Biomarkers for Alcohol Use and Abuse

A Summary

Karen Peterson, Ph.D.

Clinicians can use several biochemical measurements to objectively assess patients’ current or past alcohol use. However, none of these currently available biomarkers—including measures of various liver enzymes and blood volume—are ideal. Several more experimental markers hold promise for measuring acute alcohol consumption and relapse. These include certain alcohol byproducts, such as acetaldehyde, ethyl glucuronide (EtG), and fatty acid ethyl esters (FAEE), as well as two measures of sialic acid, a carbohydrate that appears to be altered in alcoholics. Some progress has been made in finding markers that predict people’s genetic predisposition to alcoholism, such as genetic differences in several neurotransmitters, including beta-endorphin and gamma-aminobutryic acid (GABA). KEY WORDS:screening and diagnostic method for AOD (alcohol and other drug) use; pattern of AOD use; alcohol-related biological markers; alcohol-related biochemical markers; alcohol-related genetic markers

o treat people with alcoholism whether state or trait, should be (i.e., acute) drinking patterns but also adequately, clinicians need tools sensitive—that is, accurate for most about long-term (i.e., chronic) drink- Tthat can properly assess not only if not all drinkers, not just a subset— ing patterns and whether that drinking the extent of the patients’ recent and and specific, or linked to alcohol use has been moderate or heavy. (Heavy past drinking activity but also any family but not other illnesses or problems. drinking is defined in this article as history of drinking problems (i.e., genetic The test used to measure the biomarker consuming more than 60 grams of predispositions to alcohol abuse and also should be precise and accurate. alcohol—between four and five drinks— alcoholism) they may have. A good case (For definitions of terms central to this a day, unless otherwise noted. Consuming history is certainly a start, but more article, see the accompanying Glossary.) this amount for 2 weeks or more is objective measures also are important. This article presents an overview of considered to be chronic heavy drinking.) Biochemical substances in the body current alcohol biomarkers. Although The various state biomarkers use that can indicate the presence or progress some of the markers described here several techniques to assess different of a condition, or any genetic predispo- have been in wide use for many years, levels or periods of alcohol consumption. sition toward it, are called biomarkers. some are new and under development. These markers may be related to chem- There are two kinds: state markers and The goal is to compile a large toolkit of icals produced when the body breaks trait markers. State markers are bio- biomarkers that can provide objective, down, or metabolizes, alcohol or may chemical measures that tell clinicians quantitative data to clinicians as they reflect changes in other compounds, something about people’s recent drink- evaluate patients. cells, or tissues that result from chronic ing patterns, including whether they have a history of heavy drinking and whether they have had a recent binge State Markers KAREN PETERSON, PH.D., is chief of the or even just a few drinks. Trait markers Research Policy and Special Programs are biochemical markers that reveal When clinicians evaluate a patient’s Branch in the National Institute on something about a person’s inherited history of alcohol consumption, they Alcohol Abuse and Alcoholism’s Office of risk of abusing alcohol. A good biomarker, want to know not only about recent Scientific Affairs, Bethesda, Maryland.

30 Alcohol Research & Health Biomarkers for Alcohol Use and Abuse

or acute alcohol exposure. (The table consumption. Nevertheless, research after a person stops drinking, so someone summarizes the sensitivity, specificity, finds that when otherwise healthy people could be abstinent but still show a high and potential uses of these measures. drink large amounts of alcohol, AST MCV value. In addition, other condi­ For further information on state mark­ and ALT levels in the blood increase tions may affect MCV, reducing its ers, see the figure.) (Halvorson et al. 1993). Of the two specificity and further confounding any enzymes, ALT is the more specific interpretation of results using this marker. Currently Used State Markers measure of alcohol-induced liver injury because it is found predominantly in N-Acetyl-β-Hexosaminidase (Beta-Hex), For many years, clinicians have had access the liver, whereas AST is found in sev­ an enzyme found to be elevated in to a group of biomarkers that indicate eral organs, including the liver, heart, heavy drinkers (Javors and Johnson a person’s alcohol intake. Several of these muscle, kidney, and brain. Very high 2003), has been shown in some early reflect the activity of certain liver enzymes: levels of these enzymes (e.g., 500 units studies to be both a sensitive and spe­ serum gamma-glutamyltransferase (GGT), per liter) may indicate alcoholic liver cific measure of heavy drinking. In aspartate aminotransferase (AST), disease. Clinicians often use a patient’s addition, unlike MCV, the increased alanine aminotransferase (ALT), and ratio of AST to ALT to confirm an beta-Hex subsides to normal levels after carbohydrate-deficient transferrin (CDT), impression of heavy alcohol consump­ only 7 to 10 days of abstinence. How­ a protein that has received much atten­ tion. However, because these markers ever, the beta-Hex assay is difficult to tion in recent years. Another marker, are not as accurate in patients who are obtain in the United States, so clinicians N-acetyl-β-hexosaminidase (beta-Hex), under age 30 or over age 70, they are less have little experience using it with dif­ indicates that liver cells, as well as other useful than some of the other more com­ ferent treatment populations. Other cells, have been breaking down carbo­ prehensive markers (Halvorson et al. 1993). conditions, such as diabetes and hyper­ hydrates, which are found in great numbers tension, also appear to elevate beta-Hex. in alcohol (Javors and Johnson 2003). Mean Corpuscular Volume (MCV), a Clinicians also have used red blood cell person’s volume of red blood cells, also Carbohydrate-Deficient Transferrin (CDT) volume, known as mean corpuscular is associated with heavy chronic drink­ is a version of the glycoprotein transfer­ volume (MCV), as a biomarker of ing (Neumann and Spies 2003), as the rin, a molecule responsible for carrying alcohol intake. MCV in heavy drinkers tends to exceed iron within the bloodstream. CDT, the average range. This marker is less as its name implies, is a form of this Gamma-Glutamyltransferase (GGT). useful clinically, however, because the molecule that is deficient in the carbohy­ This glycoprotein—a large molecule MCV stays high for several months drate sialic acid. Normally, transferrin made up of both proteins and carbohy- drates—aids in digestion and is found in key liver cells (or hepatocytes) and in other cells involved in bile production, GLOSSARY including biliary epithelial cells. Elevated Biomarker: A biochemical feature (a compound or series of compounds) GGT levels are an early indicator of that can be used to measure the progress of a disease or liver disease; chronic heavy drinkers, the effects of treatment. especially those who also take certain other drugs, often have increased GGT State marker: A biomarker that provides information about recent levels. However, GGT is not a very drinking activity. sensitive marker, showing up in only 30–50 percent of excessive drinkers in Trait marker: A biomarker that provides information about a person’s the general population (Conigrave et genetic predisposition toward alcohol dependence. al. 2003). Nor is it a specific marker of chronic heavy alcohol use, because other Accuracy: A measure’s ability to obtain the expected result. digestive diseases, such as pancreatitis and prostate disease, also can raise GGT levels. Precision: A measure’s “repeatability,” or ability to repeat the expected result without significant day-to-day variation. Aspartate Aminotransferace (AST) and Alanine Aminotransferace (ALT) are Sensitivity: A test’s ability to detect small differences in concentration enzymes that help metabolize amino acids, of the biomarker. the building blocks of proteins. They are an even less sensitive measure of Specificity: A test’s ability to indicate the absence of a biomarker in a alcoholism than GGT; indeed, they sample that is truly negative for that biomarker. are more useful as an indication of liver disease than as a direct link to alcohol

Vol. 28, No. 1, 2004/2005 31 contains four to six sialic acid molecules, show elevated levels of CDT. Researchers ous stages of research and development, but research indicates that drinking dis­ also find that, in general, women tend including the plasma sialic acid index rupts sialic acid’s ability to attach to trans­ to have higher CDT levels than men, of apolipoprotein J (SIJ), total serum ferrin as well as other molecules. Many regardless of their drinking history (Arndt sialic acid (TSA), 5-hydroxytryptophol versions of transferrin normally are found 2000). What causes this gender differ­ (5-HTOL), and various fatty acid ethyl in healthy people, but studies indicate ence is not clear, but some tests now on esters (FAEEs). None of these tests are that heavy drinkers have higher amounts the market claim to correct for it. commercially available, but some look of the CDT version than nondrinkers. Recently, researchers have made sev­ promising, as described in the follow­ CDT has been widely used by clini­ eral improvements in measuring CDT, ing section. cians in recent years to screen for heavy including developing agents that specif­ alcohol consumption. Although it appears ically detect CDT (i.e., immunological Plasma Sialic Acid Index of Apolipoprotein to be a highly specific measure of alco­ reagents) (Bean et al. 2001) and mea­ J (SIJ). Apolipoprotein J is a glycoprotein hol consumption, showing low rates of suring CDT levels as a percentage of found in needed complexes (i.e., lipopro­ false positives, CDT is difficult to mea­ total transferrin, rather than an abso­ teins) that are responsible for transport­ sure accurately. Distinguishing CDT lute value (Anttila et al. 2004). Some ing fats (i.e., lipids) in the blood. from other forms of transferrin is chal­ studies also have examined the useful­ Research indicates that apolipoprotein J lenging. In addition, even teetotalers have ness of combining the CDT and GGT may help transfer fats such as cholesterol low concentrations of CDT in their tests (Chen et al. 2003), finding that, from one lipoprotein to another (Javors blood, and people with generally high at least in men, using both tests is more and Johnson 2003). Like the molecule concentrations of total transferrin will sensitive than using either marker alone. transferrin, apolipoprotein J contains necessarily have high absolute numbers Despite the disadvantages of the CDT sialic acid particles that may be reduced of CDT molecules, regardless of their marker, it remains a very well-character- in number after alcohol consumption. drinking status. These difficulties affect ized biomarker for heavy alcohol intake. Apolipoprotein J has more than four times the precision and therefore the sensitivity more sialic acid chains than transferrin, of the test. Another disadvantage with Newer State Markers Under Study making it easier to measure changes in the CDT marker is that there is a rela­ sialic acid content caused by heavy alcohol tively high rate of false negative results: Several new markers for assessing alco­ consumption. More study is needed, Some patients who drink heavily do not hol intake and alcohol abuse are at vari­ but preliminary findings show promise for SIJ as a highly specific and easy-to- measure marker. 10 Total Serum Sialic Acid (TSA). Because Detection interval after ethanol has been of sialic acid’s clear potential as a highly cleared from the body 8 specific marker for alcohol use, researchers Time period neccessary for intake of have begun to study the potential of alcohol to occur in order to exceed reference ) measuring total sialic acid (TSA) levels or cutoff value 6 in patients’ blood, rather than looking at the difference in sialic acid chains only on glycoproteins such as transferrin 4 and apolipoprotein J. Early studies Time (weeks (Javors and Johnson 2003) demonstrate that, compared with social drinkers of 2 both genders, both male and female alcoholics had elevated amounts of TSA. The test for TSA has similar sensitivity 0 and specificity to the test for CDT for FAEE WBAA CDT GGT MCV measuring alcohol consumption. How­ Markers of Alcohol Consumption ever, because TSA levels take longer than either CDT or GGT to decrease during periods of abstinence, the TSA A comparison of some state markers of alcohol consumption. Bars represent approxima­ test might not be as useful for treatment tions, and some variability exists for each marker time period because of individual programs assessing patients for relapse. variability, different test manufacturers, and the like. FAEE = fatty acid ethyl esters, WBAA = whole blood–associated acetaldehyde, CDT = carbohydrate-deficient trans­ ferrin, GGT = gamma-glutamyltransferase, MCV = mean corpuscular volume. 5-Hydroxytryptophol (5-HTOL). When the body breaks down a key chemical involved in cellular communication in

32 Alcohol Research & Health Biomarkers for Alcohol Use and Abuse

the brain (the neurotransmitter serotonin), bolism of serotonin so that the body detected for approximately 5 to 15 one of the minor resulting components produces more 5-HTOL when people hours longer than standard alcohol (or metabolites) is 5-hydroxytryptophol. consume alcohol than when they do measurements, which can detect alco- Alcohol and its primary breakdown not drink. The body disposes of 5- hol in the urine for a little over an hour product, acetaldehyde, affect the meta- HTOL via the urine, where it can be for each drink consumed (Beck and

Summary of State Markers for Alcohol Consumption

Diagnostic Used Sensitivity Specificity Possible or Clinically Marker (percent) (percent) Current Use in U.S.? Gamma-glutamyl- 611 n/a Chronic Yes transferase (GGT) alcohol abuse

Alanine Method- n/a Chronic Yes aminotransferase dependent alcohol abuse (ALT)

Aspartate 561 n/a Chronic Yes aminotransferase alcohol abuse (AST)

Carbohydrate- 26–832*9 23 Heavy Yes deficient transferrin alcohol use** (CDT)

N-acetyl-β-hexosaminidase 942 912 Heavy alcohol use No

Whole blood– 1004 954 Recent alcohol Yes associated consumption at all acetaldehyde (WBAA) levels; monitoring abstinence

Mean corpuscular 471 n/a Heavy Yes volume (MCV) alcohol use

Apolipoprotein J n/a n/a Heavy No alcohol use

5-hydroxytryptophol n/a n/a Monitoring No (5-HTOL) sobriety

Salsolinol n/a n/a Chronic alcohol No consumption

Fatty acid ethyl 1005 905 Recent heavy No esters (FAEE) alcohol use

Ethyl glucuronide n/a Method- Monitoring No (EtG) dependent sobriety; forensics

* Depending on method and gender ** More than 60 grams per day (4–5 standard drinks) n/a = data not available 1 Anttila et al. 2004. 2 Stowell et al. 1997. 3 Javors and Johnson 2003. 4 Bean et al. 2001. 5 Wurst et al. 2004.

Vol. 28, No. 1, 2004/2005 33 Helander 2003). Because of its ability et al. 2001) show that when measured acetaldehyde in blood samples using to detect people’s alcohol use for up to in adipose tissue, FAEE is useful as a high-performance liquid chromatography 24 hours after they have been drinking, biomarker up to 12 hours after death in and fluorescence detection—known as 5-HTOL is considered a 24-hour alcohol-treated animals; when measured the whole blood–associated acetaldehyde biomarker for heavy alcohol consump­ in animal liver tissue, FAEE is useful up assay (WBAA) (Halvorson et al. 1993). tion. Although the marker requires to 24 hours after alcohol treatment. This assay is highly specific, extremely more study, preliminary work indicates Further study is required to fully explore sensitive (Peterson and Polizzi 1987), that it is both sensitive and specific for FAEE’s sensitivity and specificity. and has excellent precision. The insur­ detecting recent heavy alcohol consump­ ance testing industry has used WBAA tion (Beck and Helander 2003). Testing Ethyl Glucuronide (EtG). EtG is another for more than a decade to test for heavy for 5-HTOL may prove especially use­ minor metabolite of alcohol that forms alcohol consumption (FDA approval ful in forensic toxicology. Emergency in the liver when alcohol reacts with for wider clinical use is pending). Its room clinicians may find it helps detect glucuronic acid, a substance which works potential is even greater as a clinical people who consumed large amounts of to detoxify drugs by turning them into tool to monitor people in alcoholism alcohol before preparation for surgery, water-soluble compounds that can be treatment programs, because this test and treatment professionals may be able easily removed from the body. can provide a picture of alcohol use over to use this test to monitor the care of EtG can be detected in the blood time. This works because, as a person people involved in treatment maintenance for up to 36 hours and in the urine continues to drink, hemoglobin-bound programs (although the antidrinking for up to 5 days after heavy alcohol acetaldehyde accumulates in red blood medication disulfiram, which people use. In addition to blood and urine, cells over their 120-day average life in these settings may be taking, also EtG is detectable in other body fluids, span, and this buildup shows up as an can lead to increases 5-HTOL levels). hair, and body tissues (Wurst et al. increasing WBAA assay number. Levels In addition, research has shown that the 2003), although no apparent correla­ of protein-bound acetaldehyde remain ratio of 5-HTOL to another serotonin tion has been found between alcohol high for approximately a month after metabolite, 5-HIAA or 5-hydroxyindole- consumption and the presence of EtG alcohol consumption (Halvorson et al. 3-acetic acid, is a useful indication of in hair. When people test positive for 1993). The ability of the WBAA assay previous drinking (Johnson et al. 2004). EtG, it is likely that they consumed to measure alcohol consumption pat­ alcohol recently, even if there is no alco­ terns over time makes it unique among Fatty Acid Ethyl Esters (FAEE). Along hol left in their bodies. This makes EtG the biomarkers described here. with acetaldehyde, the body also produces especially useful for detecting drinking FAEE when it breaks down alcohol. FAEE relapses. Measuring EtG levels is diffi­ Salsolinol. This compound, formed is measured as a combination of four cult, however. A rather sophisticated when the neurotransmitter dopamine separate molecules and is found in the instrument, the mass spectrometer, is reacts either with alcohol’s byproduct liver, pancreas, and fat (i.e., adipose) required for an accurate reading of EtG acetaldehyde or with pyruvate (a metabo­ tissues up to 24 hours after alcohol from urine. And so far, attempts to lite of glucose that is used by cells for consumption. FAEE is a sensitive and produce a measure for urine-based EtG energy), shows some promise as a state specific marker for distinguishing social using simpler techniques or to measure marker for chronic alcohol consumption. drinkers from heavy or alcohol-dependent EtG in other body fluids or hair have However, the usefulness of salsolinol drinkers (Wurst et al. 2004; Salem et al. yielded less than satisfactory results may depend on how it is measured— 2001). Because it also is found in human (Wurst et al. 2003). Once an easy method whether, for example, in blood, urine, hair (Wurst et al. 2003; Yegles et al. 2004), of measuring EtG is developed, it has or brain tissue. Salsolinol levels in urine some researchers suggest using FAEE potential to detect relapse, to detect have been found to decrease following in hair as a marker for chronic heavy alcohol use in settings where drinking acute alcohol consumption (Haber et alcohol consumption (Wurst et al. is deemed risky, such as for testing those al. 2002), and measuring salsolinol 2004). The body cannot flush FAEE who drive vehicles, fly planes, or oper­ levels in the blood may provide a better out of hair, so the compound builds up ate other sophisticated machinery, as indication of chronic alcohol consump­ over a long period of chronic drinking. well as for forensic use. tion. A study by Haber and coworkers FAEE measured in liver and adipose (Haber et al. 2002) showed that, com­ tissue also has been used as a postmortem Acetaldehyde. The first compound the pared with nonalcoholics, alcoholics marker of alcohol consumption (Salem body produces as it metabolizes alcohol who have been abstinent for as little as et al. 2001). Such a measure is needed is acetaldehyde, which exists on its own 1 week have decreased salsolinol levels because current measures, such as blood and also can bind to certain proteins, in one type of white blood cell (lym­ alcohol levels, can be artificially high including hemoglobin (a protein in phocytes). Studies of salsolinol levels in as a result of alcohol formation in the red blood cells that carries oxygen). the brain, in contrast, found no difference body after death. So far, FAEE looks Researchers are able to measure con­ in salsolinol levels between alcoholics promising. Preliminary studies (Salem centrations of both free and bound and nonalcoholics (Musshoff et al.

34 Alcohol Research & Health Biomarkers for Alcohol Use and Abuse

2005). This may indicate problems of the status of the disease, meaning that molecules (i.e., receptors) in brain cells measuring salsolinol in the brain as it would be present whether the person (i.e., neurons) for the GABA molecule. well as inherent differences in salsolinol displayed symptoms of the disease or These molecules enable charged chlo­ levels among different biological sources. was asymptomatic (Ratsma et al. 2002). rine ions to enter and exit the cell, Biomarkers that meet these criteria and thus controlling the chemical balance Proteomics of the cells. Studies (Ratsma et al. 2002; Mihic and Harris 1996) find Researchers have begun to use proteomics, that people have different levels of the systematic study of proteins that Knowing who is at GABA and these differences are inher­ are matched to certain known genes, ited. In addition, studies show that to search for biomarkers of alcohol risk can help prevent people who are alcohol dependent consumption. Recently, investigators alcohol problems have lower levels of GABA than do used a powerful technique, surface- non-alcohol-dependent people. Thus, enhanced laser desorption/ionization– altogether, or enable at least in these preliminary studies, time of flight–mass spectrometry (SELDI- GABA fulfills two of the three require­ TOF-MS), to study serum samples a person to seek ments of a trait marker for alcoholism. from alcoholics who had consumed early treatment. more than 10 drinks a day for at least Dopamine 10 years (Nomura et al. 2004). The researchers examined the protein pro­ Another neurotransmitter, dopamine, file in the blood of these people upon show low rates of false positive and false acts at the receptor level and is believed admission to an alcoholism treatment negative results will have excellent value to be involved in the brain’s reward program and again after abstinence— in predicting the likelihood that a per­ system. A recent study (Ratsma et al. taking measures throughout the treat­ son will develop alcohol dependence. 2002) found that male alcoholics who ment program. They found measurable Much of the research in this area is pre­ had been abstinent for 7 years showed differences in the levels of two proteins, a lower level of dopamine receptor α liminary, but several markers, including a fragment of the fibrinogen E chain an enzyme and a group of neurotrans­ activity compared with nonalcoholic and a fragment of apoprotein A–II. mitters, hint at its potential. men, whereas a previous study (Balldin Specifically, patients had low levels of et al. 1985) demonstrated that alco­ the proteins when they were drinking holics, after a withdrawal period of 4 to and significantly increased levels start­ Adenylyl Cyclase (AC) Activity 7 days, showed an elevated response to ing as soon as 1 week into the treat­ A protein found in cell membranes, dopamine, indicating elevated receptor ment program. Nomura and colleagues AC plays an important role in providing activity. Other studies examining levels (2004) concluded that the two protein the cell with energy. Researchers became of the major byproduct of dopamine fragments have potential as markers of interested in AC activity as a potential metabolism, homovanillic acid, also excessive alcohol consumption in heavy trait marker when they discovered that have had contradictory results. Some drinkers seeking treatment. AC activity is inherited and the enzyme investigators (George et al. 1999) found is less active in the blood platelet cells higher levels of homovanillic acid in of abstinent alcoholics than in nonalco­ alcoholics compared with nonalcoholics, Trait Markers holics (Hoffman et al. 2002). In addition, but other researchers (Petrakis et al. AC activity increases when alcoholics 1999) found lower levels for alcoholics. Biochemical markers are being devel­ begin drinking again, suggesting that Because of these conflicting baseline oped to identify people with a genetic alcohol somehow stimulates AC activity. findings, dopamine is not considered a predisposition to alcohol abuse and Unfortunately, it appears that marijuana good candidate trait marker at this time. alcoholism. Knowing who is at risk and other drug use also affect AC activity, can help prevent alcohol problems alto­ making it an imprecise marker for alcohol Beta-Endorphin gether, or enable a person to seek early use specifically (Hoffman et al. 2002). treatment for developing problems or to Researchers now are searching for pos­ The neurotransmitter beta-endorphin experience better treatment outcomes. sible differences between alcoholics and is an opioid produced by the pituitary At a minimum, any useful trait marker nonalcoholics in the structure of genes gland. It works to activate neurons’ should satisfy at least three criteria: It associated with AC activity. opiate receptors and is thought to pro­ should be passed down from parents to duce natural pain relief and a feeling of children through the genes (i.e., be her­ Gamma-Aminobutyric acid (GABA) exhilaration. Studies find that alcoholics itable), it should be associated with the have lower levels of beta-endorphin disease in question in the general popu­ The neurotransmitter GABA is a than nonalcoholics, and that children lation, and it should be independent of chemical that acts on special docking of alcoholics have fewer opioid receptors

Vol. 28, No. 1, 2004/2005 35 than children of nonalcoholics (Volpicelli likely that researchers never will find ARNDT, T. Carbohydrate-deficient transferrin as a et al. 1990; Zalewska-Kaszubska and one marker to satisfy all clinical needs, marker of chronic alcohol abuse: A critical review of preanalysis, analysis, and interpretation. Clinical Czarnecka 2005; Oswald and Wand they eventually may develop combina­ Chemistry 47(1):13–27, 2000. 2004). These findings indicate that tions of markers for different clinical differences in beta-endorphin levels are purposes, from unselective screening BALLDIN, J.; ALLING, C.; GOTTFRIES, C.G.; ET AL. Changes in dopamine receptor sensitivity in humans both specific to alcoholism and inher­ (i.e., drinking versus not drinking) to after heavy alcohol intake. Psychopharmacology ited, fulfilling two of the three require­ confirming a suspicion of alcohol abuse 86:142–146, 1985. ments for a trait marker of alcoholism. or dependence. In addition, proteomics BEAN, P.; HARASYMIW, J.; PETERSON, C.M.; AND Researchers still need to do much more may provide “signatures,” or combina­ JAVORS, M. Innovative technologies for the diagno­ work to establish beta-endorphin as a tions of compounds that are important sis of alcohol abuse and monitoring abstinence. true trait marker. diagnostically. Alcoholism: Clinical and Experimental Research Alcohol consumption patterns, like 25(2):309–316, 2001. Serotonin most human behavior, are complex. BECK, O., AND HELANDER, A. 5-hydroxytryptophol Clinicians often need to detect patterns as a marker for recent alcohol intake. Addiction Preliminary research indicates that the of drinking other than the chronic, 98(Suppl. 2):63–72, 2003. neurotransmitter serotonin or other heavy drinking detected by GGT, AST, CHEN, J.; CONIGRAVE, K.M.; MACASKILL, P.; ET biochemicals associated with serotonin ALT, and CDT. For example, they may AL. on behalf of the World Health Organization show potential as trait markers for and the International Society for Biomedical need to know whether a person has Research on Alcoholism Collaborative Group. alcoholism. One such biochemical— done any amount of drinking recently Combining carbohydrate-deficient transferrin and the amino acid tryptophan, which or what type of drinking has occurred gamma-glutamyltransferase to increase diagnostic influences how much serotonin the (e.g., heavy or social drinking). Therefore, accuracy for problem drinking. Alcohol and brain produces—may be decreased in finding new biomarkers that measure Alcoholism 38(6):574–582, 2003. people consuming excess alcohol many different aspects of alcohol con­ CONIGRAVE, K.M.; DAVIES, P.; HABER, P.; AND (Ratsma et al. 2002; Swann et al. 1999). sumption will vastly increase the clini- WHITFIELD, J.B. Traditional markers of excessive Another line of research examines cian’s ability to detect and treat alcohol alcohol use. Addiction 98(Suppl. 2):31–43, 2003. the activity of the serotonin transporter, abuse and dependence. In addition, GEORGE, D.T.; RAWLINGS, R.R.; ECKARDT, M.J.; which controls how much serotonin is such biomarkers will help provide more ET AL. Buspirone treatment of alcoholism: Age of available to cells. Research finds natural onset, and cerebrospinal fluid 5-hydroxyindolacetic precise definitions of alcohol consump­ acid and homovanillic acid concentrations, but not differences among people in serotonin tion and alcohol use disorders not only medication treatment, predict return to drinking. transporter activity in blood platelets, in the clinic but in research where these Alcoholism: Clinical and Experimental Research and these differences appear to be terms currently are defined less precisely, 23(2):272–278, 1999. inherited. In addition, alcoholics who such as number of drinks consumed HABER, H.; JAHN, H.; EHRENREICH, H.; AND have been abstinent for extended peri­ over a certain period of time. MELZIG, M.F. Assay of salsolinol in peripheral ods of time show higher serotonin Finally, more research is necessary blood mononuclear cells of alcoholics and healthy transporter activity than nonalcoholics, subjects by gas chromatography-mass spectrometry. before clinically useful trait markers of Addiction Biology 7(4):403–407, 2002. as do children of alcoholics compared genetic predisposition to alcohol depen­ with children of nonalcoholics (Oroszi dence are fully developed. The markers HALVORSON, M.R.; CAMPBELL, J.L.; SPRAGUE, G.; and Goldman 2004). These findings ET AL. Comparative evaluation of the clinical utility first must be validated clinically by of three markers of ethanol intake: The effect of indicate that serotonin transporter testing people before they develop gender. Alcoholism: Clinical and Experimental activity in blood platelets has potential alcoholism and waiting to see how Research 17(2):225–229, 1993. as a trait marker for alcoholism. well the marker predicts later behavior. HOFFMAN, P.L.; GLANZ, J.; TABAKOFF, B.; and the As researchers further develop the WHO/ISBRA Study on State and Trait Markers of markers described here and discover Alcohol Use and Dependence Investigators. Platelet Summary adenylyl cyclase activity as a state or trait marker in more biomarkers, their work should alcohol dependence: Results of the WHO/ISBRA greatly improve clinicians’ ability to study on state and trait markers of alcohol use and The search for ideal biomarkers of objectively assess alcohol consumption dependence. Alcoholism: Clinical and Experimental alcohol consumption (state) and for as well as genetic predisposition to Research 26(7):1078–1087, 2002. the genetic predisposition toward alcohol use disorders. ■ JAVORS, M.A., AND JOHNSON, B.A. Current status alcohol dependence (trait) continues. of carbohydrate-deficient transferrin, total serum Although the state markers currently sialic acid, sialic acid index of apolipoprotein J and in use have value, their limitations and References serum beta-hexosaminidase as markers for alcohol weaknesses make it desirable to develop consumption. Addiction 98(Suppl. 2):45–50, 2003. more sensitive and specific markers. ANTTILA, P.; JARVI, K.; LATVALA, J.; AND NIEMELA, JOHNSON, R.D.; LEWIS, R.J.; CANFIELD, D.V.; AND The importance of a marker’s precision, O. Method-dependent characteristics of carbohy- BLANK, C. L. Accurate assignment of ethanol origin drate-deficient transferrin measurements in the fol- in postmortem urine: Liquid chromatographic– accuracy, sensitivity, and specificity low-up of alcoholics. Alcohol and Alcoholism 39(1): mass spectrometric determination of serotonin cannot be overstated. Although it is 59–63, 2004. metabolites. Journal of Chromatography B,

36 Alcohol Research & Health Biomarkers for Alcohol Use and Abuse

Analytical Technologies in the Biomedical and Life PETERSON, C.M., AND POLIZZI, C.M. Improved phan availability to course of illness and clinical fea­ Sciences 805(2):223–234, 2004. method for acetaldehyde in plasma and hemoglobin- tures of alcoholism: A preliminary study. associated acetaldehyde: Results in teetotalers and Psychopharmacology 143(4):380–384, 1999. MIHIC, S.J., AND HARRIS, R.A. Alcohol actions at alcoholics reporting for treatment. Alcohol the GABA-A receptor/chloride channel complex. 4(6):477–480, 1987. VOLPICELLI, J.; O’BRIEN, C.; ALTERMAN, A.; AND In: Deitrich, R.A., and Erwin, V.G., eds. Pharma­ HAYSHIDA, M. Naltrexone in the treatment of alco­ cological Effects of Ethanol on the Nervous System. PETRAKIS, I.L.; TREVISAN, L.; D’SOUZA, C.; ET AL. hol dependence: Initial observations. In: Reid, Boca Raton: CRC Press, 1996. pp. 51–72. CSF monoamine metabolite and beta endorphin L.D., ed. Opioids, Bulimia, and Alcohol Abuse and levels in recently detoxified alcoholics and healthy Alcoholism. New York: Springer-Verlag, 1990. pp. MUSSHOFF, F.; LACHENMEIER, D.W.; SCHMIDT, P.; controls: Prediction of alcohol cue-induced craving. 195–214. ET AL. Systematic regional study of dopamine, nor­ Alcoholism: Clinical and Experimental Research salsolinol, and (R/S)-salsolinol levels in human 23(8):1336–1341, 1999. WURST, F.M.; SKIPPER, G.E.; AND WEINMANN, W. brain areas of alcoholics. Alcoholism: Clinical and Ethyl glucuronide—The direct ethanol metabolite RATSMA, J.E.; VAN DER STELT, O.; AND GUNNING, Experimental Research 29(1):46–52, 2005. on the threshold from science to routine use. W.B. Neurochemical markers of alcoholism vulner­ Addiction 98(Suppl. 2):51–61, 2003. NEUMANN, T., AND SPIES, C. Use of biomarkers for ability in humans. Alcohol and Alcoholism 37(6): alcohol use disorders in clinical practice. Addiction 522–533, 2002. WURST, F.M.; ALEXSON, S.; WOLFERSDORF, M.; ET 98(Suppl. 2):81–91, 2003. AL. Concentration of fatty acid ethyl esters in hair SALEM, R.O.; REFAAI, M.A.; CLUETT-BROWN, J.E.; of alcoholics: Comparison to other biological state NOMURA, F.; TOMONAGA, T.; SOGAWA, K.; ET AL. ET AL. Fatty acid ethyl esters in liver and adipose tis­ Identification of novel and downregulated sues as postmortem markers for ethanol intake. markers and self-reported ethanol intake. Alcohol biomarkers for alcoholism by surface-enhanced Clinical Chemistry 47(4):722–725, 2001. and Alcoholism 39(1):33–38, 2004. laser desorption/ionization–mass spectrometry. YEGLES, M.; LABARTHE, A.; AUWARTER, V.; ET AL. Proteomics 4(4):1187–1194, 2004. STOWELL, L.; STOWELL, A.; GARRETT, N.; AND ROBINSON, G. Comparison of serum beta- Comparison of ethyl glucuronide and fatty acid OROSZI, G., AND GOLDMAN, D. Alcoholism: hexosaminidase isoenzyme B activity with serum ethyl ester concentrations in hair of alcoholics, Genes and mechanisms. Pharmacogenomics 5(8): carbohydrate-deficient transferrin and other mark­ social drinkers and teetotalers. Forensic Science 1037–1048, 2004. ers of alcohol abuse. Alcohol and Alcoholism International 145(2/3):167–173, 2004. 32(6):702–714, 1997. OSWALD, L.M., AND WAND, G.S. Opioids and ZALEWSKA-KASZUBSKA, J., AND CZARNECKA, E. alcoholism. Physiological Behavior 81(2):339–358, SWANN, A.C.; JOHNSON, B.A.; CLONINGER, C.R.; Deficit in beta-endorphin peptide and tendency to 2004. AND CHEN, Y.R. Relationships of plasma trypto­ alcohol abuse. Peptides 26(4):701–705, 2005.

Vol. 28, No. 1, 2004/2005 37