Hormones and aggression in childhood and adolescence--论文代写范文

一般范畴内，攻击或暴力是综合的定义。有一个单独的基因和神经控制机制,由不同的外部环境控制。基于生物学,弗洛姆认为它们是两个对立的生物概念。下面的essay代写范文进行论述。

Abstract 
  This review is a survey on recent psychobiosocial studies on association between hormones and aggression/violence in children and adolescents, with a special focus on puberty, given the rapid changes in both hormones and behavior occurring during that developmental period. Since it cannot be assumed that all readers have much background knowledge, it inevitably begins with some comments about the concept and multifaceted nature of aggression, as well as with a brief reminding about hormone candidates to be linked to aggression during human development. Then, we finish off with the status of its knowledge in today’s science, tackling in a systematic way with the main data published, hormone by hormone. 

  The origin of the gender-based differences in aggression must lie in neuroendocrinological events occurring during prenatal life or early in postnatal life. A complex and indirect effect of testosterone on aggression is proposed. A low HPA axis activity seems associated with chronic aggressive and antisocial behaviors. It is also suggested that early adrenal androgens contribute to the onset and maintenance of persistent violent and antisocial behavior, and that it begins early in life and persists into adulthood, at least in young boys. There are also some studies suggesting an association between aggression and some pituitary hormones in children, even if present data are still far from being consistent. The hormone-aggression link during development thus is not consistently reported. There can be an indirect relation in three ways: hormones can be involved in the development of aggression as a cause, as a consequence, or even as a mediator. Psychosocial factors may influence the causation and progression of violence in children through hormonal action. D 2002 Elsevier Science Ltd. All rights reserved. 
Keywords: Hormones; Aggression; Violence; Children; Adolescents

 Introduction 
  One of the biggest hurdles in the study of aggression and violence is the lack of a consensus on their definitions (Kavoussi, Armstead, & Coccaro, 1997). Although usage of both terms is recognized, there is much disagreement about their precise meaning and causes. They are used so broadly that it becomes virtually impossible to formulate a single and comprehensive definition. Under the general rubric of aggression or violence an omnibus term with a certain amount of ambiguity is subsumed, which consists of a large variety of meanings, related to several qualitatively distinct subtypes of behavior heterogeneous in nature. Even if they may be similar in appearance, each one is related to different factors, has separate genetic and neural control mechanisms, and is instigated by different external circumstances (see Andreu & Ramirez, in press; Ramı´rez, 1996, 1998, among others). 

  Some authors tend to conceive aggression as a behavior based on biology, and violence as a social construction. Erich Fromm sees them as two antithetic biological concepts. Aggression is seen as a biological behavior, natural to all the animal world, adaptive, intentional and propositional, not always necessarily negative, but sometimes justifiable and beneficial, needed for the survival of the individual and the species, and always under the limits of the self-control. Violence, on the other hand, is considered a biological alteration, privacy of humans, malign, pathological and destructive, and consequently absolutely undesirable and reprobable, that should always be controlled and replaced by an alternative behavior (Go´mez Jarabo, 1999). Another distinction is presented by Archer (1994, 2000), who understands by aggression the occurrence and frequency of acts, with no reference to their consequences; and by violence, solely the damaging consequences of aggressive acts. Many others try to include both within a continuum, rating violence as an extreme, harmful aggression, defined broadly like ‘the abusive or unjust exercise of power’ (Rivara, 2002) or as ‘hypertrophic aggression’ (Sanmartin, 2002). 

  The conceptual differences between aggression and violence thus are still to be clarified (Ramı´rez, 2000a, 2000b). Considering this conceptual confusion in this paper, terms such as violence, aggression, or aggressivity will be used synonymously, for pragmatic and operational reasons. This article will stress the importance of biology in the study of violence during developmental stages, but it does not mean that we conceptualize biology as a domain isolated from other ones. We are not slaves to our genes, nor slaves to our environment. Neglecting psychosocial factors in the causes of aggressive behavior would be as misleading as to focus on the individual’s biology without recognizing its inevitable interaction with other factors, such as cognition, emotion, or social context. 

  A close knit community with stable families and effective policing, for example, may reduce levels of violence in antisocial prone adolescents. And, on the contrary, neglected and abused children are more prone toward antisocial behavior. A developmental perspective of aggression thus is based on the assumption that aggressive behavior is multidetermined and dynamic over the life span, and a product of a complex continuous interaction of the multiple psycho-bio-social changes. This holistic approach promotes a much needed focus on the plasticity of the child (Pribram & Ramı´rez, 1980, 1981, 1995; Stoff & Cairns, 1996). The social environment thus is linked to human behavior through our biology. The most important general insight of recent years has been perhaps the recognition that life experience can shape brain chemistry in significant ways, and that experience and neurophysi- ology form a seamless web. 

  The neurobiological plasticity expressed in the functional organization of the nervous system is open to the input coming from the personal experiences, which can result in large, long-lasting and consequential change. Stressors, for example, appear to affect hormone concentrations in humans, even if these effects have received only minimal research attention. Integration of biological research with social-scientific studies thus can add to our understanding of how life experience influence interactions that involve or lead up to violence (for a longer discussion of this topic, see in this same Journal: Book, Starzyk, & Quinsey, 2001). 

  One of the many biological component systems that affect aggression, and with a very promising future given its extraordinary recent advances, is its relation to chemistry -neurotransmitters, neuromodulators, and hormones. Pharmacological and genetic studies have dramatically expanded the list of neurotransmitters, hormones, cytokines, enzymes, growth factors, and signaling molecules that influence aggression (Nelson & Chiavegatto, 2001). This neurochemical/neuropeptide/neuroendocrine ‘orchestra,’ as it has been elegantly described by Eichelman and Hartwig (1996), is played through many anatomical sites within an organism genetically prepared to function aggressively. 

  Although most of the experimental psychoendocrinological research is done in other animal species, given the many technical and ethical limitations and obstacles encountered in the direct investigation of aggressive behavior in our species (Ramı´rez, 2000b; Ramı´rez & Brain, 1985), human aggression is unique. We may have ‘inherited the biological basis’ for aggression in common with other species, but we have a unique capability for intelligence and learning, and this applies to all kinds of behavior, including the aggressive one. Humans may show overt aggression in the same situations as other animals, such as in competition over food, mates or dominance, but usually our own intelligence plus the social rules established by our culture allow a higher flexibility, preventing us from being violent in those circumstances. The motives for violence in humans are clearly more complex, having to do with self-image, reputation, and perceptions of ‘psychological’ harm (Toch, 1984). 

  This review is a systematic search of hormonal correlates to aggressive behavior in human infancy and adolescence. The main reason for much delimitation is because developmental processes may provide the common ground for understanding the processes of socio-biological integration, and reproductive transitions provide excellent periods of development in which to examine hormone-behavior relations. Age is an as important as neglected individual-differences variable in aggression research. Only a handful of psychological studies had examined age differences (O’Connor, Archer, & Wu, 2001), until the recent ISRA World Conference on Aggression (Montreal, July 28–31, 2002), which has been focused precisely to this very topic: the developmental origins of aggressive behavior.（essay代写)

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