Event-related brain potentials are different in individuals at high and low risk for developing alcoholism

Event-related Oscillations to Emotional Faces are Related to a History of Internalizing Disorders

Event-related oscillations (EROs) may represent sensitive biomarkers or endophenotypes for disorders that underlie risk behaviors such as suicidal thoughts and actions. In this study, young adults of American Indian (AI) (n = 821) and Mexican American (MA) (n = 721) ancestry (age 18-30 yrs) were clinically assessed for internalizing and externalizing disorders, and an internalizing scale was generated by extracting core diagnostic items from 6 lifetime DSM5-compatible diagnoses (social phobia, panic disorder, agoraphobia, obsessive compulsive disorder, post-traumatic stress disorder, major depressive episode) and symptoms of suicidality. EROs were generated to sad, happy and neutral faces, and energy and phase locking of delta ERO oscillations were assessed in frontal areas. An increase in delta ERO energy was found in the frontal lead (FZ) following presentation of the sad facial expressions in those with a history of 10 or more internalizing symptoms compared to those with no symptoms. Increases in delta ERO energy in FZ were also associated with a diagnosis of major depressive disorder (MDD), but not with anxiety disorders or antisocial personality disorder/conduct disorders (ASP). Major depression was also associated with increases in cross-cortical phase-locking (FZ-PZ). A decrease in the percentage of correctly identified neutral faces also was seen among those with 10 or more internalizing symptoms compared to those without internalizing symptoms, and in those with anxiety disorders, but not in those with ASP or MDD as compared to their controls. These findings suggest ERO measures may represent important potential biomarkers of depressive disorders as well as risk indicators for suicidal behaviors.

Signal in the noise: Altered brain activation among adolescent alcohol users detected via the analysis of intra-individual variability1

RATIONALE

Unlike its average level, the variability in brain activation over time or trials can capture subtle and brief disruptions likely to occur among participants with low-to-moderate levels of substance use or misuse.

OBJECTIVE

The present study used this intra-individual variability measurement approach to detect neural processing differences associated with light-to-moderate use of alcohol among 14-19-year-old adolescents.

METHOD

A total of 128 participants reporting any level of alcohol use during the previous 6 months and 87 participants reporting no use during this period completed intake questionnaires and interviews as well as an assessment of P300 electroencephalographic responses to novel stimuli recorded during two separate tasks.

RESULTS

In addition to differing in recent alcohol use, the groups differed in nicotine and cannabis use, risk-taking behavior and conduct disorder symptoms, and P300 amplitude inter-trial variability (ITV) across both tasks. Across all participants, P300 ITV was positively correlated with a family history of depression but not with a family history of alcohol dependence. There were no group differences in P300 amplitude averaged across trials.

CONCLUSIONS

Recent reports attributing brain volume or brain function differences to an effect of light-to-moderate alcohol use should be viewed with great caution. In the present analysis of brain function differences among substance-using adolescents, the group differences were small, complicated by many factors coinciding with or preceding alcohol use, and not reflected in a stable central tendency.

Alcohol and Neural Dynamics: A Meta-analysis of Acute Alcohol Effects on Event-Related Brain Potentials

BACKGROUND

An understanding of alcohol's acute neural effects could augment our knowledge of mechanisms underlying alcohol-related cognitive/motor impairment and inform interventions for addiction. Focusing on studies employing event-related brain potential methods, which offer a direct measurement of neural activity in functionally well-characterized brain networks, we present the first meta-analysis to explore acute effects of alcohol on the human brain.

METHODS

Databases were searched for randomized laboratory alcohol-administration trials assessing brain activity using event-related potentials. Hedges' g coefficients were pooled using 3-level random-effects meta-regression.

RESULTS

Sixty independent randomized controlled trials met inclusion (total N = 2149). Alcohol's effects varied significantly across neural systems, with alcohol leading to reductions in event-related potential components linked with attention (P3b), g = -0.40, 95% CI (-0.50, -0.29), automatic auditory processing (mismatch negativity), g = -0.44, 95% CI (-0.66, -0.22), and performance monitoring (error-related negativity), g = -0.56, 95% CI (-0.79, -0.33). These effects were moderated by alcohol dose, emerging as significant at doses as low as 0.026% blood alcohol concentration and increasing to moderate/large at 0.12%. In contrast, irrespective of dose, relatively small or nonsignificant alcohol effects emerged in other processing domains, including those linked to executive control (N2b responses) and stimulus classification (N2c responses).

CONCLUSIONS

Contrary to traditional conceptualizations of alcohol as a "dirty drug" with broad central nervous system depressant effects, results instead support accounts positing targeted alcohol effects in specific processing domains. By identifying alcohol effects on brain systems involved in performance monitoring and attention, results move toward the identification of mechanisms underlying alcohol-related impairment as well as factors reinforcing addiction.

Delta Event-Related Oscillations Are Related to a History of Extreme Binge Drinking in Adolescence and Lifetime Suicide Risk

Alcohol exposure typically begins in adolescence, and heavy binge drinking is associated with health risk behaviors. Event-related oscillations (EROs) may represent sensitive biomarkers or endophenotypes for early alcohol exposure as well as other risk behaviors such as suicidal thoughts and actions. In this study, young adults (age 18-30 years) of American Indian (AI) (n = 479) and Mexican American (MA) (n = 705) ancestry were clinically assessed, and EROs were generated to happy, sad and neutral faces. Extreme adolescent binge drinking (10+ drinks) was common (20%) in this population of AI/MA and associated with a significantly increased risk of a lifetime history of suicidal acts (SA, suicide attempts, deaths) but not suicidal thoughts (ST, ideation, plans). ST were reported among MA participants, whereas SA were more common among AI young adults. Extreme adolescent binge drinking was also associated with errors in detection of sad and neutral faces, increases in delta ERO energy, and decreases in phase locking (PL), particularly in parietal areas. A lifetime history of ST was associated with increases in delta ERO energy and PL, whereas SA were associated with decreases in both. These studies suggest that ERO measures may represent important potential biomarkers of adolescent extreme binge drinking and risk for suicidal behaviors.

CR-19-0950: Event-related responses to alcohol-related stimuli in Mexican-American young adults: Relation to age, gender, comorbidity and "dark side" symptoms

BACKGROUND

Electrophysiological variables may represent sensitive biomarkers of vulnerability to or endophenotypes for alcohol use disorders (AUD).

METHODS

Young adults (age 18-30 yrs, n = 580) of Mexican American heritage were assessed with the Semi-Structured Assessment for the Genetics of Alcoholism and event-related oscillations (EROs) generated in response to a task that used pictures of objects, food, and alcohol-related and non-alcohol-related drinks as stimuli.

RESULTS

Decreases in energy in the alpha and beta frequencies and higher phase synchrony within cortical brain areas were seen in response to the alcohol-related as compared to the non-alcohol-related stimuli. Differences in ERO energy and synchrony responses to alcohol-related stimuli were also found as a function of age, sex, AUD status and comorbidity. Age-related decreases in energy and increases in synchrony were found. Females had significantly higher energy and lower synchrony values than males. Participants with AUD had higher synchrony values specifically in the beta frequencies, whereas those with a lifetime diagnosis of conduct disorder and/or antisocial personality disorder had lower alpha power and synchrony, and those with any affective disorder had lower ERO energy in the beta frequencies. Those with substance-associated affective "dark-side" symptoms had slower reaction times to the task, lower energy in the beta frequencies, lower local synchrony in the theta frequencies, and higher long-range synchrony in the delta and beta frequencies.

CONCLUSIONS

These findings suggest that EROs recorded to alcohol-related stimuli may be biomarkers of comorbid risk factors, symptoms and disorders associated with AUD that also can differentiate those with "dark-side symptoms".

Neurobiological phenotypes associated with a family history of alcoholism

BACKGROUND

Individuals with a family history of alcoholism are at much greater risk for developing an alcohol use disorder (AUD) than youth or adults without such history. A large body of research suggests that there are premorbid differences in brain structure and function in family history positive (FHP) individuals relative to their family history negative (FHN) peers.

METHODS

This review summarizes the existing literature on neurobiological phenotypes present in FHP youth and adults by describing findings across neurophysiological and neuroimaging studies.

RESULTS

Neuroimaging studies have shown FHP individuals differ from their FHN peers in amygdalar, hippocampal, basal ganglia, and cerebellar volume. Both increased and decreased white matter integrity has been reported in FHP individuals compared with FHN controls. Functional magnetic resonance imaging studies have found altered inhibitory control and working memory-related brain response in FHP youth and adults, suggesting neural markers of executive functioning may be related to increased vulnerability for developing AUDs in this population. Additionally, brain activity differences in regions involved in bottom-up reward and emotional processing, such as the nucleus accumbens and amygdala, have been shown in FHP individuals relative to their FHN peers.

CONCLUSIONS

It is critical to understand premorbid neural characteristics that could be associated with cognitive, reward-related, or emotional risk factors that increase risk for AUDs in FHP individuals. This information may lead to the development of neurobiologically informed prevention and intervention studies focused on reducing the incidence of AUDs in high-risk youth and adults.

Reward processing deficits and impulsivity in high-risk offspring of alcoholics: A study of event-related potentials during a monetary gambling task

BACKGROUND

Individuals at high risk to develop alcoholism often manifest neurocognitive deficits as well as increased impulsivity. The goal of the present study is to elucidate reward processing deficits, externalizing disorders, and impulsivity as elicited by electrophysiological, clinical and behavioral measures in subjects at high risk for alcoholism from families densely affected by alcoholism in the context of brain maturation across age groups and gender.

METHODS

Event-related potentials (ERPs) and current source density (CSD) during a monetary gambling task (MGT) were measured in 12-25 year old offspring (N=1864) of families in the Collaborative Study on the Genetics of Alcoholism (COGA) Prospective study; the high risk (HR, N=1569) subjects were from families densely affected with alcoholism and the low risk (LR, N=295) subjects were from community families. Externalizing disorders and impulsivity scores were also compared between LR and HR groups.

RESULTS

HR offspring from older (16-25 years) male and younger (12-15 years) female subgroups showed lower P3 amplitude than LR subjects. The amplitude decrement was most prominent in HR males during the loss condition. Overall, P3 amplitude increase at anterior sites and decrease at posterior areas were seen in older compared to younger subjects, suggesting frontalization during brain maturation. The HR subgroups also exhibited hypofrontality manifested as weaker CSD activity during both loss and gain conditions at frontal regions. Further, the HR subjects had higher impulsivity scores and increased prevalence of externalizing disorders. P3 amplitudes during the gain condition were negatively correlated with impulsivity scores.

CONCLUSIONS

Older male and younger female HR offspring, compared to their LR counterparts, manifested reward processing deficits as indexed by lower P3 amplitude and weaker CSD activity, along with higher prevalence of externalizing disorders and higher impulsivity scores.

SIGNIFICANCE

Reward related P3 is a valuable measure reflecting neurocognitive dysfunction in subjects at risk for alcoholism, as well as to characterize reward processing and brain maturation across gender and age group.

Understanding alcohol use disorders with neuroelectrophysiology

Neurocognitive deficits associated with impairments in various brain regions and neural circuitries, particularly involving frontal lobes, have been associated with chronic alcoholism, as well as with a predisposition to develop alcohol use and related disorders (AUDs). AUD is a multifactorial disorder caused by complex interactions between behavioral, genetic, and environmental liabilities. Neuroelectrophysiologic techniques are instrumental in understanding brain and behavior relationships and have also proved very useful in evaluating the genetic diathesis of alcoholism. This chapter describes findings from neuroelectrophysiologic measures (electroencephalogram, event-related potentials, and event-related oscillations) related to acute and chronic effects of alcohol on the brain and those that reflect underlying deficits related to a predisposition to develop AUDs and related disorders. The utility of these measures as effective endophenotypes to identify and understand genes associated with brain electrophysiology, cognitive networks, and AUDs has also been discussed.

Evidence for a Heritable Brain Basis to Deviance-Promoting Deficits in Self-Control

PURPOSE

Classic criminological theories emphasize the role of impaired self-control in behavioral deviancy. Reduced amplitude of the P300 brain response is reliably observed in individuals with antisocial and substance-related problems, suggesting it may serve as a neurophysiological indicator of deficiencies in self-control that confer liability to deviancy.

METHODS

The current study evaluated the role of self-control capacity - operationalized by scores on a scale measure of trait disinhibition - in mediating the relationship between P300 brain response and behavioral deviancy in a sample of adult twins (N=419) assessed for symptoms of antisocial/addictive disorders and P300 brain response.

RESULTS

As predicted, greater disorder symptoms and higher trait disinhibition scores each predicted smaller P300 amplitude, and trait disinhibition mediated observed relations between antisocial/addictive disorders and P300 response. Further, twin modeling analyses revealed that trait disinhibition scores and disorder symptoms reflected a common genetic liability, and this genetic liability largely accounted for the observed phenotypic relationship between antisocial-addictive problems and P300 brain response.

CONCLUSIONS

These results provide further evidence that heritable weaknesses in self-control capacity confer liability to antisocial/addictive outcomes and that P300 brain response indexes this dispositional liability.

The P300 event-related brain potential as a neurobiological endophenotype for substance use disorders: a meta-analytic investigation

Endophenotypes are intermediate phenotypes on the putative causal pathway from genotype to phenotype and can aid in discovering the genetic etiology of a disorder. There are currently very few suitable endophenotypes available for substance use disorders (SUD). The amplitude of the P300 event-related brain potential is a possible candidate. The present study determined whether the P300 amplitude fulfils two fundamental criteria for an endophenotype: (1) an association with the disorder (disease marker), and (2) presence in unaffected biological relatives of those who have the disorder (vulnerability marker). For this purpose, two separate meta-analyses were performed. Meta-analysis 1 investigated the P300 amplitude in relation to SUD in 39 studies and Meta-analysis 2 investigated P300 amplitude in relation to a family history (FH+) of SUD in 35 studies. The findings indicate that a reduced P300 amplitude is significantly associated with SUD (d=0.51) and, though to a lesser extent, with a FH+ of SUD (d=0.28). As a disease maker, the association between reduced P300 amplitude and SUD is significantly larger for participants that were exclusively recruited from treatment facilities (d=0.67) than by other methods (i.e., community samples and family studies; d=0.45 and 0.32, respectively), and larger for abstinent SUD patients (d=0.71) than for current substance users (d=0.37). Furthermore, in contrast to FH+ males, a P300 amplitude reduction seems not to be present in FH+ females (d=-0.07). Taken together, these results suggest that P300 amplitude reduction can be both a useful disease and vulnerability marker and is a promising neurobiological endophenotype for SUD, though only in males. Implications and future directions are discussed.

D2 dopamine receptor (DRD2) gene, P300, and personality in children of alcoholics

The D2 dopamine receptor (DRD2) gene has been associated with alcoholism and other drug use disorders. Reduced P300 amplitude has been noted in individuals with psychiatric disorders. Personality variables are also associated with reduced P300 amplitude. The current study was conducted to determine whether variants of the DRD2 would show differential relationships among P300 amplitude and personality traits. The study consisted of 101 adolescent children of alcoholics; 39 carried the A1(+) genotype (A1A1, A1A2) and 62 carried the A1(-) genotype (A2A2). The A1(+) genotype group had higher IQ and Self-Directedness scores than the A1(-) genotype group. As predicted, the negative relationship between Novelty Seeking and Harm Avoidance was present in A1(-) but not A1(+) participants. Additionally, in A1(+) but not in A1(-) participants, there was a negative relationship between Novelty Seeking and Self-Directedness and a positive relationship between P300 amplitude and Cooperativeness. The results suggest that in adolescent children of alcoholics, dopaminergic genetic determinants are critical modifiers of the relationship between neurocognitive and personality endophenotypes proposed as vulnerability markers for substance use disorders.

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.

Genetic contribution to the P3 in young and middle-aged adults

Previous studies in young and adolescent twins suggested substantial genetic contributions to the amplitude and latency of the P3 evoked by targets in an oddball paradigm. Here we examined whether these findings can be generalized to adult samples. A total of 651 twins and siblings from 292 families participated in a visual oddball task. In half of the subjects the age centered around 26 (young adult cohort), in the other half the age centered around 49 (middle-aged adult cohort). P3 peak amplitude and latency were scored for 3 midline leads Pz, Cz, and Fz. No cohort differences in heritability were found. P3 amplitude (approximately 50%) and latency (approximately 45%) were moderately heritable for the 3 leads. A single genetic factor influenced latency at all electrodes, suggesting a single P3 timing mechanism. Specific genetic factors influenced amplitude at each lead, suggesting local modulation of the P3 once triggered. Genetic analysis of the full event-related potential waveform showed that P3 heritability barely changes from about 100 ms before to 100 ms after the peak. Age differences are restricted to differences in means and variances, but the proportion of genetic variance as part of the total variance of midline P3 amplitude and latency does not change from young to middle-aged adulthood.

Lower P300 amplitude in eight-year-old offspring of alcoholic fathers with a delinquent history

The aim of the present study was to investigate the P300 amplitude as a possible vulnerability marker in children of alcoholic (COA) fathers with and without paternal delinquency. Event-related potentials (ERPs) of 122 children aged 8 years (63 boys, 59 girls) were compared depending on father's alcoholism subtype: 30 COAs without paternal delinquency, 10 COAs with paternal delinquency, and 82 children of non-alcoholic and non-delinquent fathers. ERPs were recorded from Fz, Cz, and Pz, using an auditory oddball paradigm. Sinus tones of 60 dB HL were presented binaurally at 1,000 Hz (standard stimulus) and 2,000 Hz (target stimulus), at a relative frequency ratio of 80:20. Two trial blocks of 250 stimuli each were collected. Results indicated that only COAs with paternal delinquency displayed significant differences from the control group, characterized by reduced P300 amplitude at frontal site and in the second trial block. Thus, the combination of fathers' alcoholism and delinquency was more likely to relate to attenuated P300 amplitude in the offspring than paternal alcoholism alone. Our results suggest that both alcoholic and delinquent family history appear to play a role in P300 amplitude reduction in the offspring.

P300 amplitude as an indicator of externalizing in adolescent males

Reduced P300 amplitude is reliably found in individuals with a personal or family history of alcohol problems. However, alcoholism is part of a broader externalizing spectrum that includes other substance use and antisocial disorders. We hypothesized that reduced P300 is an indicator of the common factor that underlies disorders within this spectrum. Community males (N=969) were assessed at age 17 in a visual oddball task. Externalizing was defined as the common factor underlying symptoms of alcohol dependence, drug dependence, nicotine dependence, conduct disorder, and adult antisocial behavior. A robust association was found between reduced P300 amplitude and the externalizing factor, and this relation accounted for links between specific externalizing disorders and P300. Our findings indicate that reduced P300 amplitude is an indicator of the broad neurobiological vulnerability that underlies disorders within the externalizing spectrum.

The utility of neurophysiological markers in the study of alcoholism

OBJECTIVE

This review attempts to differentiate neuroelectric measures (electroencephalogram (EEG), event-related potentials (ERPs) and event-related oscillations (EROs)) related to acute and chronic effects of alcohol on the brain from those that reflect underlying deficits related to the predisposition to develop alcoholism and related disorders. The utility of these neuroelectric measures as endophenotypes for psychiatric genetics is evaluated.

METHODS

This article reviews the main findings of EEG and ERP abnormalities in alcoholics, offspring of alcoholics at high risk to develop alcoholism and the electrophysiological effects of alcohol on high risk compared to low-risk offspring. It highlights findings using EROs, a fast developing tool in examining brain function and cognition. It also reviews evidence of genetic findings related to these electrophysiological measures and their relationship to clinical diagnosis.

RESULTS

Many of these abnormal neuroelectric measures are under genetic control, may precede the development of alcoholism, and may be markers of a predisposition toward the development of a spectrum of disinhibitory conditions including alcoholism. Genetic loci underlying some neuroelectic measures that involve neurotransmitter systems of the brain have been identified.

CONCLUSIONS

Quantitative neuroelectric measures (EEG, ERPs, EROs) provide valuable endophenotypes in the study of genetic risk to develop alcoholism and related disorders.

SIGNIFICANCE

Genetic studies of neuroelectric endophenotypes offer a powerful strategy for identifying susceptibility genes for developing psychiatric disorders, and provide novel insights into etiological factors.

Direct and mediated associations between P300 amplitude in childhood and substance use disorders outcome in young adulthood

BACKGROUND

Attenuated amplitude of the P300 wave has been frequently documented in youths at high risk for substance use disorders (SUDs). This investigation had two aims: 1) determine whether P300 amplitude in late childhood is a predictor of SUD outcome by age 19; and 2) evaluate whether neurobehavior disinhibition (ND) mediates this association.

METHODS

Boys (aged 10-12) were recruited through proband biological fathers with either a lifetime DSM-III-R diagnosis of SUD (N = 67) or no adult psychiatric disorder (N = 94). P300 amplitude was recorded during an auditory oddball task. Neurobehavior disinhibition was evaluated using tests of executive cognitive function, behavior under control, and emotion dysregulation. The relationship is assessed using multiple and logistic regressions.

RESULTS

Substance use disorder by age 19 was significantly predicted by P300 amplitude (odds ratio [OR] = .958; 95% confidence interval [CI] = .918-.999; Wald chi (2) = 3.992; df = 1; p = .045) and ND score (OR = 1.060; 95% CI = 1.023-1.098; Wald chi (2) = 10.267; df = 1; p = .0014) measured at age 10 to 12. P300 amplitude also significantly correlated with ND severity (beta = -.217; t = -2.412; df = 6,160; p = .017). Low P300 amplitudes were observed in children who succumbed to SUD by age 19.

CONCLUSIONS

These results indicate that ND mediates the association between attenuated P300 amplitude in childhood and SUD at age 19; however, P300 amplitude is not a specific childhood marker of SUD.

Alcoholism risk, tobacco smoking, and P300 event-related potential

OBJECTIVE

The P300 event-related potential (ERP) is sometimes larger for individuals at low- compared to high-risk for alcoholism. These effects are inconsistent, and how P300 is affected by tobacco smoking in the context of alcoholism risk is unknown. The present study used P300 to examine the inter-relationship between alcoholism heritability and smoking status.

METHODS

P300 was elicited with a visual discrimination task from young adults at low- and high-risk for alcoholism. Half of the subjects in each risk category reported that they did not smoke cigarettes, and the other half reported that they smoked regularly, with equal numbers of male and female subjects assessed. ERPs were recorded, and subjects were instructed to respond only to an infrequently presented target stimulus that occurred in a series of standard and distracter stimuli.

RESULTS

P300 amplitude from the target stimuli was larger for the low-risk compared to high-risk subjects overall. However, smoking status demonstrated even stronger effects, with non-smokers producing consistently larger component amplitudes than smokers and accounting for more variance than alcoholism risk. These group factors also significantly affected P300 scalp topography. No reliable alcoholism risk or smoking group effects were obtained for the ERPs from the other stimuli.

CONCLUSIONS

The findings suggest that P300 measures of alcoholism risk in young adults are moderated by smoking status. Theoretical implications are discussed.

Alcoholism risk and the P300 event-related brain potential: Modality, task, and gender effects

The P300 event related potential (ERP) was elicited from young adults at low- (LR) and high-risk (HR) for alcoholism (n = 24/risk group), with equal numbers of male and female subjects employed. The effects of stimulus modality, task difficulty, and gender were assessed with analogous auditory and visual paradigms (tone location/head rotation and tone matching/shape matching). Although task performance was generally comparable across risk groups, LR subjects produced smaller P300 amplitudes than HR subjects for the visual matching tasks. No consistent risk group P300 latency effects were obtained. Gender, task difficulty, and scalp topography differentially modulated the risk group outcomes across paradigms. These findings suggest that P300 amplitude reflects risk-for-alcoholism in male and female young adults, but the specific task conditions and electrode location affect the strength of risk group differences.

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.

The inebri-actometer: a device for measuring the locomotor activity of Drosophila exposed to ethanol vapor

Drosophila melanogaster can be used as a model organism for probing the genetic basis for alcohol sensitivity. In this paper, we describe a new device, the inebri-actometer, which measures the locomotor activity of up to 128 individual flies simultaneously. The device consists of 128 pairs of emitter/detector photodiodes connected in series through a computer interlink. A single fly is placed in each of the 128 chambers and humidified air or air containing variable amounts of ethanol vapor is pumped through the chambers. When a fly blocks the infrared signal transmitted by an emitter photodiode, the computer records one movement for that fly. We present preliminary results showing the effect of ethanol on the activity of wild-type Oregon R Drosophila. Five preliminary runs with 95% ethanol vapor revealed that this concentration induces an approximately 3- to 4-fold increase in locomotor activity which peaks at about 5 min after the addition of ethanol vapor. This is followed by a gradual decrease in activity leading to a nearly total cessation of movement after 30 min. Statistically significant dose-related activity increases were obtained for ethanol concentrations of 8, 19, 50, and 100% of maximum, assessed in two replications at each dose. Unlike the complete suppression of locomotion seen in the last 10 min of the session at maximum ethanol exposure, the initial stimulation effect at the 19% concentration was maintained across the 30-min session.

Event-related potentials elicited by a visual continuous performance task in children of alcoholics

Event-related potentials (ERPs) were recorded from a group of young children of alcoholics (HR; n = 17, 7 females) with a high-density family-history of alcoholism and from a control group (CN; n = 19, 10 females), ages 7-15 years old, during a visual continuous performance task. The P3 peak amplitude and the mean amplitude at five latency windows (300-800 ms) were measured at frontal (F3-Fz-F4), central (C3-Cz-C4) and parietal (P3-Pz-P4) electrodes. Data were analyzed using a mixed-model risk-group by stimulus-type (matching vs. nonmatching) by Electrode ANCOVA, with age as a covariate, for each of the scalp regions. The risk-group by stimulus-type interactions were significant at the parietal region for the P3 peak amplitude and for the 300-400 ms mean amplitude, although there were no risk-group main differences. The HR group manifested smaller differences between the amplitude of the matching and nonmatching condition than the CN group. These results suggest a deficient electrophysiological differentiation between relevant and irrelevant information and are discussed in relation to previous reports and to the characteristics of the sample.

P300 decrements in teenagers with conduct problems: implications for substance abuse risk and brain development

BACKGROUND

The purpose of this study was to evaluate the effects of conduct disorder problems, family history, gender, and age on P300 electroencephalographic potentials in teenagers.

METHODS

The 257 subjects, aged 15 to 20 years, were assigned to one of twelve groups defined by the crossing of three between-subjects factors: 1) gender; 2) ranking below vs above the median number of conduct disorder problems for their gender; and 3) no family history of alcohol or drug dependence vs familial alcohol dependence vs familial heroin or cocaine dependence.

RESULTS

P300 amplitude was smaller among subjects reporting a greater number of conduct problems prior to age 15 vs those reporting fewer problems of this type. No family history effects were detected. Another set of analyses examined the effects of age on conduct problem-related decrements in P300. Smaller P300 amplitudes within the posterior scalp region were associated with a greater number of conduct problems among subjects younger than 16.5 years. Among subjects greater than this median age, the effects of these behaviors were only apparent over the frontal scalp.

CONCLUSIONS

It is concluded that P300 decrements previously attributed to familial alcohol/substance dependence might be the result of a coincident increase in the prevalence of conduct disorder problems. The analysis of age interactions suggests that P300 amplitude decrements observed at posterior scalp sites among subjects with more conduct problems disappear at approximately 16 to 17 years of age. After that age, decrements in frontal brain function may begin to emerge in the subset of conduct problem subjects who are at risk for developing adult antisocial personality disorder.

Visual P3a in male subjects at high risk for alcoholism

BACKGROUND

Voltage of the P300 component of event-related potentials (ERPs) has been proposed as a phenotypic marker of risk for alcoholism. P3a elicited by intrusive events is important in the context of deficits in inhibition found during psychophysiological and behavioral evaluations in children of alcoholics.

METHODS

ERPs were recorded from a group of adult children of alcoholics (n = 26) and controls (n = 23) with a three-stimulus visual oddball paradigm. The task required a difficult perceptual discrimination between a frequent (.80) vertical line and an infrequent (.10) 2 degrees tilted line (target). An easily discriminable nontarget infrequent horizontal line also occurred (.10). Subjects were required to press a button to the target. P3a was compared using mixed-model ANCOVAs at 31 sites organized in 5 scalp regions. Current source density (CSD) maps were also analyzed.

RESULTS

High-risk (HR) subjects manifested reduced P3a amplitudes compared to controls at frontal, central, parietal, and temporal electrodes. CSD analyses supported these findings with group differences found for all the scalp regions.

CONCLUSIONS

The results are discussed in relation to previous HR studies. P3a reductions may be related to deficits in neuronal inhibition during stimulus processing. These results suggest that P3a amplitude may be important as a marker for vulnerability to alcoholism.

P300, alcoholism heritability, and stimulus modality

The P300 event-related brain potential (ERP) was elicited with auditory and visual stimuli from members of 13 families who were at high risk (HR) for alcoholism (father diagnosed as alcoholic) and 13 families at low risk (LR) for alcoholism. Each family consisted of a father, mother, and at least two biological children. The intrafamily member correlations (father vs. child, mother vs. child, child vs. child) for P300 amplitude were obtained for 15 electrode sites. P300 amplitude from auditory stimuli was not correlated among HR family members, but was positively correlated among LR family members. P300 amplitude from visual stimuli was positively correlated among both HR and LR family members. When taken in conjunction with previous findings, the present results suggest that P300 amplitude from auditory stimuli may not be as reliable as ERPs from visual stimuli for the assessment of alcoholism heritability.

Visual and auditory event-related potentials in young children of alcoholics from high- and low-density families

Event-related potentials (ERPs), particularly the P3 wave, have been proposed as biological markers of genetic risk for alcoholism. The present study assesses the ERPs from 102 boys and girls (7 to 15 years old) divided into three groups: two groups of sons and daughters of alcoholic fathers, with and without other first- or second-degree relatives affected, and a control group of children of nonalcoholics. Both visual and auditory discrimination tasks with three stimuli (standard, target, and infrequent nontarget) were used. P3 amplitudes did not reach significant reduction for the high-risk males and were complex for females. There were significant differences among females in P3 visual latency elicited by targets; delays in this variable were associated with multigenerational familial alcoholism. Results are discussed in light of the tasks used for eliciting the ERPs and the characteristics of the selected sample.

Effects of alcohol consumption on lateralized aggression in Anolis carolinensis

Previous work has suggested that the lizard Anolis carolinensis, like many other reptiles, has a functionally split brain. Specifically, the left eye of this species projects primarily to the right hemisphere (and vice versa), there is no corpus callosum, and the physical placement of the eyes restricts their field(s) of vision to one region of hemispace. The current experiment used this preparation to examine the effect of alcohol administration and withdrawal on lateralized brain functioning during territorial aggression. Thirteen adult males were divided into control (CON) or alcohol (ETOH) groups. Baseline territorial aggression was assessed, following which ETOH subjects were then given twice daily solutions of 19% alcohol. After 19 days of ETOH consumption, territorial aggression was again assessed. Eye use during aggressive encounters was measured either following short periods (24 h) of alcohol withdrawal, or 90 m following alcohol consumption. Control subjects were found to have a predominance of left eye/right hemisphere-mediated aggressive responses, as has previously been reported. Alcohol withdrawn subjects were found to have a suppression of left eye/right hemisphere-mediated aggression. This reached statistical significance on several measures of aggression, including the number of dewlaps and headbob (P < 0.001) and the total number of aggressive responses (P = 0.001). Consumption of ETOH reversed this pattern and reinstated the normal pattern of left eye/right hemisphere dominance during aggression. Conversely, right eye/left hemisphere mediation of aggression was found to be increased, or not affected, during alcohol withdrawal, and to show no differences from CON following ETOH administration. Extrapolating from other recent findings in this species, these results suggest that the stress caused by ETOH withdrawal on the CNS may differentially effect the right hemisphere of the brain while having little effect on the left.

Alcohol, auditory functioning and deafness

This paper reviews studies of alcohol and auditory impairment and the treatment of deaf people with alcohol problems and concludes that: (a) alcohol affects auditory functioning, (b) prenatal exposure to alcohol is a risk factor for hearing impairment in FAS children,

Alcoholism: the role of different motivational systems

Individuals use and misuse alcohol (and other drugs) because of the pharmacologically mediated effects these substances have on the operation of 4 psychobiological systems, mediating response to motivationally relevant unconditioned and conditioned stimuli. These 4 systems have unique neuroanatomical structure, biochemical modes of operation, association with affect, behavior and cognition, and responsiveness to drugs of abuse. Individual variation in the operation of these systems determines individual susceptibility to initiation and maintenance of drug use and abuse. Sources of such variation differ, in a vitally important fashion, in various specific populations of individuals at heightened risk for drug abuse. Nonalcoholic sons of male alcoholics, with multigenerational family histories of male alcoholism, appear to be at heightened risk for the development of alcohol abuse because alcohol eliminates their heightened response to threat, and because they are hypersensitive to ethanol's psychomotor stimulant effects. Anxiety-sensitive individuals also appear attracted to alcohol for its anxiolytic properties. Many other important sources of idiosyncratic variability exist. Detailed analysis of such sources may lead to the development of more effective prevention and treatment programs.

Alpha-theta brainwave neurofeedback training: an effective treatment for male and female alcoholics with depressive symptoms

This was an experimental study of 14 alcoholic outpatients using the Peniston and Kulkosky (1989, 1991) brainwave treatment protocol for alcohol abuse. After temperature biofeedback pretraining, experimental subjects completed 20 40-minute sessions of alpha-theta brainwave neurofeedback training (BWNT). Experimentally treated alcoholics with depressive syndrome showed sharp reductions in self-assessed depression (Beck's Depression Inventory). On the Millon Clinical Multiaxial Inventory-I, the experimental subjects showed significant decreases on the BR scores: schizoid, avoidant, dependent, histrionic, passive-aggression, schizotypal, borderline, anxiety, somatoform, hypomanic, dysthmic, alcohol abuse, drug abuse, psychotic thinking, and psychotic depression. Twenty-one-month follow-up data indicated sustained prevention of relapse in alcoholics who completed BWNT.

EEG dimension in sons of alcoholics

Recent advances in the field of nonlinear dynamics have provided new conceptual models, as well as novel analytical techniques applicable to studies in alcohol research. One measurement technique, which has been developed in an attempt to characterize nonlinear systems in physics and biology, is the estimation of attractor dimension. This dimension may be seen as a measure of the information required to describe the current behavior of a system. We have applied these techniques to the analysis of EEG collected from 17 men with alcoholic fathers and 19 men with no alcoholic relatives. The men with alcoholic fathers were found to have a lower EEG attractor dimension than their matched controls. This suggests that the EEG of young men with alcoholic fathers may be "more organized" or "less complex" than men with no alcoholic relatives. Although more studies will be needed to explore this hypothesis, these studies suggest that further development of nonlinear approaches to the analysis of brain systems are likely to generate new clinical measures, as well as new ways of viewing brain electrical function and alcoholism.

Event-related potentials in alcoholic men, their high-risk male relatives, and low-risk male controls

A total of 217 adult male subjects were evaluated utilizing event-related potentials (ERPs) elicited with two different auditory tasks (Counting and Choice Reaction). Ninety-eight alcoholics from high-density, multigenerational families were evaluated along with 39 first-degree nonalcoholic relatives from the same high-density families. Eighty controls, selected for low density of alcoholism in their extended families, were also studied. Using both conventional and topographic analyses, no significant differences in the amplitude of the P300 component could be found with either of the auditory tasks. No significant differences in amplitude of N250 were seen. The latency of N250 increased with increasing conditional probabilities (0.33, 0.67, and 1.00), a trend that was amplified in the Counting task as compared with the Choice Reaction task. This prolongation in a task not requiring a reaction response (button press) tended to increase the latency more for alcoholics than controls or high-risk nonalcoholic subjects. Age, lifetime, and recent drinking were treated as covariates in all analyses. The absence of P300 amplitude differences between adult high- and low-risk subjects is discussed in the context of the much more reliable differences seen between high- and low-risk children from the same high- and low-density families, when evaluated with the same auditory tasks.

Acute effects of alcohol on P300 in Asians with different ALDH2 genotypes

Asian men were genotyped for alleles of aldehyde dehydrogenase (ALDH2) and tested on two separate occasions following oral administration of placebo and 0.75 ml/kg alcohol. Sixty minutes after beverage ingestion, event-related potentials were elicited using an auditory oddball paradigm. Repeated measures ANOVA revealed that alcohol produced significant increases in P300 latency and significant decreases in P300 amplitude compared with placebo. Subjects with ALDH2*1/2*2 genotype (n = 14) demonstrated some significantly greater P300 effects after alcohol than subjects with ALDH2*1/2*1 genotype (n = 15), despite equivalent blood alcohol concentrations. These data suggest that neurocognitive functioning may be more impaired following alcohol in subjects with an ALDH2*2 allele. These findings further suggest that a genetically controlled factor (deficiency in ALDH enzyme activity) might contribute to a decreased likelihood of alcohol intake and protection from alcoholism, because of an enhanced sensitivity to alcohol.

Genetic Influences Affecting Alcohol Use Among Asians

Aldehyde dehydrogenase (ALDH) is one of the two enzymes primarily involved in alcohol metabolism. Several variants exist of the gene that produces ALDH. One of these gene variants, which generates a nonfunctional enzyme, is present in Asians but not in Caucasians and African-Americans. People with two copies of the defective gene respond to alcohol consumption with intense flushing and other unpleasant reactions, such as nausea. Consequently, these people consume very little alcohol and are at a much lower risk for alcoholism than people with functional ALDH genes. People with one copy of the defective gene also flush after ingesting alcohol and are at relatively lower risk for alcoholism than people with fully functional genes. In addition, these people have more intense, but not necessarily less pleasant, reactions to alcohol as assessed by both physiological and psychological measures. People with the defective gene variant also respond to alcohol consumption with characteristic changes in brain activity.

Frontal P300 decrements in antisocial personality disorder

Event-related potentials (ERPs) were recorded from 83, 21- to 25-year-old nonalcoholic men varying in alcoholism vulnerability due to the presence/absence of an alcoholic family history or a personal history of antisocial personality disorder. ERPs were elicited by a visual oddball task in which the target was presented more frequently than the nontarget, in order to elicit impulsive or perseverative responding. Analyses of N200 and P300 revealed no group differences in the nontarget response. However, analyses of the target response revealed a significantly smaller P300 in the antisocial personality (ASP)+ group compared with the ASP- groups. The P300 decrement was limited to frontal electrode sites and is interpreted as indicating the presence of subtle anterior brain dysfunction among ASP+ subjects.

Effects of an acute dose of palm alcohol on normal brain functioning: an auditory, event-related-potential study

The effects of an acute and high dose of palm alcohol (900 mg/kg bodyweight) on brain functioning were investigated in 10 healthy, non-alcoholic men. Each was given randomly-interspaced, paired, frequent standard (80%) and rare target auditory stimuli and asked to detect and signal the target tone by pressing a push button. These brain function tests were carried out before (control) and 1 and 4 h after the subjects began drinking the alcohol. During each experimental session, late, event-related-potential (ERP) components were recorded at the central midline scalp location (Cz). At both times after alcoholization, contingent negative variations and late auditory ERP were lower than those recorded during the control session. Maximal amplitude reduction for N1 and P3 waves was seen 240 min after ingesting alcohol. Reaction times were not significantly longer than those recorded pre-alcoholization but performances were lower at both times post-alcoholization. The results are consistent with the ERP changes reported in subjects under acute ethanol intoxication but they are more pronounced and probably reflect a momentary disruption of central processes rather than sensory impairment at the peripheral level.

Prolonged P300 latency in children with the D2 dopamine receptor A1 allele

Previous studies have indicated the presence of a hereditary component in the generation of the P300, or P3, a late positive component of the event-related potential. Moreover, the dopaminergic system has been implicated in the P3. In the present study, 98 healthy Caucasian boys, mean age of 12.5 years and of above-average intelligence, were studied. The sample was composed of 32 sons of active alcoholic (SAA) fathers, 36 sons of recovering alcoholic (SRA) fathers, and 30 sons of social drinker (SSD) fathers, with none of them having yet begun to consume alcohol or other drugs. TaqI A D2 dopamine receptor alleles (A1 and A2) were determined. A significant difference in the frequency of the A1 allele was found among these three groups of boys, with the SAA group having the highest A1 allele frequency (.313), followed by the SRA (.139) and the SSD (.133) groups. The relationship of the A1 and A2 alleles to P3 amplitude and latency was also determined. The results showed no significant difference in P3 amplitude between boys with the A1 and A2 allele. However, P3 latency was significantly longer in the total sample of boys with the A1 allele compared with those carrying the A2 allele. These findings suggest that polymorphism of the D2 dopamine receptor gene is an important determinant of P3 latency.

Covert effects of alcohol revealed by event-related potentials

Contradictory evidence as to the effects of alcohol on early information processing stages has been obtained from behavioral and psychophysiological investigations. In the present study, choice reaction times, error rates, and event-related potentials (ERPs) were recorded in a task in which variations in stimulus discriminability and of the (task irrelevant) correspondence between stimulus location and response location were orthogonally combined. Both discriminability and stimulus-response correspondence affected reaction time and electrophysiological chronometric measures as expected. However, no behavioral effects of alcohol were observed, possibly because of strategic adjustments. Psychophysiological chronometric measures indicated that alcohol leaves the initial flow of perceptual evidence to motor stages unimpaired, whereas it appears to increase the duration of stimulus evaluation. Interestingly, a number of alcohol effects appeared in the ERP amplitudes. Decrements in early ERP components indicate alcohol-induced impairments of involuntary visual attention and/or the automatic stimulus location-dependent activation of response channels. In contrast, a strong enhancement of a late slow-wave component under alcohol may reflect the investment of processing resources in order to maintain normal performance levels.

Risk markers for alcoholism in high-density families

This review summarizes the efforts of our research program to identify markers for alcoholism risk, which broadly fall within the domain of temperament and those which may be described as attentional or information-processing capacities. Analyses of three-generation pedigrees that include minor children at higher risk of becoming alcoholic indicate that event-related potential characteristics differ between high- and low-risk children. Newer results concerning cardiac responsivity both in minor children and adult high-risk individuals are presented. These results suggest a relationship between personality or temperament on the one hand, and cardiac responsivity on the other. Additional neurobehavioral markers are addressed including static ataxia. Recent segregation analyses and linkage to particular DNA segments are also included.

Information processing, neuropsychological function, and the inherited predisposition to alcoholism

Sons of male alcoholics are at particularly heightened risk for the development of alcoholism. This heightened risk frequently appears in association with increased incidence of conduct disorder or hyperactivity, with deficits in abstract thinking and poor school performance, with abnormalities in cued psychophysiological response, and with increased sensitivity to the putatively stress-response-dampening effects of alcohol intoxication. This risk and its associated features are discussed within the context of a neuropsychological theory, predicted on the notions (1) that deficits in cognitive functions theoretically dependent upon the intact functioning of the prefrontal cortex could underlie manifestation of the idiosyncracies commonly attributed to sons of male alcoholics, and (2) that acute alcohol intoxication could relieve the subjective discomfort associated with the consequences of such deficits.

Cognitive impairments in abstinent alcoholics

Impaired cognitive functioning in alcoholics is widespread during the first months of detoxification. Between half and two thirds of abstinent alcoholics exhibit cognitive impairments during this period, with residual deficits persisting for years after detoxification in some patients. The most severe deficits have been observed in visuospatial abilities, perceptual-motor integration, abstract reasoning, and new learning. The most significant predictors of cognitive dysfunction in persons recovering from alcoholism are the time elapsed since the last drink and the person's age. Surprisingly, the pattern and duration of a patient's alcohol abuse are relatively weak determinants of neuropsychological impairment during abstinence. Research investigating the hypothesis that cognitive impairments may be related to alcoholic persons resuming drinking has yielded mixed results, but a higher level of neuropsychological functioning is associated with increased rates of completing treatment programs and with greater success in the work environment after discharge from treatment. The possibility of cognitive limitations should be taken into account in planning treatment programs for alcoholism.

The genetic epidemiology of alcoholism

Despite the variability in sampling and methodology, the majority of the family, twin and adoption studies suggest that alcoholism is familial, a significant proportion of which can be attributed to genetic factors. However, the specific components of alcoholism that may be inherited have yet to be identified. To date, there are no biological trait markers for which there is evidence for specificity for alcoholism. The three major levels of enquiry regarding possible mechanisms for the transmission of alcoholism and the involvement of genes and gene products in its development are factors related to exposure, metabolism, or pharmacological effects of ethanol. Exposure to ethanol is an obvious precondition for the development of tolerance and/or dependence. Therefore, identification of factors which enhance (or decrease) exposure are important goals of studies of the pathogenesis of alcoholism. It is likely that demographic, cultural and environmental factors (i.e. sex, age, religious affiliation, social group influences, income, availability of alcohol, etc.) play a crucial role in mediating exposure to alcohol. The key to alcoholism is likely to reside in the effects of alcohol on the brain. In contrast to nicotine, the opioids, and catecholamines, no specific receptor for ethanol has been found. Thus, one major focus of current research on possible central nervous system (CNS) mechanisms for the effect of alcohol includes assessment of the role of alcohol in the stimulation of brain reward or reinforcement systems. Alternately, alcohol may produce dependence by normalizing abnormal baseline states such as irritability, hyperexcitability, dysphoria, impulsiveness, or stress/tension level. The results of animal studies have yielded information on the central effects of alcohol including sensitivity of neuronal membranes, proteins, and ion channels to alcohol, and factors related to the binding and release of neurotransmitters and neuromodulators including dopamine, norepinephrine, gamma aminobutyric acid, pro-opiomelanocortin, glutamate receptors and the endorphin system (Institute of Medicine, 1987). In addition to possible genetic explanations for the strong degree of familial aggregation of alcoholism, alternative explanations need to be further evaluated. These include: modelling of parental behaviour; possible changes in the susceptibility of the foetus to alcohol as a result of in utero maternal ingestion of alcohol; results of negligent rearing manifested in dietary deficiency, exposure to toxic substances, or brain trauma, which so often characterize the homes of alcoholic parents; or damage to paternal germ cells from alcohol.

Event-related potential characteristics in children of alcoholics from high density families

Sons and daughters (ages 8-14) of male alcoholics without psychiatric problems were compared with sons and daughters of controls employing two auditory paradigms to elicit event-related potentials (ERPs). All of the children of alcoholics were from high density families (each father had an average of 3.7 first and second-degree relatives meeting criteria for alcoholism). Subjects were presented with high- and low-pitched tones with global probabilities of 25% and 75% of total trials, respectively. Subjects were instructed to count silently the number of "high" tones (rare targets) but not the number of "low" tones (non-targets) and report the number heard. In a second auditory paradigm (Choice Reaction task), subjects were asked to perform a different motor response to each high or low tone. The amplitude of the P300 component was influenced significantly by event probability (decreased amplitudes were associated with increased event probability). A greater rate of decrease in P300 amplitude occurred among the high risk children as event probability increased. In addition, greater negativity beginning at approximately N250 was observed for both tasks at the frontal electrode for the high risk children as compared to controls. This enhanced frontal negativity is interpreted in terms of a maturational lag hypothesis.