Caffeine is a widely-used drug that modifies the psychological condition of the consumers. At high doses, it causes various caffeine-related symptoms such as agitation, as well as the restless legs syndrome. Since caffeine is a habit forming drug, it allows the development of tolerance and withdrawal symptoms. It also alters sleep patterns in accordance with the consumed daily caffeine dose. Although its arousal of the central nervous system can induce pleasant effects at relatively lower doses, caffeine can impair concentration and attention at increased doses. The present study, therefore, examines the various adverse effects of consuming caffeine at high doses. The paper starts out with an examination of the chemical nature of caffeine and then investigates its mechanism of action. Subsequently, the effect of caffeine on psychiatric and psychological disorders, as well as its role in the development of the restless legs syndrome, is investigated. The study then explores caffeine’s adverse effects on mood, performance, and behavior. Finally, an examination of the possible benefits of high caffeine intake is conducted. The study, however, concludes that such benefits are presented in outdated studies and fail to offset the numerous potential risks outlined in the current research.
Keywords: Caffeine, psychological disorders, psychiatric disorders, restless legs syndrome
Caffeine or 1, 3, 7-trimethylxanthine is the most common psychoactive drug worldwide (Caffeine: Read about Side Effects, n. d.). Although the stimulant is obtained from various plants, it is derived primarily from coffee beans (Higdon & Frei, 2006). Other major sources of natural caffeine include guarana (Paulina cupana), green tea (Camellia sinensis), and cacao beans (Tsvetkova, Klisurov, Pankova, & Zlatkov, 2014). In Canada, for example, most adults obtain thirty percent of their caffeine from tea and sixty percent from coffee (Health Canada, 2007). The remaining ten percent is obtained from medicines, chocolate products, and cola beverages. However, children between the ages of one and five years receive nearly 55% of their caffeine from cola drinks, fourteen percent from chocolate, thirty percent from tea, and the rest from sources such as medicines (Health Canada, 2007). Caffeine is also found in various weight control products and combination medications (Caffeine: Read about side effects, n. d.). Typically, its biological effects result from the antagonism of A2A and A1 adenosine receptor subtypes (Higdon & Frei, 2006). Since the endogenous neuromodulator Adenosine (Figure 1) has inhibitory impacts, the caffeine’s adenosine antagonism causes stimulatory effects on the body.
Figure 1. Caffeine and Adenosine (Source: Higdon & Frei, 2006). The diagram illustrates the chemical structures of adenosine and caffeine.
Typically, caffeine is quickly absorbed in the small intestine before its distribution to the body tissues. Its metabolism occurs mainly in the liver with “cytochrome P450 isoform CYP1A2” causing almost ninety-five percent of the activities involved in caffeine metabolism (Higdon & Frei, 2006, p. 102). Whether consumed in food or medicine, caffeine alters the functioning of the brain and affects behavior (Caffeine: Read about side effects, n. d.). Its primary effect on the body is improving wakefulness but can also cause adverse effects in different individuals (Medicines in my home, 2007). For example, persons with cardiac disease should avoid the intake of caffeine because it exacerbates heart problems. Moreover, it can aggravate the conditions of persons with panic attacks or anxiety problems (Medicines in my home, 2007). The body gains tolerance when caffeine is consumed daily. As a result, the individual consumes more caffeine to produce the desired effects of wakefulness (Medicines in my home, 2007). Nevertheless, the increased caffeine consumption causes addiction or physical dependence and withdrawal symptoms may include irritability, muscle aches, severe headaches, and temporary depression (The Hidden Dangers of Caffeine, n. d.). Researchers agree that taking more than four cups of coffee on a daily basis results in excessive consumption of caffeine (Medicines in my home, 2007). Doctors, therefore, suggest that taking less than two cups of coffee results in moderate caffeine consumption and, hence, poses no danger to human health. Nevertheless, the effects of caffeine vary with the size, sensitivity, and sex of different individuals. Its overdose has also been shown to cause death in certain individuals (Medicines in my home, 2007). Moreover, caffeine’s physiological effects, such as stimulation of the central nervous system and increased metabolic rate, have been shown to modify the psychological state negatively (Chawla, 2013). Consequently, the present study investigates the adverse psychological impacts of consuming high amounts of caffeine. The thesis statement argues that a high caffeine dosage has adverse psychological effects and, therefore, should be avoided.
Mechanism of Action
Caffeine’s adverse effects on the body occur through five primary mechanisms. First, caffeine causes the blockage of adenosine receptors and, hence, inhibits their activities (Pesta, Angadi, Burtscher & Roberts, 2013). Caffeine can reduce blood flow to the cerebrum and antagonize various blood vessels’ adenosine receptors. Consequently, it can decrease adenosine-mediated vasodilatation and reduce myocardial blood flow. The second mechanism is increased fatty acid oxidation, which decreases the body’s reliance on the utilization of glycogen (Pesta et al., 2013). Caffeine changes “substrate preference from glycogen to fat by increasing hormone sensitive lipase (HSL) activity and inhibition of glycogen phosphorylase activity” (Pesta et al., 2013). Thirdly, caffeine inhibits phosphodiesterase enzymes through its non-selective competitive activity. Typically, phosphodiesterases induce the hydrolysis of the phosphodiesterase bond in cyclic adenosine monophosphate (cAMP) molecules and, thus, prevent the breakdown of cAMP (Pesta et al., 2013). The cAMP molecule is significant in epinephrine cascade and has a critical role in the activation of protein kinase A, which phosphorylates several enzymes during lipid and glucose metabolism (Pesta et al., 2013). Fourthly, caffeine may affect the body functions by increasing the accumulation of post-exercise muscle glycogen. The last mechanism is intracellular calcium mobilization. Caffeine often ameliorates the release of calcium from sarcoplasmic reticulum and prevents its reuptake (Pesta et al., 2013).The mechanism allows caffeine to improve contractile force that occurs during submaximal contractions in non-habitual or habitual caffeine consumers.
Although the different mechanisms may function to induce ergogenic effects, caffeine has diuretic characteristics that may cause ergolytic impacts during endurance sporting events. Different mechanisms are involved in caffeine’s diuretic activity. For example, diuresis may occur when caffeine decreases the resorption of chlorine and sodium ions in proximal channels of the kidney (Tsvetkova et al., 2015). Secondly, caffeine improves glomerulus filtration and, hence, induces diuresis. Thirdly, it increases the blood’s plasma volume by reducing tissue hydrophilicity and inhibits the antidiuretic hormone secretion by stimulating volumetric receptors (Tsvetkova et al., 2015). The public, therefore, is encouraged to avoid the consumption of caffeine in situations where the risk of dehydration is high, for example, during long-haul flights (Winston, Hardwick, & Jaberi, 2005). Moreover, high caffeine doses may promote tremor, restlessness, and tachycardia in different individuals (Pesta et al., 2013).
Caffeine’s Negative Effects on Various Psychiatric Disorders
Caffeine has been reported to induce and promote various sleep disorders, particularly insomnia (Winston et al., 2005). For example, it minimizes slow-wave sleep during the initial sleep cycle phase and then decreases the rapid eye movement sleep. Consequently, high caffeine doses in late evening increase wakefulness, as well as the time required to fall asleep. In the elderly persons, the taking of medication that contains caffeine increases the risk of wakefulness at night (Winston et al., 2005).
Clinical experience demonstrates that individuals with eating problems, such as anorexia nervosa and bulimia nervosa, drink large quantities of caffeine-containing beverages in the effort to suppress appetite and promote metabolic rate (Winston et al., 2005). Since persons with anorexia nervosa face an increased risk of arrhythmia, the caffeine’s stimulant effect on heart muscles may promote the risk of cardiac arrest.
Caffeine’s impacts on psychotic disorders have been studied in schizophrenic individuals. Since the brain’s dopaminergic system and adenosine A2A receptors have a significant connection, the adenosine’s inhibition of dopaminergic neurotransmission allows caffeine to block the A2A receptors (Winston et al., 2005). Clinically, caffeine intoxication produces symptoms that are similar to medications’ side effects or signs of psychosis. Similarly, the drowsiness and fatigue associated with caffeine cessation can mimic the side-effects associated with psychotropic drugs (Winston et al., 2005). Research has also demonstrated that schizophrenic people consume high caffeine doses to eliminate the sedating effects linked to antipsychotic medication. Since psychotropic drugs cause a dry mouth, the schizophrenic persons feel compelled to increase their intake of caffeinated drinks (Winston et al., 2005). Nearly 80% of schizophrenic persons are smokers and have the tendency to consume large amounts of caffeine because heavy smoking increases the elimination of caffeine from the body. Episodes of hallucinations and delusions have also been reported after psychotic or nonpsychotic individuals consumed large amounts of caffeine (Winston et al., 2005).
Caffeine and Psychological Disorders
Individuals with psychiatric problems have been shown to present various symptoms of excessive intake of caffeine (Bolton & Null, 1981). Such signs resemble anxiety neurosis and may include twitching, irritability, gastrointestinal disturbance, and recurrent headache. Caffeine-containing medications often include the potential for abuse and numerous persons ingest several symptom-producing doses every day. Different studies have supported the relationship between caffeine and psychological disorders. In one study, for example, a prisoner who drank fifty cups of coffee daily developed severe symptoms of anxiety, which disappeared after the individual quit coffee (Bolton & Null, 1981). Excessive coffee consumption is common among prisoners and often causes a vicious cycle. Boredom also encourages increased intake of coffee, which stimulates various anxiety problems. Additionally, a correlation between caffeine consumption and the level of mental illness has been noted in psychiatric patients (Bolton & Null, 1981). Although it is unclear whether caffeine intensifies psychiatric disorders or patients with severe problems consume relatively more coffee, various studies have noted a relationship between coffee and psychiatric disorders. In an interview involving eighty-three hospitalized psychiatric patients, several symptoms were associated with high caffeine consumption (Bolton & Null, 1981). Nearly 22% of the patients, representing the high caffeine consumers, scored higher on the Beck Depression Scale and State-Trait anxiety index than the lower caffeine consumers. Furthermore, the high caffeine consumers presented relatively worse physical health, more clinical symptoms, and a tendency to use more hypnotics, sedatives, and minor tranquilizers (Bolton & Null, 1981). The high caffeine consumers also showed an increased tolerance to the effects of sleep, which could be attributed to changes in metabolism or body kinetics.
Typically, catecholamines promote depression and, hence, prompt patients to consume more caffeinated drinks to minimize stress. Since caffeine influences the levels of catecholamine and prevents phosphodiesterase disintegration of C-AMP, it sensitizes receptor sites and increases the development of depressive symptoms (Bolton & Null, 1981). Consequently, caffeine may be considered as a psychotropic drug that is consumed excessively and on a daily basis by more than 25% of the population (Bolton & Null, 1981). Caffeine is also found in a large percentage of inpatients suffering from various psychological problems. Nevertheless, the use of caffeine in psychiatric treatment to minimize the drowsiness associated with psychotropic medications should be avoided due to the complications of diagnosing caffeine-induced symptoms in the patients. Additionally, excess intake of caffeine may induce mixed depressive states. As a result, unipolar II depressives often consume more caffeine in response to the development of depression (Bolton & Null, 1981).
Since caffeine is a false antidepressant, it may provide only temporary relief and reduce the effectiveness of antipsychotic and anxiolytic medications. Caffeine has been linked to particular schizophrenic-like conditions that resemble the neurosis symptoms in persons who consume caffeine in large quantities. For example, Bolton and Null (1981) described the case of a Caucasian male in a catatonic condition who went on a coffee jag and posed a threat to his mother. In another incident, a thirty-year-old White lady developed auditory and paranoid hallucinations after an anxiety state associated with high intake of coffee (Bolton & Null, 1981). Finally, the symptoms of one psychoneurotic woman were shown to disappear after reducing her coffee intake. The lady had developed insomnia, irregular fever, irritability, and anorexia after consuming a large amount of coffee (Bolton & Null, 1981). Such incidents suggest that high caffeine dosage should be considered as a significant factor in the diagnosis and treatment of psychiatric patients.
Caffeine and Restless Legs Syndrome
Restless legs syndrome is often linked to clinical states such as depression and anxiety, but the syndrome is caused primarily by caffeine (Bolton & Null, 1981). Since caffeine is a stimulant of the nervous system, it has direct contractile impacts on the striated muscles and leads to conditions such as insomnia, anxiety, and depression. The increased proprioceptive awareness, therefore, causes the restless legs syndrome. The condition, typically, involves nervousness and a distressing sensation that causes frequent leg movements (Bolton & Null, 1981). The symptoms, which often occur at night, prevent the patient from lying still and, hence, cause insomnia. Research shows that the symptoms in most cases of restless legs can be eliminated when caffeine is excluded from the diet (Bolton & Null, 1981). Apart from caffeine, the syndrome can be caused by psychiatric disturbances, such as stress and hysteria, which cause high arousal in the central nervous system. Nevertheless, restless legs syndrome was first observed in England after the introduction of tea and coffee into the country. Therefore, the frequent cause of the condition is the high dosage of caffeine (Bolton & Null, 1981).
Caffeine’s Adverse Effects on Mood, Performance, and Behavior
Research has demonstrated that the consumption of excessive quantities of caffeine causes a spike in anxiety (Bolton & Null, 1981). Moreover, some psychiatric patients often associate their problems with high caffeine dosages whereas patients with anxiety disorders report that caffeine exasperates their condition. Various studies have assessed the validity of such reports and concluded that the administration of over 300 mg of single bolus doses of caffeine led to a significant increase in anxiety (Psychological and physical effects, 2012). The dosage is considered to be several times higher than the caffeine amount in one serving of a cup of coffee. Lower doses, nevertheless, have minimal impact on anxiety and may also lower the anxiety levels in some individuals. Although high caffeine doses have been shown to reduce fatigue, different patients have reported increased nervousness and tension after consuming large amounts of caffeine-containing beverages (Bolton & Null, 1981). Research, therefore, suggests that anxiety spikes following the consumption of caffeine only occur during excessive intake.
Different researchers have suggested that the consumption of huge amounts of caffeine increases arousal and, hence, results in the impairment of hand steadiness. Although early research failed to support such effects, recent studies have confirmed isolated cases of caffeine-induced impairment, which negatively affects physical performance (Kushner, 2006). Furthermore, adverse effects of caffeine on behavior have been noted by different researchers. Such impacts are associated primarily with excessive consumption of caffeine. Nonetheless, persons with high sensitivity to caffeine may also present negative behavior after consuming caffeinated drinks (Chawla, 2013).
Caffeine’s stimulating effects on various body organs and central nervous system can cause particular behavior-oriented effects. At low doses, caffeine stimulates rapid and clear thinking due to its role in decreasing fatigue and drowsiness (Bolton & Null, 1981). For example, typists work relatively faster and make fewer errors after taking a cup of coffee. However, activities that require accurate timing and delicate muscular coordination can become impaired after taking about two cups of coffee. Therefore, the increase in caffeine dosage can have negative impacts on performance and behavior. Researchers have also reported that high caffeine doses impair motor performance and induce effects similar to the activities of hallucinogenic drugs (Bolton & Null, 1981).
Positive Psychological Effects of High Caffeine Dosage
Although current research shows that high caffeine consumption has numerous disadvantages, some past studies demonstrate its positive impacts on psychological health. For example, The Psychologist (2004) pointed out that high caffeine consumption brings numerous cognitive and physical health benefits. High consumption of caffeine-containing green tea on a daily basis has been reported to reduce the risk of cancer development and delay the onset of carcinoma (The Psychologist, 2004). Unfortunately, such benefits were not observed in persons that consumed less than three cups of the green tea. In addition, the polyphenols in green tea help to decrease serum lipids and, hence, lower the risk of heart disease in the heavy consumers of green tea. Martyn and Gale (2003) also reported that long-term consumption of coffee lowered the risk of Parkinson’s disease by nearly 30%, and heavy intake of caffeine reduced the risk of Type 2 diabetes significantly. The Psychologist (2004) explained that older adults who consumed high doses of caffeine demonstrated significant improvement in cognitive health. Thus, “the more caffeine consumed over a lifetime, the better the cognitive performance in old age” (The Psychologist, 2004). Additionally, the individuals who consume high amounts of caffeine show relatively better performance in various concentration, attention, and memory tasks. In a related study, Ennis (n. d.) conducted a literature review to demonstrate the benefits of heavy caffeine consumption. Although the study noted several risks associated with excessive caffeine intake, it argued that the benefits outweighed the possible risks. For example, high caffeine dosage enhanced pain relief, alertness, physical performance, and decreased cognitive impairment significantly (Ennis, n. d.). Coffee and Health (n. d.) also concluded that high caffeine consumption was an efficient countermeasure to the decrements in performance associated with sleep deprivation. Typically, painkillers such as acetaminophen include caffeine as an active ingredient in the treatment of headaches. Caffeine can also treat gallbladder disease, asthma, and the shortness of breath (Caffeine, n. d.). Furthermore, high caffeine doses are combined with ephedrine to provide legal alternatives to banned stimulants. Athletes also use caffeine legally and regularly to enhance their performance.
Despite the evidence demonstrating the benefits of high caffeine consumption, current studies conclude that the potential risks associated with high caffeine intake offset the benefits. For example, a recent study involving 6000 participants reported that long-term consumption of caffeine increased stress, depressed mood, and anxiety levels (Cline, n. d.). Additional current evidence shows that minimal benefits are gained from the regular intake of caffeine because caffeine withdrawal reduces most of the psychological benefits. For example, the overnight caffeine withdrawal decreases alertness and performance levels, whereas increased consumption increases anxiety in susceptible persons (Cline, n. d.). Moreover, a correlation between high caffeine consumption and the increased risk of heart disease has been demonstrated in recent studies. Since most current studies emphasize the consumption of low caffeine to promote psychological health (Psychological and Physical Benefits, 2012), the present investigation notes that past research suggesting the psychological significance of high caffeine intake is unreliable. For example, numerous overt behaviors in adolescent individuals, such as impulsive extravagance, dissociative behaviors, insecurity, and sleep disturbance, have been shown to disappear after the teenagers eliminated their caffeine intake (Cline, n. d.). Current research also shows that high caffeine consumers experience significant nutritional deficiency because the caffeine stresses the glandular system and depletes the body’s supply of vitamins and micronutrients (Cline, n. d.). Therefore, the mental and physical health risks associated with high caffeine dosage outweigh the benefits obtained from such dosages (Kushner, 2006). Additionally, the increase in the daily consumption of fruits and vegetables can provide a safer alternative source of the beneficial antioxidant properties associated with high caffeine intake. Although the world continues to search for commercial products aimed at increasing alertness, stimulation, and energy, the use of caffeine should be moderated to prevent its adverse effects.
The present study has demonstrated that high caffeine dosage has a significant function in the adverse modification of the consumer’s psychological condition. As a result, it supports the research thesis that high caffeine intake should be avoided because it causes adverse psychological effects on the body. Caffeine is among the most common drugs and the individuals that consume tea, coffee, and other caffeinated drinks are susceptible and potential candidates for its effects. The average person can expect expressions that are subtle at low caffeine doses and unconcealed at increased doses. Furthermore, heavy caffeine consumers can become victims of habit and, hence, develop tolerance and acute withdrawal symptoms. Consequently, the enjoyable stimulant feeling experienced at low caffeine doses is often replaced by various psychological conditions at high doses. Such symptoms may resemble depressive neuroses and anxiety. Additionally, excessive caffeine intake can induce or heighten the symptoms of persons with severe psychological conditions. Caffeine’s physiological activity can also significantly alter behavior by modifying sleeping patterns and causing insomnia. Furthermore, the toxic nature of high caffeine dosage may cause adverse effects on task-tailored performance, concentration, and attention. At lower doses, however, such effects may appear beneficial. Finally, research demonstrates that the restless legs syndrome is related to various agitations, but its primary causative agent is high caffeine intake. Caffeine, therefore, is a potent drug whose adverse effects on the nervous system and human behavior are evident. Although some outdated studies have demonstrated the benefits of high caffeine dosage, the adverse psychological effects of the stimulant should be presented to the public and medical community to enhance awareness. Hopefully, the effort would minimize the consumption of caffeinated drinks and medications.
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