Biomedical subjects

Richard E Tremblay

Publications and source records attributed to Richard E Tremblay.

15 recordsLinked to original sources

PubMed2003

Alcohol promotes dopamine release in the human nucleus accumbens.

Microdialysis experiments in rodents indicate that ethanol promotes dopamine release predominantly in the nucleus accumbens, a phenomenon that is implicated in the reinforcing effects of drugs of abuse. The aim of the present study was to test the hypothesis in humans that an oral dose of ethanol would lead to dopamine release in the ventral striatum, including the nucleus accumbens. Six healthy subjects underwent two [(11)C]raclopride PET scans following either alcohol (1 ml/kg) in orange juice or orange juice alone. Subjective mood changes, heart rate, and blood-alcohol levels were monitored throughout the procedure. Personality traits were evaluated using the tridimensional personality questionnaire. PET images were co-registered with MRI and transformed into stereotaxic space. Statistical parametric maps of [(11)C]raclopride binding potential change were generated. There was a significant reduction in [(11)C]raclopride binding potential bilaterally in the ventral striatum/nucleus accumbens in the alcohol condition compared to the orange juice condition, indicative of increased extracellular dopamine. Moreover, the magnitude of the change in [(11)C]raclopride binding correlated with the alcohol-induced increase in heart rate, which is thought to be a marker of the psychostimulant effects of the drug, and with the personality dimension of impulsiveness. The present study is the first report that, in humans, alcohol promotes dopamine release in the brain, with a preferential effect in the ventral striatum. These findings support the hypothesis that mesolimbic dopamine activation is a common property of abused substances, possibly mediating their reinforcing effects.

Adult↗

PubMed2003

Adolescent pain sensitivity is associated with cardiac autonomic function and blood pressure over 8 years.

Low pain sensitivity has been reported in hypertensive subjects as well in groups deemed to be at increased risk of development of the disorder. However, it is uncertain whether individual differences in pain sensitivity are associated prospectively with increases in blood pressure. In the current study, 24-hour blood pressure and heart rate variability were recorded in 110, 22-year-old men previously assessed at age 14 years for casual blood pressure and pain sensitivity (mechanical finger pressure). Significant correlations were observed between pain tolerance in 14-year-olds and current 24-hour systolic blood pressure (r=0.37, P<0.01) and diastolic blood pressure (r=0.36, P<0.01). Hierarchical multiple regression analyses indicated that information regarding pain tolerance improved prediction of systolic and diastolic blood pressure at age 22 years beyond that afforded by differences in blood pressure, parental history of hypertension, and body mass index at age 14 years. Similar analyses revealed that average pain sensitivity at age 14 was also associated with 24-hour high-frequency heart rate variability (r=0.28, P<0.01) and low-frequency/high-frequency heart rate variability at age 22 (r=-0.35, P<0.01), suggesting increased sympathetic and reduced parasympathetic tone among individuals less sensitive to pain. These results provide further evidence that blood pressure related hypoalgesia might be related to processes involved in blood pressure regulation as well as in the development of sustained high blood pressure.

Adolescent↗

PubMed2003

Developmental trajectories of boys' delinquent group membership and facilitation of violent behaviors during adolescence.

Being part of a delinquent group has been shown to facilitate the expression of an individual's own delinquent propensities. However, this facilitation effect has not been investigated from a developmental perspective within a population heterogeneity model. Using a semiparametric mixture model with data from the Montreal Longitudinal Experimental Study, this article addresses important issues in the developmental trends of membership to delinquent groups. We explore how the rate of violent behaviors follows delinquent peer group trajectories and investigate a differential facilitation effect of delinquent peers on violence across multiple developmental pathways. Results suggest that 25% of males followed a childhood or an adolescence delinquent group affiliation trajectory. These two groups account far most of the violent acts assessed during adolescence. In addition, the rate of violent behaviors follows these developmental trajectories. Controlling for these delinquent group trajectories, we also found that being involved in a delinquent group at any specific time during adolescence is associated with an increased rate of violent behaviors, and that leaving these groups results in a decrease in violent behaviors. This facilitation effect appears homogeneous over time and across developmental trajectories. Results are discussed from a social interactional perspective.

Adolescent↗

PubMed2003

Life course turning points: the effect of grade retention on physical aggression.

Our objective is to advance the life course analytical framework by demonstrating a model for testing two of its tenets. The first is whether the individual's developmental history conditions the response to a turning point event. The second is whether the influence of a major life event upon an individual's developmental course depends upon the timing of the event. We test both propositions in an analysis of the effect of grade retention on a child's trajectory of physical aggression. Our analysis is based on data from a longitudinal study of 1,037 boysfrom schools in the lowest socioeconomic areas in Montreal, Canada. We find clear evidence that a developmental history of physical aggression conditions the child's response to grade retention. The evidence on whether the timing of retention affects this response is less clear.

Adolescent↗

PubMed2003

Developmental trajectories of childhood disruptive behaviors and adolescent delinquency: a six-site, cross-national study.

This study used data from 6 sites and 3 countries to examine the developmental course of physical aggression in childhood and to analyze its linkage to violent and nonviolent offending outcomes in adolescence. The results indicate that among boys there is continuity in problem behavior from childhood to adolescence and that such continuity is especially acute when early problem behavior takes the form of physical aggression. Chronic physical aggression during the elementary school years specifically increases the risk for continued physical violence as well as other nonviolent forms of delinquency during adolescence. However, this conclusion is reserved primarily for boys, because the results indicate no clear linkage between childhood physical aggression and adolescent offending among female samples despite notable similarities across male and female samples in the developmental course of physical aggression in childhood.

Adolescent↗

PubMed2003

Exaggerated ethanol-induced cardiac reactivity as an indicator of increased risk for gambling.

Pathological gambling and alcohol dependence show a high rate of co-occurrence. Some individuals at risk for alcohol dependence display an exaggerated heart rate (HR) increase following alcohol consumption, a characteristic suggesting sensitivity to reward. This study examined whether exaggerated ethanol-induced cardiac reactivity was associated with increased gambling behaviors. One hundred five young men (M = 20.13 years, SD = 1.07) consumed 1 ml of ethanol (95% volume) per kilogram of body weight. HR was measured and participants completed the South Oaks Gambling Screen (SOGS; H. R. Lesieur & S. B. Blume, 1987). Those with higher intoxicated HRs reported significantly greater scores on the SOGS (p = .02). This suggests that ethanol-induced HR increase is a possible marker for addictive disorders.

Adult↗

PubMed2003

Aggressiveness, family history of alcoholism, and the heart rate response to alcohol intoxication.

Some sons of male alcoholics (SOMAs) are characterized by an increased heart rate (HR) response to alcohol intoxication, which is thought to reflect increased sensitivity to alcohol-induced reward. Such a response has also been related to increased physical aggression. However, the confounding effect of aggression in SOMAs may be obscuring the interpretation of these findings. The HR response to alcohol was therefore assessed in 4 groups: high/low aggressive SOMAs and high/low aggressive non-SOMAs. Results indicate that aggressive SOMAs had the highest intoxicated HR response and that they reported the most alcohol consumption. This suggests that in some cases the high comorbidity between alcohol misuse and aggression is related to an increased sensitivity to alcohol-induced reward.

Adolescent↗

PubMed2002

A longitudinal-experimental approach to testing theories of antisocial behavior development.

A longitudinal study with a nested preventive intervention was used to test five hypotheses generated from developmental theories of antisocial behavior. The longitudinal study followed 909 boys from their kindergarten year up to 17 years of age. The randomized multimodal preventive intervention targeted a subsample of boys who were rated disruptive by their kindergarten teacher. Semiparametric analyses of developmental trajectories for self-reported physical aggression, vandalism, and theft identified more types of trajectories than expected from recent theoretical models. Also, these trajectories did not confirm theoretical models, which suggest a general increase of antisocial behavior during adolescence. The majority of boys were on either a low-level antisocial behavior trajectory or a declining trajectory. Less than 6% appeared to follow a trajectory of chronic antisocial behavior. Comparisons between disruptive and nondisruptive kindergarten boys confirmed the hypothesis that disruptive preschool children are at higher risk of following trajectories of frequent antisocial behavior. Comparisons between treated and untreated disruptive boys confirmed that an intensive preventive intervention between 7 and 9 years of age, which included parent training and social skills training, could change the long-term developmental trajectories of physical aggression, vandalism, and theft for disruptive kindergarten boys in low socioeconomic areas. The results suggest that trajectories of violent behavior can be deflected by interventions that do not specifically target the physiological deficits that are often hypothesized to be a causal factor. The value of longitudinal-experimental studies from early childhood onward is discussed.

Adolescent↗

PubMed2002

A longitudinal study of pain sensitivity and blood pressure in adolescent boys: results from a 5-year follow-up.

A growing literature has observed a significant reduction in pain sensitivity among hypertensive animals and humans. It is uncertain whether a reduced sensitivity to pain can be observed in nonnotensive individuals who go on to develop high blood pressure. Blood pressure (BP) was reassessed in one hundred fifteen 19-year-old boys initially tested at age 14, when they were also presented with a pain stimulus (mechanical finger pressure). Hierarchical regression analyses indicated that information regarding pain tolerance improved prediction of changes in systolic and diastolic blood pressure beyond that afforded by differences in BP at age 14, parental history of hypertension, and body mass index. These analyses suggest that pain sensitivity may be associated with physiological processes involved in the development of sustained high blood pressure.

Adolescent↗

PubMed2002

Prevalence of methylphenidate use and change over a two-year period: a nationwide study of 2- to 11-year-old Canadian children.

OBJECTIVE: To provide age- and sex-specific estimates of methylphenidate use and to determine use changes over a 2-year period. STUDY DESIGN: We examined the first and second data collection cycles of the National Longitudinal Survey of Children and Youth, a Canadian household survey of children. Participants were children aged 2 years to 11 years at both the first and second cycles whose mothers responded; thus, 16,798 (13,059) children were assessed for the first (second) cycle. Logit modeling was used to estimate prevalence of methylphenidate use, to determine sex and age effects on prevalence, and to examine use changes from cycle 1 to 2. RESULTS: Methylphenidate prevalence ranged from 0.09% to 3.89% across 2- to 11-year old children from the first cycle. Boys were 4.6 times more likely than girls to consume methylphenidate. Use was >4 times greater among 6- to 7-year-old children compared with 4- to 5-year-old children and almost 2 times greater among 8- to 9-year-old children compared with 6- to 7-year-old children. Methylphenidate prevalence increased by 36% from cycle 1 to 2. CONCLUSIONS: Methylphenidate prevalence was relatively low. Boys and school-age children had higher rates of methylphenidate use, and use among 2- to 11-year-old children appeared to be increasing over time.

Age Factors↗

PubMed2002

Childhood behavioral profiles leading to adolescent conduct disorder: risk trajectories for boys and girls.

OBJECTIVE: To examine the link between childhood behavioral dimensions and adolescent conduct disorder (CD) among a large sample of boys and girls monitored longitudinally. METHOD: Teachers rated the behaviors of 1,569 children every year between kindergarten and grade 6. On the basis of these seven yearly ratings, groups of children who followed distinct trajectories on three behavioral dimensions--hyperactivity, fearfulness, and helpfulness--were identified with a semiparametric statistical analysis. Children were then categorized into one of eight behavioral profiles, representing different combinations of the trajectories. Logistic regressions were used to estimate the relation between the profiles and CD in adolescence (mean = 15.7 years). RESULTS: Boys had a significant risk for CD if they were hyperactive (odds ratio [OR] = 4.27; 95% confidence interval [CI], 1.8-10.16); hyperactive and unhelpful (OR = 2.83; CI, 1.07-7.46); or hyperactive, fearless, and unhelpful (OR = 3.93; CI, 1.27-12.17). Girls had a significant risk for CD only if they were both hyperactive and unhelpful (OR = 4.61; CI, 1.31-16.24). More boys than girls exhibited profiles of risk and met criteria for CD in adolescence. CONCLUSIONS: Sex-specific childhood behavioral profiles that represented risk for CD in adolescence were identified. There were sex differences in the prevalence of the childhood profiles representing risk for CD.

Adolescent↗

PubMed2002

Response perseveration in adolescent boys with stable and unstable histories of physical aggression: the role of underlying processes.

BACKGROUND: It was unclear whether response perseveration and underlying processes, often related to antisocial externalizing disorders, were also related to histories of physical aggression. METHOD: Boys of age 13 years were selected on the basis of childhood histories of physical aggression: stable, unstable, and non-aggressive. Performance on a Card Playing Task provided a perseveration index. RESULTS: Physical aggression, regardless of history, predicted perseveration in adolescence. However, qualitative differences revealed that Neuroticism increased the risk for perseveration only in the unstable aggressive group relative to the other groups. Perseveration in the stable aggressive group maybe related to a more fundamental information-processing deficit. CONCLUSION: The identification of these processes has implications for developmental theories of physical aggression; they may help discriminate those children who show early physical aggression and who will remain aggressive from those who will only show occasional physical aggression during later childhood.

Adolescent↗

PubMed2002

Reactively and proactively aggressive children: antecedent and subsequent characteristics.

BACKGROUND: Reactive and proactive subtypes of aggressive 10-11-12-year-old children were compared with non-aggressive children to examine whether the two forms of aggression were differentially related to antecedent and subsequent measures. METHOD: A large community sample of boys and girls was used. Reactive and proactive aggression was measured through teacher ratings when the children were 10, 11 and 12 years old. Antecedent measures were age 6 temperament and behavioral dispositions; subsequent measures were age 13 delinquency and depressive symptoms. RESULTS: Results indicated that reactive and proactive children had distinctive profiles on antecedent and subsequent measures. CONCLUSIONS: We conclude that children characterized by reactive or proactive aggression differ on several dimensions of personal functioning, and that reactive and proactive aggression are distinct forms of aggression, although both co-occur in a large proportion of aggressive children.

Adolescent↗

PubMed2002

The development of impulsivity, fearfulness, and helpfulness during childhood: patterns of consistency and change in the trajectories of boys and girls.

BACKGROUND: The objective of the present study was to describe the development of boys and girls during the elementary-school years on three dimensions that conceptually and empirically represent risk for maladjustment. METHOD: Every year between kindergarten and grade six, teachers rated the impulsivity, fearfulness, and helpfulness dimensions among a sample of 1,865 children representative of kindergarten boys and girls in the province of Quebec (Canada) in 1986-87. A group-based trajectory method was used to 1) identify groups of boys and girls following distinct-level trajectories of behaviours (on each dimension) during the elementary-school years; 2) estimate the proportion of children in each of the identified trajectory groups; and 3) estimate the patterns of consistency and variations in trajectories. RESULTS: The results indicated that the best models comprised three distinct-level trajectory groups on fearfulness and helpfulness (a low, moderate, and high group) and four distinct-level trajectory groups on impulsivity. The helpfulness and fearfulness trajectory groups were generally more stable than the impulsivity groups. The broad patterns of development were similar across sexes. However, there were more boys on the higher impulsivity trajectories and low helpfulness trajectory, while there were more girls on the high fearfulness trajectory. CONCLUSION: We found that behavioural consistency over middle childhood varied across trajectory groups and across dimensions, and we identified sex differences in the distribution of children in the different trajectory groups that may reflect gender-specific risks for psychopathology.

Child↗

PubMedDate not supplied

Obstetrical complications and violent delinquency: testing two developmental pathways.

This study focused on the interaction between specific obstetrical complications and early family adversity in predicting violent behavior during childhood and adolescence, in a sample of 849 boys from low socioeconomic areas of Montreal, Canada. Obstetrical complication data from medical records were used to create three scales using a nonlinear principal component analysis followed by rotation. Family adversity and teacher-rated physical aggression were assessed when the boys were in kindergarten and self-reports of delinquency were collected when they were 17. Elevated scores on the Deadly Risk Situation scale of obstetrical complications (preeclampsia, umbilical cord prolapse, and induced labor) increased the risk of being violent at both 6 and 17 years of age, only among boys who grew up in high adverse familial environments. Moreover, this interaction partly accounted for the continuity between violence in childhood and adolescence. Interventions for young pregnant women from deprived environments and their babies are discussed in light of these results.

Adolescent↗