Electrophysiological responses to affective stimuli in Southwest California Indians: relationship to alcohol dependence

OBJECTIVE

Native Americans have some of the highest rates of alcohol abuse and dependence, yet potential risk factors associated with the problem drinking seen in some tribes remain relatively unknown. The present investigation evaluated associations between the P350 and P450 components of the event-related potential (ERP) elicited by affective stimuli and potential vulnerability factors associated with risk of alcohol dependence in Southwest California (SWC) Indian adults.

METHOD

Data from 517 Native American SWC Indian adults between the ages of 18 and 70 were used in the analyses. ERPs were collected using a task that required discrimination among faces with neutral, sad, and happy facial expressions.

RESULTS

P450 amplitudes were significantly reduced in participants who met lifetime Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, criteria for alcohol dependence in centroparietal leads. In contrast, participants who met personal lifetime criteria for affective disorder were found to have higher P350 and P450 amplitudes in frontal leads. Neither P350 nor P450 component amplitudes were significantly altered based on a family history of alcohol dependence, a personal history of antisocial personality disorder/conduct disorder, or the presence of drug dependence other than alcohol.

CONCLUSIONS

These findings suggest, in this select population, that P450 amplitudes are selectively affected by both alcohol dependence and affective disorder. However, reductions in P450 amplitude were restricted to those participants with alcohol dependence, confirming that it may be an important putative endophenotype for genetic studies of that disorder in this high-risk population.

Electrophysiological responses to affective stimuli in Mexican Americans: Relationship to alcohol dependence and personality traits

The relationship between the P450 component elicited by affective stimuli and: a personal history of alcohol dependence, antisocial personality disorder/conduct disorder (ASPD/CD) or affective anxiety disorders (ANYAXAF) was examined in Mexican Americans, a group with high rates of heavy drinking. Data from two hundred and twenty two young adults between the ages of 18 and 30 were used in the analyses. ERPs were collected using a task that required discrimination between faces with neutral, sad and happy facial expressions. DSM-IIIR diagnoses were obtained using a structured interview and personality traits were indexed using the Maudsley personality inventory. Men had significantly diminished P450 responses, when compared to women which were further reduced in men with ASPD/CD; whereas, a significant increase in P450 amplitudes was seen in those participants with ANYAXAF. P450 amplitudes were also significantly increased in men with high extraversion scores and in women with high neuroticism scores. No significant associations were seen between the P450 amplitude and the diagnosis of alcohol dependence. These data suggest that interpretations of P450 responses in Mexican Americans need to take into account the interactions between gender, the affective valence of the eliciting stimuli, as well as psychiatric status.

Heritability of illicit drug use and transition to dependence in Southwest California Indians

OBJECTIVE

Native Americans have high rates of drug use and dependence yet little is known concerning its etiology or clinical course. These analyses were conducted to describe the heritability of the use of a variety of illicit drugs, as well as the conditional probability of transitioning from use to dependence for each drug class in a community sample of Native American men and women.

METHODS

The sample included 460 participants (190 men and 270 women), recruited through community effort, from eight contiguous Indian reservations in Southern California. Participants were assessed using the Semi-Structured Assessment for the Genetics of Alcoholism. The Semi-Structured Assessment for the Genetics of Alcoholism interview retrospectively asks about the initial use and drug dependence of the following illicit drug classes: marijuana, cocaine, stimulants, sedatives, opiates, hallucinogens, and solvents. Heritability of initial use was determined using SOLAR (http://www.sfbr.org/solar/).

RESULTS

Ninety-one percent of this select Indian population had tried at least one of the illicit drug classes. The most commonly tried substance was marijuana (88%), followed by stimulants (60%), cocaine (44%), hallucinogens (34%), and solvents (20%). The heritability of initiation of drug use ranged from 0.14 for cocaine to 0.59 for marijuana. The conditional probability of transition from initiation to drug dependence ranged from 0.66 for stimulants to 0.06 for hallucinogens.

CONCLUSIONS

These findings suggest that heritability of the initiation of substance use, in Southwest California Indians, may be similar to other population samples. In this population, however, high rates of dependence on marijuana, opiates, and stimulants are seen once initiation of the use of the substance has occurred.

Association of ALDH1 Promoter Polymorphisms With Alcohol-Related Phenotypes in Trinidad and Tobago*

OBJECTIVE

Two polymorphisms in the promoter region of the gene encoding cytosolic aldehyde dehydrogenase (ALDH1A1), ALDH1A1*2 and ALDH1A1*3, have recently been identified. The present study sought to determine whether an association exists between ALDH1A1 genotypes, alcohol dependence, drinking history, and liver function tests in the two major ethnic groups of Trinidad and Tobago (TT).

METHOD

The participants in this study were 137 alcohol dependents of either East Indian ancestry (Indo-TT) or African ancestry (Afro-TT) and 108 controls matched by age, gender, and ethnicity. A structured interview was used to gather information on demographics, psychiatric diagnoses, and personal drinking and drug use. A blood sample was obtained from each participant, and leukocyte DNA was extracted and used to genotype for the presence of the ALDH1A1 promoter polymorphisms. Serum levels of hepatic enzymes, as well as presence of HIV, hepatitis B surface antigen, and antihepatitis C virus antibody, were also determined.

RESULTS

Twenty-four participants (10%) possessed the ALDH1A1*1/*2 genotype (frequency = .05), 4 were Afro-TT (2 alcohol dependents, 2 controls), and 20 were Indo-TT (18 alcohol dependents, 2 controls). Two participants (1 Indo-TT alcohol dependent, 1 Afro-TT alcohol dependent) had the ALDH1A1*2/*2 genotype. Four participants possessed ALDH1A1*3, all of whom were Afro-TT controls. Indo-TT participants with at least one ALDH1A1*2 allele were more likely to have a lifetime diagnosis of Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised, alcohol dependence (p < .002). Indo-TT participants with ALDH1A1*2 also reported significantly higher levels of current alcohol consumption (p < .05). The small number of Afro-TT participants with atypical polymorphisms limits any conclusions on the possible impact on alcohol dependence in that population.

CONCLUSIONS

Results from this study suggest that ALDH1A1*2 may be associated with increased risk for the development of alcohol dependence in Indo-Trinidadians.

Genomic screen for substance dependence and body mass index in southwest California Indians

Substance abuse and obesity are health disparities that may afflict Native Americans more than some other ethnic groups. One theoretical assumption concerning Native people is that the long history of dependence on foraging and subsistence agriculture may have led to selective enrichment of traits that improve genetic fitness, so called 'thrifty' or 'fat sparing' genes. We have speculated that this same selective pressure may have enriched for genetic variants that increase the risk for consumption of alcohol and drugs of abuse. Here, we report the results of a genome scan that compared findings for two consumption phenotypes: 'any drug dependence and/or regular tobacco use' and body mass index (BMI) in southwest California (SWC) Indian families. Variance component analyses from SOLAR were used to generate log of the odds ratio (LOD) scores. Evidence for linkage was found on chromosome 6 for both the 'any drug' (LOD score = 3.3) and BMI (LOD score = 2.3) phenotypes. Bivariate analyses of the two phenotypes revealed a combined LOD score of 4.1 at that location. Additional loci on chromosomes 6, 15, 16 and 21 were found for the 'any drug' phenotype, and on chromosomes 8, 16 and 18 for BMI (LOD scores ranged between 1.2 and 2.3). These results provide suggestive evidence for linkage for substance abuse and BMI in this Mission Indian population and, furthermore, provide preliminary data suggesting that 'consumption phenotypes' may share some genetic determinants.

Association of EEG alpha variants and alpha power with alcohol dependence in Mexican American young adults

Several studies support an association between electroencephalogram (EEG) voltage and alcohol dependence. However, the distribution of EEG variants also appears to differ depending on an individual's ethnic heritage, suggesting significant genetic stratification of this EEG phenotype. The present study's aims were to investigate the incidence of EEG alpha variants and spectral power in the alpha frequency range in Mexican American young adults based on gender, and personal and family history of alcohol dependence. Clinical ratings (high-, medium-, and low alpha voltage variants) and spectral characteristics of the EEG in the alpha frequency range (7.5-12 Hz) were investigated in young adult (age 18-25 years) Mexican American men (n=98) and women (n=138) who were recruited from the community. Nineteen percent (n=45) of the participants had a low-voltage alpha EEG variant, 18% had a high-voltage variant, and 63% had a medium-voltage variant. There were no significant differences in the distribution of the EEG variants based on family history of alcohol dependence. There was a significant relationship between gender and the three alpha variants (chi2=9.7; df=2; P<.008), and there were no male participants with alcohol dependence with high alpha variants (chi2=5.8; df=2; P<.056). Alcohol dependence, but not a family history of alcohol dependence, was associated with lower spectral power in the alpha frequency range in the right (F=4.4; df=1,96; P<.04) and left (F=5.3; df=1.96; P<.02) occipital areas in the men but not in the women. In conclusion, in this select population of Mexican American young adults, male gender and alcohol dependence are associated with an absence of high-voltage alpha variants and lower alpha power in the EEG. These data suggest that EEG low voltage, a highly heritable trait, may represent an important endophenotype in male Mexican Americans that may aid in linking brain function with genetic factors underlying alcohol dependence in this ethnic group.

Association of the ADHIB*3 Allele With Alcohol-Related Phenotypes in Trinidad

BACKGROUND

Two of the class I alcohol dehydrogenase (ADH) genes located on chromosome 4 (ADH1B and ADH1C) encode for multiple isozymes that differ in their kinetic properties. At the ADH1B locus, 3 polymorphisms are present (ADH1B(*)1, ADH1B(*)2, ADH1B(*)3). ADH1B(*)2 (found mostly in individuals of East Asian and Jewish descent) and ADH1B(*)3 (found mostly in individuals of African decent) alleles encode for a more active enzyme variants than ADH1B(*)1 and the presence of these alleles has been associated with protection from alcohol dependence. The relationship between these alleles and alcohol-associated phenotypes has not been previously investigated in individuals living in the Caribbean.

METHODS

One hundred thirty-three alcohol-dependent individuals of either East Indian or African ancestry and 98 controls matched by age, sex, education, and ethnicity participated in the study. A structured interview [the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA)] was used to gather information on demographics, psychiatric diagnoses, personal drinking, and drug use history. Leukocyte DNA extracted from a blood sample obtained from each participant was genotyped at the ADH1B locus. Serum levels of the liver enzymes alanine and aspartate aminotransferase (ALT, AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT) as well as the presence of HIV, hepatitis B surface antigen, and antihepatitis C virus antibody were also assayed. The specific aim of the study was to investigate the associations between ADH1B alleles and alcohol dependence, drinking history, and liver function in individuals from the 2 major ethnic groups of Trinidad (individuals of African and East Indian ancestry).

RESULTS

Twenty-eight of the Afro-Trinidadian (Afro-TT) participants (41%) and 1 Indo-Trinidadian (Indo-TT) (>1%) had at least 1 ADH1B(*)3 allele and 3 Afro-TT were homozygous for the allele. African participants with at least 1 ADH1B(*)3 allele were found to be significantly less likely to be alcohol dependent (p<0.018), and to have lower alcohol consumption levels (p<0.05). Among those participants who were alcohol dependent, ADH1B(*)3 was associated with significantly higher levels of ALT (p<0.05).

CONCLUSIONS

This study suggests, in this sample of Trinidadians, that the ADH1B(*)3 allele is associated with protection from the development of alcoholism but is also associated with enhanced risk for elevated serum ALT levels in those individuals who do become alcohol dependent.

Age of first marijuana use and the occurrence of marijuana use disorders in Southwest California Indians

In several national surveys a younger age of substance usage has been associated with a higher likelihood of the development of dependence. Some studies have suggested that age at first use is primarily an environmentally driven variable, whereas others suggest that it may be partially mediated by a general vulnerability to exhibit problem behaviors. Although Native Americans, overall, have the highest prevalence of substance dependence of any US ethnic group, the relationship of age of first marijuana use on the development of dependence in Native American populations is relatively unknown. Demographic information and DSM-III-R diagnoses were obtained from 525 Southwest California Indian adults residing on contiguous reservations. Multinomial logistic regression was used to investigate the relationship between age of first use and marijuana use disorders. Early marijuana use was found to be strongly associated with abuse and dependence in this population, even in the presence of several other risk factors including externalizing diagnoses. These data suggest that effective environmental prevention efforts at reducing early marijuana use may be an important strategy to lower the prevalence of use disorders in this high risk population.

P3 components and adolescent binge drinking in Southwest California Indians

In adolescence, consuming a large number of drinks over a short interval of time (e.g. binging) is not an uncommon occurrence. Since adolescence is an important neurodevelopmental period, the effect of binge drinking on brain and behavior has become a significant health concern. The present study evaluated event-related potentials (ERPs) in young adult Southwest California Indians who had a history of binge drinking during their adolescence. One hundred twenty five participants who were currently 18-25 yrs of age who were free of Axis I psychiatric diagnoses were categorized as: 1) reporting no binge drinking during adolescence (>5 drinks per occasion before age 18) or drug dependence diagnoses 2) reporting binge drinking during adolescence with no drug dependence diagnoses 3) reporting binge drinking during adolescence and drug dependence diagnoses. ERPs were collected using a facial discrimination task. Adolescent alcohol and drug exposure was found to be associated with decreases in the latency of an early P3 component (P350). Decreases in a later component amplitude (P450) were also found in young adults exposed to alcohol, and those exposed to alcohol and drugs. However, that finding appears to be a combined result of predisposing factors such as family history of alcoholism and presence of other externalizing diagnoses. Taken together these preliminary studies suggests that adolescent binge drinking may result in a decreases in P3 component latencies and amplitudes perhaps reflecting a loss or delay in the development of inhibitory brain systems.

Variations in ADH and ALDH in Southwest California Indians

Native Americans as a group have the highest rates of alcohol-related deaths of all ethnicities in the United States; however, it remains unclear how and why a greater proportion of individuals in some Native American communities develop alcohol-related problems and alcohol use disorders (AUDs). One potential factor that can influence responses to alcohol are variations in alcohol-metabolizing enzymes. Researchers have analyzed the frequencies of variants in the alcohol-metabolizing enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) in some Native American populations. So far the studies have yielded no evidence that an ALDH2 variant, which has shown protective effects in other populations, is found in either American Indians or Alaska Natives. A variant of the ALDH1 enzyme that is encoded by the ALDH1A1*2 allele, however, was found in a small proportion of a group of Southwest California Indians and had a protective effect against alcoholism in that population. Furthermore, a variant of the ADH1B enzyme that is encoded by the ADH1B*3 allele was found in a similar proportion of Southwest California Indians and also was associated with a protective effect. However, these findings do not explain the high prevalence of alcoholism in the tribes investigated.

Variations in alcohol-metabolizing enzymes in people of East Indian and African descent from Trinidad and Tobago

The population of Trinidad and Tobago is composed mainly of people of East Indian (Indo-Trinidadians) and African (Afro-Trinidadians) ancestry. Differences in alcoholism rates exist between these two ethnic groups, and researchers have investigated whether these differences can be explained in part by variations in the genes encoding the alcohol-metabolizing enzymes alcohol dehydrogenase (ADH) 1B and 1C, and aldehyde dehydrogenase (ALDH) 1 and 2. Studies have demonstrated that a certain variant of the gene encoding ADH1B (ADH1B*3) is associated with a reduced risk of alcoholism in Afro-Trinidadians, as is a variant of the gene encoding ADH1C (i.e., ADH1C*1) in Indo-Trinidadians. An ALDH2 variant shown to have protective effects primarily in East Asians was not found in either Trinidadian ethnic group. However, a variant in the gene encoding cytosolic ALDH1A (i.e. ALDH1A1*1/*2) was found to be associated with an increase in alcohol dependence in Indo-Trinidadians.

Increased alcohol drinking in isolate-housed alcohol-preferring rats

Alcoholism is a complex disorder influenced by interactions between genetic and environmental risk factors. This study examined the influence of isolate housing on ethanol intake in alcohol-preferring (P) and non-alcohol-preferring (NP) rats. Rats were isolate-housed or pair-housed for 8 weeks when between 45 and 96 days old. Ethanol drinking was assessed using a 24-hr preference test (10% ethanol vs. water) and 20-min limited access tests. A behavioral test battery was used to assess anxiety-like, depressive-like, acoustic startle, and motor behavior. Isolate housing increased home cage drinking in both lines and increased limited access drinking selectively in P rats. Isolation also reduced swim test immobility and prepulse inhibition in P rats and increased locomotor stereotypies in NP rats. Taken together, these data demonstrate that LinexEnvironment interactions influence the effects of isolation. Furthermore, isolation selectively increased ethanol intake in high drinking P rats. This effect was not correlated with changes in other behaviors. Selective enhancement of limited access ethanol drinking in P rats may represent a model whereby genetic liability to excessive drinking is enhanced by specific environmental exposures.

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.

Age at First Intoxication and Alcohol Use Disorders in Southwest California Indians

BACKGROUND

In several national surveys, a younger age of onset of first drink and/or regular drinking has been associated with a higher likelihood of the development of alcohol dependence. Some studies have suggested that age at first drink is primarily an environmentally driven variable whereas others suggest that it may be partially mediated by a general vulnerability to exhibit problem behaviors. Although Native Americans, overall, have the highest prevalence of alcohol dependence of any U.S. ethnic group, the relationship of age of onset of intoxication with alcohol dependence in Native American populations is relatively unknown.

METHODS

Demographic information and DSM-III-R diagnoses were obtained from 525 Southwest California (SWC) Indian adults residing on contiguous reservations. Survival analyses and Cox and logistic regression were used to investigate the relationship between age of onset of first intoxication and the development of alcohol dependence. Heritability of the age of onset of first intoxication was also determined using SOLAR.

RESULTS

Age at first intoxication was not found to be heritable in this population. Early onset of intoxication, however, was found to be significantly associated with both a shorter time to onset of alcohol dependence and increased prevalence in this population, even on taking into account several other risk factors including externalizing diagnoses.

CONCLUSIONS

These data suggest that effective environmental prevention efforts at reducing underage drinking may be an important strategy to lower the prevalence of alcohol dependence in this high-risk population.

Testing of an orthogonal measure of cultural identification with adult mission Indians

The Orthogonal Cultural Identification Scale (OCIS; Oetting & Beauvais, 1990-91) has been validated among Native American youth, but not adults. The present study sought to test the reliability (internal consistency) and validity (construct and factorial) of the OCIS among an adult Native American sample consisting of 389 Mission Indians (61% female). Participants were recruited from reservations using a venue sampling strategy. The OCIS was completed as part of a self-assessment packet of questionnaires. Internal consistency for OCIS subscale scores ranged from 0.76 to 0.91. Both concurrent and discriminant validity were demonstrated. Confirmatory factor analysis revealed 2 factors: (1) Anglo American Identification and (2) Native American Identification. These results indicate the OCIS is a reliable and valid instrument for use with adult Native Americans.

Electrophysiological Responses to Affective Stimuli in American Indians Experiencing Trauma With and Without PTSD

American Indians are at high risk for exposure to violence and other traumatic events, yet few studies have investigated posttraumatic stress disorder (PTSD) or its neurobiological consequences in Indian communities. In the present study, a sample of American Indians (n = 146) were given a structured diagnostic interview that additionally indexed traumatic life events and symptoms emerging following those events. Electroencephalogram (EEG) spectra and visual event-related potentials (ERPs) to happy, sad, and neutral faces were also recorded from each participant. Ninety-nine percent of the sample had experienced at least one category of trauma with the mean number being 5, 27% had experienced at least 8 categories, and 13% met DSM-IV criteria for PTSD. The PTSD group did not differ on any demographic or diagnostic variables from the larger sample. An electrophysiological signature for PTSD was found that included increases in high-frequency gamma activity (20-40 Hz, F = 8.7, P < 0.004) in frontal leads, higher N1 amplitudes to sad stimuli in frontotemporal leads (F = 12.4, P < 0.001, F = 5.0, P < 0.03), and longer latency P3 components to happy stimuli in midline, central, and right frontal leads (F = 4.7, P < 0.03; F = 4.1, P < 0.04; F = 4.0, P < 0.05). These findings were observed in participants with PTSD, but not in a group with equivalently high trauma counts. These findings suggest that PTSD is associated with EEG hyperarousal, higher attentional levels to sad stimuli, and slower processing of happy stimuli. They also partially confirm ERP data reported in combat victims with PTSD suggesting that PTSD may induce neurobiological consequences that transcend type of eliciting trauma as well as ethnic and cultural factors.

ADH1C*2 allele is associated with alcohol dependence and elevated liver enzymes in Trinidad and Tobago

Variants in alcohol dehydrogenase (ADH) genes differ between ethnic groups and have, in some studies, been found to be associated with alcohol dependence and alcoholic liver disease. This study sought to determine whether an association exists between ADH (ADH1C previously ADH3, ADH1B*2 previously ADH2*2) genotypes, alcohol dependence, drinking history, and liver function tests in the two major ethnic groups of Trinidad and Tobago (TT). One hundred and forty-five alcohol-dependent individuals of both East Indian (Indo-TT) and African (Afro-TT) ancestry, and 108 controls matched by age, sex, and education participated in the study. Serum levels of alanine and aspartate aminotransferase (ALT, AST), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), and gamma-glutamyltransferase (GGT) as well as presence of HIV, hepatitis B surface antigen, and anti-hepatitis C virus antibody were determined. There was a significant difference in the distribution of ADH1C allele polymorphisms between the ethnic groups (P<.0001). Forty-three percent of the Indo-TT were found to have one ADH1C*2 allele and 5% were homozygous, whereas, only 23% of Afro-TT had one allele and one was homozygous. Only three individuals had an ADH1B*2 allele (one Indo-TT alcohol dependent, two Indo-TT controls). The ADH1C*2 allele was significantly associated with alcohol dependence overall and within Indo-TT ancestry, however, it was not associated with current or heaviest alcohol consumption levels. Individuals with at least one ADH1C*2 allele also had significantly elevated levels of ALP (P<.02) and GGT (P<.02) as compared to individuals homozygous for ADH1C*. Additionally, GGT levels were also found to be elevated (P<.02) within Indo-TT alcohol dependents with at least one ADH1C*2 allele but not within the Afro-TT alcohol dependents with that allele. A linear regression that included alcohol dependence and levels of alcohol consumption confirmed that levels of serum GGT were significantly associated with the ADH1C*2 genotype. These results suggest that ADH1C polymorphisms are associated with alcohol dependence and alcohol associated elevations of liver enzymes in a population with a low frequency of ADH1B2 alleles.

Genomic screen for loci associated with tobacco usage in Mission Indians

Background

The prevalence of tobacco usage in Native American adults and adolescents is higher than any other racial or ethnic group, yet biological risk and protective factors underlying tobacco use in this ethnic group remain unknown. A genome scan for loci associated with tobacco use phenotypes was performed with data collected from a community sample of Mission Indians residing in Southwest California.

Methods

A structured diagnostic interview was used to define two tobacco use phenotypes: 1) any regular tobacco usage (smoked daily for one month or more) and 2) persistent tobacco usage (smoked at least 10 cigarettes a day for more than one year). Heritability was determined and a linkage analysis was performed, using genotypes for a panel 791 microsatellite polymorphisms, for the two phenotypes using variance component methods implemented in SOLAR.

Results

Analyses of multipoint variance component LOD scores for the two tobacco use phenotypes revealed two scores that exceeded 2.0 for the regular use phenotype: one on chromosomes 6 and one on 8. Four other loci on chromosomes 1,7,13, and 22 were found with LOD scores between 1.0 and 1.5. Two loci of interest were found on chromosomes 1 and 4 for the persistent use phenotype with LOD scores between 1.3–1.5. Bivariate linkage analysis was conducted at the site on chromosome 4 for persistent tobacco use and an alcohol drinking severity phenotype previously identified at this site. The maximum LOD score for the bivariate analysis for the region was 3.4, however, there was insufficient power to exclude coincident linkage.

Conclusion

While not providing evidence for linkage to specific chromosomal regions these results identify regions of interest in the genome in this Mission Indian population, for tobacco usage, some of which were identified in previous genome scans of non-native populations. Additionally, these data lend support for the hypothesis that cigarette smoking, alcohol dependence and other consumptive behaviors may share some common risk and/or protective factors in this Mission Indian population.

Antagonism of neuropeptide YY1 receptors does not inhibit ethanol's effects on cortical EEG and ERPs in Wistar rats

OBJECTIVE

Ethanol and neuropeptide Y (NPY) can have additive neurobehavioral effects. In the present study, the NPY Y1 receptor antagonist BIBP3226 was administered alone or in combination with a moderate dose of ethanol to determine whether it interacted with the neurobehavioral effects of ethanol.

METHOD

Male Wistar rats were implanted with cortical recording electrodes and a lateral ventricular cannula. The effects of 1 nmol BIBP3226, 0.75 g/kg ethanol and the combination (BIBP3226 + EtOH) on neurophysiological activity and locomotion were then assessed.

RESULTS

Ethanol significantly increased 1-2 Hz parietal cortical power and this effect was partially antagonized by BIBP3226. Peak frequencies in the parietal cortical 6-8 Hz and 8-16 Hz bands were also altered by ethanol, but these effects were not reversed by BIBP3226. BIBP3226 or ethanol, when administered alone, did not alter motor activity or cortical event-related potentials (ERPs) but administration of BIBP3226 + EtOH reduced motor activity, reduced parietal cortical N1 ERP amplitude and increased frontal cortical N1 ERP latency.

CONCLUSIONS

In the present study, the most prominent effect of antagonizing central NPY Y1 receptors was a facilitation of the effects of ethanol. In particular, the effects of combined administration of BIBP3226 and ethanol are indicative of enhanced sedation and possibly cognitive impairment.

The effects of social isolation on neuropeptide Y levels, exploratory and anxiety-related behaviors in rats

NPY is one of the most abundantly expressed peptides within the CNS, and has been previously demonstrated to be altered in several animal models of depression, as well as to be differentially regulated by acute and repeated stress. The effect of social deprivation, through isolation housing, on brain NPY concentrations in adult rats has not been previously investigated. The effects of 12 weeks of social isolation, in adult rats, on anxiety-related behaviors and central concentrations of NPY in: hypothalamus, amygdala, caudate-putamen, hippocampus, and frontal cortex were evaluated. Single housed animals spent significantly more time on the open arms of the elevated plus maze and in the central area of the open field as compared to pair housed controls. These data are most likely indicative of enhanced exploration and novelty seeking. Concentrations of neuropeptide Y were increased in the caudate-putamen of the single housed subjects. NPY levels in caudate/putamen and hypothalamus were also significantly correlated with time spent in the open arms of the elevated plus maze. These data suggest that chronic social isolation, in these adult Wistar rats, did not increase anxiety but produced enhanced exploration in tests of anxiety, an effect that was associated with NPY concentrations in the striatum and hypothalamus.

Association between nocturnal vagal tone and sleep depth, sleep quality, and fatigue in alcohol dependence

BACKGROUND

This study examined whether nocturnal vagal tone as indexed by the high-frequency (HF) power component of heart rate variability is related to measures of sleep depth and daytime perceptions of sleep quality, sleepiness, and fatigue in alcohol dependence.

METHODS

Abstinent alcohol-dependent patients (n = 14) and comparison control subjects (n = 14) underwent all-night polysomnography along with assessment of heart rate variability during an awake period before sleep and during sleep. Sleep-quality perceptions, along with self-reported sleepiness and levels of energy and fatigue, were obtained in the morning.

RESULTS

As compared with control subjects, alcohol-dependent persons showed marked decreases in delta sleep along with impairments of sleep quality and daytime energy. In addition, alcoholics showed a decrease of the HF power component of heart rate variability during the awake period before sleep and during nocturnal sleep as compared with control subjects. HF power during the awake period before sleep correlated with electroencephalographic delta sleep and delta power observed during the subsequent sleep period. HF power during the awake period before sleep also correlated with morning reports of sleep quality, sleepiness, and fatigue.

CONCLUSIONS

Alcohol dependence compromises vagal output measured before sleep onset, which correlates with loss of delta sleep and with morning reports of sleep impairments. Testing of interventions that target sympathovagal balance might identify new strategies for partial amelioration of the sleep disturbances and impairments in daytime functioning observed in persons with alcohol dependence.

Adolescent vulnerabilities to chronic alcohol or nicotine exposure: findings from rodent models

This article presents an overview of the proceedings from a symposium entitled "Is adolescence special? Possible age-related vulnerabilities to chronic alcohol or nicotine exposure," organized by Susan Barron and Linda Spear and held at the 2004 Research Society on Alcoholism Meeting in Vancouver, British Columbia. This symposium, co-sponsored by the Fetal Alcohol Syndrome Study Group and the Neurobehavioral Teratology Society, focused on our current knowledge regarding the long-term consequences of ethanol and/or nicotine exposure during adolescence with the emphasis on data from rodent models. The support from these two societies represents the understanding by these research groups that adolescence represents a unique developmental stage for the effects of chronic drug exposure and also marks an age in which many risky behaviors including alcohol consumption and smoking typically begin. The speakers included (1) Aaron White, who presented data on the effects of adolescent ethanol exposure on subsequent motor or cognitive response to an ethanol challenge in adulthood; (2) Richard Bell, who presented data suggesting that genetic differences could play a role in adolescent vulnerability to ethanol; (3) Craig Slawecki, who presented data looking at the effects of chronic exposure to alcohol or nicotine on neurophysiologic and behavioral end points; and (4) Ed Levin, who presented data on acute and long-term consequences of adolescent nicotine exposure. Finally, Linda Spear provided some summary points and recommendations regarding unresolved issues and future directions.

Enhanced prepulse inhibition following adolescent ethanol exposure in Sprague-Dawley rats

OBJECTIVES

Recent studies have demonstrated that ethanol exposure differentially affects adolescents and adults. The current studies were designed to compare the effects of 2-week exposure to ethanol during adolescence or adulthood on the acoustic startle response (ASR) and prepulse inhibition (PPI) METHODS: Male Sprague-Dawley rats were exposed to ethanol vapor 12 hr/d (on from 6 pm to 6 am) for 14 days during adolescence or adulthood. Six days after the cessation of ethanol vapor exposure, the ASR and PPI were assessed.

RESULTS

During ethanol treatment, overall blood alcohol levels averaged 230 to 250 mg/dl in the adolescent and adult treatment groups. Assessment of the ASR revealed that latency to startle was more rapid in adolescents than in adults, but ASR latency was not altered by ethanol exposure. In addition, ASR magnitude was lower in adolescents and was decreased in ethanol-exposed rats on startle trials. Ethanol exposure significantly enhanced PPI, but only after adolescent exposure

CONCLUSIONS

These data further demonstrate a differential sensitivity of adolescents and adults to the effects of ethanol exposure. Specifically, a 2-week period of ethanol exposure during adolescence selectively enhanced PPI, a neurobehavioral index of sensorimotor gating. However, ASR magnitude was decreased by ethanol exposure regardless of age. On the basis of previous studies, the effects of ethanol exposure on PPI data could indicate that adolescent rats exposed to ethanol are more likely to exhibit behavioral inflexibility and that ethanol exposure acts as a more potent physical stressor in adolescent rats.

Increased CRF-like and NPY-like immunoreactivity in adult rats exposed to nicotine during adolescence: relation to anxiety-like and depressive-like behavior

OBJECTIVE

Recently, animal models have been developed that demonstrate that adolescent nicotine exposure produces neurobehavioral changes which persist into adulthood. This study further examined the impact of adolescent nicotine exposure on anxiety-like and depressive-like behavior, as well as on levels of corticotropin-releasing factor (CRF) and neuropeptide Y (NPY) in this model.

METHODS

Male adolescent rats (35-40 days old) were administered nicotine using Nicoderm CQ patches (Smith-Kline Beecham). Behavior in the elevated plus maze (EPM) and forced swim test (FST) was assessed 2-3 weeks after exposure ended. Brain levels of CRF and NPY were then assessed 5-6 weeks after behavioral tests were completed. In addition, blood and brain levels of nicotine resulting from nicotine treatment were examined.

RESULTS

After 5 days of exposure to 5 mg/kg/day nicotine, blood levels of nicotine averaged 66+/-5 ng/ml and brain nicotine levels averaged 52+/-4 ng/g. Rats exposed to nicotine displayed an anxiety-like profile in the EPM (i.e., decreased time spent in the open arms) and an antidepressant-like profile in the FST (i.e., less time spent immobile). Rats exposed to nicotine also had increased hypothalamic and frontal cortical CRF, increased hypothalamic and hippocampal NPY, and a decreased ratio of NPY to CRF in the amygdala.

CONCLUSIONS

This study demonstrates that adolescent nicotine exposure produces lasting increases in anxiety-like behavior and may reduce depressive-like behavior. These behavioral changes also occurred in concert with alterations in CRF and NPY systems. Thus, lasting neurobehavioral changes associated with adolescent nicotine exposure may be related to allostatic changes in stress peptide systems.

Genomic scan for alcohol craving in Mission Indians

Alcohol dependence is a leading cause of morbidity and mortality in Native Americans, yet etiologic factors contributing to the disorder remain obscure. Complex psychiatric disorders may be influenced by a number of genes that may be difficult to detect because each has a small effect on a disorder that is broadly defined within a social context. However, such genes might be detected if they have a major effect on a more narrowly defined phenotype. Underlying alcohol dependence are appetitive drive states or instincts that lead to drug 'craving', contribute to compulsive drug usage, and influence relapse following abstinence. A whole genome scan in Mission Indian families provides evidence for genetic linkage to 'craving for alcohol' on chromosome 5. Identification of genes contributing to alcohol craving may give clues to the etiology of the disorder and also provide targets for the development of new medications to treat alcohol dependence.