Central sites of action of caffeine

The widespread use of caffeine-containing beverages has focused research on the mechanisms underlying the central effects of caffeine.1-3 While the effects of moderate doses of caffeine on behavior are complex, it appears likely that blockades at A1- and A2A-adenosine receptors are the primary molecular sites of action for caffeine. There are at least four types of adenos-ine receptors in brain.4,5 The A1-class can be inhibitory to adenylate cyclase, stimulatory to potassium channels,...

General effects of caffeine on cerebral blood flow

Methylxanthines such as caffeine or theophylline induce vasodilation, except in the central nervous system where they raise cerebrovascular resistance this actually contributes to a reduction in cerebral blood flow. The cerebral vasoconstrictive properties of methylxanthines have been demonstrated in humans48-51 and animals.15,16,52,53 In rats, as shown in Figure 3.5, caffeine induces a decrease in the rates of LCBF, mainly in the areas where it increases metabolism, i.e., in monoaminergic cell...

Effects on behavior and performance

There has been relatively little work concerning the effects of habitual caffeine use on task performance. While there appears to be no effect on some tasks,137,144 including reaction time and anagram performance,21 behaviors involving focused attention may be affected. In one investigation, we found a borderline difference (p< .06) in recall performance favoring high caffeine consumers.77 In another, habitual consumption significantly facilitated paired-associate memory performance when a...

Caffeinism

Caffeine is only one of a number of factors that enter into the development and expression of symptomatology in most anxiety disorders, but can it be a direct, primary causal factor It would appear that the answer is yes. The first published report of caffeinism essentially an anxiety disorder based on chronic high caffeine consumption appeared in 1967 and described the case of a woman thought to have an anxiety disorder until it was determined that she was consuming 15 to 18 cups of brewed...

Caffeine cerebral blood flow and pathology

In adult rats, rabbits, and dogs, theophylline has been shown to significantly attenuate, reduce the duration, or even block the increase in cerebral blood flow recorded during moderate and severe hypoxia,64-67 whereas dipy-ridamole and papaverine, inhibitors of adenosine uptake, have the opposite effects.68 Conversely, theophylline produces no significant effect on hyper-capnia-induced increase in cerebral blood flow.64,69 These results confirm the specificity of action of theophylline and...

Caffeine and effect

If cognition is one side of the psychological coin, emotion is the other, and caffeine has been shown to have important effects on this aspect of functioning as well. Depending upon dosage level and other concurrent factors, caffeine can result in either positive or negative mood changes. 1. Caffeine and mood state Several studies have shown that caffeine can improve mood states, increasing the frequency of positive mood self-reports 14,45,87,190-193 in both regular caffeine users and...

Caffeine and nicotine

Like caffeine, nicotine is classed as a stimulant. Its behavioral effects are due to a number of actions, including agonist activity at central nicotinic cholin-ergic receptors.1 At moderate doses, nicotine can increase rates of schedule-controlled responding, an effect that is blocked by the nicotinic receptor antagonist mecamylamine.2 Nicotine is administered in the form of tobacco smoke, other tobacco products, nicotine chewing gum, and transdermal patches. Studies of coffee drinking and...

Caffeine and benzodiazepines

Benzodiazepines are widely used for the treatment of anxiety and insomnia as well as a variety of other disorders. In most countries they are available on medical prescription. Problems of dependence and abuse have been recognized for some time, although the dependence potential of these drugs remains a matter of contention.14 In addition to their anxiolytic and hypnotic effects, benzodiazepines produce sedation, muscle relaxation, and cognitive and psychomotor impairment. A number of studies...

The relationship between neurochemical and behavioral effects of caffeine

Caffeine can affect several types of behavior. Studies have investigated these effects on spontaneous motor activity, learning, memory, and mental performance, vigilance, endurance, social behavior, aggressiveness, and mood, anxiety, and sleep (see Reference 78 for a review). The broad findings are that caffeine tends to produce a more rapid and clearer flow of thought, to allay drowsiness and fatigue, sustain intellectual affect and a more perfect sensory association of ideas, and to produce a...

Effects of caffeine on the nigrostriatal dopaminergic system and on locomotor activity

The nigrostriatal dopaminergic system originates in neurons located in the substantia nigra, mainly in the pars compacta and to a lesser extent in the pars reticulata. These neurons project via the median forebrain bundle and the lateral hypothalamus to the globus pallidus and terminate in the caudate nucleus.13,14 This system is involved in the control of locomotion. The stimulant effects of caffeine on LCMRglcs in the structures mediating locomotor activity have been shown previously at quite...

About the Editors

Gupta is a professor of psychology at Banaras Hindu University, Vara-nasi, India. He received his M.A. and Ph.D. degrees from the Department of Psychology at Panjab University, Chandigarh, India. Before coming to Banaras Hindu University, he taught at Meerut University in Meerut and Guru Nanak Dev University in Amritsar, India. He has published numerous research articles and book chapters on behavioral effects of drugs and Ayurvedic herbs, drug abuse, verbal conditioning, personality,...

Adenosine analogs and xanthines

The synergy with respect to behavioral depression observed with combinations of A1- and A2A- selective agonists45 may explain the high potency of the mixed A1 A2 agonist NECA as a behavioral depressant, and might explain the enhanced depressant effects of all adenosine analogs after the chronic caffeine-elicited up-regulation of A1-adenosine receptors. The converse to synergisms for agonists appears to apply with respect to the behavioral stimulation elicited by xanthines. Thus,...

Effects of caffeine on the mesolimbic dopaminergic system and psychostimulant effects

The possible dependence on caffeine has been considered by several groups for over a decade.33-37 The mesolimbic dopaminergic system plays a critical role in drug dependence.38 The mesolimbic dopaminergic system originates in the ventral tegmental area, projects to the nucleus accumbens, and terminates in the medial prefrontal cortex. The nucleus accumbens that plays a central role in the mechanism of drug dependence is functionally and morphologically divided into a core and a shell part. The...