A comparison of genetic variants between proficient low- and high-risk sport participants.

Athletes participating in high-risk sports consistently report higher scores on sensation-seeking measures than do low-risk athletes or non-athletic controls. To determine whether genetic variants commonly associated with sensation seeking were over-represented in such athletes, proficient practitioners of high-risk (n = 141) and low-risk sports (n = 132) were compared for scores on sensation seeking and then genotyped at 33 polymorphic loci in 14 candidate genes. As expected, athletes participating in high-risk sports score higher on sensation seeking than did low-risk sport athletes (P < .01). Genotypes were associated with high-risk sport participation for two genes (stathmin, (P = .004) and brain-derived neurotrophic factor (P = .03)) as well as when demographically matched subsets of the sport cohorts were compared (P < .05); however, in all cases, associations did not survive correction for multiple testing.

Increased patterns of risky behaviours among helmet wearers in skiing and snowboarding.

BACKGROUND: There has been an ongoing debate as to whether wearing helmets in skiing and snowboarding increases the risk tolerance of participants. OBJECTIVE: To investigate the roles of demographic and personality variables, and helmet usage in predicting risk taking behaviours in a cross-sectional sample of intermediate and proficient skiers and snowboarders. METHODS: Risk taking in skiing was measured using a validated 10-item self-report measure which was designated as the outcome variable in a three step hierarchical regression. Independent predictors included age, sex, education, sport, ability, helmet usage, and personality traits that have been associated with risk taking: impulsivity and sensation seeking. RESULTS: In the final regression model, helmet use significantly predicted variance in risk taking (standardized ß=.10, p=.024), and the relationship remained after accounting for variance due to demographic variables and general trait measures. The partial relationship between risk taking and sex, ability, impulsivity, and sensation seeking were also significant (p<.05). CONCLUSION: High sensation seeking, high impulsivity, male sex, and proficiency were associated with increased patterns of risky behaviours in skiers and snowboarders, and after accounting for these factors, helmet use was a significant predictor of risk taking. The relationship between helmet use and risk taking was modest suggesting that the costs of increased risk taking is not likely to outweigh the protective benefits of a helmet.

Variants in the dopamine-4-receptor gene promoter are not associated with sensation seeking in skiers.

Sensation seeking is a personality trait that has been associated with disinhibited behaviours including substance use and gambling, but also with high-risk sport practices including skydiving, paragliding, and downhill skiing. Twin studies have shown that sensation seeking is moderately heritable, and candidate genes encoding components involved in dopaminergic transmission have been investigated as contributing to this type of behaviour. To determine whether variants in the regulatory regions of the dopamine-4-receptor gene (DRD4) influenced sport-specific sensation seeking, we analyzed five polymorphisms (-1106T/C, -906T/C, -809G/A, -291C/T, 120-bp duplication) in the promoter region of the gene in a cohort of skiers and snowboarders (n = 599) that represented a broad range of sensation seeking behaviours. We grouped subjects by genotype at each of the five loci and compared impulsive sensation seeking and domain-specific (skiing) sensation seeking between groups. There were no significant associations between genotype(s) and general or domain-specific sensation seeking in the skiers and snowboarders, suggesting that while DRD4 has previously been implicated in sensation seeking, the promoter variants investigated in this study do not contribute to sensation seeking in this athlete population.

Differential relationships between sub-traits of BIS-11 impulsivity and executive processes: an ERP study.

There is mixed evidence for a relationship between impulsivity and executive functions. Although impulsivity is heterogeneous, previous research did not examine partial relationships controlling for shared variance across sub-traits to evaluate the specificity of these associations. Eighty-five undergraduates completed the Barratt Impulsiveness Scale-11 (BIS-11) and the AX-expectancy version of the Continuous Performance Task (AX-CPT). This task engenders a conflict between two response tendencies by manipulating the frequency of specific trial types. We conducted mixed model analyses to determine the unique variance in behavioral and electrophysiological indices of relevant cognitive functions accounted for by the facets of BIS-11. Motor Impulsiveness was associated with smaller P3 across sites and conditions suggesting a general cognitive limitation not specific to the condition requiring the most inhibition, and larger N2 in some conditions indicating heightened conflict detection. Non-Planning Impulsiveness was related to smaller N2 when inhibiting a primed response and with greater P3 in some contexts. Attentional Impulsiveness appeared to be associated with an inefficient conflict detection system indicated by relatively normal engagement in trials involving the non-potent response, but relatively over engagement in the prepotent condition. Our findings suggest that sub-traits of impulsivity are differentially related to executive processes.

Impulsivity is not always associated with student drinking: a moderation study of impulsivity and drinking by positive alcohol expectancies.

Student drinking is a major problem on North American campuses and impulsivity is a significant risk factor for heavy drinking. The present study investigates the moderation of the impulsivity-drinking relationship by the expectation that having a drink will lead to positive experiences. Undergraduate drinkers (n=292) completed measures of impulsivity (Barratt Impulsiveness Scale 11; BIS-11), positive drinking expectancies, and alcohol use. Expectancies moderated the relationship between BIS-11 scores and alcohol use. BIS-11 scores were significantly related to typical alcohol quantity, frequency, quantity X frequency, and binge drinking frequency for individuals with average and high levels of positive expectancies, but not for those with few positive expectancies. Implications for interventions targeted at highly impulsive students, using expectancy modification are discussed.

ERPs on a continuous performance task and self-reported psychopathic traits: P3 and CNV augmentation are associated with Fearless Dominance.

Both augmented and reduced P3 amplitude have been associated with psychopathic personality. The Two Process Theory (TPT) suggests that there are two etiologically distinct traits underling psychopathy. One of these traits appears to be related to enhanced attention engagement and reduced anxiety. The other is related to impulsivity, social deviance and poor executive function. P3 is a multi-determined component indexing attention and working memory processes related to executive function. As such, we hypothesized that dissociable relationships would exist between these two dimensions and P3. We recorded P3 and the Contingent Negative Variation (CNV), an ERP response shown to be augmented in psychopaths, during an expectancy AX-continuous performance task from 60 undergraduates. We administered the Psychopathic Personality Inventory (PPI). One factor of the PPI, Fearless Dominance, was related to the dimension of the TPT predicted to reflect relatively better executive function. We found that Fearless Dominance was uniquely associated with P3 augmentation. More negative CNV and faster reaction time were also specifically related to Fearless Dominance. These results illustrate the need to examine the differential relationships between psychopathic traits and P3 amplitude.

Disinhibited characteristics and binge drinking among university student drinkers.

Binge drinking is a major problem at North American universities. Disinhibited traits have provided insight on other patterns of alcohol involvement, but less is known about how they relate to bingeing. Drinkers at a large urban university (n=293) completed the Barratt Impulsiveness Scale 11 (BIS-11), the Aggression Questionnaire, and the Thrill and Adventure Seeking and Boredom Susceptibility scales. Binge drinking was assessed using the NIAAA recommendation for standardizing binge frequency. Hierarchical regression was used to evaluate relationships between disinhibited traits and bingeing. BIS-11 Motor Impulsiveness, Thrill and Adventure Seeking and Boredom Susceptibility predicted bingeing. As about 15% of the variability in bingeing was due to disinhibition facets, they should be considered in future models of student vulnerability to bingeing.

Visual P3 amplitude and self-reported psychopathic personality traits: frontal reduction is associated with self-centered impulsivity.

Past studies have examined P3 amplitude as an index of cognitive function related to psychopathy with mixed results. Psychopathy is a heterogeneous set of dissociable traits, and no previous study has examined relationships between P3 and specific traits. A Two Process Theory (TPT) of psychopathy has recently been advanced predicting that P3 reductions are related to only one dimension. We evaluated the relationship between P3 and the two factors of the Psychopathic Personality Inventory (PPI) in 96 undergraduates who performed a visual task. One factor of the PPI, Self-Centered Impulsivity, is related to the dimension of the TPT predicted to underlie P3 reduction. Frontal amplitude reduction was uniquely and inversely related to this trait. The other PPI factor, Fearless Dominance, was associated with faster reaction times. Future work on psychopathic personality and P3 should evaluate whether relationships are unique to one personality dimension.

Deviant P300 amplitude development in males is associated with paternal externalizing psychopathology.

Boys at risk for alcoholism show deviant P300 amplitude development. Genetic influences on P300, however, are related to a range of externalizing disorders. This study examined whether P300 development from adolescence to early adulthood differed between groups varying in severity of paternal externalizing. Parietal P300 was assessed during the "rotated heads" task on up to 3 times between the ages of 17 and 24 years. Participants were divided into 3 paternal externalizing groups: (a) severe (father has adult antisocial behavior), (b) intermediate (father has alcohol dependence but not a more severe disorder), and (c) low (father has no externalizing disorders or substance treatment and is not extreme in alcohol use). Mixed models were used to evaluate linear change in amplitude. P300 decreased with age. The severe-risk group had smaller P300 initially and changed less with time than did the low-risk group. The intermediate-risk group did not differ significantly from the low-risk group, but differed marginally from the severe-risk males. Externalizing and early-onset substance disorders in the sons were associated with smaller initial values of P300. Measures of deviant P300 development may be vulnerability markers for externalizing psychopathology.

P300 amplitude, externalizing psychopathology, and earlier- versus later-onset substance-use disorder.

P300 amplitude predicts substance use or disorder by age 21. Earlier- versus later-onset substance disorders may reflect different levels of an externalizing psychopathology dimension. P300 in adolescence may not be as strongly related to later-onset substance problems as it is to earlier-onset ones. In the present study, visual P300 amplitude was measured at age 17 in a community-representative sample of young men. Substance and externalizing disorders were assessed at approximately ages 17, 20, and 24. Earlier-onset (by age 20) substance disorder was associated with higher rates of externalizing disorders than were later-onset problems. P300 amplitude was reduced in subjects with earlier-onset substance disorders, relative to later-onset and disorder-free subjects. Amplitude was also reduced in subjects with an externalizing disorder but no substance disorder. Earlier-onset subjects had reduced P300, even in the absence of an externalizing disorder. The results could not be attributed to a concurrent disorder or to recent substance use at the time of the P300 recording. The findings are consistent with P300 indexing an externalizing spectrum. Earlier-onset substance disorders are more strongly related to P300 and externalizing than are later-onset problems.

Heritability of P300 amplitude development from adolescence to adulthood.

Early adulthood is a period of late brain development corresponding to the age of onset for psychopathology associated with P300 amplitude reductions. Although amplitude from a single occasion is heritable, little is known about genetic influences on change during this period. This is the first study of P300 change to combine latent growth and twin models. P300 at Pz was measured up to three times at approximately ages 17, 20, and 23 in monozygotic and dizygotic male twins using a visual task. P300 decreased with age. Correlations indexing the stability of amplitude over time were high (median r=.72) and almost 90% of the stable variance (i.e., the model intercept) was attributable to genetic influences. The rate of decrease was heritable, and the genes influencing intercept may be the same ones influencing change. Finally, intercept was more heritable than amplitude at any single time point. Intercept may be a more useful aid in the search for genes associated with relevant psychopathology than single measures of P300. Over a broader age range growth indices may be useful "developmental" endophenotypes.

P300 amplitude in nonalcoholic adolescent twin pairs who become discordant for alcoholism as adults.

Past reports suggest that reduced P300 amplitude is associated with risk for alcoholism. We examined whether visual P300 amplitude could identify familial risk for alcohol disorders in individuals not known to be at risk at the time P300 was recorded. These individuals were twins from pairs where neither twin had an alcohol disorder at age 17 but familial risk was established at age 20 when one twin developed an alcohol disorder whereas the other did not. Of special interest was the P300 of the unaffected twin recorded at age 17 when both twins were alcoholism free. We found reduced P300 in the unaffected twin compared to pairs where both members were continuously disorder free. Hence, P300 was reduced in alcohol disorder-free individuals whose twin siblings subsequently developed alcoholism, further supporting reduced P300 amplitude as an endophenotype indexing familial risk for alcoholism.

P300 amplitude in adolescent twins discordant and concordant for alcohol use disorders.

The sons of alcoholics have repeatedly been found to have reduced P300 amplitude. Further, quantitative behavioral genetic and molecular genetic studies indicating a genetic influence on P300 amplitude have fueled speculation that this component may be a biological vulnerability marker for alcoholism. To further explore this possibility, we examined P300 in adolescent twin pairs from an epidemiological sample who were (a) discordant for alcohol abuse/dependence, (b) concordant for alcohol abuse/dependence, or (c) concordant for the absence of alcohol abuse/dependence and other relevant disorders. For discordant pairs, the alcohol abusing/dependent twins' amplitude did not differ from that of non-alcoholic co-twins. Pairs free of psychopathology had greater amplitudes than both alcoholism discordant and concordant pairs. P300 amplitude was more similar in monozygotic than dizygotic discordant pairs, suggesting a genetic influence on P300 amplitude in this group. The findings are consistent with P300 amplitude being a marker of vulnerability to alcohol use disorders.

Etiologic connections among substance dependence, antisocial behavior, and personality: modeling the externalizing spectrum.

A hierarchical biometric model is presented of the origins of comorbidity among substance dependence, antisocial behavior, and a disinhibited personality style. The model posits a spectrum of personality and psychopathology, united by an externalizing factor linked to each phenotype within the spectrum, as well as specific factors that account for distinctions among phenotypes within the spectrum. This model fit self-report and mother-report data from 1,048 male and female 17-year-old twins. The variance of the externalizing factor was mostly genetic, but both genetic and environmental factors accounted for distinctions among phenotypes within the spectrum. These results reconcile evidence for general and specific causal factors within the externalizing spectrum and offer the externalizing factor as a novel target for future research.

P3 event-related potential amplitude and the risk for disinhibitory disorders in adolescent boys.

BACKGROUND: The children of parents who abuse alcohol typically show reduced amplitude of the P3 event-related potential wave. We determined if this effect was present in a population-based sample of older adolescent boys, whether it was associated with paternal antisocial personality and drug use, and whether it appeared in youth with childhood externalizing and substance use disorders. METHODS: A statewide sample of 502 male youth, identified from Minnesota birth records as members of twin pairs, had their P3 amplitude measured, using a visual oddball paradigm when they were approximately 17 years old. Structured clinical interviews covering attention-deficit/hyperactivity disorder, conduct disorder, oppositional defiant disorder, antisocial personality disorder, and substance use disorders were administered in person to the youth and his parents at the time of the P3 assessment and again to the youth 3 years later. RESULTS: Reduced P3 was associated with disorders and paternal risk for disorders, reflecting a behavioral disinhibition spectrum that included attention-deficit/hyperactivity disorder, oppositional defiant disorder, conduct disorder, antisocial personality disorder, alcoholism, nicotine dependence, and illicit drug abuse and dependence. Reduced P3 at age 17 predicted the development of substance use disorders at age 20. Most effect sizes associated with these group differences exceeded 0.70, indicating medium to moderately large group differences. Maternal alcoholism and substance use during pregnancy were unrelated to P3 amplitude in offspring. CONCLUSION: Small amplitude P3 may indicate genetic risk for a dimension of disinhibiting psychiatric disorders, including childhood externalizing, adult antisocial personality disorder, and substance use disorders.