Archive for category Amphetamines'

Empirical Evidence of the Effects of Amphetamine on Aggression

The effect of methamphetamine () on aggressive behavior has not been studied. However, anecdotal evidence provided by numerous judicial and clinical workers suggests a high correlation between aggressive acts and the use of drugs, most prominently stimulants such as methamphetamine. The effects of the d- and L-isomers of amphetamine on aggressive behavior have been studied in rats, mice, humans, and nonhuman primates. In this chapter we assume that the effects of methamphetamine on aggressive behavior are similar to the effects of amphetamine. This is most likely, but not necessarily the case. Speculation has been made that the potential combination of the induced psychoactive effects of amphetamines can lead to dangerous and aggressive behavior (). However, there is a body of research suggesting that high doses of amphetamine essentially reduce aggressive behavior (antiaggressive effects), while lower doses may potentiate aggressive responses. Rodents and primates are frequently used as analogous models for humans in experimentation because ethical considerations preclude the use of human subjects. Further, the brain structures of these animals are similar enough to those of humans to allow us to gather a great deal Read more […]

Administration of Amphetamines to Rodent Subjects

As mentioned above, ethical concerns preclude the use of humans in many experimental situations; however, we can understand many features of the human central nervous system by understanding the brains of other animals. The animal most widely used in the area of amphetamine experimentation is the rodent, which has an analogous, rather than homologous, brain structure to humans. In the following sections, we examine the modification of aggressive behavior in rodents by amphetamines. The various aspects of aggressive behavior include the tendency for provoked attack, the influence of environment on behavior, social factors, and the neurological basis of aggression. Behavioral Observations When using nonhuman subjects to study aggressive behavior, the typical research methodologies most usually employed by experimenters include pain-, isolation-, and brain stimulation-induced aggression. However, when making a comparison between animals of different species the outcomes of these tests yield varying and somewhat contradictory results, which in turn hampers one’s ability to generalize to the human population. Additionally, it has been found that the most important aspects of amphetamine-stimulated aggressive and defensive Read more […]

Amphetamines and Their Effects on Dominance Hierarchy in Primates

Humans are primates, as are monkeys and apes. Evolution tends to be very conservative and so the brains of humans are very similar to our cousins. In fact, genetically we are about 98% the same as our primate cousins. Although research that involves monkeys demonstrates the same dose-dependent effects of amphetamine as shown with rodent subjects, the resultant effects on aggressive behavior favor a positive rather than negative relationship (). Primarily, the effects that amphetamine has on primates’ dominance rank have been examined. Analysis has suggested that these effects are a function of social status and group dynamics (). Differences of Effects between Ranks The behavior of dominant animals differs drastically from that of subordinate animals (). We tend to categorize dominant styles of behavior as aggressive and subordinate styles of behavior as defensive. Dominant and subordinate animals also differ from each other neurochemically and hormonally. We can identify the rank of a primate within its hierarchy by observing behavior. When amphetamine is administered to monkeys of different social status within an established colony, the subjects express behavior dependent on their position in the hierarchy. For Read more […]

Amphetamines and Their Effects on Human Aggressive Behavior

Because the possession, use, and distribution of amphetamine are illegal and because the compound causes brain damage, ethical concerns have prevented experimental research on the behavioral effects of amphetamine. Thus, the available literature on the effects of amphetamine in human participants is all correlational. Although there have been reports of high correlations between violent crime and amphetamine use, these studies may be confounded because other drugs such as alcohol are often involved and users that commit these acts sometimes have aggressive tendencies beforehand (). The existing literature does give some indication regarding the effects of various doses and the possible predictions one can make concerning the long-term effects on mental health, but until more research can be performed we are limited in our understanding the relationship of amphetamine with human aggressive behavior. Subjective Analysis The advantage of experiments involving human subjects is that people have the ability to describe their immediate emotional states and report their feelings and thoughts. However, these subjective analyses can sometimes be inaccurate, and in a sense become “contaminated” because of participants’ biases Read more […]

Drug-Drug Interactions of Amphetamines

Adrenergic neuron blocking drugs Amphetamines and other stimulatory anorectic agents, apart from fenfluramine, would be expected to impair the hypotensive effects of adrenergic neuron blocking drugs such as guanethidine. Not only do they release noradrenaline from stores in adrenergic neurons and block the reuptake of released noradrenaline into the neuron, but they also impair re-entry of the antihypertensive drugs. Alcohol Alcohol increases blood concentrations of amphetamines. Barbiturates Barbiturates can enhance amfetamine hyperactivity. Benzodiazepines Benzodiazepines can enhance amfetamine hyperactivity. Estradiol Preclinical studies (as well as anecdotal clinical reports) have shown that estrogens, through effects on the central nervous system, can influence behavioral responses to psychoactive drugs. In an unusual crossover study, the subjective and physiological effects of oral D-amfetamine 10 mg were assessed after pretreatment with estradiol. One group of healthy young women used estradiol patches (Estraderm TTS, total dose 0.8 mg), which raised plasma estradiol concentrations to about 750 pg/ml, and a control group used placebo patches. Most of the subjective and physiological effects of amfetamine Read more […]