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 Alcohol's
Effects > Factors that Effect Intoxication |
Absorption Rate Factors | Distribution Factors | Elimination Factors | Setting and Expectations | Other Factor | Now What
All of the factors reviewed below will determine your perception of intoxication. It is important that you are both knowledgeable about these factors and put this knowledge to work by noting how these factors effect your intoxication on different occasions and in different situations and environments.
Absorption Rate Factors
Alcohol is absorbed from all parts of the gastrointestinal tract largely
by simple diffusion into the blood. However the small intestine is by
far the most efficient region of the gastrointestinal tract for alcohol
absorption because of its very large surface area. Both ingestion of food
and strength of drink can effect absorption:
| Food | In a fasting individual, it is generally agreed that 20% to 25% of a dose of alcohol is absorbed from the stomach and 75% to 80% is absorbed from the small intestine. Thus, in fasting people, peak BACs are achieved in 0.5 to 2.0 hours; while in non-fasting people, peak alcohol BACs are achieved in 1.0 to 6.0 hours. Food taken along with alcohol results in a lower, delayed blood alcohol concentration peak (the point of greatest intoxication). When food is ingested, the pyloric valve at the bottom of the stomach will close in order to hold food in the stomach for digestion and thus keep the alcohol from reaching the small intestine. While alcohol will be absorbed from the stomach, it is a slower and less efficient transition. Because alcohol is absorbed most efficiently in the small intestine, the ingestion of food can slow down the absorption of alcohol by keeping the alcohol in the stomach longer. The larger the meal and closer in time between eating and drinking, the lower the peak alcohol concentration, studies indicate a 9% to 23% reduction. Peak BAC’s are achieved in fasting people within 0.5 to 2.0 hours, while non-fasting people exhibit peak alcohol concentrations within 1.0 to as much as 6.0 hours. Thus, food taken with alcohol will result in a lower and delayed peak BAC. The type of food ingested (carbohydrate, fat, protein) has not been shown to have a measurable influence on this affect but the larger the meal and closer in time between eating and drinking, the greater the diminution of peak alcohol concentration. |
| Strength of Drink | Obviously, stronger drinks will result in higher BACs. But differences in drink strength can also cause small differences in the rate at which alcohol is absorbed by the gastrointestinal tract. Alcohol is most rapidly absorbed when the concentration of the drink is between 10% and 30%. When the alcohol content is less than 10%, the concentration gradient in the gastrointestinal tract is low and absorption is slowed. On the other hand, drink concentrations higher than 30% tend to irritate the mucous membranes of the gastrointestinal tract and the pyloric sphincter, causing increased secretion of mucous and delayed gastric emptying. |
Distribution
FactorsAbsorbed
alcohol is rapidly carried throughout the body in the blood and an equilibrium
is reached such that blood at all points in the system contains approximately
the same concentration of alcohol. The concentration of alcohol in different
organs, including the brain depends on several distribution factors, including
percent body fat, body type, and body weight:
| Body Fat | Alcohol has a high affinity for water and is therefore found in body tissues and fluids inasmuch as they contain water. Thus person's with a lower percent body fat will, in general, have lower BACs than individuals with a higher percent body fat. In general, but by no means in all cases, women tend to have a higher percentage of body fat and thus a lower percentage of body water. Therefore, in general, if a man and a woman of the same weight ingest the same amount of alcohol the woman will tend to have a higher BAC. This, of course, would not be true if the woman was very fit and the man was somewhat obese, but on average, this is the case. |
| Body Type | However, for people of the same weight, a well muscled individual will be less affected than someone with a higher percentage of fat since fatty tissue does not contain very much water and will not absorb very much alcohol. Thus, for those with more fat tissue, the alcohol is distributed in a smaller percentage of the total body mass and will result in a higher BAC. |
| Body Weight | In general, the less you weigh the more you will be affected by a given amount of alcohol. As detailed above, alcohol has a high affinity for water. Basically one's blood alcohol concentration is a function of the total amount of alcohol in one's system divided by total body water. Thus, when two individuals with similar body compositions and different weights ingest equal amounts of alcohol, the larger individual will have a lower BAC than the smaller individual. |
Elimination FactorsThe
liver is responsible for the elimination of alcohol. The liver eliminates
of 95% of ingested alcohol from the body through metabolism. The remainder
of the alcohol is eliminated through excretion of alcohol in breath, urine,
sweat, feces, milk and saliva. Healthy people metabolize alcohol at a
fairly consistent rate. As a rule of thumb, a person will eliminate one
average drink or .5 oz (15 ml) of alcohol per hour. Several factors influence
this rate. In general, the rate of elimination tends to be higher when
the BAC in the body is very high or very low. Elimination factors include
rate of consumption, tolerance, and gender:
| Rate of Consumption | Blood alcohol concentration depends on the amount of alcohol consumed and the rate at which the user's body metabolizes alcohol. Because the body metabolizes alcohol at a fairly constant rate (somewhat more quickly at higher and lower alcohol concentrations), ingesting alcohol at a rate higher than the rate of elimination results in a cumulative effect and an increasing blood alcohol concentration. Consumption at a rate of one drink per hour will, for most people, maintain your current BAC. |
| Tolerance | Tolerance is the diminution of the effectiveness of a drug after a period of prolonged or heavy use of that drug or a related drug (cross-tolerance). There are two types of tolerance at work with alcohol.:
The net result of tolerance is a reduction in BAC and a decrease in functional impairment. Charts used to estimate BAC take tolerance into account, as they are based on average levels of tolerance. Tolerance is always a sign of growing dependence on alcohol. A 50% increase in tolerance is one of the major warning signs of alcohol dependence. |
| Gender Differences | Another gender based difference is in the elimination of alcohol. Although not explained, studies indicate that women eliminate alcohol from their bodies at a rate 10% greater than that of men. It is important to remember that this difference in the eliminate rate is by far outweighed by gender differences related to distribution factors. Thus, women will, in most cases, reach higher BACs as their male counterparts that consume the same amount of alcohol. |
Setting and
ExpectationsWe
have specific expectations of what we will experience while under the
influence of alcohol. These expectancies develop as a result of observing
what others’ experience when they drink and what the media and other
sources tell us about the effects of alcohol. These expectancies are very
important, as they can be self-fulfilling prophecies. In other words,
what we expect to happen under the influence of alcohol is often what
we actually experience. In fact, as we anticipate the consumption of alcohol
we begin to experience these effects, even before we begin consuming alcohol.
Research
Confirms:
A series of experiments in the 1970s and 1980s illustrates these effects. The goal of these studies was to determine how much of what we feel when under the influence of alcohol is a result of: a) our expectations concerning alcohol’s effects, and b) the actual pharmacological effects of alcohol.
Participants completed a questionnaire to determine what they expected alcohol to do for them. This was taken a number of weeks before the drinking experiment as was set up so that participants thought it was part of another study. Participants were then randomly assigned to one of four conditions (see Table at right): 1) expected and received alcohol (upper left cell); 2) expected alcohol, but received no alcohol, only tonic water (upper right cell); 3) expected no alcohol, only tonic water, but received alcohol (lower left cell); and 4) expected and received no alcohol, only tonic water (lower right cell). Participants drank in a laboratory at University of Washington that was designed to look like a barroom. Before they began consuming their beverage and at different times while drinking they completed a questionnaire to assess how they were feeling.
Results:
| 1. |
As you might expect, participants
who expected to receive alcohol, and then actually received alcohol,
felt what they expected to feel a result of drinking. |
| 2. |
But interestingly, participants
who expected alcohol, but actually received no alcohol, also felt
things they expected to feel as a result of drinking. The drinking
setting itself was enough to make participants believe they had
consumed alcohol. The belief that they had consumed alcohol was
enough for both men and women to feel less inhibited. |
| 3. |
Participants who did not
expect to receive alcohol, but actually did receive alcohol, felt
none of the effects of the alcohol. In other words, the belief that
they would not receive alcohol was enough to offset the pharmacological
effects of alcohol. |
| 4. |
People’s
expectancies concerning the effects of alcohol contributed strongly
to the “buzz” the participants felt, even when they expected
alcohol but received only tonic water. The buzz people felt was
a result of: a) what they expected to happen, and b) the setting
in which they were drinking. |
| Among participants
who expected to receive alcohol, researchers also found that: |
|
| 5. |
Regardless of whether they
actually received alcohol, men generally felt less social anxiety,
while women felt greater social anxiety. |
| 6. |
Again regardless of whether
they actually received alcohol, men felt greater sexual arousal,
although actual sexual arousal was actually dampened in both men
and women. |
As you can see, much of what we feel while under the influence of alcohol is related to our expectations. If we expect alcohol will decrease our inhibitions, then we will feel less inhibited. In addition, the drinking setting alone causes us to feel these effects, even when we only believe we are consuming alcohol. We have all experiences this, as we begin to feel less inhibited, less stress, and more social when we enter a party or bar, even before our first drink.
The bottom line, is that, when partying, the drinking setting and our expectations concerning alcohol's effects are have as much or more of an effect on our mood and behavior than actually consuming alcohol. Thus, it is actually not necessary to consume large quantities of alcohol to feel the positive effects of alcohol. In fact, you will experience these positive effects after just a few drinks, or just by being in the party or bar setting.
| Medications or Other Drugs | Because alcohol is a depressant, any depressant drug will increase the effects of alcohol by as much as 10 times. In addition, many other drugs can interact with alcohol in unpredictable ways. For example, aspirin, when mixed with alcohol, may cause damage to the stomach lining, decreasing blood clotting and resulting in internal bleeding. In addition, acetomyophin (i.e., Tylenol), when mixed with alcohol, can cause liver damage. Always follow the instructions on any medication you take, and consult your doctor or pharmacist if you are unsure about possible side-effects that may result from drinking alcohol. |
| Fatigue | Fatigue causes many of the same symptoms that are caused by alcohol intoxication. These and other symptoms will be amplified if alcohol intoxication is concurrent with fatigue. |
| Mood | Because alcohol is a depressant, alcohol will have a greater effect on you when you’re depressed or under a lot of stress. |
| Tiredness | When you’re tired your liver is less efficient at eliminating alcohol, because of your low energy level . So drinking the same amount of alcohol when you’re tired will result in a higher BAC than when you’re rested. |
| Illness | When you’ve been sick or are currently sick, , you will be dehydrated. Dehydration has a number of effects that cause greater intoxication. First you have less water in your body, so the alcohol has less area to go to in the body, resulting in greater intoxication. Dehydration can also make your liver less efficient at eliminating alcohol, so if you are ill, you will have a higher BAC than you would have when you are not dehydrated. |
Knowing how your body reacts to alcohol can provide valuable insights into your own drinking pattern, and the things you experience as a result of drinking. This knowledge can help you become a low-risk drinker, by making you more aware of the various factors that determine your level of intoxication.
All of the factors reviewed below will determine your perception of intoxication. It is important that you are both knowledgeable about these factors and put this knowledge to work by noting how these factors effect your intoxication on different occasions and in different situations and environments.
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