of alcohol consumed, even though 95 percent of the alcohol a person drinks is metabolized before the body excretes it. Only about 5 percent of the absorbed alcohol is eliminated unchanged, in the urine or through the lungs, but it is enough to result in "alcohol breath"—and the proportion exhaled stays constant enough to give a very accurate estimate of how much alcohol is in the blood.

Most alcohol is metabolized by the liver, where an enzyme called alcohol dehydrogenase, or ADH, breaks ethanol down into acetaldehyde, which in turn is broken down by another enzyme called acetaldehyde dehydrogenase into acetate, which then becomes part of the energy cycle of the cell. The intermediate product, acetaldehyde, is a toxic chemical that can make a per­son feel sick. Although under normal conditions acetaldehyde is broken down quite rapidly, if it accumulates in the body, intense feelings of nausea and illness result. One early drug therapy for alcoholism was a drug called disulfiram (or Antabuse), which allows the concentration of acetaldehyde to accumulate, making a person feel quite ill after drinking and less likely to drink again. While this strategy appeared promising initially, it has not resulted in consistent positive clinical outcomes with alcohol-dependent patients.

The rate at which alcohol is metabolized and eliminated from the body is critical for understanding how long a person can expect to be affected by drinking. The rate of alcohol metabolism is constant across time. In gen­eral, an adult metabolizes the alcohol from one ounce of whiskey (which is about 40 percent alcohol) in about one hour. The liver handles this rate of

metabolism efficiently. If the drinker consumes more than this amount the system becomes saturated and the additional alcohol simply accumu­lates in the blood and body tissues and waits its turn for metabolism. The results are higher blood alcohol concentrations and more intoxication.

In addition, continued drinking increases the enzymes that metabolize alcohol. The increased level of these enzymes promotes metabolism of some other drugs and medications, harming the drinker in a variety of ways. For example, some medications used to prevent blood clotting and to treat dia­betes are metabolized more rapidly in chronic drinkers and are thus less effective. Similarly, these enzymes increase the breakdown of the painkiller acetaminophen (found in Tylenol) into substances that can be toxic to the liver. Finally, metabolic tolerance to alcohol results in similar tolerance to other sedative drugs, such as barbiturates, even if the individual has never taken barbiturates. This is called cross tolerance and may place the drinker at greater risk for the use or abuse of such drugs.

TYPES OF "ALCOHOLS"

The alcohol that is used in beverages is called ethanol. It is actually only

 one of many different types. The alcohol a nurse rubs on the skin as a dis‑

infectant before giving an injection or drawing a blood sample is not the

same—it is isopropyl alcohol. The chemical structures of most alcohols

 make them quite toxic to the human body. Ethanol is the only one that

should ever be consumed, but people regularly poison themselves with

other alcohols. For example, methanol, produced in home-distilling oper‑

 ations, can cause blindness. A case of methanol poisoning requires immediate medical attention. Therefore, home-distilled liquor, or "moonshine," should always be avoided.

Wilkie Wilson