Effects of Alcohol

The following material is from CMI, Inc., the manufacturer of the Intoxilyzer 5000. While I may not agree with all of their conclusions, it is still interesting reading.

Alcohol is classified in different ways, depending on who is doing the classification. Generally alcohol is considered to be a DRUG; specifically, a CENTRAL NERVOUS SYSTEM DEPRESSANT. There are other drugs grouped in this category including: METHADONE, MORPHINE, METHAQUALONE AND BARBITURATES.

The effects of alcohol can be seen in all the sensory and motor functions of the body. However in our work we are concerned primarily with the effect of alcohol on the brain. Alcohol depresses the transmissions in the nervous system between the brain and the rest of the body. The disruption of these transmissions have dramatic effects on the mental and physical performance of the body.

For our purposes, the brain will be divided into four sectors: THE HIGHER CENTER OF LEARNING, THE MIDLINE BRAIN FUNCTIONS, MOTOR SKILLS and THE BRAIN STEM.

Alcohol affects the brain in the reverse order to the way the brain develops in a fetus. Alcohol initially affects the brain in the THE HIGHER CENTER OF LEARNING. This

is where a person’s JUDGMENT functions reside and where we make our decisions. This is where our social behavior is programmed, our religious beliefs reside, our standards and ethics, risk assessment, self evaluation, inhibitions and general sense of reality Alcohol affects this part of the brain at very low concentration levels (0.02 -0.04%), resulting in loss of the ability to assess one’s own impairment, the risk involved in taking certain actions, and the ability to make correct decisions in any given situation or activity.

It is particularly interesting that the vomit control center is contained in the higher center of learning. The body self monitors levels of substances which are toxic and if a toxin exceeds a sufficient quantity the vomit mechanism is activated. Research has shown that the trigger for the vomit mechanism regarding alcohol is an alcohol concentration of 0.12%. In theory, an individual should not be able to exceed the 0.12% concentration level. However, since the vomit control center is part of the higher center of learning, its function can be impaired by the alcohol in the brain and rendered inoperative.

If the alcohol concentration in the brain increases, more and more of our mental and physical capabilities are affected and, therefore, cannot be relied upon.

As the concentration of alcohol continues to increase the mid line brain functions are affected. These include the senses of sight, hearing, touch, smell and taste. These senses are affected at alcohol concentrations of 0.05% and greater. For example, alcohol increases the acoustical threshold. This means that as a person continues to drink sounds must be louder and tones more distinct for the person to hear them. This is a slow process and few notice the hearing loss. With heavy drinking, the effect is as if the person were driving an automobile through heavy traffic wearing earplugs.

The eye exhibits changes due to increasing alcohol concentration as well. Studies have shown that there can be changes in color and depth perception, blurring of vision, and diplopia (double vision) at concentration levels as low as 0.08%. Visual acuity was affected at concentration levels as small 0.01% in novice drinkers to 0.04% in heavy users. The ability to visually track an object or focus is generally not affected until concentration levels of .08% are exceeded. In research looking at both tracking ability and the ability to focus, performance of the eye on both measures was affected at low levels of alcohol. Two of the most dangerous effects of alcohol are the lengthening of time necessary for the eye to recover from a bright light and from light fixation. The amount of time the eye takes to adjust to different levels of light is usually very short. Alcohol in the brain can cause this time to increase by a factor of six. For example, in driving, glare blindness caused by the passing of a vehicle in the opposite direction is generally less than a second. This time can increase to 2 to 4 seconds in a person who has been drinking to make a very dangerous situation. Light fixation is when an intoxicated person becomes so intently focused on a light source, especially one that is flashing, that the person ignores all other external stimuli. This is why patrol cars parked on the side of the road with their lights are occasionally hit by intoxicated drivers. Another important effect of alcohol in the brain is the distortion in the ability to estimate distances. An individual under the influence of alcohol consistently over estimates the distance between two points. The consequence of such a change is the underestimation of that person’s own speed. Even more important, an individual who has been drinking may believe that they have more distance to pass a vehicle than they actually have. A number of head on crashes have been caused by intoxicated drivers attempting to pass other vehicles.

The sense of smell is very quickly dulled by alcohol. Sometimes the sense of smell is an important safety factor. Have you ever stopped your car because something did not smell right? A car which is over heating or burning oil or burning brake fluid creates very distinct odors. If a person’s ability to detect these problems is hampered, it is hazardous.

The sense of touch changes with increasing alcohol concentration in that increasing pressure is necessary before the person senses the contact. This can result in a change in a person’s grip strength for the steering wheel and the pressure the person exerts on the gas or brake pedal. The ability to determine different textures also becomes less efficient.

Alcohol affects the sense of taste by causing most food to be bland.

If alcohol concentration continues to increase “MOTOR SKILLS” are affected. There will be less muscular coordination. Nerve transmissions from the brain to a muscle are impeded, affecting the performance of the muscle. This depression of nerve transmissions causes a dramatic change in reaction time. At low levels of alcohol concentration (0.06%), fine muscle (motor) coordination is affected. The person’s ability to perform tasks requiring finger dexterity, such as the extraction of a driver’s license from a wallet, are affected. As alcohol concentration continues to increase, larger muscle groups are affected (gross muscle or motor coordination). At levels of 0.08% and above, the typical visual clues to intoxication begin to manifest themselves, such as staggering walk, problems with balance, hand to eye coordination and slurring speech.

Alcohol acts as a “VASODILATOR”. This means that blood vessel walls relax under the influence of alcohol, and more blood is delivered to the extremities (arms, legs, feet and hands). The flushed face observed in some individuals is the result of vasodilation effect. A consequence of additional blood being sent to extremities can be loss of heat at the body core. Alcohol should never be given to a person suffering from cold exposure since this will result in further lowering of the body’s core temperature.

If alcohol concentration continues to increase, the final area of the brain to be affected is the “BRAIN STEM”. This part of the brain controls all of the body’s autonomic functions. If alcohol reaches a level in excess of 0.10% changes are evident in the heartbeat, respiration and body temperature. If alcohol concentration exceeds 0.40% the respiration function can cease. Death due to alcohol poisoning is usually caused by stoppage of respiration.

Alcohol in Combination with Other Drugs

Visual indications of alcohol intoxication can be mimicked by other drugs as well as illnesses and diseases. Visual symptoms which can be attributed to alcohol intoxication include slurred speech, staggering, drowsiness, loss of equilibrium, and loss of motor skills. Other drugs such as valium can have similar affects. In a DUI arrest, these symptoms can be a result of drugs, alcohol, or a combination of both.

Pharmacologically alcohol produces a feeling of euphoria, or relaxation and well being. This feeling normally peaks at alcohol concentration of approximately 0.08%. At this concentration level there are very few symptoms evident to indicate intoxication. If alcohol concentration increases beyond this point then the familiar “overdose” symptoms begin to appear.

One of the real dangers of alcohol is its reaction when other drugs are present. Alcohol when taken in combination with other drugs can produce “additive” or “synergistic” effects. “Additive” effects are when a person’s impairment level is simply the sum of the impairing effect of the alcohol and the drug present. Alcohol in combination with Phenobarbital is an example of an additive effect. The synergistic effect of alcohol with Valium, is greater than a simple additive effect of alcohol with the Valium. There is no known example of a drug which can decrease the intoxicating effect of alcohol. Therefore, WHEN ANY DRUG IS COMBINED WITH ALCOHOL, THE ABILITY OF THE INDIVIDUAL IS MORE IMPAIRED THAN WHEN ONLY ALCOHOL OR THE DRUG ARE PRESENT.

Usage of drugs, whether illicit, prescribed, or over the counter, is common. It is difficult to determine what drug a person has consumed from the visual effects. A breath alcohol analysis cannot detect or determine the presence of drugs. Those people who misuse drugs know this and occasionally attempt to “mask” their use of a drug by consuming a strongly aromatic alcoholic beverage such as whiskey or beer. The odor of an alcoholic beverage can cause the law enforcement officer to investigate the use of alcohol, not thinking that drugs may also be present. In other words, the smell of alcohol can produce an “alcohol mindset” in the officer and limit the investigation before drug use is uncovered.

Even though a breath alcohol test cannot detect the presence of drugs, the fact that the alcohol concentration does not correlate with the symptoms being observed in the individual is a sign that further investigation is warranted.

Alcohol still remains the number one cause of accidents and motor vehicle fatalities. It has been estimated, however, that drugs may be present in drivers suspected of DUI in over 40% of the cases. Some studies have indicated that alcohol and drugs are present in approximately 25% of all accidents and 1/3 of these involve two or more drugs. The use of alcohol with drugs is a dangerous development.

The effects of intoxication can be mimicked by illness or diseases. Examples include diabetes, epilepsy and certain types of trauma, especially head trauma.

Alcohol Tolerance

A person’s TOLERANCE to alcohol is often misunderstood. With most drugs, tolerance is thought of as the need to increase dosage of a drug to obtain a desired pharmacological result on the person. With alcohol, the person does not develop a tolerance in the normal pharmacological sense due to chronic use of alcohol. Alcohol tolerance is usually seen with regards to the exhibited effects of alcohol consumption. The two distinct categories of tolerance are: “NATURAL” and “LEARNED”.

Natural tolerance is further divided into INBORN, PHYSICAL, and STRESS TOLERANCE. Inborn tolerance is the body’s own response to a given concentration of alcohol. Inborn tolerance is only effective at relatively low levels of alcohol concentration. In fact, no individual has been shown to have immunity to the effects of alcohol above concentration of 0.08%. Studies have shown inborn tolerance to be most prominent up to concentrations levels of 0.04% to 0.06%.

The term physical tolerance refers to the effect of a given dose of alcohol on a person who is ill. The individual’s physical and mental abilities, already diminished by illness, are further diminished by the presence of alcohol. This effect does not work both ways. For example, a person in superb physical health is not less affected by alcohol than the average healthy individual.

Stress tolerance is often encountered by law enforcement officers but sometimes not recognized. A classic example of stress tolerance is an individual’s performing poorly in the roadside sobriety test then performing well a few minutes later in a reassessment at the lock-up facility. In high stress situations or when a person has increased anxiety, adrenaline is released in the body. Adrenaline has been shown to cause some intoxicated individuals to appear less intoxicated than they really are. It is not clear whether this effect is due to an increased metabolic rate, which masks the effects of the alcohol, or to the individual becoming more aware of their situation, and an attempt to cover-up the intoxication. Stress tolerance is a temporary phenomenon and lasts for only a few minutes. However, those few minutes can make a great deal of difference in the performance of a field sobriety test.

There are three forms of learned tolerance: “PSYCHOLOGICAL, ACQUIRED and ACUTE TOLERANCE”.

Psychological tolerance results from all of a person’s life experiences. A persons behavior is controlled by a number of factors, for example the social setting, our basic ideas of right and wrong, religious training received, current mental state, the people we associate with and many other factors. An individual might normally refrain from certain

actions, but the consumption of alcohol can lessen the person’s inhibitions. Strong evidence of this is the number of crimes which are committed under the influence of alcohol versus the number of crimes where no alcohol or drugs are present.

The most common type of tolerance observed is acquired tolerance. Acquired tolerance is only established by habitual users of alcohol. The chronic drinker can learn to compensate for some of the more obvious effects of alcohol intoxication. An individual who can perform field sobriety maneuvers well with a high alcohol concentration is a classic example of acquired tolerance. It is important to remember that the chronic drinker can compensate for the effect of alcohol on gross motor functions, but cannot compensate in the areas of judgment, reaction time and perceptions of risk.

Acute tolerance, also referred to as the “MELLANBY EFFECT”, is the brain’s tendency to continually compare its current condition to its condition at a previous time. For example, during the pre-peak phase on the alcohol curve, the individual comparing his current feelings to how he felt when there was no alcohol present will likely overestimate his level of intoxication. Once the individual enters the post-peak phase, however, he begins comparing his current state to a previously higher level of intoxication and consequently will underestimate his level of intoxication. This is a dangerous situation with regards to operating a motor vehicle.

There is no form of tolerance which reverses the effects of alcohol with regard to diminished physical and mental abilities in the operation of a motor vehicle.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website

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One Response to “Effects of Alcohol”

  1. Excellent entry. I am interested in the effects of adrenalin on the appearance of intoxication. Can you respond?

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