Diva Eensoo

Platelet monoamine oxidase in healthy 9- and 15-years old children: the effect of gender, smoking and puberty.

1. The effect of gender, smoking and pubertal development on platelet monoamine oxidase (MAO) activity was described in a randomly selected, large sample of 9- and 15-years old healthy children. 2. Platelet MAO activity was measured in 1129 children by a radioenzymatic method with beta-phenylethylamine as the substrate. Smoking habits were reported in an anonymous questionnaire. Pubertal status was assessed visually using Tanners stages. 3. Boys, younger children and smokers had significantly lower platelet MAO activity than girls, older children and non-smokers, respectively. Girls in Tanners stage V for breast and pubic hair development had significantly lower MAO than girls in stage IV. 4. Differences in gender, age, pubertal status and smoking habits must be taken into account if the relationship between platelet MAO activity, personality and psychiatric disorders is studied in children.

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

RationalePlatelet 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.ObjectivesThe present study explores impulsivity and platelet MAO activity among people with driving violations.Materials and methodsWe 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.ResultsWhile 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.ConclusionsThis 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.

Association between substance use, personality traits and platelet MAO activity in preadolescents and adolescents

This study examined the relationship between alcohol/illicit drug use, the Five-Factor Model (FFM) personality traits, aggressiveness (Agg), and hyperactivity (Hyp), and platelet monoamine oxidase (MAO) activity in a population-derived representative sample of preadolescents and adolescents (n=1172). Alcohol and illicit drug use was self-reported. The FFM personality inventories were filled in by mothers of the participants, and Agg and Hyp were rated by their class teachers. Higher scores in extraversion (E), Agg, and Hyp and lower scores in conscientiousness (C) together with older age were significant predictors of more frequent alcohol use in adolescents. No significant association was found between alcohol illicit drug use, and platelet MAO activity.

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

RationaleLow 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.ObjectiveThe authors compared platelet MAO activity and impulsivity in police-referred subjects caught driving while intoxicated and in control subjects, controlling for smoking.MethodsPlatelet MAO activity was measured radioenzymatically and impulsivity scores obtained from questionnaires. Smoking status was self-reported.ResultsSubjects 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.ConclusionsThese 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.

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

BackgroundMetabolic 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.MethodsWe 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.ResultsThe 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.ConclusionsA 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.

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

RationalePlatelet 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.ObjectiveThe study aims to explore the effect of both platelet MAO activity and NOS1 ex1f-VNTR genotype on impulsivity in a population-derived sample.MethodsThis 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.ResultsNo 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.ConclusionsThis 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.

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.

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.

Platelet monoamine oxidase activity in association with childhood aggressive and hyperactive behaviour: the effect of smoking?

Abstract Monoamine oxidase (MAO) activity in platelets is known to be a marker of certain personality traits and behavioural preferences in adults, but less is known of the association of platelet MAO and behaviour in children. Platelet MAO activity was measured in 1129 randomly sampled 9- and 15-year old children by a radioenzymatic method with β-phenylethylamine as the substrate. Ratings of children’s Aggressiveness, Motor Restlessness and Concentration Difficulties were obtained from teachers. Smokers had significantly lower MAO activity and they were also given significantly higher scores in Aggressiveness, Motor Restlessness and Concentration Difficulties than non-smokers. In 15-year but not 9-year-old children, significant associations were found between platelet MAO activity and behavioural ratings. However, these associations disappeared when smokers were excluded from the analysis. It is concluded that the causal relationship between behavioural measures and platelet MAO can only be revealed with longitudinal studies, considering smoking as a confounding factor.

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 (Asn107Ile) 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.