Relationship of genetically transmitted alpha EEG traits to anxiety disorders and alcoholism

Vulnerable at rest? A resting-state EEG study and psychosocial factors of young adult offspring of alcohol-dependent parents

BACKGROUND

Offspring of parents with alcohol use disorder (AUD) are more susceptible to developing AUD, with an estimated heritability of around 50%. Vulnerability to AUD in first-degree relatives is influenced by biological factors, such as spontaneous brain activity, and high-risk psychosocial characteristics. However, existing resting-state EEG studies in AUD offspring have shown inconsistent findings regarding theta, alpha, and beta band frequencies. Additionally, research consistently demonstrates an increased risk of internalizing and externalizing disorders, self-regulation difficulties, and interpersonal issues among AUD offspring.

METHODS

This study aimed to investigate the absolute power of theta, alpha, and beta frequencies in young adult offspring with a family history of AUD compared to individuals without family history. The psychosocial profiles of the offspring were also examined in relation to individuals without a family history of AUD. Furthermore, the study sought to explore the potential association between differences in frequency bands and psychosocial variables. Resting-state EEG recordings were obtained from 31 young adult healthy offspring of alcohol-dependent individuals and 43 participants with no family history of AUD (age range: 16-25 years). Participants also completed self-report questionnaires assessing anxiety and depressive symptoms, impulsivity, emotion regulation, and social involvement.

RESULTS

The results revealed no significant differences in spontaneous brain activity between the offspring and participants without a family history of AUD. However, in terms of psychosocial factors, the offspring exhibited significantly lower social involvement than the control group.

CONCLUSIONS

This study does not provide evidence suggesting vulnerability in offspring based on differences in spontaneous brain activity. Moreover, this investigation highlights the importance of interventions aimed at enhancing social connections in offspring. Such interventions can not only reduce the risk of developing AUD, given its strong association with increased feelings of loneliness but also improve the overall well-being of the offspring.

The Computer Simulation for Triggering Anxiety in Panic Disorder Patients Modulates the EEG Alpha Power during an Oddball Task

Aim: The present study investigated the differences between the Panic Disorder (PD) patients groups’ and healthy controls for the EEG alpha dynamics under the frontal cortex and reaction time during the oddball task. Material and Methods: The reaction time during the oddball paradigm concomitant to EEG alpha power was tested in nine PD patients and ten healthy controls before and after a computer simulation presentation. Results: The findings revealed a decrease in EEG alpha power in PD patients concerning the control group (p ≤ 0.0125). However, both groups demonstrated an increased cortical oscillation after the computer simulation, except for the Fp1 electrode during M3 moment in the experimental group. The experimental group has a fast reaction time compared to healthy individuals during the oddball task (p = 0.002). Conclusions: We propose that the decrease in EEG alpha power in the PD patients may indicate an increase in processing related to an anxiogenic stimulus and interference of the anxiety state that compromises the inhibitory control. The reaction time task reveals cognitive symptoms in the experimental group, which may be related to the faster reactivity and high impulsivity to stimuli.

Alterations of Functional Connectivity During the Resting State and Their Associations With Visual Memory in College Students Who Binge Drink

This study investigated the characteristics of neural oscillation and functional connectivity (FC) in college students engaging in binge drinking (BD) using resting-state electroencephalography (EEG). Also, the associations of visual memory, evaluated by the Rey-Osterrieth Complex Figure Test (RCFT), and neural oscillation with FC during the resting state were investigated. The BD (n = 35) and non-BD (n = 35) groups were selected based on scores of the Korean version of the Alcohol use disorders (AUDs) Identification Test and the Alcohol Use Questionnaire. EEG was performed for 6 min while the participants rested with eyes closed. The theta, lower-alpha, and upper alpha powers did not differ between the BD and non-BD groups. Concerning FC, the BD group exhibited stronger theta coherence than that of the non-BD group, and in the lower and upper alpha bands, the BD group showed stronger coherence in some areas but weaker coherence in others compared with the non-BD group. However, these significant results were not observed after Bonferroni correction. The BD group showed significantly lower delayed recall scores on the RCFT than did the non-BD group. A positive correlation between the left prefrontal-parietal-occipital midline connection and performance on the delayed recall of the RCFT was observed in the BD group. The present results could suggest that binge drinkers have alterations in brain FC, which may be related to their visual memory deficits.

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".

Whole genome sequence association and ancestry-informed polygenic profile of EEG alpha in a Native American population

EEG alpha activity is the dominant oscillation in most adult humans, is highly heritable, and has been associated with a number of cognitive functions. Two EEG phenotypes, low- and high-voltage alpha (LVA & HVA), have been demonstrated to have high heritabilities. They have different prevalence depending on a population's ancestral origins. In the present study we assessed the influence of ancestry admixture on EEG alpha power, and conducted a whole genome sequencing association analysis and an ancestry-informed polygenic study on those phenotypes in a Native American (NA) population that has a high prevalence of LVA. Seven common variants, in LD with each other upstream from gene ASIC2, reached genome-wide significance (p = 2 × 10-8 ) having a positive association with alpha voltage. They had lower minor allele frequencies in the NAs than in a global population sample. Overall correlations between lower degrees of NA (higher degree European) ancestry and HVA, and higher degrees of NA and LVA were also found. Additionally a rare-variant gene-based study identified gene TIA1 being negatively associated with LVA. Approximately 3% of SNPs exhibited a 15-fold enrichment that explained nearly half of the total SNP-heritability for EEG alpha. These regions showed the most significant anti-correlations between NA ancestry and alpha voltage, and were enriched for genes and pathways mediating cognitive functions. Our findings suggested that these regions likely harbor causal variants for HVA, and lacking of such variants could explain the high prevalence of LVA in this NA population, possibly illuminating the ancestral origin and genetic basis for EEG alpha.

Endophenotype best practices

This review examines the current state of electrophysiological endophenotype research and recommends best practices that are based on knowledge gleaned from the last decade of molecular genetic research with complex traits. Endophenotype research is being oversold for its potential to help discover psychopathology relevant genes using the types of small samples feasible for electrophysiological research. This is largely because the genetic architecture of endophenotypes appears to be very much like that of behavioral traits and disorders: they are complex, influenced by many variants (e.g., tens of thousands) within many genes, each contributing a very small effect. Out of over 40 electrophysiological endophenotypes covered by our review, only resting heart, a measure that has received scant advocacy as an endophenotype, emerges as an electrophysiological variable with verified associations with molecular genetic variants. To move the field forward, investigations designed to discover novel variants associated with endophenotypes will need extremely large samples best obtained by forming consortia and sharing data obtained from genome wide arrays. In addition, endophenotype research can benefit from successful molecular genetic studies of psychopathology by examining the degree to which these verified psychopathology-relevant variants are also associated with an endophenotype, and by using knowledge about the functional significance of these variants to generate new endophenotypes. Even without molecular genetic associations, endophenotypes still have value in studying the development of disorders in unaffected individuals at high genetic risk, constructing animal models, and gaining insight into neural mechanisms that are relevant to clinical disorder.

Heritability and molecular-genetic basis of resting EEG activity: a genome-wide association study

Several EEG parameters are potential endophenotypes for different psychiatric disorders. The present study consists of a comprehensive behavioral- and molecular-genetic analysis of such parameters in a large community sample (N = 4,026) of adolescent twins and their parents, genotyped for 527,829 single nucleotide polymorphisms (SNPs). Biometric heritability estimates ranged from .49 to .85, with a median of .78. The additive effect of all SNPs (SNP heritability) varied across electrodes. Although individual SNPs were not significantly associated with EEG parameters, several genes were associated with delta power. We also obtained an association between the GABRA2 gene and beta power (p < .014), consistent with findings reported by others, although this did not survive Bonferroni correction. If EEG parameters conform to a largely polygenic model of inheritance, larger sample sizes will be required to detect individual variants reliably.

Low voltage alpha EEG phenotype is associated with reduced amplitudes of alpha event-related oscillations, increased cortical phase synchrony, and a low level of response to alcohol

Low voltage EEG (LVEEG) is a heritable phenotype that differs depending on ancestral heritage, yet its impact on brain networks and cognition remain relatively unexplored. In this study we assessed energy and task related phase locking of event-related oscillation (EROs), behavioral responses, measures of IQ and personality, and expected responses to alcohol in a large sample of individuals with LVEEG compared to those with higher voltage variants. Participants (n=762) were recruited from a Native American community and completed a diagnostic interview, the Quick Test, the Subjective High Assessment Scale Expectation Version (SHAS-E) and the Maudsley Personality Inventory. Clinical and spectral analyzed EEGs were collected for determination of the presence of a LVEEG variant. EROs were generated using a facial expression recognition task. Participants with LVEEG (n=451) were significantly more likely to be older, married and have higher degrees of Native American heritage but did not differ in gender, income or education. Individuals with LVEEG were also found to have decreased energy in their alpha EROs, increased phase locking between stimulus trials, and increased phase-locking between cortical brain areas. No significant differences in the cognitive tests, personality variables or alcohol dependence or anxiety diagnoses were found, however, individuals with LVEEG did report a larger number of drinks ever consumed in a 24-h period and a less intense expected response to alcohol. These data suggest that alpha power in the resting EEG is highly associated with energy and cortical connectivity measures generated by event-related stimuli, as well as potentially increased risk for alcohol use.

Genetic psychophysiology: advances, problems, and future directions

This paper presents an overview of historical advances and the current state of genetic psychophysiology, a rapidly developing interdisciplinary research linking genetics, brain, and human behavior, discusses methodological problems, and outlines future directions of research. The main goals of genetic psychophysiology are to elucidate the neural pathways and mechanisms mediating genetic influences on cognition and emotion, identify intermediate brain-based phenotypes for psychopathology, and provide a functional characterization of genes being discovered by large association studies of behavioral phenotypes. Since the initiation of this neurogenetic approach to human individual differences in the 1970s, numerous twin and family studies have provided strong evidence for heritability of diverse aspects of brain function including resting-state brain oscillations, functional connectivity, and event-related neural activity in a variety of cognitive and emotion processing tasks, as well as peripheral psychophysiological responses. These data indicate large differences in the presence and strength of genetic influences across measures and domains, permitting the selection of heritable characteristics for gene finding studies. More recently, candidate gene association studies began to implicate specific genetic variants in different aspects of neurocognition. However, great caution is needed in pursuing this line of research due to its demonstrated proneness to generate false-positive findings. Recent developments in methods for physiological signal analysis, hemodynamic imaging, and genomic technologies offer new exciting opportunities for the investigation of the interplay between genetic and environmental factors in the development of individual differences in behavior, both normal and abnormal.

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.

Electroencephalographic findings in panic disorder

Some studies have reported the importance of electroencephalography (EEG) as a method for investigating abnormal parameters in psychiatric disorders. Different findings in time and frequency domain analysis with regard to central nervous system arousal during acute panic states have already been obtained. This study aimed to systematically review the EEG findings in panic disorder (PD), discuss them having a currently accepted neuroanatomical hypothesis for this pathology as a basis, and identify limitations in the selected studies. Literature search was conducted in the databases PubMed and ISI Web of Knowledge, using the keywords electroencephalography and panic disorder; 16 articles were selected. Despite the inconsistency of EEG findings in PD, the major conclusions about the absolute power of alpha and beta bands point to a decreased alpha power, while beta power tends to increase. Different asymmetry patterns were found between studies. Coherence studies pointed to a lower degree of inter-hemispheric functional connectivity at the frontal region and intra-hemispheric at the bilateral temporal region. Studies on possible related events showed changes in memory processing in PD patients when exposed to aversive stimuli. It was noticed that most findings reflect the current neurobiological hypothesis of PD, where inhibitory deficits of the prefrontal cortex related to the modulation of amygdala activity, and the subsequent activation of subcortical regions, may be responsible to trigger anxiety responses. We approached some important issues that need to be considered in further researches, especially the use of different methods for analyzing EEG signals.

Alpha absolute power measurement in panic disorder with agoraphobia patients

BACKGROUND

Panic attacks are thought to be a result from a dysfunctional coordination of cortical and brainstem sensory information leading to heightened amygdala activity with subsequent neuroendocrine, autonomic and behavioral activation. Prefrontal areas may be responsible for inhibitory top-down control processes and alpha synchronization seems to reflect this modulation. The objective of this study was to measure frontal absolute alpha-power with qEEG in 24 subjects with panic disorder and agoraphobia (PDA) compared to 21 healthy controls.

METHODS

qEEG data were acquired while participants watched a computer simulation, consisting of moments classified as "high anxiety"(HAM) and "low anxiety" (LAM). qEEG data were also acquired during two rest conditions, before and after the computer simulation display.

RESULTS

We observed a higher absolute alpha-power in controls when compared to the PDA patients while watching the computer simulation. The main finding was an interaction between the moment and group factors on frontal cortex. Our findings suggest that the decreased alpha-power in the frontal cortex for the PDA group may reflect a state of high excitability.

CONCLUSIONS

Our results suggest a possible deficiency in top-down control processes of anxiety reflected by a low absolute alpha-power in the PDA group while watching the computer simulation and they highlight that prefrontal regions and frontal region nearby the temporal area are recruited during the exposure to anxiogenic stimuli.

EEG in adolescent anorexia nervosa: impact of refeeding and weight gain

OBJECTIVE

To examine resting awake EEG in adolescent AN participants before and after refeeding to determine if EEG abnormalities in Anorexia Nervosa (AN) are reversible.

METHOD

In 37 adolescent first admission AN patients and 45 healthy controls, EEG was recorded during short duration "eyes open" and "eyes closed" awake resting conditions. Repeat testing occurred in 28 AN participants after refeeding and subsequent weight gain.

RESULTS

In "eyes open," underweight AN participants exhibit reduced relative alpha power and increased beta power in frontal brain regions. A significant increase in alpha, and decrease in beta and delta power was observed within participants after refeeding. In "eyes closed", underweight AN participants had elevated theta in parietal-occipital regions which remained after refeeding.

DISCUSSION

EEG abnormalities (reduced alpha/increased beta power) in AN normalizes with refeeding, while increased theta power persists in parietal-occipital regions in an eyes closed context.

EEG spectral phenotypes: heritability and association with marijuana and alcohol dependence in an American Indian community study

Native Americans have some of the highest rates of marijuana and alcohol use and abuse, yet neurobiological measures associated with dependence on these substances in this population remain unknown. The present investigation evaluated the heritability of spectral characteristics of the electroencephalogram (EEG) and their correlation with marijuana and alcohol dependence in an American Indian community. Participants (n=626) were evaluated for marijuana (MJ) and alcohol (ALC) dependence, as well as other psychiatric disorders. EEGs were collected from six cortical sites and spectral power determined in five frequency bands (delta 1.0-4.0 Hz, theta 4.0-7.5 Hz, alpha 7.5-12.0 Hz, low beta 12.0-20.0 Hz and high beta/gamma 20-50 Hz). The estimated heritability (h(2)) of the EEG phenotypes was calculated using SOLAR, and ranged from 0.16 to 0.67. Stepwise linear regression was used to detect correlations between MJ and ALC dependence and the spectral characteristics of the EEG using a model that took into account: age, gender, Native American Heritage (NAH) and a lifetime diagnosis of antisocial personality and/or conduct disorder (ASPD/CD). Increases in spectral power in the delta frequency range, were significantly correlated with gender (p<0.001) and marijuana dependence (p<0.003). Gender, age, NAH and ASPD/CD were all significantly (p<0.001) correlated with theta, alpha and beta band power, whereas alcohol dependence (p<0.01), gender (p<0.001), and ASPD/CD (p<0.001) were all correlated with high beta/gamma band power. These data suggest that the traits of EEG delta and high beta/gamma activity are correlated with MJ dependence and alcohol dependence, respectively, in this community sample of Native Americans.

P3 components of the event-related potential and marijuana dependence in Southwest California Indians

Native Americans have some of the highest rates of marijuana use and abuse, yet neurobiological measures associated with addiction to marijuana in this population remain unknown. The present investigation evaluated associations between the P350 and P450 components of the event-related potential (ERP) elicited by affective stimuli, and marijuana dependence in a population of Southwest California (SWC) Indian adults. Three hundred and seventeen participants with a mean age of 30 years who were free of major Axis I and psychiatric diagnoses and antisocial personality disorder were categorized as: (1) no marijuana use disorders or other drug dependence diagnoses; (2) marijuana dependence and no other drug dependence diagnoses; and (3) marijuana dependence and other drug dependence diagnoses. ERPs were collected using a facial discrimination task that generated a late positive component with two peaks at approximately P350 and P450 milliseconds. Multivariate analyses of variance was used to detect associations between the two component peaks and the three participant groups taking into consideration age, gender and the presence of a lifetime diagnosis of alcohol dependence. Increases in the latency of both the P350 and P450 component peaks were found to be associated with the diagnosis of marijuana dependence and marijuana dependence co-morbid with other drug dependence. Women appeared to be more impacted than men are. A diagnosis of marijuana dependence was not associated with any changes in late component amplitudes. Taken together these studies suggest that marijuana dependence may be associated with delays in the evaluation and identification of emotional stimuli in SWC Indians.

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.

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.

Modulation of feeding behaviour by blocking purinergic receptors in the rat nucleus accumbens: a combined microdialysis, electroencephalographic and behavioural study

The nonspecific P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS), the nonspecific P1 receptor antagonist 8-(p-sulphophenyl)-theophylline (8-SPT) and the combination of both were applied by retrograde microdialysis into the nucleus accumbens (NAc) before and during feeding of 18-h food-deprived rats. In addition to the registration of behavioural parameters, such as the amount and duration of food intake, the feeding-induced changes in dopamine (DA) concentration and the concomitant changes of neuronal activity in the NAc and the ventral tegmental area (VTA) were simultaneously determined. The perfusion with PPADS (20 microm) diminished the amount of food intake and the duration of feeding. Furthermore, the P2 receptor antagonist blocked the feeding-induced DA release and prevented the feeding-elicited changes of the electroencephalography (EEG) power distribution which was characterised by an increase in the power of the 8.0-13.0-Hz frequency band in the NAc and the VTA. The effects of PPADS could be completely prevented by the concomitantly perfused adenosine receptor antagonist 8-SPT (100 microm). When given alone, 8-SPT increased the amount of food ingested, the duration of feeding and the EEG power of the higher frequency range, particularly between 19.0 and 30.0 Hz, in both the NAc and the VTA. The feeding-elicited DA release was supplemented to the enhanced DA level caused by the perfusion with 8-SPT in an additive manner. The P2 and P1 receptor antagonists interact antagonistically in the modulation of feeding behaviour and the feeding-induced changes of EEG activity suggesting that both endogenous extracellular ATP and adenosine are involved in the regulation of the feeding-associated mesolimbic neuronal activity in a functionally antagonistic manner.

EEG phenotype in alcoholism: increased coherence in the depressive subtype

OBJECTIVE

Electroencephalography (EEG) power and coherence changes may be trait markers for alcoholism providing clues to brain mechanisms of vulnerability. However, it is unclear whether alpha power and coherence differences reflect reversible toxic or withdrawal effects of alcohol.

METHOD

The EEGs of 10 non-abstinent and 16 long-term abstinent alcoholics (7.7 +/- 5.8 years) and 25 controls were analyzed. Levels of anxiety and depression were assessed by questionnaire.

RESULTS

No statistically significant EEG power differences were observed between groups, although the numerical difference between alcoholics and controls was similar to that previously reported. Bilateral, intrahemispheric, posterior coherences were significantly increased in the alpha and beta frequency bands both in long-term abstinent and non-abstinent alcohol-dependent subjects - particularly when depressiveness was included as a covariate.

CONCLUSION

These results suggest that increased EEG-coherence (cortical synchronization) may serve as endophenotype for alcoholism in conjunction with increased depressiveness and point to a possible involvement of GABAergic and/or glutamatergic neurotransmission.

EEG low-voltage alpha and alpha power in African American young adults: relation to family history of alcoholism

BACKGROUND

Several studies support an association between having a low-voltage EEG and alcohol dependence; however, it is not clear whether this measure represents a risk marker or is a result of years of heavy drinking. The present study's aims were to investigate the prevalence of low-voltage alpha EEG variants in African American young adults who have not yet developed alcohol dependence and to test for associations between low-voltage alpha (LVA) EEG, alpha power, and a family history of alcohol dependence.

METHODS

Clinical ratings and spectral characteristics of the EEG, collected using bipolar recordings, were investigated in 81 African American young adult men and women (18-25 years old) who had no personal history of alcohol dependence. Information on psychiatric diagnoses, personality features, personal drinking and drug use history, and family history (FH) of alcoholism was obtained.

RESULTS

Thirty-two percent (n = 26) of the participants had an LVA EEG variant, and an additional 22% (n = 18) had borderline LVA. The presence of an LVA variant was not associated with drinking status, a family history of alcoholism, or a personal history of anxiety disorders but was associated with significantly higher extroversion scores. Participants who had an FH of alcoholism had significantly higher spectral power in the slow alpha frequencies (7.5-9 Hz). FH was not associated with any significant differences in any other EEG frequency band.

CONCLUSIONS

These findings suggest that considerable ethic variation may exist in the prevalence of LVA EEG variants. In addition, like findings in other populations of non-African descent, having an FH of alcohol dependence may be associated with significantly higher voltage in the alpha frequency ranges.

Genetic origins of anxiety in women: a role for a functional catechol-O-methyltransferase polymorphism

OBJECTIVE

Women are more prone to anxiety than men. The catechol- -methyltransferase functional polymorphism, Val158Met, is likely to be implicated in anxiety vulnerability. We hypothesized that, particularly in women, the low-activity Met158 allele would be associated with higher anxiety scores and a biological trait, low-voltage alpha resting electroencephalogram (EEG), previously associated with alcoholism and anxiety disorders.

METHODS

DNA was obtained from two independent groups of participants ascertained as community samples: 149 predominantly Caucasian individuals (92 women, 57 men), and 252 Plains American Indians (149 women, 103 men). Dimensional measures of anxiety (Tridimensional Personality Questionnaire harm avoidance subscales HA1 and HA2) were obtained and DSM-III-R lifetime psychiatric diagnoses were determined. EEGs were recorded and EEG phenotypes assigned.

RESULT

In both populations, women showed significant associations between catechol- -methyltransferase genotype and elevated harm avoidance scores, and the Met158/Met158 genotype was most strongly associated: predominantly Caucasian participants: HA1, P=0.03, HA2, P =0.03; and Plains American Indians: HA2, P=0.01. This was also the case with low-voltage alpha resting EEG: predominantly Caucasian participants: P=0.01, odds ratio=5.0 (95% confidence interval, 1.3-18.7); Plains American Indians: P=0.03, odds ratio=3.7 (95% confidence interval, 1.1-12.7).

CONCLUSIONS

The results of the present study suggest that an inherited difference in catecholamine metabolism is important in the pathogenesis of anxiety in women.

Genetics of alcoholism using intermediate phenotypes

This article represents the proceedings of a symposium at the 2002 meeting of the Research Society on Alcoholism in San Francisco, CA. It was organized by Mary-Anne Enoch and David Goldman and chaired by David Goldman. The presentations were (1) Two functional polymorphisms and their intermediate phenotypes in complex behaviors: COMT/executive cognition and anxiety and HTT/anxiety, by David Goldman; (2) Role of the EEG in determining genetic risk for alcoholism and anxiety disorders, by Mary-Anne Enoch; (3) The response to alcohol as an intermediate phenotype for alcoholism, by Marc A. Schuckit; and (4) Pharmacogenomic approaches to alcoholism treatment: toward a hypothesis, by Bankole A. Johnson.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Genetics of alcoholism and substance abuse

Twin studies have demonstrated that addictive disorders are genetically and environmentally influenced. Our knowledge of behavioral differences predisposing to addiction is advancing rapidly, particularly in alcoholism but also in the other addictions, through studies on animals and humans. Recently, linkage analyses in humans and rodents have pointed to genomic regions harboring genes which influence addiction or drug-associated behaviors. There is increasing evidence that the addictions have common as well as distinct neurobiological pathways. These advances in the understanding of the genetics of addictive disorders should facilitate the development of specific pharmacotherapies and the more accurate targeting of therapies using molecular diagnostic approaches.

Electroencephalographic responses to alcohol challenge in Native American Mission Indians

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Electrophysiology in neuropsychiatric research: a network perspective

A growing number of anatomic and physiologic studies have shown that parallel sensory and motor information processing occurs in multiple cortical areas. These findings challenge the traditional model of brain processing, which states that the brain is a collection of physically discrete processing modules that pass information to each other by neuronal impulses in a stepwise manner. New concepts based on neural network models suggest that the brain is a dynamically shifting collection of interpenetrating, distributed, and transient neural networks. Neither of these models is necessarily mutually exclusive, but each gives different perspectives on the brain that might be complementary. Each model has its own research methodology, with functional magnetic resonance imaging supporting notions of modular processing, and electrophysiology (eg, electroencephalography) emphasizing the network model. These two technologies might be combined fruitfully in the near future to provide us with a better understanding of the brain. However, this common enterprise can succeed only when the inherent limitations and advantages of both models and technologies are known. After a general introduction about electrophysiology as a research tool and its relation to the network model, several practical examples are given on the generation of pathophysiologic models and disease classification, intermediate phenotyping for genetic investigations, and pharmacodynamic modeling. Finally, proposals are made about how to integrate electrophysiology and neuroimaging methods.

Results of a genome-wide genetic screen for panic disorder

Panic disorder is characterized by spontaneous and recurrent panic attacks, often accompanied by agoraphobia. The results of family, twin, and segregation studies suggest a genetic role in the etiology of the illness. We have genotyped up to 23 families that have a high density of panic disorder with 540 microsatellite DNA markers in a first-pass genomic screen. The thirteen best families (ELOD > 6.0 under the dominant genetic model) have been genotyped with an ordered set of markers encompassing all the autosomes, at an average marker density of 11 cM. Over 110,000 genotypes have been generated on the whole set of families, and the data have been analyzed under both a dominant and a recessive model, and with the program SIBPAIR. No lod scores exceed 2.0 for either parametric model. Two markers give lod scores over 1.0 under the dominant model (chromosomes 1p and 20p), and four do under the recessive model (7p, 17p, 20q, and X/Y). One of these (20p) may be particularly promising. Analysis with SIBPAIR yielded P values equivalent to a lod score of 1.0 or greater (i.e., P < .016, one-sided, uncorrected for multiple tests) for 11 marker loci (2, 7p, 8p, 8q, 9p, 11q, 12q, 16p, 20p and 20q).

Quantitative EEG (QEEG) predicts relapse in patients with chronic alcoholism and points to a frontally pronounced cerebral disturbance

The capability of predicting relapse in chronic alcoholism using quantitative EEG was investigated. For this purpose, 78 in-patients with alcoholism underwent EEG recordings (eyes closed) 7 days after the beginning of detoxification. Additionally, other clinical evaluations were carried out. After discharge from hospital, patients were regularly re-evaluated for the duration of 3 months in order to determine whether they relapsed or abstained from alcohol during this time. For classification of the two diagnostic subgroups (relapsers vs. abstainers), multivariate discriminant analysis as well as artificial neural network technology has been applied. Correct classification of patients' EEGs was achieved in 83-85% and thus outperformed classification with clinical variables considerably. Furthermore, artificial neural networks (ANN) improved classification results when compared with discriminant analysis. It was found that, in comparison to abstainers, relapsers had EEGs that were more desynchronized over frontal areas, which was interpreted as a functional disturbance of the prefrontal cortex.

Neuronal nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4) and panic disorder: an association study

Anxiety disorders have been reported to be associated with low-voltage EEG (LVEEG). Some cases with LVEEG (approximately 1/3) have been linked to chromosome 20q13.2q13.3. In the same chromosomal region, the gene for the neuronal nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4) has been located. We therefore tested the hypothesis that polymorphisms in the CHRNA4 gene show an allelic association with panic disorder. We examined the allele frequencies of three different CHRNA4 polymorphisms in patients with panic disorder and in healthy controls. No significant differences in the allele frequencies of these three polymorphisms were noted. This study does not support an association between panic disorder and the CHRNA4 gene.