Substance use patterns in 9-10 year olds: Baseline findings from the adolescent brain cognitive development (ABCD) study.

BACKGROUND: The Adolescent Brain Cognitive Development ™ Study (ABCD Study®) is an open-science, multi-site, prospective, longitudinal study following over 11,800 9- and 10-year-old youth into early adulthood. The ABCD Study aims to prospectively examine the impact of substance use (SU) on neurocognitive and health outcomes. Although SU initiation typically occurs during teen years, relatively little is known about patterns of SU in children younger than 12. METHODS: This study aims to report the detailed ABCD Study® SU patterns at baseline (n = 11,875) in order to inform the greater scientific community about cohort's early SU. Along with a detailed description of SU, we ran mixed effects regression models to examine the association between early caffeine and alcohol sipping with demographic factors, externalizing symptoms and parental history of alcohol and substance use disorders (AUD/SUD). PRIMARY RESULTS: At baseline, the majority of youth had used caffeine (67.6 %) and 22.5 % reported sipping alcohol (22.5 %). There was little to no reported use of other drug categories (0.2 % full alcohol drink, 0.7 % used nicotine, <0.1 % used any other drug of abuse). Analyses revealed that total caffeine use and early alcohol sipping were associated with demographic variables (p's<.05), externalizing symptoms (caffeine p = 0002; sipping p = .0003), and parental history of AUD (sipping p = .03). CONCLUSIONS: ABCD Study participants aged 9-10 years old reported caffeine use and alcohol sipping experimentation, but very rare other SU. Variables linked with early childhood alcohol sipping and caffeine use should be examined as contributing factors in future longitudinal analyses examining escalating trajectories of SU in the ABCD Study cohort.

Baseline brain function in the preadolescents of the ABCD Study.

The Adolescent Brain Cognitive Development (ABCD) Study® is a 10-year longitudinal study of children recruited at ages 9 and 10. A battery of neuroimaging tasks are administered biennially to track neurodevelopment and identify individual differences in brain function. This study reports activation patterns from functional MRI (fMRI) tasks completed at baseline, which were designed to measure cognitive impulse control with a stop signal task (SST; N = 5,547), reward anticipation and receipt with a monetary incentive delay (MID) task (N = 6,657) and working memory and emotion reactivity with an emotional N-back (EN-back) task (N = 6,009). Further, we report the spatial reproducibility of activation patterns by assessing between-group vertex/voxelwise correlations of blood oxygen level-dependent (BOLD) activation. Analyses reveal robust brain activations that are consistent with the published literature, vary across fMRI tasks/contrasts and slightly correlate with individual behavioral performance on the tasks. These results establish the preadolescent brain function baseline, guide interpretation of cross-sectional analyses and will enable the investigation of longitudinal changes during adolescent development.

Genome-wide association study identifies a novel locus for cannabis dependence.

Despite moderate heritability, only one study has identified genome-wide significant loci for cannabis-related phenotypes. We conducted meta-analyses of genome-wide association study data on 2080 cannabis-dependent cases and 6435 cannabis-exposed controls of European descent. A cluster of correlated single-nucleotide polymorphisms (SNPs) in a novel region on chromosome 10 was genome-wide significant (lowest P=1.3E-8). Among the SNPs, rs1409568 showed enrichment for H3K4me1 and H3K427ac marks, suggesting its role as an enhancer in addiction-relevant brain regions, such as the dorsolateral prefrontal cortex and the angular and cingulate gyri. This SNP is also predicted to modify binding scores for several transcription factors. We found modest evidence for replication for rs1409568 in an independent cohort of African American (896 cases and 1591 controls; P=0.03) but not European American (EA; 781 cases and 1905 controls) participants. The combined meta-analysis (3757 cases and 9931 controls) indicated trend-level significance for rs1409568 (P=2.85E-7). No genome-wide significant loci emerged for cannabis dependence criterion count (n=8050). There was also evidence that the minor allele of rs1409568 was associated with a 2.1% increase in right hippocampal volume in an independent sample of 430 EA college students (fwe-P=0.008). The identification and characterization of genome-wide significant loci for cannabis dependence is among the first steps toward understanding the biological contributions to the etiology of this psychiatric disorder, which appears to be rising in some developed nations.

Visual P300 and the self-directedness scale of the Temperament and Character Inventory.

Reduced amplitude of the P300 event-related brain potential has been associated with several psychopathological conditions and is thought to represent brain dysfunction in such conditions. Predisposition to personality disorders and psychopathology in general is also associated with low scores on the self-directedness (SD) scale of the Temperament and Character Inventory. The present preliminary study investigated the relationship between amplitudes of P300 elicited by rare target stimuli in a visual oddball task and SD scores in 58 healthy participants. P300 was found to be significantly reduced in subjects with low SD, as supported by correlational analysis and by comparison of groups formed on the basis of SD scores. This finding may be relevant to prior findings indicating reduced P300 amplitudes in a variety of psychopathological conditions and suggests that a common vulnerability factor, reflected in the low SD personality scores, may contribute to the P300 reduction in psychiatric populations.

Genetic correlation between the P300 event-related brain potential and the EEG power spectrum.

Previous studies have demonstrated moderate heritability of the P300 component of event-related brain potentials (ERPs) and high heritability of background electroencephalogram (EEG) power spectrum. However, it is unclear whether EEG and ERPs are influenced by common or independent genetic factors. This study examined phenotypic and genetic correlations between EEG spectral power and P300 amplitude using data from 206 Dutch twin pairs, age 16 years. Multivariate genetic models (Cholesky decomposition) were fitted to the observed twin covariances using Mx software. In males, genetic correlations between P300 and EEG power measures were high (0.54-0.74); 30% of the total P300 variance could be explained by genetic factors influencing EEG delta power and 26% by P300-specific genetic factors (total heritability 56%). In females, 45% of P300 variance could be attributed to familial influences that were shared with the EEG. However, it was not possible to distinguish between the genetic versus shared environmental factors, consistent with previous analysis of P300 in this sample (van Beijsterveldt et al., 1998). The results suggest that a substantial proportion of genetic influences on P300 amplitude can be explained by strong heritability of slow EEG rhythms contributing to P300.

The P300 brain potential is reduced in smokers.

RATIONALE: Tobacco smoking is the most prevalent type of substance abuse, yet its biobehavioral etiology is little understood. Identification of differences between smokers and non-smokers on basic characteristics of neurocognitive functioning may help to elucidate the mechanisms of tobacco dependence. OBJECTIVES: This study assessed the relationship between smoking status and the P300 component of event-related potential (ERP) while controlling for potential confounders such as alcoholism, drug abuse, and psychopathology. METHODS: The ERP responses elicited by a visual oddball task were measured at the mid-parietal site in 905 current smokers, 463 ex-smokers, and 979 never smokers. RESULTS: P300 amplitude was significantly lower in current cigarette smokers compared to never-smokers. Ex-smokers did not differ significantly from never-smokers. P300 reduction was also associated with alcoholism, drug dependence, and family density of alcoholism. However, after controlling for smoking, only family density of alcoholism remained a significant predictor of P300 amplitude. CONCLUSIONS: The results indicate a significant effect of smoking status on P300 amplitude which is additive to family history of alcoholism and suggest that either (1) long-term tobacco smoking may produce a reversible change in brain function, or (2) reduced P300 may be a marker of risk for nicotine dependence.

Complexity of electrocortical dynamics in children: developmental aspects.

Dimensional complexity (DCx) is an EEG measure derived from nonlinear systems theory that can be indicative of the global dynamical complexity of electrocortical activity. This study examined developmental changes in DCx, as well as the effects of cognitive tasks, gender, and brain topography, and compared DCx with traditional spectral power measures. EEG was recorded in three groups of children at mean age of 7.5 (n = 37), 13.8 (n = 42), and 16.4 (n = 56) years at rest and during the performance of verbal and spatial cognitive tasks. DCx measured both at rest and during tasks increased with age. Specific effects of brain topography, condition, and gender became stronger with age, suggesting an increase in structural and functional differentiation of the cortex. Hemispheric asymmetry of DCx recorded during tasks also increased with age, with the task-induced DCx reduction being stronger in the left hemisphere. Gender differences in DCx suggested faster cerebral maturation in girls over late adolescence. Relationships between DCx and spectral power varied as a function of tasks and scalp locations, suggesting that these EEG measures can reflect different aspects of cortical functioning.

Brain event-related potentials, dopamine D2 receptor gene polymorphism, and smoking.

This paper explores the relationship between the DRD2 gene polymorphism, P300, and smoking. Both smoking and DRD2 have significant reducing effects on P300 amplitude. The effect of smoking is apparent only in the presence of the A1 allele of the DRD2 locus. Transmission/disequilibrium analyses show a negative association between the A2 allele and smoking initiation, suggesting a protective effect of this allele. When the sample is stratified into lower- and higher-P300 categories, we find a significant association between A1 and current smoking only in individuals with lower P300. Both concordance for smoking and DRD2 genotype are significant predictors of sib-pair similarity in P300 amplitude. These results suggest a synergistic effect of different neurogenetic risk factors contributing to nicotine dependence. Neurocognitive variation (P300) may moderate the association between DRD2 and smoking. Alternatively, DRD2 genotype may modulate the long-term impact of nicotine on neurocognitive functioning.

Spatiotemporal organization of brain dynamics and intelligence: an EEG study in adolescents.

This study investigated relationships between global dynamics of brain electric activity and intelligence. EEG was recorded monopolarly from 10 symmetric leads (10-20 system) in 37 (17 males) healthy subjects (mean age 13.7 years) at rest and during performance of two visually presented cognitive tasks, verbal (semantic grouping) and spatial (mental rotation). On another occasion, the subjects were administered the Intelligence Structure Test (IST). Both total IST score and some individual subtests of specific abilities showed significant positive correlations with EEG coherence in the theta band and significant negative relationships with EEG dimension, a measure of complexity and unpredictability of neural oscillatory dynamics underlying the EEG time series. Furthermore, EEG coherence and dimensional complexity were inversely related. Taken together, these EEG metrics accounted for over 30% of the variability of the total IST score in this sample. No significant effects of the task type (spatial vs. verbal) or specific abilities were observed. Long-distance theta coherence between frontal and parieto-occipital areas showed the most consistent relationship with cognitive abilities. The results suggest that order to chaos ratio in task-related brain dynamics may be one of the biological factors underlying individual differences in cognitive abilities in adolescents.

EEG frequency ranges during perception and mental rotation of two- and three-dimensional objects.

Spectral EEG powers were compared in 4 frequency ranges (8-13, 15-25, 25-35, and 35-45 Hz) in a group of 20 subjects during the performance of tasks requiring mental rotation of two- and three-dimensional objects. Only those EEG segments corresponding to tasks with identical solution times were analyzed. The spectral powers of oscillations in the alpha range were higher in control conditions than during task performance. Power in the frequency range 15-45 Hz was greater during task performance than in control conditions; this supports the concept that alpha rhythm desynchronization accompanies the synchronization of higher-frequency EEG rhythms. Frequency power during task performance with two-dimensional objects was greater than that during tasks with three-dimensional objects. Since the angle of rotation between two-dimensional objects was greater than that between three-dimensional objects, this factor, rather than the depth of the perceived space, increased the level of cortical activation. In all experimental situations, power at frequencies of 15-45 Hz was significantly greater in the occipital regions than any other regions, reflecting the visual modality of the stimulus. Particular changes were noted in the gamma range (35-45 Hz), where power in the first second of task performance was significantly higher than in the second second; this may provide evidence that this range is more closely associated with perception and recognition processes than with mental transformation of the image.

[The EEG frequency spectra during the perception and mental rotation of 2- and 3-dimensional objects]. / Chastotnye diapazony EEG pri vospriiatii i myslennoi rotatsii dvu- i trekhmernykh ob''ektov.

The EEG spectral power in 4 frequency ranges (8-13, 15-25, 25-35, and 35-45 Hz) was studied during mental rotation of two- and three-dimensional objects. Only those EEG segments were analyzed which corresponded to the tasks with similar time of solving. The EEG spectral power of the alpha range was higher under control conditions than during task solving. The spectral power in the range of 15-45 Hz was higher under the operation than under the control conditions. This finding confirms the assumption that EEG desynchronization in the alpha range is accompanied by the high-frequency synchronization. The EEG high-frequency power was higher during mental rotation of two-dimensional objects than three-dimensional ones. Since the angular difference between the two-dimensional objects was larger than between the three-dimensional ones, the rotation angle rather than the "depth" of space increased cortical activation. Under experimental conditions, EEG spectral power in the range of 15-45 Hz was always the highest in the occipital areas, which was associated with the visual modality of stimuli. The EEG spectral power in the gamma range (35-45 Hz) was substantially higher at the first second of operation as compared with the second one testifying that EEG changes in this range are more related with the processes of perception and recognition than with mental operations with images.

[The spectral rearrangements of the EEG and the organization of the cortical connections during spatial and verbal thinking]. / Spektral'nye perestroiki EEG i organizatsiia korkovykh sviazei pri prostranstvennom i verbal'nom myshlenii.

Solution of spatial and verbal tasks was studied in 43 subjects using the advanced version of the method of intracortical interaction mapping (IIM) and analysis of EEG spectra in short (250 ms) intervals. Comparison between the IIM and coherence methods during solving simple motor tasks revealed some advantages of the IIM for studying of labile cortical connections. Several stages were separated in the process of solution of the mental task in accordance with patterns of cortical connections. The duration of the stages was similar in both kinds of tasks and corresponded to that revealed in psychological experiments. Cortical connections in the theta range were generalized and reflected the level of general tension. This unspecific tension was high for the whole period of the spatial task solution while in the verbal task the tension increased to the stage of decision making. Task-specific patterns were revealed in the beta range. The right parietal and temporal regions were the centers of EEG connections during solution of the spatial task while the left central area was essential for the verbal task solution. The left parietal area was involved in solution of both kinds of tasks. The frequency parameters of connections in the beta range were stable during the spatial task solving, and in the process of verbal task solving the dominant frequency changed after the initial (perception) stage probably due to switching to another thinking mechanism.

Self-regulation of interhemispheric asymmetry in humans.

Five healthy right-handed subjects learned to control hemispheric asymmetry with biofeedback of the amplitude difference of slow cortical potentials between the left and the right precentral areas. Six training sessions were conducted with subject I, 12 sessions with subjects II and III, and 14 sessions, with subjects IV and V. Performance of four out of five subjects improved continuously as a function of sessions. Towards the end of training, these subjects demonstrated highly significant differentiation between conditions where right versus left precentral negativity was required. In subject V, no improvement was observed after 14 training sessions. The data indicate that most subjects can learn to self-generate fast electroencephalograph (EEG) differences between the left and the right sensorimotor cortical regions.

Age increases brain complexity.

This study investigated age-related changes in the human brain function using both traditional EEG analysis (power spectra) and the correlational dimension, a measure reflecting the complexity of EEG dynamics and, probably, the complexity of neurophysiological processes generating the EEG. Assuming that the accumulation of individual experience is determined by the formation of functionally related groups of neurons showing a repetitive synchronous activation (cell assemblies), an increase in the number of such independently oscillating cortical cell assemblies can be expected, despite a decline of some metabolic and memory functions with normal ageing. Thus, the "wisdom of old age' may find its neurophysiological basis in greater complexity of brain dynamics compared to young ages. The experimental hypothesis was that EEG dimension steadily increases with age. In order to test this hypothesis the resting EEGs of 5 age groups from 7 to 60 were analysed. The results confirm the hypothesis: after a jump in the brain dynamics complexity during puberty a linear increase with age is observed. During maturation (7-25 years), the maximum gain in complexity occurs over the frontal associative cortex.

[Genetic and demographic structure of the Talysh population]. / Genetiko-demograficheskaia struktura populiatsii Talyshei.

Investigation was carried out in Talysh population in mountain region of South Azerbaijan. There is extended reproduction in the population. From XVIII till the beginning of XX century there were 3-3.6 offsprings in a family. In the last generation with completed reproduction, the family size raised to 7.13. Modern factors of population size dynamics are considered. It turned out that the main new factor (in conditions of increased family size) is the intensive migration from the population, mainly in men, that results in transformation of sex index in the reproductive age (ratio men/women is 0.77), and a large part of women stay unmarried. Crow index is Itot = 0.426, its components are Im = 0.115, If = 0.260.