Driving risks of young drivers with symptoms of attention deficit hyperactivity disorder: association with the dopamine transporter gene VNTR polymorphism.

BACKGROUND: Road traffic injuries are a leading cause of death for young adults, and young drivers with higher expression of symptoms of attention deficit-hyperactivity disorder (ADHD) could pose an even greater risk in traffic. Dopaminergic dysfunction has been found to occur in ADHD, with the dopamine transporter (DAT) gene VNTR polymorphism (DAT1 VNTR; rs28363170) being one of the most consistent genetic markers. Thus, we aimed at clarifying how the ADHD symptoms and the DAT1 VNTR relate to risk-taking behaviour in traffic, impulsivity and driving anger in young drivers. METHOD: We used data of two traffic behaviour study samples (n = 741, mean age = 23.3 ± 7.2 years; n = 995, mean age = 22.9 ± 8.1 years) and the Estonian Children Personality Behaviour and Health Study (ECPBHS; traffic behaviour data n = 1,016, mean age = 25.2 ± 2.1 years). ADHD symptoms were assessed by self-report with the Adult ADHD Self-Report Scale (ASRS v1.1) and impulsivity with the Adaptive and Maladaptive Impulsivity Scale. Traffic behavioural measures were either self-reported (Driver Behaviour Questionnaire, Driving Anger Scale) or obtained from databases (registered accidents and violations). RESULTS: Drivers with more self-reported ADHD symptoms also reported more risk-taking in traffic and had more of recorded traffic accidents and violations. DAT1 9 R carriers had a higher probability of high traffic risk behaviour only if they also had ADHD symptoms. CONCLUSION: Higher level of ADHD symptoms is a significant risk factor in traffic, and carrying of the DAT1 9 R allele appears to aggravate these risks.

Low cardiorespiratory fitness and obesity for ADHD in childhood and adolescence: A 6-year cohort study.

Attention-deficit/hyperactivity disorder (ADHD) is a prevalent disorder in childhood and identifying risk factors associated with developing ADHD during childhood and adolescence is relevant from a clinical and epidemiological point of view. This work examines (a) whether overweight/obesity and low cardiorespiratory fitness (CRF) are associated with increased ADHD symptoms in childhood (cross-sectional analysis), and (b) whether overweight/obesity and low CRF levels during childhood predict increased ADHD symptoms in adolescence (longitudinal analysis). Data were examined from a longitudinal study of Estonian inhabitants who took part in the European Youth Heart Study (EYHS) in 1998 and 1999 (baseline age 9 years), who were re-evaluated 6 years later as part of the longitudinal Estonian Children Personality Behaviour and Health Study (ECPBHS). CRF was determined via an incremental maximal cycle-ergometer test, overweight/obesity was based on body mass index (BMI), and the 7-point af Klinteberg Hyperactivity Scale was used to assess ADHD symptoms at both time points. In the cross-sectional analysis, children with overweight/obesity were at greater risk of ADHD symptoms compared to underweight/normal weight children, as were those unfit compared to fit children (OR = 1.92 and 95%CI = 1.02-3.55, and OR = 1.84 and 95%CI = 1.13-2.98, respectively). The cross-sectional association between BMI and ADHD symptoms was mediated by CRF (z = 2.116, 42.9%; P = .034). The longitudinal analysis showed being unfit in childhood was associated with a greater risk of increased ADHD symptoms 6 years later in adolescence (OR = 2.26 and 95%CI = 1.14-4.47), even after adjusting for baseline ADHD symptoms and BMI. Our result suggests that being unfit is an additional risk factor for increased ADHD symptoms during childhood and adolescence. The association between BMI and ADHD symptoms was mediated by CRF in the cross-sectional analysis, and no association was seen between overweight/obesity and increased ADHD symptoms.

Efficacy of intervention at traffic schools reducing impulsive action, and association with candidate gene variants.

OBJECTIVE: Road traffic injuries are the leading cause of death among young people. Recognition of the contribution of impulsive behaviour may help novice drivers to behave more safely. Previously a brief intervention focusing on impulsive traffic behaviour conducted by psychologists in driving schools had been effective. The aim of this study was an independent re-evaluation of the effect of the intervention, as conducted by driving school teachers, and assessment of the potential associations with candidate genotypes. METHODS: Driving school students (mean age 22.5, SD=7.9) were divided into intervention (n=704) and control (n=737) groups. Driving school teachers were trained to administer the intervention which consisted of a lecture and group work (1.5 h in total) on impulsivity. Traffic offences and crashes were monitored during 3 years, using police and traffic insurance fund databases. Functional polymorphisms of the dopamine transporter (DAT) and serotonin transporter genes (DAT1 VNTR and 5-HTTLPR) were assessed. RESULTS: The intervention significantly lowered general traffic risk and prevalence of traffic accidents. DAT1 VNTR 9R carriers, particularly males, had higher general traffic risk in the whole sample. Female 5-HTTLPR s' allele carriers of the intervention group had the lowest general traffic risk. Intervention was most effective in female DAT1 VNTR 10R/10R homozygotes. CONCLUSIONS: Brief impulsivity-centred intervention appears as a promising strategy for preventing risk-taking behaviour in novice drivers and can be fully integrated to driving school curriculum.

Orexin/hypocretin receptor gene (HCRTR1) variation is associated with aggressive behaviour.

Orexins, alternatively called hypocretins, are neuropeptides with crucial role in maintaining wakefulness. The orexin system is thought to mediate a coordinated defense response but thus far investigated from the flight, but never fight, response perspective. An HCRTR1 gene variant (rs2271933 G > A) leading to amino acid substitution (Ile408Val) has been associated with migraine and mood disorders. We genotyped, and assessed aggressive behaviour in both birth cohorts (n = 655 and 583) of the Estonian Children Personality Behaviour and Health Study (ECPBHS). Measures of aggressiveness were collected at age 25 or 33 and data on stressful life events (SLE-s) at age 15. Violations of traffic law were monitored in the samples of the Estonian Psychobiological Study of Traffic Behaviour. In both birth cohorts of the ECPBHS, the HCRTR1 the A/A homozygotes reported higher aggression in both Buss-Perry Aggression Questionnaire and the Life History of Aggression Interview. With either measure of aggressiveness, the HCRTR1 genotype effect was dependent on experience of SLE, the highest level of aggressiveness increase by environment being found in female A/A homozygotes. The HCRTR1 A/A homozygotes scored higher in the ANGER facet of the Affective Neuroscience Personality Scale, while such an effect on FEAR was found only in females. Male HCRTR1 A/A homozygotes were more likely to relapse into drunk driving of a passenger car, and in two independent samples the A-allele carriers were causing traffic accidents more often. Conclusively, self-report, interview, and traffic record data converge indicating that the HCRTR1 Ile408Val genotype is associated with aggressiveness and breach of law. This article is part of the Special Issue entitled 'Current status of the neurobiology of aggression and impulsivity'.

Relapse of drunk driving and association with traffic accidents, alcohol-related problems and biomarkers of impulsivity.

OBJECTIVE: Individual biological predispositions should play a role in risky driving behaviour. Platelet monoamine oxidase (MAO) activity, dopamine transporter gene (DAT1) and neuropeptide S receptor 1 (NPSR1) gene polymorphisms have been identified as markers of impulsivity, alcohol use and excessive risk-taking. We aimed to find out how this knowledge on neurobiology of impulsivity applies to drunk driving and traffic behaviour in general. METHODS: We have longitudinally examined the behaviour of drunk drivers (n = 203) and controls (n = 211) in traffic, in association with their alcohol-related problems, personality measures and the three biomarkers. We analysed differences between the subjects based on whether they had committed driving while impaired by alcohol (DWI) violation in a 10-year time period after recruitment or not and investigated further, what kind of predictive value do the different biomarkers have in committing DWI and other traffic violations and accidents. RESULTS: The original drunk drivers group had lower platelet MAO activity but further DWI was not significantly associated with this measure. Being a NPSR1 T-allele carrier contributed to the risk of repeatedly committing DWI. DAT1 9R carriers in contrast were involved in more traffic accidents by their own fault (active accidents), compared to 10R homozygotes in the whole sample. All groups with DWI also had significantly more alcohol-related problems and higher scores in maladaptive impulsivity compared to controls without DWI. CONCLUSIONS: Established biological markers of alcohol use and impulsivity can be reliably associated with everyday traffic behaviour and help in contributing to the understanding of the need for more personalized prevention activities.

Risky driving and the persistent effect of a randomized intervention focusing on impulsivity: The role of the serotonin transporter promoter polymorphism.

Road traffic accidents are a serious public health issue, and real-life traffic offences are an excellent indicator of the behavioural tendencies of impulsivity and risk-taking. We have previously reported on short-term efficacy of a brief intervention in driving schools to reduce traffic risks (Paaver et al., Accid. Anal. Prev., 2013; 50, 430-437), and have now addressed the question of whether does the impact of the intervention last for a few years, and whether traffic behaviour and the intervention effect are associated with the serotonin transporter polymorphism (5-HTTLPR) genotype as the central serotonin system is strongly associated with impulse control. Participants of the study were 1866 novice car-drivers (mean age 23.0, SD = 7.2 years). Data on traffic violations were obtained four years after intervention from the police database and on traffic collisions from the national traffic insurance database. DNA samples were available for 767 participants and 5-HTTLPR genotypes were classified using the triallelic model. For the observation period after the intervention, speeding, drunk driving and involvement in traffic accidents were significantly lower in the intervention group. 5-HTTLPR genotype was associated with traffic behaviour: The S'-allele carriers had significantly lower odds for speeding offences and traffic accidents. The lower prevalence of S'-allele carriers among those who had committed speeding offences was statistically significant in females, while the lower prevalence of having been involved in a traffic accident was rather observed in males. Statistically significant intervention effects were observed only in the L'/L' homozygotes who had higher prevalence of traffic incidents. Conclusively, the brief intervention in traffic schools had a significant impact on traffic safety within subsequent four years, and traffic behaviour was associated with the serotonin transporter genotype. These findings suggest that subjects who are less likely to self-regulate their driving habits while gaining experience would benefit from training of impulsivity recognition.

The association of measures of the serotonin system, personality, alcohol use, and smoking with risk-taking traffic behavior in adolescents in a longitudinal study.

Studies on the neurobiological basis of risk-taking behavior have most often focused on the serotonin system. The promoter region of the gene encoding the serotonin transporter contains a polymorphic site (5-HTTLPR) that is important for the transcriptional activity, and studies have demonstrated its association with brain activity and behavior. Another molecular mechanism that reflects the capacity of the central serotonin system is the activity of the enzyme monoamine oxidase (MAO) as measured in platelets. The purpose of the present study was to examine how measures of the serotonin system (platelet MAO activity and the 5-HTTLPR polymorphism), personality variables, alcohol use and smoking are associated with risk-taking traffic behavior in schoolchildren through late adolescence. The younger cohort of the longitudinal Estonian Children Personality Behaviour and Health Study (originally n = 583) filled in questionnaires about personality traits, smoking status, alcohol use and traffic behavior at age 15 and 18 years. From venous blood samples, platelet MAO activity was measured radioenzymatically and 5-HTTLPR was genotyped. During late adolescence, subjects with lower platelet MAO activity were more likely to belong to the high-risk traffic behavior group. Male 5-HTTLPRs'-allele carriers were more likely to belong to the high-risk traffic behavior group compared to the l'/l' homozygotes. Other variables predicting risk group were alcohol use, smoking and Maladaptive impulsivity.The results suggest that lower capacity of the serotoninergic system is associated with more risky traffic behavior during late adolescence, but possibly by different mechanisms in boys and girls.

A New Risk Factor for Traumatic Spinal Cord Injury.

Several behavioral factors such as violence, impulsivity, and alcohol-related problems are associated with traumatic spinal cord injury (TSCI). Such factors have been associated with inherently low neuronal serotonergic capacity that in turn is reflected in low activity of monoamine oxidase (MAO) as measured in platelets. The aim of the study was to characterize platelet MAO activity and impulsivity in persons with TSCI. Data were collected from 93 patients with TSCI and compared with 93 age- and gender-matched control subjects. Platelet MAO activity was measured radioenzymatically and expressed as nanomoles of beta-phenylethylamine oxidized per 10 to the tenth power platelets per minute. Facets of impulsivity were self-reported using Barratt Impulsiveness Scale (BIS-11). Most of the patients were men (87%). The mean time from TSCI was 4.3 ± 3.7 years. Twenty-one (24%) patients reported social problems associated with alcohol, and 30 (39%) patients had consumed alcohol before the trauma. Platelet MAO activity was significantly lower among the patients with TSCI (6.4 ± 3.2 vs.10.8 ± 5.2, p < 0.0001). This difference was not affected by consideration of their smoking status. The patients with TSCI had significantly higher BIS-11 impulsivity compared with the controls (62.8 ± 10.0 vs. 55.4 ± 8.6, p = 0.0001). The patients with TSCI have lower platelet MAO activity, and they are more impulsive compared with the healthy controls. Our results indicate that both low platelet MAO activity and high impulsivity are important risk factors for TSCI that can have predictive value and aid in undertaking preventive measures.

Further evidence for the association of the NPSR1 gene A/T polymorphism (Asn107Ile) with impulsivity and hyperactivity.

Administration of neuropeptide S (NPS) elicits anxiolysis, arousal and higher activity in rodents. In humans, the NPS receptor (NPSR1) gene rs324981 A/T (Asn(107)Ile) polymorphism is associated with fear responses and anxiety. We have recently revealed an association of NPSR1 with impulsivity-related traits and psychopathology. In the present study the association of the NPSR1 genotype with impulsivity and attention-deficit/hyperactivity disorder (ADHD)-related symptoms was re-examined in two independent non-clinical cohorts. We used self-reports of two population-derived samples of the Estonian Psychobiological Study of Traffic Behaviour (EPSTB): a community car driving sample (n=491, MAge=37) and a driving school student sample (n=773, MAge=24). Impulsivity was measured with the Adaptive and Maladaptive Impulsivity Scale (AMIS) in both samples, and with the Barratt Impulsivity Scale (BIS) in driving schools only. For the latter sample, also measurement of ADHD symptoms was carried out with the Adult ADHD Self-Report Scale (ASRS). NPSR1 T-allele carriers had higher scores of impulsivity, motor restlessness and total ADHD scores. The effect on impulsivity originated from male participants but for ADHD symptoms the association was independent of sex. Thus we have confirmed in two additional population-derived samples that the T-allele of the NPSR1 rs324981 polymorphism is associated with increased impulsivity and ADHD-related traits.

Preventing risky driving: A novel and efficient brief intervention focusing on acknowledgement of personal risk factors.

Impulsive personality is an important predictor of risky driving. Acknowledging their impulsive tendencies may help novice drivers to drive more safely. The aim of this study was to evaluate the efficacy of a novel brief intervention targeting novice drivers' risky behavior in traffic, taking into account potential moderator effects. Driving school students (n=1866) were divided into an intervention group and a control group. The intervention consisted of a lecture and group work (1.5h). Subjects' traffic offenses and crashes were monitored during the following year using police and traffic insurance fund databases. The groups were similar in their baseline characteristics. The intervention group had half as many speeding violations in the year following the intervention compared with the controls. The proportion of speeders was significantly lower in the intervention group compared with the control group in subgroups of subjects with medium cognitive abilities and low or medium BIS-11 impulsiveness levels. In alpha(2A)-adrenoceptor gene (ADRA2A) G allele carriers, general traffic risk and speeding decreased in response to the intervention, unlike in subjects with the CC genotype. It is concluded that brief interventions that are integrated into the driving education program and focus on personal psychological risk factors may be effective for improving traffic safety.

Drunk driving among novice drivers, possible prevention with additional psychological module in driving school curriculum.

Road traffic collisions caused by drunk driving pose a significant public health problem all over the world. Therefore additional preventive activities against drunk driving should be worked out. The aim of the study was to assess drunk driving in novice drivers after a psychological intervention taking into account also impulsivity, law obedience, and alcohol-related measures. An intervention study was started with 1889 car driver's license attempters during their driving school studies. Subjects were classified as intervention group (n=1083, mean age 23.1 (SD=7.4) years), control group (n=517, mean age 22.8 (SD=7.1) years) and "lost" group (n=289, mean age 23.0 (SD=6.9) years). "Lost" group subjects had been assigned into the intervention group, but they did not participate in the intervention. Subjects of the intervention group participated in a psychological intervention on the dangers of impulsive behavior in traffic. After a three year follow-up period it appeared that in the control group and in the lost group there was a significantly higher proportion of drunk drivers than in the intervention group, 3.3% (n=17), 3.5% (n=10) and 1.5% (n=10) (p=0.026), respectively. Survival analysis confirmed that psychological intervention had a significant impact on drunk driving (p=0.015), and the impact of the intervention was persistent also in the case of higher scores in Mild social deviance. In subjects with higher scores in impulsivity measures and alcohol-related problems the impact of short psychological intervention was not sufficient for preventing drunk driving. It can be concluded that psychological intervention used during the driving school studies is an effective primary prevention activity against drunk driving. However, for drivers with high scores in impulsivity measures and alcohol-related problems, the short psychological intervention is not sufficient in reducing drunk driving behavior.

Stability of the factorial structure of metabolic syndrome from childhood to adolescence: a 6-year follow-up study.

BACKGROUND: Metabolic syndrome (MS) is a clustering of cardiometabolic risk factors that is considered a predictor of cardiovascular disease, type 2 diabetes and mortality. There is no consistent evidence on whether the MS construct works in the same way in different populations and at different stages in life. METHODS: We used confirmatory factor analysis to examine if a single-factor-model including waist circumference, triglycerides/HDL-c, insulin and mean arterial pressure underlies metabolic syndrome from the childhood to adolescence in a 6-years follow-up study in 174 Swedish and 460 Estonian children aged 9 years at baseline. Indeed, we analyze the tracking of a previously validated MS index over this 6-years period. RESULTS: The estimates of goodness-of-fit for the single-factor-model underlying MS were acceptable both in children and adolescents. The construct stability of a new model including the differences from baseline to the end of the follow-up in the components of the proposed model displayed good fit indexes for the change, supporting the hypothesis of a single factor underlying MS component trends. CONCLUSIONS: A single-factor-model underlying MS is stable across the puberty in both Estonian and Swedish young people. The MS index tracks acceptably from childhood to adolescence.

Factors associated with speeding penalties in novice drivers.

Novice drivers are an important risk group in traffic and speed limit exceeding is one of the major risk factors for traffic collisions. In this paper we explore how impulsivity measures, driving skills and driving safety are associated with speed limit exceeding in novice drivers if described variables are measured on the same subjects. Participants of the study were 909 novice car-drivers (mean age 24.7(SD=7.5) years). Subjects filled Barratt Impulsivity Scale, Adaptive and Maladaptive Impulsivity Scale (AMIS), Social Motivation Scale and Driver Skill Inventory (DSI). The data on traffic violations were obtained from the police database and the data on traffic collisions from the national traffic insurance database. During the one year follow-up time 49 drivers received penalties by the traffic police for exceeding the speed limits. Based on the traffic police penalties for speed limit exceeding, subjects were classified as speed limit exceeders (cases) and controls. Among speed limit exceeders, the proportions of drunk drivers (6.1% vs 0.7%), subjects with other violations (44.9 % vs 12.7%), and passive traffic collisions (the subject was not guilty in the traffic collisions) (18.4 % vs 6.4%) were greater in comparison with controls. Simple logistic regression analysis revealed that speed limit exceeders were more likely to have higher scores in Excitement Seeking (OR(95%CI)=1.09(1.02-1.16)) and Fast Decision-Making (OR(95%CI)=1.09(1.02-1.17)) in AMIS, and in Driving skills in DSI (OR(95%CI)=1.19(1.13-1.25)) than controls. Overestimated Driving skills in DSI was the strongest predictor of speed limit exceeding if compared to other psychometrical variables in the total sample and in men, and besides Disinhibition in women. The results show that speed limit exceeders perceive their driving skills inadequately. We see a need to develop new possibilities where drivers can objectively estimate their own skills and impulsivity tendencies.

The effect of a functional NOS1 promoter polymorphism on impulsivity is moderated by platelet MAO activity.

RATIONALE: Platelet monoamine oxidase (MAO) activity is associated with impulsivity in clinical samples. Recently, a functional promoter polymorphism of neuronal nitric oxide synthase (NOS1) termed NOS1 ex1f-VNTR was found to have an effect on impulsivity-related traits and resulting psychopathology. OBJECTIVE: The study aims to explore the effect of both platelet MAO activity and NOS1 ex1f-VNTR genotype on impulsivity in a population-derived sample. METHODS: This study was on a non-clinical sample of adult male subjects, previously used to investigate the effect of platelet MAO activity on impulsivity-related behaviour (Paaver et al., Psychopharmacology 186:32-40, 2006). Six hundred thirty-seven male subjects were genotyped for the NOS1 ex1f-VNTR promoter polymorphism. Impulsivity was self-reported. Effects of age and smoking, known to affect platelet MAO activity, were controlled for. RESULTS: No main effect of either NOS1 genotype or platelet MAO activity was present. However, significant interactions were found between effects of the NOS1 genotype and platelet MAO activity on impulsivity measures. Impulsivity and in particular the aspects of adaptive impulsivity (e.g. fast decision-making and excitement-seeking behaviour) were higher in subjects with the NOS1 ex1f-VNTR short/short genotype if they belonged to the platelet MAO medium activity (interquartile) range. CONCLUSIONS: This study supports evidence for higher impulsivity in the NOS1 short/short genotype subjects and further suggests that this is present in the subset of subjects who have close to average platelet MAO activity.

The transcription factor TFAP2B is associated with insulin resistance and adiposity in healthy adolescents.

Insulin resistance and central adiposity are strong risk indicators for type 2 diabetes and coronary heart disease. An important role for adipose tissue in the etiology and progression of these conditions has recently become more evident. A transcription factor, TFAP2B, has been shown to participate in the regulation of adipocyte metabolism, by facilitating glucose uptake and lipid accumulation, while simultaneously reducing insulin sensitivity, and recently a direct function for TFAP2B as an inhibitor of adiponectin expression was observed. In this study, we have investigated how insulin resistance, plasma adiponectin, and central adiposity, in a normal population of adolescents, are affected by genetic variability in TFAP2B. Our results show that both insulin sensitivity, as measured from levels of fasting glucose and insulin, and central adiposity, estimated by subscapular skinfold thickness, were significantly associated to genetic variability in TFAP2B. This association was restricted to males only, where carriers of the 4-repeat allele of intron 2 had higher insulin sensitivity and lower subscapular skinfold thickness. Levels of adiponectin did not show any association to the TFAP2B polymorphism, but was negatively correlated to central adiposity in females. These results suggest that reduction of TFAP2B expression could have a protective effect against future risk of complications associated with decreased insulin sensitivity and central adiposity, such as type 2 diabetes and coronary heart disease.

Associations between an alpha 2A adrenergic receptor gene polymorphism and adolescent personality.

The aim of this study was to investigate the impact of the C-1291G polymorphism in the promoter region of the alpha 2A adrenoreceptor gene (ADRA2A) to the personality traits. In the present study, data of the younger cohort of the Estonian Children Personality Behaviour and Health Study was used (N = 419). Personality traits were assessed by 240-item (Estonian Personality Item Pool NEO (EPIP-NEO)). Restriction enzyme MspI was used after PCR amplification to genotype the subjects according to C-1291G polymorphism of the ADRA2A. There were no significant differences on the level of the Big Five personality domains between genotypes; however, there were three significant differences on the level of different subscales. The subjects with GG genotype had significantly higher scores on Depression and significantly lower scores on Morality and Orderliness compared to subjects with CC and CG genotypes. There was a significant interaction between sex and ADRA2A polymorphism regarding E1, Friendliness; E2, Gregariousness; and E6, Cheerfulness. With CC and CG genotypes girls had higher scores on extraversion scales than boys, but with GG genotype boys score higher than girls with GG genotype. It is concluded that the gene polymorphism in the ADRA2A has an influence on personality traits in adolescents.

Association of traffic behavior with personality and platelet monoamine oxidase activity in schoolchildren.

PURPOSE: Estimations, attitudes and behavioral decisions in everyday life, including traffic-related situations, are influenced by personality traits. It is known that that there is a strong link between certain personality traits, particularly impulsivity, and central serotonergic functioning. This study examined associations between traffic behavior, personality and platelet monoamine oxidase activity, a marker of central nervous system serotonergic neurotransmission, in schoolchildren. METHODS: Participants were 483 schoolchildren (aged 15.3 +/- .5 years) who filled in questionnaires on traffic behavior and personality. Platelet monoamine oxidase activity was measured radioenzymatically. RESULTS: Simple logistic regression analysis revealed that subjects with riskier traffic behavior had higher impulsivity (both adaptive as maladaptive facets) as well as lower Openness, Agreeableness, and Conscientiousness. In multiple logistic regression analysis, many of these associations became nonsignificant, but the high traffic risk group was more likely to have lower Agreeableness and lower platelet MAO activity. Low platelet MAO activity was a significant predictor of risky traffic behavior only in girls who were also influenced by higher Excitement Seeking. Smoking was an independent predictor of all groups with high traffic risks. CONCLUSION: Risky traffic behavior in schoolchildren is associated with basic personality dimensions, most consistently with Agreeableness, and with different aspects of impulsivity. Some of these traits, particularly in girls, may be related to central serotonergic neuronal activity.

Adaptive and maladaptive impulsivity, platelet monoamine oxidase (MAO) activity and risk-admitting in different types of risky drivers.

RATIONALE: Platelet monoamine oxidase (MAO) activity reflects serotonergic functioning associated with impulsive behaviour, but the significance of these associations to real-life impulsive behaviour in healthy subjects is not clear. OBJECTIVES: The present study explores impulsivity and platelet MAO activity among people with driving violations. MATERIALS AND METHODS: We compared facets of impulsivity and platelet MAO activity in 1,004 male drivers, out of whom 203 had been caught by the police driving drunk and 292 had been caught exceeding speed limits and committing other non-alcohol-related driving violations. Subjects with speeding and other non-alcohol-related violations were further divided according to their self-reported risk-admitting of exceeding speed limits. RESULTS: While drunk driving was associated only with maladaptive types of impulsivity, exceeding speed limits was associated with functional impulsivity and excitement seeking and, to a lesser degree, with dysfunctional impulsivity. Drunk drivers had lower platelet MAO activity. Risk-admitting high-risk drivers had higher platelet MAO activity, neuroticism-related impulsivity, dysfunctional impulsivity and excitement seeking compared to all other groups and higher functional impulsivity compared to controls. Risk-denying high-risk drivers had only higher functional impulsivity compared to controls. CONCLUSIONS: This study demonstrates different expressions of functional and dysfunctional impulsivity in behaviour. While platelet MAO activity is lower in alcohol-related risky behaviour, non-alcohol-related self-acknowledged risky behaviour is related to higher platelet MAO activity. Thus, deviance towards lower as well as higher end of central serotonergic functioning may lead to impulsive behaviour. While self-reported impulsivity did not correlate with MAO activity, both MAO activity and impulsivity were related to risky behaviour.

Predicting drunk driving: contribution of alcohol use and related problems, traffic behaviour, personality and platelet monoamine oxidase (MAO) activity.

AIMS: The aim of the study was to characterize the predictive value of socio-economic data, alcohol consumption measures, smoking, platelet monoamine oxidase (MAO) activity, traffic behaviour habits and impulsivity measures for actual drunk driving. METHODS: Data were collected from 203 male drunk driving offenders and 211 control subjects using self-reported questionnaires, and blood samples were obtained from the two groups. RESULTS: We identified the combination of variables, which predicted correctly, approximately 80% of the subjects' belonging to the drunk driving and control groups. Significant independent discriminators in the final model were, among the health-behaviour measures, alcohol-related problems, frequency of using alcohol, the amount of alcohol consumed and smoking. Predictive traffic behaviour measures were seat belt use and paying for parking. Among the impulsivity measures, dysfunctional impulsivity was the best predictor; platelet MAO activity and age also had an independent predictive value. CONCLUSIONS: Our results support the notion that drunk driving is the result of a combination of various behavioural, biological and personality-related risk factors.

Low platelet MAO activity associated with high dysfunctional impulsivity and antisocial behavior: evidence from drunk drivers.

RATIONALE: Low platelet monoamine oxidase (MAO) activity is associated with problem drinking and other deviant behaviors. Since the majority of alcohol abusers are smokers, and tobacco smoke has a direct inhibitory effect on the enzyme, these associations may not be meaningful. OBJECTIVE: The authors compared platelet MAO activity and impulsivity in police-referred subjects caught driving while intoxicated and in control subjects, controlling for smoking. METHODS: Platelet MAO activity was measured radioenzymatically and impulsivity scores obtained from questionnaires. Smoking status was self-reported. RESULTS: Subjects caught driving while intoxicated had significantly higher dysfunctional impulsivity and lower platelet MAO activity than control subjects. This difference in platelet MAO activity between the two groups was significant in non-smokers and ex-smokers. CONCLUSIONS: These findings demonstrate that platelet MAO activity is lower in subjects with socially deviant behavior, and the association of low platelet MAO and problem drinking is not an artifact of smoking.