The Limits of Tolerance: Convicted Alcohol-Impaired Drivers Share Experiences Driving Under the Influence
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Original rESEarCH & COnTriBUTiOnS Special Report The Limits of Tolerance: Convicted Alcohol-Impaired Drivers Share Experiences Driving Under the Influence Sandra C Lapham, MD, MPH, FASAM vorite hobby, biking—he owns a The National Institute on Alcohol Abstract Harley—keeps him amused on his Abuse and Alcoholism estimates Most people are aware that reg- days off. During his weekend for- that consuming five or more drinks ular alcohol drinkers can become ays, B stops at bars or parks along in about two hours (four or more tolerant to the effects of alcohol. the way to drink beer. B says his drinks for adult females) brings the Tolerance can lessen the outward risky behavior has lessened since BAC to 0.08% or above, the legal manifestations of intoxication, his younger days. Now he doesn’t limit for driving in all 50 states.1 and this poses challenges for drink “hard stuff” on days he rides The estimated BACs for children the drinker and other observers, his motorcycle. are different. With five drinks within including law enforcement of- two hours (the level used to define ficers. On the basis of a National Blood Alcohol Content binge drinking among college stu- Institutes of Health-funded longi- Apparently, B assumes beer dents), children, ages 9 to 13 years, tudinal study examining a cohort is more benign than rum. In my may have BACs two to three times of convicted alcohol-impaired experience, this is a common mis- the adult legal limit for intoxication.2 drivers, this article presents com- conception among convicted drunk Several factors moderate the ab- mentary regarding this phenom- drivers. A number of offenders have sorption, distribution, and metabo- enon in offenders convicted of told me flat out that they can’t be lism of beverage alcohol. The pres- driving under the influence and alcoholics because they only drink ence of food in the stomach slows the implications for traffic safety. beer. Beer does contain less alcohol absorption. Drinking slowly and per ounce than hard liquor, and drinking more diluted alcohol al- B’s Story perhaps people mistakenly equate lows the body to metabolize it while The arrest for driving under the liquor’s quick high with addiction at the same time absorbing an in- influence (DUI) came as a surprise predilection. Beer is by far the pre- coming dose. Most people eliminate to B. Still, he took it pretty well. On ferred drink among convicted DUI about one drink each hour from one hand, he had known that he offenders, but a standard drink of a their system. An enzyme produced was breaking the law; on the other, 12-oz can of beer, a 1 ½ oz “shot” of in the stomach, glutathione-depen- he had concluded long ago that the 80-proof distilled spirits, or a 5-oz dent formaldehyde dehydrogenase, law did not apply to him. B, age 47 glass of wine all contain the same breaks down alcohol, decreasing years, is divorced, employed, and, amount of pure alcohol, 13.7 gr (0.6 its bioavailability. Alcohol is dis- unless sick, drinks a fifth of rum oz). The total amount of alcohol tributed in tissues according to most days. Drinking is important to consumed, plus other moderating water content. A person’s weight B. It calms his nerves and lifts his factors, not the type of alcoholic and sex determine the total vol- mood. Besides, he is often bored. drink, determines the blood alcohol ume of body water and, therefore, Drinking, combined with his fa- concentration (BAC). the BAC after drinking a certain Sandra C lapham, MD, MPh, fASAM, is a Board-Certified Specialist in Internal and Addiction Medicine. She is Director of the Behavioral Health Research Center of the Southwest, a center of the Pacific Institute for Research and Evaluation and Principal Investigator for an NIH-funded longitudinal study examining a cohort of convicted alcohol-impaired drivers. E-mail: [email protected]. 26 The Permanente Journal/ Summer 2010/ Volume 14 No. 2 Original rESEarCH & COnTriBUTiOnS The Limits of Tolerance: Convicted Alcohol-Impaired Drivers Share Experiences Driving Under the Influence amount of alcohol. In general, the ing than the descending portion of obesity, iron overload, infection, more a person weighs, the larger the BAC curve.8 Most experienced and genetic factors.12 The drinker the volume of body water and the drinkers develop some form of ac- typically is unaware of this process, lower the BAC. Alcohol pharmaco- quired or chronic tolerance. Chronic but when liver function declines kinetics differ by gender.3,4 Women tolerance is a bodily adaptation that below a certain threshold, tolerance have lower glutathione-dependent makes a person need to drink more declines. If the drinking continues, formaldehyde dehydrogenase ac- and more alcohol to get the same the drinker begins to realize that tivity, leading to increased alcohol effect, or inversely, an adaptation they can no longer continue to absorption. They also generally that causes less and less response “hold their liquor.” have a higher fat content and less to a recurring dose. There is a correlation between total body water, where ethanol The degree of tolerance, how- BAC and the drug’s behavioral and is distributed. This contributes to ever, varies both within and among emotional effects, but there is also higher BACs, an enhanced rate of individuals. How and why different considerable variability. For exam- … I was the alcohol oxidation in the liver, a people develop different manifes- ple, tolerance enables some very designated driver slower rate of gastric emptying of tations of tolerance are perplex- heavy drinkers to survive BAC lev- because my alcohol, and higher vulnerability ing.6 Metabolic tolerance refers to els considered lethal (in the range friends say I can to the toxic effects of alcohol.5 But changes in the absorption, distri- of 0.40% to 0.50%).10,13 Memorable drive better than another phenomenon, “tolerance,” bution, metabolism, and excretion patients with BACs this high have anybody when affects not only the BAC, but also of alcohol.9 These changes lead to been reported as conscious and I’m intoxicated. the body’s capacity to cope with a more rapid clearance of alcohol able to carry on conversations.10 high levels of this toxic chemical. from the body. Tolerance also oc- One report from Sweden describes curs at a cellular level in the brain a woman arrested for drunken driv- Tolerance itself (called functional tolerance), ing with a BAC of 0.55%.14 It is well known that regular which reduces signs of intoxica- drinkers, like B, develop tolerance, tion, even at high BACs. Because of T’s Story broadly defined as the ability to re- tolerance, habitual users may show It is commonly believed that peo- sist the action of a drug.6 Most peo- minimal effects of a dose that would ple who are alcohol dependent are ple, including B, are familiar with cause an intense reaction in a naïve tolerant to all the effects of alcohol, the term, “tolerance.” “I have real drinker. Whereas social drinkers and that tolerance protects a person high tolerance,” he bragged during may show clear signs of intoxication from impairment caused by alcohol his interview. “I can drive fine after at a BAC of 0.10%, such as nausea, intoxication.10 T, another person a few drinks; actually pretty good slurred speech, and lack of coordi- interviewed for my study on the even after drinking a lot.” nation, heavy drinkers at that BAC drinking and driving experiences of In effect, drink for drink, B feels may not show these signs.10 Added DUI offenders, fits this description. less drunk and may have less alco- to this, some drinkers are simply “Usually I was the designated hol-induced impairment in speech, less sensitive, by nature, to alcohol’s driver because my friends say I gait, and fine and gross coordina- effects.11 This is characteristic of can drive better than anybody tion than his light-drinking coun- people with alcohol dependence. when I’m intoxicated. Other terparts. The biologic mechanisms Learned expectancies and Pavlovian people, five beers and they’re of tolerance are complex. Different conditioning also influence toler- slurring their words or some- forms of tolerance have different ance to alcohol’s effects.10 thing, but five beers is nothing mechanisms of action. Far from be- Still, tolerance has its own limi- to me. Even when I first started ing a simple homeostatic response tations, for as the drinking career drinking, I could drink a 12- to the presence of alcohol in the progresses, over days, years and pack before I felt much effect brain, tolerance can develop within decades, so does liver damage from from the alcohol.” various time frames.7 Acute toler- alcohol’s toxic effects. Factors that ance, also called “tachyphylaxis,” may affect the development of liver Driving Under happens within a single drinking injury include the dose, duration, the Influence episode. In acute tolerance, signs and type of alcohol consumed, Both B and T fail to grasp the of intoxication at the same BAC are drinking patterns, gender, ethnic- limitations of their alcohol toler- more pronounced on the ascend- ity, and other risk factors, such as ance. Alcohol’s detrimental effects The Permanente Journal/ Summer 2010/ Volume 14 No. 2 27 Original rESEarCH & COnTriBUTiOnS The Limits of Tolerance: Convicted Alcohol-Impaired Drivers Share Experiences Driving Under the Influence on vision, vigilance, hand-eye co- nice guy, well thought of by friends with judges and prosecutors who ordination, anticipatory judgments, and relatives. On a warm Sunday are trained in adjudicating DUI balance, gait, mental alertness, afternoon, O enjoyed a backyard cases; community-based health problem-solving ability, estimates barbecue with friends and their care interventions for alcohol-use of distance, and quick reaction families in Santa Fe, NM.