Alcohol elimination in Native American Mission Indians: an investigation of interindividual variation

Subjective response to alcohol and ADH polymorphisms in a select sample of young adult male East Indians and Africans in Trinidad and Tobago

OBJECTIVE

Level of response to alcohol has been associated with risk of alcohol dependence in a number of ethnic groups. In the present study, subjective and objective responses to alcohol were evaluated in Indo-Trinidadians (Indo-T) and Afro-Trinidadians (Afro-T). Associations of alcohol dehydrogenase polymorphisms with response to alcohol, using the Subjective High Assessment Scale (SHAS), and breath alcohol concentrations (BrAC) were tested.

METHOD

Regular male drinkers without alcohol dependence (n = 112) ages 18-25 years participated in alcohol challenge sessions consisting of placebo and two doses of alcohol (target BrAC: 0 g/dl for placebo, .04 g/dl low dose, and .08 g/dl high dose) and genotyped for variants in ADH1B*3 and ADH1C*2.

RESULTS

Indo-T had significantly higher BrAC, pulse rates, and cortisol levels when compared with Afro-T but did not have significantly higher SHAS values. Higher responses on the SHAS items muddle/confused and nauseated were significantly associated with the presence of at least one ADH1B*3 allele following the high dose of alcohol in Afro-T. Indo-T with at least one ADH1C*2 allele displayed significantly different Drug × Time interactions for the SHAS item effects of alcohol at the low dose and for the SHAS items clumsy, muddle/confused, effects of alcohol, floating, drunk, and total at the high dose from Indo-T with two ADH1C*1 alleles.

CONCLUSIONS

This is the first study that has investigated individual sensitivity to alcohol in a Caribbean population and in people of East Indian descent. Indo-T with at least one ADH1C*2 allele may be at higher risk for heavy drinking by feeling less of the effects of alcohol, including nausea. In Afro-T, having at least one ADH1B*3 allele appears to exert a protective effect by enhancing the unpleasant effects of alcohol, such as nausea and confusion.

Association of alcohol dehydrogenase genes with alcohol-related phenotypes in a Native American community sample

BACKGROUND

Previous linkage studies, including a study of the Native American population described in the present report, have provided evidence for linkage of alcohol dependence and related traits to chromosome 4q near a cluster of alcohol dehydrogenase (ADH) genes, which encode enzymes of alcohol metabolism.

METHODS

The present study tested for associations between alcohol dependence and related traits and 22 single-nucleotide polymorphisms (SNPs) spanning the 7 ADH genes. Participants included 586 adult men and women recruited from 8 contiguous Native American reservations. A structured interview was used to assess DSM-III-R alcohol dependence criteria as well as a set of severe alcohol misuse symptoms and alcohol withdrawal symptoms.

RESULTS

No evidence for association with the alcohol dependence diagnosis was observed, but an SNP in exon 9 of ADH1B (rs2066702; ADH1B*3) and an SNP at the 5' end of ADH4 (rs3762894) showed significant evidence of association with the presence of withdrawal symptoms (p = 0.0018 and 0.0012, respectively). Further, a haplotype analysis of these 2 SNPs suggested that the haplotypes containing either of the minor alleles were protective against alcohol withdrawal relative to the ancestral haplotype (p = 0.000006).

CONCLUSIONS

These results suggest that variants in the ADH1B and ADH4 genes may be protective against the development of some symptoms associated with alcohol dependence.

Alcohol dehydrogenase 1B genotype and fetal alcohol syndrome: a HuGE minireview

Fetal alcohol syndrome (FAS), 1 of the most common developmental disabilities in the United States, occurs at a rate of 0.5-2.0:1000 live births. Animal model, family, and twin studies suggest a genetic component to FAS susceptibility. Alcohol dehydrogenases (ADHs) catalyze the rate-limiting step in alcohol metabolism. Studies of genetic associations with FAS have focused on the alcohol dehydrogenase 1B (ADH1B) gene, comparing mothers and children with the alleles ADH1B*2 or ADH1B*3, associated with faster ethanol metabolism, with those homozygous for ADH1B*1. While most studies have found a protective effect for genotypes containing ADH1B*2 or ADH1B*3, results have been conflicting, and further investigation into the association between the ADH1B genotype and FAS is needed. Whether increased alcohol intake accounts for the elevated risk reported for the ADH1B*1/ADH1B*1 genotype should be addressed, and future studies would benefit from consistent case definitions, enhanced exposure measurements, larger sample sizes, and careful study design.

Impact of theAlcohol-Dehydrogenase(ADH)1CandADH1Bpolymorphisms on drinking behavior in nonalcoholic Japanese

A linkage disequilibrium (LD) between the alcohol-dehydrogenase 1B (ADH1B) and alcohol-dehydrogenase 1C (ADH1C) polymorphisms adds complexity to differentiating the significance of these two genetic polymorphisms on drinking behavior and alcoholism. We have recently shown the importance of the ADH1B polymorphism on habitual drinking in the Japanese population; however, the issue regarding the LD between the ADH1B and ADH1C polymorphisms remains to be clarified. Here, we conducted a cross-sectional study in 2,299 nonalcoholic Japanese individuals. Drinking behavior was examined with regard to haplotypes of the ADH1B and ADH1C polymorphisms. Strength of association was assessed by sex and aldehyde-dehydrogenase 2 (ALDH2) adjusted odds ratios (OR) and their 95% confidence intervals (CIs) for the haplotype of the ADH1B and ADH1C polymorphisms. The ORs for habitual drinking were significant for ADH1B*2(rapid)-ADH1C*2(slow) (OR = 1.03; 95% CI: 1.01-1.05), ADH1B*1(slow)-ADH1C*1(rapid) (OR = 1.15; 95% CI: 1.14-1.16), and ADH1B*1(slow)-ADH1C*2(slow) (OR = 1.31; 95% CI: 1.29-1.32) compared with ADH1B*2(rapid)-ADH1C*1(rapid). This trend was evident among males. Similarly, a significantly increased risk of heavy drinking was observed for each haplotype compared with ADH1B*2(rapid)-ADH1C*1(rapid). In conclusion, this study showed a significant impact of the ADH1C polymorphism on habitual drinking, regardless of the ADH1B/ALDH2 polymorphisms.

Co-Morbidity of Select Anxiety, Affective, and Psychotic Disorders with Cannabis Dependence in Southwest California Indians

Cannabis dependence is co-morbid with psychiatric disorders in general population surveys, but whether co-morbidity exists in American Indian populations is unknown. The aim of this study was to assess co-morbidity between cannabis dependence and psychiatric disorders in a community sample of Southwest California (SWC) Indians. Demographic information and DSMIII- R diagnoses, including differentiation of independent and cannabis-induced psychiatric disorders, were obtained using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) developed for the Collaborative Study on the Genetics of Alcoholism (COGA) from 513 SWC Indian adults residing on contiguous reservations. Although SWC Indians in this sample had high rates of cannabis dependence (43% in men and 24% in women), cannabis-induced psychiatric disorders each occurred in 1% or less of the sample. No significant co-morbidity with independent psychiatric disorders was found. In SWC Indians, cannabis dependence may be less etiologically related to psychiatric disorders than in the general population.

Heritability of substance dependence in a native American population

OBJECTIVES

To estimate the heritability of substance dependence and associated symptoms in a sample of Southwest California (Mission) Indians.

METHODS

Families from eight contiguous Indian reservations were recruited in order to ascertain information on substance dependence symptoms and diagnoses using a semi-structured diagnostic interview. Dependence diagnoses for alcohol, marijuana, stimulants and a measure of regular tobacco usage, any drug dependence or tobacco usage were obtained. Composite measures of alcohol dependence symptoms for withdrawal, drinking severity, antisocial problems and interpersonal problems were constructed from the nine groups of symptoms summarized in the diagnostic interview. Heritability estimates were calculated using variance component methods, as implemented in SOLAR.

RESULTS

In this population, marijuana dependence (0.38) and regular tobacco use (0.43), alcohol dependence (DSM-III-R 0.19; ICD-10, 0.29) and stimulant dependence (0.25) showed evidence for moderate genetic influences as determined by heritability estimates. Four phenotypes constructed using the composite symptoms of alcohol dependence revealed that withdrawal had the highest heritability estimate (0.71), followed by antisocial problems (0.36) and drinking severity (0.34). Symptom clusters reflecting interpersonal problems did not appear to be highly heritable (0.19).

CONCLUSION

Marijuana dependence, regular tobacco usage and composite phenotypes constructed from alcohol dependence symptoms for antisocial problems, drinking severity and withdrawal generally have patterns of familial aggregation, suggesting that they can be successfully used for linkage analysis in this Southwest California Indian sample.

Functionality of allelic variations in human alcohol dehydrogenase gene family: assessment of a functional window for protection against alcoholism

Alcohol dehydrogenase (ADH) catalyses the rate-determining reaction in ethanol metabolism. Genetic association studies of diverse ethnic groups have firmly demonstrated that the allelic variant ADH1B*2 significantly protects against alcoholism but that ADH1C*1, which is in linkage with ADH1B*2, produces a negligible protection. The influence of other potential candidate genes/alleles within the human ADH family, ADH1B*3 and ADH2, remains unclear or controversial. To address this question, functionalities of ADH1B3 and ADH2 were assessed at a physiological level of coenzyme and substrate range. Ethanol-oxidizing activities of recombinant ADH1B1, ADH1B2, ADH1B3, ADH1C1, ADH1C2 and ADH2 were determined at pH 7.5 in the presence of 0.5 mm NAD with 2-50 mm ethanol. The activity differences between ADH1B2 and ADH1B1 were taken as a threshold for effective protection against alcoholism and those between ADH1C1 and ADH1C2 as a threshold for null protection. Over 2-50 mm ethanol, the activities of ADH1B3 were found 2.9-23-fold lower than those of ADH1B2, largely attributed to the Km effect (ADH1B2, 1.8 mm; ADH1B3, 61 mm). Strikingly, the ADH1B3 activity was only 84% that of ADH1B1 at a low ethanol concentration, 2 mm, but increased 10-fold at 50 mm. Corrected for relative expression levels of the enzyme in liver, the hepatic ADH2 activities were estimated to be 18-97% those of ADH1B1 over 2-50 mm ethanol and were 28-140% of the activity differences between ADH1C1 and ADH1C2. The assessment based on the proposed functional window for the human ADH gene family indicates that ADH1B*3 may show some degree of protection against alcoholism and that the ADH2 functional variants appear to be negligible for this protection.

Comorbidity of select anxiety and affective disorders with alcohol dependence in southwest California Indians

BACKGROUND

Native Americans, overall, have the highest prevalence of alcohol dependence of any US ethnic group. In several large national surveys, alcohol dependence has been significantly associated with higher rates of anxiety and affective disorders (comorbidity). However, the frequencies of these disorders and their comorbidity with alcohol dependence in Native American populations are relatively unknown.

METHODS

Demographic information and DSM-III-R diagnoses were obtained by using the Semi-Structured Assessment for the Genetics of Alcoholism developed for the Collaborative Study on the Genetics of Alcoholism from 483 Southwest California Indian adults residing on contiguous reservations. The Semi-Structured Assessment for the Genetics of Alcoholism allowed differentiation of each anxiety and affective disorder into one of three types: independent of substance use, concurrent with alcohol use, and concurrent with drug use.

RESULTS

Sixty-six percent of the men and 53% of the women sampled had a lifetime diagnosis of alcohol dependence. Fourteen percent of the sample had a lifetime independent anxiety disorder, and 14% of the sample had a lifetime independent affective disorder. Alcohol- and/or drug-concurrent major depression occurred in 8%, and other alcohol- and/or drug-concurrent anxiety and affective disorders each occurred in less than 1.1% of the sample. No significant comorbidity was found between alcohol dependence and independent agoraphobia, social phobia, or major depressive disorder.

CONCLUSIONS

In this Southwest California Indian sample, rates of anxiety and affective disorders were substantially similar to those reported in the National Comorbidity Survey; however, comorbidity of independent disorders with alcohol dependence was not as pervasive as in the National Comorbidity Survey. Rates of concurrent anxiety and affective disorders were low. These data support the hypothesis that despite high rates of alcohol dependence, Southwest California Indians do not have higher rates of anxiety and affective disorders or comorbidity of these disorders with alcohol dependence than those reported in large surveys of non-American Indian populations.

Influence of Genetic Variations of Ethanol-Metabolizing Enzymes on Phenotypes of Alcohol-Related Disorders

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase-2 (ALDH2) play central roles in the metabolism of ethanol and its metabolite, acetaldehyde, in the liver. In ADH2, one nucleotide replacement causes either a super-active beta 2 subunit encoded by the ADH2*2 allele or a less active beta 1 subunit (ADH2*1 allele). In the same way, a G/A replacement at codon 487 of the ALDH2 gene produces an inactive form of the enzyme. Because the geno-types of these genes may explain individual differences in concentration and elimination of ethanol and acetaldehyde in the blood after drinking, they could be used as models to elucidate the contribution of these substances to the development of addiction and various types of organ damage. We have examined the influence of genetic variations of these enzymes on alcohol-related disorders in the Japanese. The results revealed that (1) the less active allele of the ADH2 gene (ADH2*1) is associated with an increased risk for alcohol dependence, alcohol-induced persistent amnestic disorder, alcohol withdrawal syndrome, and cancer of the upper GI tract; (2) the inactive allele of the ALDH2 gene (ALDH2*2) is associated with a decreased risk for alcohol dependence, and an increased risk for alcoholic polyneuropathy and cancer in the same region; and (3) these genetic variations modify clinical features of alcohol dependence. Possible mechanisms of altered risk for these disorders are discussed.

Genomic screen for loci associated with alcohol dependence in Mission Indians

Alcohol dependence is a leading cause of morbidity and mortality in Native Americans, yet biological factors underlying the disorder in this ethnic group remain elusive. This study's aims were to map susceptibility loci for DSM-III-R alcohol dependence and two narrower alcohol-related phenotypes in Mission Indian families. Each participant gave a blood sample and completed an interview using the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA) that was used to make alcohol dependence diagnoses and the narrower phenotypes of withdrawal, and drinking severity. Genotypes were determined for a panel 791 microsatellite polymorphisms. Analyses of multipoint variance component LOD scores for the dichotomous DSM-III-R phenotype revealed no peak LOD scores that exceeded 2.0 at any chromosome location. Two chromosomes, 4 and 12, had peak LOD scores that exceeded 2 for the alcohol use severity phenotype and three chromosomes 6, 15, 16 were found to have peaks with LOD scores that exceeded 2 for the withdrawal phenotype. Evidence for linkage to chromosomes 4 and 15, and 16 have been reported previously for alcohol related phenotypes whereas no evidence has as yet been reported for chromosomes 6 and 12. Combined linkage and association analysis suggest that alcohol dehydrogenase 1B gene polymorphisms are partially responsible for the linkage result on chromosome 4 in this population. These results corroborate the importance of several chromosomal regions highlighted in prior segregation studies in alcoholism and further identify new regions of the genome that may be unique to either the restricted phenotypes evaluated or this population of Mission Indians.

Genes associated with addiction: alcoholism, opiate, and cocaine addiction

Drug addiction is a complex disorder that has a large spectrum of causes. Vulnerability to addiction has been shown in twin studies to have a robust genetic component. This genetic basis for addiction has general and specific components for each drug abused. Although many genes have been implicated in drug addiction, only a handful have either been replicated to have an association or to have an identified functional mechanism related to specific effects of abused drugs. A few selected genetic variants that currently look promising for the study of alcohol, opiate, and cocaine addiction are discussed in this article.

Visual P3 findings in Mission Indian youth: relationship to family history of alcohol dependence and behavioral problems

Native Americans have some of the highest rates of alcohol abuse and dependence, yet risk factors for problem drinking remain relatively unknown. The amplitude of the P3 component of the event-related potential (ERP) has been suggested to be an index of 'vulnerability to alcoholism', especially when it is elicited by visual tasks in younger individuals. Visual P3 tasks, however, have not been previously investigated in Native American youth. One hundred and four Mission Indian youth between the ages of 7 and 13 years participated in the study. ERPs were collected using two visual target paradigms: a facial discrimination and an estimation of line orientation task. Analyses of covariance revealed that participants with a first degree family history of alcoholism had lower P3 component amplitudes in frontal leads to the facial discrimination task. Lower P3 amplitudes, in posterior areas, were found in the line discrimination task in children who scored above the 75th percentile in delinquent behaviors on the Achenbach Child Behavior Checklist. These findings are consistent with investigations in non-Indian populations demonstrating that the late positive component of the event related potential is sensitive to both familial history of alcohol dependence as well as personal history of externalizing behaviors.

Research advances in ethanol metabolism

The pharmacokinetics of alcohol determines the time course of alcohol concentration in blood after the ingestion of an alcoholic beverage and the degree of exposure of organs to its effects. The interplay between the kinetics of absorption, distribution and elimination is thus important in determining the pharmacodynamic responses to alcohol. There is a large degree of variability in alcohol absorption, distribution and metabolism, as a result of both genetic and environmental factors. The between-individual variation in alcohol metabolic rates is, in part due to allelic variants of the genes encoding the alcohol metabolizing enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). This review summarizes recent developments in the investigation of the following influences on alcohol elimination rate: gender, body composition and lean body mass, liver volume, food and food composition, ethnicity, and genetic polymorphisms in alcohol metabolizing enzymes as well as in the promoter regions of the genes for these enzymes. Evaluation of the factors regulating the rates of alcohol and acetaldehyde metabolism, both genetic and environmental, will help not only to explain the risk for development of alcoholism, but also the risk for development of alcohol-related organ damage and developmental problems.

EEG asymmetry: relationship to mood and risk for alcoholism in Mission Indian youth

BACKGROUND

Left frontal electroencephalogram (EEG) alpha dominance has been hypothesized to be related to depressed mood as well as aversive motivation and emotion. However, few studies have prospectively evaluated electroencephalogram asymmetry during development in high-risk adolescents and children.

METHODS

EEG alpha asymmetry was investigated in 134 Mission Indian children who were between 7 and 13 years of age. The relationships between electroencephalogram alpha asymmetry and age, gender, parental history of alcohol dependence, Native American heritage, and mood/ approach behaviors were explored.

RESULTS

No significant relationship was found between frontal alpha asymmetry and age, gender, or behavioral measures of depressed mood and/or approach behaviors. However, participants with > or = 50% Native American heritage were significantly more likely to have greater electroencephalogram alpha power in the left frontal cortex than in the right.

CONCLUSIONS

The present findings suggest that the hypothesized relationship between EEG alpha asymmetry and measures of depressed mood, aversive motivation, and emotion may not be universal in all age or ethnic groups. Additionally, though the relationship between greater degrees of Native American heritage and alpha asymmetry are not as yet clear, we suggest it may be more related to substance abuse than depression in this population of Mission Indians.

Determinants of the risk and timing of alcohol and illicit drug use onset among natives and non-natives: similarities and differences in family attachment processes

This study examines data from Native Ontario reserve residents (Embree, 1993) and a sample from the Ontario Health Survey Supplement (1990-91) in order to compare and contrast the importance of family attributes such as parent-child attachment to Native and Non-native patterns of drug and alcohol use onset. Proportional Hazards modeling (Cox, 1972) was employed to identify factors associated with the risk and timing of onset of alcohol and illicit drugs for both cultural groups. For both Natives and Non-natives alike, and considering both drinking and drug use onset together, age cohort predominates as a risk factor, with youngest groups at greatest risk, and especially in the case of drug use other than alcohol. For the model of drug use timing, age of alcohol use onset is the second best predictor for Natives, although its effect is still apparent, albeit weaker, in the case of Non-natives. As for family characteristics, a number of factors emerge as determinants of risk and depend, in part, on the cultural group and the substance under consideration. Consistent with attachment theory's prediction about the universal applicability of the need for close parent-child relations (Bowlby, 1969), the findings for both Natives and Non-natives alike point to the salience of psychosocial attachment and other indicators of family functioning in affecting early onset drinking and drug use, behaviors well-recognized to lead to potentially adverse mental and physical health consequences as well as to negative social outcomes.

Historical and cultural roots of drinking problems among American Indians

Roots of the epidemic of alcohol-related problems among many Native North Americans are sought in cultural responses to European arrival, the role of alcohol in frontier society, and colonial and postcolonial policies. Evidence from the historical record is considered within the framework of current social science. Initially, Native American's responses to alcohol were heavily influenced by the example of White frontiersmen, who drank immoderately and engaged in otherwise unacceptable behavior while drunk. Whites also deliberately pressed alcohol upon the natives because it was an immensely profitable trade good; in addition, alcohol was used as a tool of "diplomacy" in official dealings between authorities and natives. The authors argue that further research into the origins of modern indigenous people's problems with alcohol would benefit from an interdisciplinary "determinants of health" approach in which biological influences on alcohol problems are investigated in the context of the cultural, social, and economic forces that have shaped individual and group drinking patterns.

Electroencephalographic responses to alcohol challenge in Native American Mission Indians

BACKGROUND

Native Americans have some of the highest rates of alcohol abuse and dependence, yet potential central nervous system risk factors responsible for the problem drinking seen in some tribes remain relatively unknown.

METHODS

Background electroencephalographic (EEG) variants and response to alcohol were investigated in 48 Native American Mission Indian men between 18 and 25 years old.

RESULTS

Subjects with 50% or greater Native American heritage had a significantly higher proportion of low-voltage EEG variants. Within this sample of Mission Indian men, however, a family history of alcohol dependence was associated with a greater incidence of high voltage alpha EEGs. Mission Indian men also evidenced a "less depressant, more stimulating" response to alcohol as quantified by less alcohol-induced reductions in alpha, greater EEG stability, and increased alcohol-induced beta activity.

CONCLUSIONS

These findings demonstrate that certain genetically regulated EEG variants that have been previously associated with risk for alcoholism in Caucasians may also be more common in these Mission Indian men. Additionally, EEG measures of response to alcohol do not provide support for the commonly held idea that Indians are more sensitive to the depressant effects of alcohol.