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Biomedical subjects

Jean-Marc Assaad

Publications and source records attributed to Jean-Marc Assaad.

10 recordsLinked to original sources
PubMed2006

Salivary testosterone and aggression, delinquency, and social dominance in a population-based longitudinal study of adolescent males.

Testosterone (T) has been found to have a stimulating effect on aggressive behavior in a wide range of vertebrate species. There is also some evidence of a positive relationship in humans, albeit less consistently. In the present study we investigated the relationship between T and aggression, dominance and delinquency over time, covering a period from early adolescence to adulthood. From a large population-based sample (n = 1.161) a subgroup of 96 boys was selected whose behavior had been assessed repeatedly by different informants from age 12 to 21 years, and who had provided multiple T samples over these years of assessment. On the whole, a decrease in aggressive and delinquent behavior was observed in a period in which T rises dramatically. Boys who developed a criminal record, had higher T levels at age 16. In addition, positive associations were observed between T and proactive and reactive aggression and self-reported delinquent behavior. Over the pubertal years different forms of aggressive and delinquent behavior were positively related to T, which may indicate that specific positive links are dependent on the social setting in which this relationship is assessed.

Adolescent↗
PubMed2006

Intoxicated behavioral disinhibition and the heart rate response to alcohol.

This study examined the association between the heart rate (HR) response to alcohol intoxication, which is thought to reflect sensitivity to alcohol-induced reward and alcohol-induced behavioral disinhibition. High- and low-HR responders to alcohol participated in a go/no-go task, under sober and intoxicated conditions. Errors of commission on this task have previously been related to behavioral disinhibition. High-HR responders made more intoxicated commission errors as compared with low-HR responders. High-HR responders also reported increased alcohol consumption, and controlling for the latter did not alter the significant association between high-HR responders and increased intoxicated errors of commission. These results are consistent with previous findings of an increased risk for addictive and disinhibited behavioral propensities in individuals with a high-HR response to alcohol intoxication.

Alcoholic Intoxication↗
PubMed2006

Heart rate response to alcohol and intoxicated aggressive behavior.

BACKGROUND: This study examined the elevated heart rate (HR) response to alcohol intoxication, thought to reflect an increased sensitivity to alcohol-induced reward, as a potential factor in the increased likelihood of alcohol-induced aggression. METHODS: Three groups, intoxicated high (n=37) and low (n=37) HR responders and sober controls (n=73), participated in a laboratory measure of physical aggression, the Taylor Aggression Paradigm. RESULTS: Results revealed that intoxicated high HR responders were more aggressive than the intoxicated low HR responders and sober controls. CONCLUSIONS: These findings are interpreted within a hypothetical model relating increased alcohol-induced aggression to a dysregulation in the motivational system responding to rewards.

Adult↗
PubMed2004

Cognitive-neuropsychological function in chronic physical aggression and hyperactivity.

Histories of violence and of hyperactivity are both characterized by poor cognitive-neuropsychological function. However, researchers do not know whether these histories combine in additive or interactive ways. The authors tested 303 male young adults from a community sample whose trajectories of teacher-rated physical aggression and motoric hyperactivity from kindergarten to age 15 were well defined. No significant interaction was found. In a 1st model, both histories of problem behavior were independently associated with cognitive-neuropsychological function in most domains. In a second model controlling for IQ, General Memory, and test motivation, none of the three Working Memory tests (relevant to executive function) remained associated with physical aggression or hyperactivity. These results support an additive model but no specificity to executive function [corrected].

Adolescent↗
PubMed2004

Heightened heart rate response to alcohol intoxication is associated with a reward-seeking personality profile.

BACKGROUND: The psychomotor stimulant theory of addiction posits that sensitivity to the positively rewarding properties of alcohol puts certain individuals at higher risk for alcohol abuse. A valid and reliable index of overactivation in the reward system has been a heightened baseline heart rate (HR) increase on the ascending limb of the blood alcohol curve. The main goal of this study was to investigate the relationship between this HR response and a questionnaire measuring sensitivity to reward and sensitivity to punishment. Additional goals included looking at (1). the association between a high HR response and various personality traits (hopelessness/introversion, anxiety sensitivity, impulsivity, and sensation-seeking) and (2). the relationship between these personality traits and stimulant use. METHODS: A total of 18 low- and 19 high-HR responders completed the Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ), the Substance Use Risk Profile Scale (SURPS), and a modified version of the Addiction Severity Index. RESULTS: High-HR responders obtained significantly higher scores than low-HR responders on the sensitivity to reward scale of the SPSRQ, as well as increased sensation-seeking scores on the SURPS. High-HR responders were not at significantly higher risk of having used stimulants, but stimulant use was associated with higher impulsivity scores on the SURPS. CONCLUSIONS: Novelty/sensation-seeking is among the personality traits that have been linked to heavy alcohol use. This study suggests that reward sensitivity might mediate the relationship between this personality profile and drinking behavior.

Adolescent↗
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

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 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↗