João Carlos Centurion Cabral

Behavioural, hormonal and neurobiological mechanisms of aggressive behaviour in human and nonhuman primates

Aggression is a key component for social behaviour and can have an adaptive value or deleterious consequences. Here, we review the role of sex-related differences in aggressive behaviour in both human and nonhuman primates. First, we address aggression in primates, which varies deeply between species, both in intensity and in display, ranging from animals that are very aggressive, such as chimpanzees, to the nonaggressive bonobos. Aggression also influences the hierarchical structure of gorillas and chimpanzees, and is used as the main tool for dealing with other groups. With regard to human aggression, it can be considered a relevant adaptation for survival or can have negative impacts on social interaction for both sexes. Gender plays a critical role in aggressive and competitive behaviours, which are determined by a cascade of physiological changes, including GABAergic and serotonergic systems, and sex neurosteroids. The understanding of the neurobiological bases and behavioural determinants of different types of aggression is fundamental for minimising these negative impacts.

Ethanol during adolescence decreased the BDNF levels in the hippocampus in adult male Wistar rats, but did not alter aggressive and anxiety-like behaviors

OBJECTIVE To investigate the effects of ethanol exposure in adolescent rats during adulthood by assesssing aggression and anxiety-like behaviors and measuring the levels of inflammatory markers. METHODS Groups of male Wistar rats (mean weight 81.4 g, n = 36) were housed in groups of four until postnatal day (PND) 60. From PNDs 30 to 46, rats received one of three treatments: 3 g/kg of ethanol (15% w/v, orally, n = 16), 1.5 g/kg of ethanol (12.5% w/v, PO, n = 12), or water (n = 12) every 48 hours. Animals were assessed for aggressive behavior (resident x intruder test) and anxiety-like behaviors (elevated plus maze) during adulthood. RESULTS Animals that received low doses of alcohol showed reduced levels of brain-derived neurotrophic factor (BDNF) in the hippocampus as compared to the control group. No significant difference was found in prefrontal cortex. CONCLUSIONS Intermittent exposure to alcohol during adolescence is associated with lower levels of BDNF in the hippocampus, probably due the episodic administration of alcohol, but alcohol use did not alter the level agression toward a male intruder or anxiety-like behaviors during the adult phase.

Psychological changes arising from an Antarctic stay: systematic overview

Long-term stays in extreme environments, such as Polar Regions, may cause significant changes in the health and well-being of individuals. A systematic overview aimed to map studies about the psychological effects on Antarctic expeditioners. The reviewed data were categorized and divided into two thematic axes: Negative Effects, resulting from harmful psychophysiological variations caused by exposure to the polar stressors, which may present seasonal symptom patterns, altering cognitive performance, mood and interpersonal relationships; and Positive Effects, such as salutogenic results arising from successful adaption to environmental adversities. Due to the great deal of evidence, it is suggested that protection factors should be promoted through preventive approaches, such as psychological training and support in order to reduce symptoms and generate satisfactory adaptation to Antarctica.

Reciprocal effects between dominance and anger: A systematic review

Dominance and high status are directly associated with perception of angry expressions. However, studies that have sought to empirically assess the causal mechanisms between these construct are still relatively scarce. Moreover, several variables can influence and be influenced by both anger and dominance, increasing the complexity of synthesizing the findings related to the association between these agonistic behaviors. We conducted a systematic review in five electronic databases. A total of 207 potentially relevant publications were identified and screened. Of those, 20 articles were found eligible for detailed review, with 26 empirical studies. All reviewed studies reported an association between dominance and anger. Social status and dominance have a direct effect on the perception of anger. In turn, the perception of anger has a consistent effect on attributions of dominance for those who express this emotion. There are mutual effects between dominance and anger, which, if recurring and positively feedback-regulated, at least in perceptual terms, can lead to the establishment and maintenance of dominance hierarchies in social groups.

Stress and Cognitive Reserve as independent factors of neuropsychological performance in healthy elderly

Exposure to high levels of cortisol and self-reported stress, as well as cognitive reserve, have been linked to Alzheimers disease pathology. However, there are no studies on the interaction of these variables. The present study aims to assess the associations of measures of cortisol, self-reported stress, and cognitive reserve with neuropsychological performance in healthy elderly people; besides, to test the interactions between these variables. Cross-sectional analyzes were conducted using data on stress, cognitive reserve and clinical conditions in 145 healthy elderly adults. A neuropsychological battery was used to assess executive functions, verbal memory and processing speed. Measurement of salivary cortisol at the circadian nadir was taken. A negative association between different stress measures and performance on tasks of memory, executive functions and processing speed was observed. Elderly people with higher cognitive reserve showed superior performance on all neuropsychological measures. No significant interaction between stress and cognitive reserve to neuropsychological performance was observed. These results indicate that older adults with high levels of stress and reduced cognitive reserve may be more susceptible to cognitive impairment.

Eliciting Negative Affects Using Film Clips and Real-Life Methods

Although audio-visual stimuli are among the most frequently used methods to elicit emotional reactions in experimental conditions, real-life manipulations have increasingly been used in different countries. However, the applicability of such protocols has not yet been tested in Brazilian Portuguese speakers. Thus, we conducted two experiments to investigate the effectiveness of both methods. In the first experiment, we used film clips to induce negative emotions (i.e., anger, fear, or sadness) or an emotionally neutral condition in 321 undergraduate students. After watching one of the online videos, volunteers completed an emotional assessment. As expected, there were significant differences in all groups. Our results corroborate the relatively discrete patterns in emotion elicitation using films. In the second experiment, anger was elicited in 18 male undergraduates through a hostile social interaction with a confederate and measured by the corrugator muscle activity and cortisol responses. Indeed, there was an increase in corrugator activity in the group exposed to anger induction, even after a few minutes from the end of the experimental manipulation. Implications for experiments on the negative emotions are discussed.

Exposure to methylphenidate during infancy and adolescence in non-human animals and sensitization to abuse of psychostimulants later in life: a systematic review

INTRODUCTION Attention deficit hyperactivity disorder (ADHD) is a neuropsychiatric pathology that has an important prevalence among young people and is difficult to diagnose. It is usually treated with methylphenidate, a psychostimulant with a mechanism of action similar to that of cocaine. Previous studies show that repeated use of psychostimulants during childhood or adolescence may sensitize subjects, making them more prone to later abuse of psychostimulant drugs such as cocaine and methamphetamine. OBJECTIVE To review experimental studies in non-human models (rodents and monkeys) treated with methylphenidate during infancy or adolescence and tested for reinforcing effects on psychostimulant drugs in adulthood. METHOD Systematic collection of data was performed on four databases (Web of Knowledge, PsycARTICLE, PubMed and SciELO). The initial search identified 202 articles published from 2009 to 2014, which were screened for eligibility. Seven articles met the inclusion criteria and were reviewed in this study. RESULTS The findings indicate that early exposure to methylphenidate has an effect on an ADHD animal model, specifically, on spontaneously hypertensive strain rats, especially those tested using the self-administration paradigm. CONCLUSION Future studies should prioritize the spontaneously hypertensive rat strain - an animal model of ADHD. Experimental designs comparing different behavioral paradigms and modes of administration using this strain could lead to improved understanding of the effects of exposure to methylphenidate during childhood and adolescence.

Consumo de Álcool na Adolescência e Relação com Uso Excessivo de Bebidas Alcóolicas dos Pais: Estudantes de Quatro Escolas de Porto Alegre

O objetivo geral do estudo foi investigar a relacao entre o consumo de alcool pelos adolescentes com a percepcao dos mesmos sobre a quantidade de bebidas alcoolicas ingeridas pelos pais. A amostra foi composta de 74 adolescentes estudantes com idade entre 10 e 16 anos, de escolas publicas e privadas de Porto Alegre, RS. Foi aplicado um questionario sobre o primeiro uso de alcool e drogas. Verificou-se associacao estatisticamente significativa entre considerar que alguem na familia bebe excessivamente e qual familiar tem tal comportamento (χ² = 74; gl = 4; p < 0,001). 74% dos adolescentes de 15 e 16 anos ja experimentaram algum tipo de bebida alcoolica. Foi possivel observar relacao significativa entre considerar que um familiar bebe excessivamente e o consumo do alcool pelo adolescente. Concluiu-se que adolescentes que consideram que seus familiares bebem em demasia, consomem alcool mais precocemente, com mais intensidade e bebidas com percentual alcoolico maior.