Behavioral Correlates of Caffeine Consumption by Children Alan Leviton, M.D.
Introduction
(e.g., coffee, 12 to 20 to 8 mg/oz; cola, 3.0 mg/oz; cocoa beverage, 1 mg/oz; mg/oz; sources
tea, 6
of the attention caffeine receives in the lay press, health professionals often are questioned about the effects of caffeine on children. This paper was prepared to meet the need for a current and accurate review for pediatricians. The basic goal was to determine if caffeine consumption in any group of children should be limited. ecause
Consumption In children, caffeine intake as a function of body weight is highest below age five 5 years. 1,2 Based on data obtained by the Marketing Research Corporation of America, the 90th percentile levels of caffeine intake among consumers (in mg/kg) are estimated to be 0.7 for infants, 2.1 for children 1 to 5 years of age, and 1.4 for children 6 to 1’7 years.’ Children tended to get most of their caffeine from coffee and tea, with decreasing amounts from cola and chocolate products.2 This largely reflects differences in caffeine content of the Harvard Medical School and Children’s Hospital, Boston, Massachusetts Address correspondence to: Alan Leviton, M.D., Gardner 445, 300 Longwood Avenue, Boston, MA 02115 First presented at the 60th Annual Meeting, American Academy of Pediatrics, New Orleans, Louisiana, October 27, 1991.
742
chocolate, 35 In a recent study, adults were recruited who acknowledged consuming three to seven cups of coffee per day to determine the effects of caffeine.36 When given blind access to both caffeine-containing and decaffeinated coffee, less than half displayed reliable caffeine self-administration.
con-
might reflect a balance between positive effects (i.e., &dquo;liking&dquo;), and negative response (i.e., the jitters). The following summary of adult studies is more extensive than that for children because little has been written about these phenomena in children and much has been written about studies in adults. Moreover, it is possi-
Children
Compared with their peers who consumed relatively small amounts of caffeine (i.e., less than 50 mg/day) , 10 year-old children who consumed relatively large amounts (i.e., reported intake of at least 500 mg/day) were more likely to be considered &dquo;disobedient&dquo; by their parents.’ This observation leads to
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inferences: caffeine consumption promotes disobedience, and children who are disobedient and impulsive (and perhaps have attention-deficit disorder with hyperactivity) want to ingest more caffeine than children who do not have this disorder. The latter possibility would occur if caffeine has a benefit that can be perceived by children who have attention-deficit disorder. When evaluated while consuming caffeine (5 mg/kg at 8 a.m. and at 3 p.m.), the low consumers were more likely than high consumers to have an increase in scores on the parent-completed Conners 10item behavioral scale, which measures restlessness, irritability, and disruptive behavior. When evaluated while consuming placebo, the two
low
consumers
also tended
to
have
higher measures of electrodermal activity. These differences prompted Rapoport and her colleagues4 to suggest that children choose to consume amounts of caffeine that minimize adverse effects and maximize beneficial effects.
Performance In normal prepubertal boys, caffeine in a dose-dependent fashion appears to shorten reaction time and reduce errors of omission on a continuous-performance task, but it does not improve scores on assessments of cognition.&dquo; The reduction in errors of omission is more obvious in children who
tend to consume the most caffeine than in those who consume little caffeine.4 Consumption of 3 mg/kg is followed by a decrease in motor activity.’ On the other hand, consumption of 10 mg/kg is associated with increased motor activity23,37 and higher scores on the Conners abbreviated parent-rating scale 22 Speech production (words/min) increases with increasing dose of caffeine.23 These observations suggest that a little caffeine (equivalent to two 12-oz cans of cola per day consumed by a 25- to 30-kg child) is helpful, whereas
considerably higher consumption (e.g., the equivalent of ’7r/2 cans per day) has some disadvantages.
Hyperactivity In the 19’70s, before the diagnosis of attention-deficit disorder was a readily available option, 11 studies were published of the effects of caffeine on measures of hyperactivity (Table 2). In only three did the investigators conclude that caffeine was beneficial. The one study from the 1980s found that 300 mg given in the morning and again at noon reduced the number of errors of commission and increased the reaction times on a continuous-performance test.38 No study reported adverse effects with caffeine doses equivalent to the consumption of 90% of children. Unless their consumption exceeds these bounds, hyperactive children need not limit their caffeine consumption. Some symptoms of attentiondeficit disorder persist into adulthood. In light of support for the self-selection and titration hypotheses of caffeine consumption, it seems reasonable that some adults consume caffeine to ameliorate their attention-deficit disorder symptoms. Dalby39 has offered the
provocative hypothesis that, as per capita caffeine consumption con-
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745
tinues to decrease, symptoms of attention-deficit disorder in adults may become more evident, resulting in an increased prevalence of attention-deficit disorder beyond the childhood years.
Aggressive Behavior in Adults
The removal of caffeinated beverages from the canteen and vending machines of a state psychiatric facility in California was accompanied by a decrease in the number of reported episodes of assaultive behavior and property destruction.4° At another California state hospital, which did not change its policy on the availability of caffeine-
containing beverages, however, similar decreases were reported in the rate of verbal and physical aggression requiring seclusion or restraint.41 Others have also found that caffeine does not have adverse effects on psychiatric patients.42 In studies of adults under laboratory conditions, caffeine showed some tendency to reduce the probability of aggressive behavior.43,44 Aggressiveness by children following caffeine administration appears not to have been a subject of similar study.
Dependency People talk of
addiction to food, This has led some to consider that the word &dquo;addiction&dquo; has been abused.&dquo; To counter this problem, investigators prefer the term &dquo;dependency. &dquo;46,47 Those who study the biology of drug dependence in human volunteers are more likely to obtain institutional review board (IRB) approval if their proposed study is of caffeine rather than of a potentially highly addictive drug. This appears to be one of the main rea-
exercise, and
746
sex.
sons
some
pendence categories
or
choice. Choice is the human equivalent of self-administration in laboratory animals. Often the experimental task is to distinguish between placebo and selected doses of the putative psychoactive substance. Investigators often link discrimination tasks with attempts to identify the basis for the discrimination (e.g., whether it is an item on the &dquo;liking scale&dquo;).
investigators suggest
&dquo;that caffeine may be useful for studying basic mechanisms involved in drug dependency.&dquo;48 The very reason IRBs give their approval is that the risk/benefit ratio for adult volunteers is acceptable. The risk is minimal, but then, so is the benefit. Nevertheless, IRBs tend to be very protective of children. Thus, much of what follows is from studies of adults. Caffeine is not listed as one of the substances under the drug de-
nondependent-abuse
of the International Classification of Diseases (ICD-9).49 Similarly, caffeine is not one of the substances identified with diagnoses of psychoactive substance dependence or with psychoactive substance abuse in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IIl-R).47 A recommendation has been made recently that caffeine abuse/dependence not be included as a diagnosis in DSM-IV or ICD-lO.sO Claims that caffeine is addictive/abused should be evaluated using criteria for psychoactive substance dependence. Based on several sources, drug dependence can be defined as &dquo;the repetitive consumption of a psychoactive drug&dquo; (caffeine satisfies this criterion) &dquo;despite adverse consequences to the individuals or society&dquo; (this is the criterion that caffeine does not appear to satisfy) .46,47,Sl Criteria for psychoactive substance dependence can usually be dichotomized into characteristics of the substance and behavioral characteristics associated with consumption of the substance.
Characteristics of Caffeine The reinforcing properties of a substance are those that influ-
ence
Liking Several &dquo;liking scales&dquo; have been used by investigators to assess a substance’s ability to reinforce selfadministration.46 One has such true-false statements as, &dquo;I feel more clearheaded than dreamy,&dquo; &dquo;I feel less discouraged than usual,&dquo; &dquo;I am full of energy,&dquo; and &dquo;Things around me seem more pleasing than usual. &dquo;S2 Single doses of up to 300 mg caffeine given to adults have been followed by significant increases in &dquo;liking. &dquo;31,33,3S,S3-S6 Single doses of 400 caffeine mg, however, produce significant increases in &dquo;disliking. &dquo;31,33 These
findings
are
not
always reproduc-
ible.s7,s8 Others, however, report that high doses tend to produce undesirable effects, including increases in tension, anxiety, and
nervousness.33,34,58-62 This pattern of a benefit with low doses and a liability with modestly higher doses is seen repeatedly with caffeine. It is seen with liking scales, self-administration studies, and assessments of performance. Perhaps this is why an individual’s caffeine consumption does not escalate progressively. Although the extrapolation of these data to children may be limited, younger adult (18 to 37 years) caffeine consumers are more likely than older adult (65 to 75 years) caffeine consumers to report that caffeine ingestion is followed by feeling more alert, steady, and calm.63
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Tolerance
Reinforcement The
reinforcing properties
substance
are
of a
those that influence
choice, including discrimination, drug liking, and preference
strength. Stem and his colleagues,35 after studying the responses of 18 doses of 100 mg and 300 mg caffeine, concluded that their major finding &dquo;was the failure of caffeine to serve as a reinforcer.&dquo; Indeed, the 300-mg dose was chosen less often than would be expected by chance, prompting the authors to consider &dquo;that this dose served as a punisher.&dquo; Subsequently, similar findings were reported by Brockwell et al,64 but dissimilar data were reported by Olivetto,6s Hughes,66 and their respective colleagues. After reviewing the adult literature, Griffiths and his colleagueS13 concluded that &dquo;studies of caffeine-induced mood changes... provide meager evidence for the reinforcing effects of caffeine.&dquo;
adults
to
Tolerance is the diminished responsiveness associated with repeated ingestion. Tolerance and
withdrawal
ence that children limit their caffeine intake because they associate uncomfortable feelings with consuming &dquo;too much&dquo; caffeine.
phenomena are not es-
sential for addictive drug-seeking behavior. They are important, however, because they are felt &dquo;to strengthen the control of the drug
behavior.&dquo;&dquo; Associated with tolerance is the desire for a higher dose in order to achieve the effect no longer experienced with the usual dose. This phenomenon is highly unlikely to occur with caffeine because &dquo;high&dquo; doses tend to produce dysphoria. At doses of 10 mg/kg/day, children were appreciably more likely to feel jittery and nervous than when they ingested only 3 mg/kg/day.4 This leads to the inferover
&dquo;
Drug-Dependence Criteria
In a report (about nicotine) prepared for the Surgeon General, criteria for drug dependence were
tabulated and discussed.&dquo; These listed in Table 3 along with an
are
assessment of whether or not caffeine satisfies each criterion.
Primary Criteria Highly Controlled or Compulsive Use. This criterion is satisfied when &dquo;drug-taking behavior is driven by strong, often irresistible
~~~~~~~~~~~S~~~~~ M~ FM ~6 M~~~~~ &dquo;
Physical Dependence Just as caffeine choice can reflect a positive effect (i.e., &dquo;liking&dquo;) caffeine choice might also reflect an attempt to avoid a negative response (i.e., withdrawal symptoms). The withdrawal syndrome that accompanies abstinence after habitual use is the primary expression of physical dependence induced by a drug. In adults, caffeine withdrawal is sometimes followed by headache, sleepiness, laziness, and decreased alertness. In one study, the mean onset latency period of headache was 19 hours. 31,55 No similar syndrome has been described in children, even when &dquo;high&dquo; consumers were asked to eliminate dietary caffeine in a double-blind study of the effects of caffeine.’ Therefore, physical dependence in children may not occur or is less evident than in adults.
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747
urges.&dquo;&dquo; In the extreme, drugseeking may involve great risk (e.g., stealing, prostitution). For widely available substances, such as ethanol and nicotine, compulsive use reflects relative inability to quit despite repeated attempts. Adults and children appear to be able to give up caffeine either voluntarily or when medically necessary (e.g., fasting before and following surgery). Thus, caffeine does not satisfy the criterion of
compulsive use. Psychoactive Effects. Although some adults appear to recognize that at low doses caffeine improves their alertness, in general, results of most studies of the psychoactive properties of caffeine are equivocal. 67 A reasonable inference then is that caffeine has weak psychoactive properties. Drug-Reinforced Behavior. The section above, dealing with reinforcement, documents that students of drug dependency find little or no evidence that caffeine has reinforcing properties. In light of these perceptions, caffeine should not be viewed as reinforcing future consumption.
Secondary
Criteria
Among the additional (i.e., secondary, or minor) criteria of drug dependency are two sets of characteristics that define primary criteria. For example, one primary criterion, highly controlled or compulsive use, includes three secondary criteria: consumption despite harmful effects, relapse following abstinence, and recurrent drug cravings. The previous conclusion that caffeine consumption did not promote compulsive consumption based on decisions about each of these characteristics. Adults and children show no desire to consume caffeine at levels expected
was
to
promote
searched for,
748
dysphoria.1-3 Although no
report was found of
child’s
keeping with that impression. Cafat levels consumed by most
cravings for cafis there documentation of a high relapse rate following abstinence. The pattern of highest caffeine consumption in the moming is easily modified (consider all those people trying to minimize jet lag) and is not worthy of the term a
feine,
recurrent
feine,
nor
children, does not appear to produce adverse effects. REFERENCE 1. Morgan KJ,
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&dquo;
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Introduction
(e.g., coffee, 12 to 20 to 8 mg/oz; cola, 3.0 mg/oz; cocoa beverage, 1 mg/oz; mg/oz; sources
tea, 6
of the attention caffeine receives in the lay press, health professionals often are questioned about the effects of caffeine on children. This paper was prepared to meet the need for a current and accurate review for pediatricians. The basic goal was to determine if caffeine consumption in any group of children should be limited. ecause
Consumption In children, caffeine intake as a function of body weight is highest below age five 5 years. 1,2 Based on data obtained by the Marketing Research Corporation of America, the 90th percentile levels of caffeine intake among consumers (in mg/kg) are estimated to be 0.7 for infants, 2.1 for children 1 to 5 years of age, and 1.4 for children 6 to 1’7 years.’ Children tended to get most of their caffeine from coffee and tea, with decreasing amounts from cola and chocolate products.2 This largely reflects differences in caffeine content of the Harvard Medical School and Children’s Hospital, Boston, Massachusetts Address correspondence to: Alan Leviton, M.D., Gardner 445, 300 Longwood Avenue, Boston, MA 02115 First presented at the 60th Annual Meeting, American Academy of Pediatrics, New Orleans, Louisiana, October 27, 1991.
742
chocolate, 35 In a recent study, adults were recruited who acknowledged consuming three to seven cups of coffee per day to determine the effects of caffeine.36 When given blind access to both caffeine-containing and decaffeinated coffee, less than half displayed reliable caffeine self-administration.
con-
might reflect a balance between positive effects (i.e., &dquo;liking&dquo;), and negative response (i.e., the jitters). The following summary of adult studies is more extensive than that for children because little has been written about these phenomena in children and much has been written about studies in adults. Moreover, it is possi-
Children
Compared with their peers who consumed relatively small amounts of caffeine (i.e., less than 50 mg/day) , 10 year-old children who consumed relatively large amounts (i.e., reported intake of at least 500 mg/day) were more likely to be considered &dquo;disobedient&dquo; by their parents.’ This observation leads to
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inferences: caffeine consumption promotes disobedience, and children who are disobedient and impulsive (and perhaps have attention-deficit disorder with hyperactivity) want to ingest more caffeine than children who do not have this disorder. The latter possibility would occur if caffeine has a benefit that can be perceived by children who have attention-deficit disorder. When evaluated while consuming caffeine (5 mg/kg at 8 a.m. and at 3 p.m.), the low consumers were more likely than high consumers to have an increase in scores on the parent-completed Conners 10item behavioral scale, which measures restlessness, irritability, and disruptive behavior. When evaluated while consuming placebo, the two
low
consumers
also tended
to
have
higher measures of electrodermal activity. These differences prompted Rapoport and her colleagues4 to suggest that children choose to consume amounts of caffeine that minimize adverse effects and maximize beneficial effects.
Performance In normal prepubertal boys, caffeine in a dose-dependent fashion appears to shorten reaction time and reduce errors of omission on a continuous-performance task, but it does not improve scores on assessments of cognition.&dquo; The reduction in errors of omission is more obvious in children who
tend to consume the most caffeine than in those who consume little caffeine.4 Consumption of 3 mg/kg is followed by a decrease in motor activity.’ On the other hand, consumption of 10 mg/kg is associated with increased motor activity23,37 and higher scores on the Conners abbreviated parent-rating scale 22 Speech production (words/min) increases with increasing dose of caffeine.23 These observations suggest that a little caffeine (equivalent to two 12-oz cans of cola per day consumed by a 25- to 30-kg child) is helpful, whereas
considerably higher consumption (e.g., the equivalent of ’7r/2 cans per day) has some disadvantages.
Hyperactivity In the 19’70s, before the diagnosis of attention-deficit disorder was a readily available option, 11 studies were published of the effects of caffeine on measures of hyperactivity (Table 2). In only three did the investigators conclude that caffeine was beneficial. The one study from the 1980s found that 300 mg given in the morning and again at noon reduced the number of errors of commission and increased the reaction times on a continuous-performance test.38 No study reported adverse effects with caffeine doses equivalent to the consumption of 90% of children. Unless their consumption exceeds these bounds, hyperactive children need not limit their caffeine consumption. Some symptoms of attentiondeficit disorder persist into adulthood. In light of support for the self-selection and titration hypotheses of caffeine consumption, it seems reasonable that some adults consume caffeine to ameliorate their attention-deficit disorder symptoms. Dalby39 has offered the
provocative hypothesis that, as per capita caffeine consumption con-
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745
tinues to decrease, symptoms of attention-deficit disorder in adults may become more evident, resulting in an increased prevalence of attention-deficit disorder beyond the childhood years.
Aggressive Behavior in Adults
The removal of caffeinated beverages from the canteen and vending machines of a state psychiatric facility in California was accompanied by a decrease in the number of reported episodes of assaultive behavior and property destruction.4° At another California state hospital, which did not change its policy on the availability of caffeine-
containing beverages, however, similar decreases were reported in the rate of verbal and physical aggression requiring seclusion or restraint.41 Others have also found that caffeine does not have adverse effects on psychiatric patients.42 In studies of adults under laboratory conditions, caffeine showed some tendency to reduce the probability of aggressive behavior.43,44 Aggressiveness by children following caffeine administration appears not to have been a subject of similar study.
Dependency People talk of
addiction to food, This has led some to consider that the word &dquo;addiction&dquo; has been abused.&dquo; To counter this problem, investigators prefer the term &dquo;dependency. &dquo;46,47 Those who study the biology of drug dependence in human volunteers are more likely to obtain institutional review board (IRB) approval if their proposed study is of caffeine rather than of a potentially highly addictive drug. This appears to be one of the main rea-
exercise, and
746
sex.
sons
some
pendence categories
or
choice. Choice is the human equivalent of self-administration in laboratory animals. Often the experimental task is to distinguish between placebo and selected doses of the putative psychoactive substance. Investigators often link discrimination tasks with attempts to identify the basis for the discrimination (e.g., whether it is an item on the &dquo;liking scale&dquo;).
investigators suggest
&dquo;that caffeine may be useful for studying basic mechanisms involved in drug dependency.&dquo;48 The very reason IRBs give their approval is that the risk/benefit ratio for adult volunteers is acceptable. The risk is minimal, but then, so is the benefit. Nevertheless, IRBs tend to be very protective of children. Thus, much of what follows is from studies of adults. Caffeine is not listed as one of the substances under the drug de-
nondependent-abuse
of the International Classification of Diseases (ICD-9).49 Similarly, caffeine is not one of the substances identified with diagnoses of psychoactive substance dependence or with psychoactive substance abuse in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IIl-R).47 A recommendation has been made recently that caffeine abuse/dependence not be included as a diagnosis in DSM-IV or ICD-lO.sO Claims that caffeine is addictive/abused should be evaluated using criteria for psychoactive substance dependence. Based on several sources, drug dependence can be defined as &dquo;the repetitive consumption of a psychoactive drug&dquo; (caffeine satisfies this criterion) &dquo;despite adverse consequences to the individuals or society&dquo; (this is the criterion that caffeine does not appear to satisfy) .46,47,Sl Criteria for psychoactive substance dependence can usually be dichotomized into characteristics of the substance and behavioral characteristics associated with consumption of the substance.
Characteristics of Caffeine The reinforcing properties of a substance are those that influ-
ence
Liking Several &dquo;liking scales&dquo; have been used by investigators to assess a substance’s ability to reinforce selfadministration.46 One has such true-false statements as, &dquo;I feel more clearheaded than dreamy,&dquo; &dquo;I feel less discouraged than usual,&dquo; &dquo;I am full of energy,&dquo; and &dquo;Things around me seem more pleasing than usual. &dquo;S2 Single doses of up to 300 mg caffeine given to adults have been followed by significant increases in &dquo;liking. &dquo;31,33,3S,S3-S6 Single doses of 400 caffeine mg, however, produce significant increases in &dquo;disliking. &dquo;31,33 These
findings
are
not
always reproduc-
ible.s7,s8 Others, however, report that high doses tend to produce undesirable effects, including increases in tension, anxiety, and
nervousness.33,34,58-62 This pattern of a benefit with low doses and a liability with modestly higher doses is seen repeatedly with caffeine. It is seen with liking scales, self-administration studies, and assessments of performance. Perhaps this is why an individual’s caffeine consumption does not escalate progressively. Although the extrapolation of these data to children may be limited, younger adult (18 to 37 years) caffeine consumers are more likely than older adult (65 to 75 years) caffeine consumers to report that caffeine ingestion is followed by feeling more alert, steady, and calm.63
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Tolerance
Reinforcement The
reinforcing properties
substance
are
of a
those that influence
choice, including discrimination, drug liking, and preference
strength. Stem and his colleagues,35 after studying the responses of 18 doses of 100 mg and 300 mg caffeine, concluded that their major finding &dquo;was the failure of caffeine to serve as a reinforcer.&dquo; Indeed, the 300-mg dose was chosen less often than would be expected by chance, prompting the authors to consider &dquo;that this dose served as a punisher.&dquo; Subsequently, similar findings were reported by Brockwell et al,64 but dissimilar data were reported by Olivetto,6s Hughes,66 and their respective colleagues. After reviewing the adult literature, Griffiths and his colleagueS13 concluded that &dquo;studies of caffeine-induced mood changes... provide meager evidence for the reinforcing effects of caffeine.&dquo;
adults
to
Tolerance is the diminished responsiveness associated with repeated ingestion. Tolerance and
withdrawal
ence that children limit their caffeine intake because they associate uncomfortable feelings with consuming &dquo;too much&dquo; caffeine.
phenomena are not es-
sential for addictive drug-seeking behavior. They are important, however, because they are felt &dquo;to strengthen the control of the drug
behavior.&dquo;&dquo; Associated with tolerance is the desire for a higher dose in order to achieve the effect no longer experienced with the usual dose. This phenomenon is highly unlikely to occur with caffeine because &dquo;high&dquo; doses tend to produce dysphoria. At doses of 10 mg/kg/day, children were appreciably more likely to feel jittery and nervous than when they ingested only 3 mg/kg/day.4 This leads to the inferover
&dquo;
Drug-Dependence Criteria
In a report (about nicotine) prepared for the Surgeon General, criteria for drug dependence were
tabulated and discussed.&dquo; These listed in Table 3 along with an
are
assessment of whether or not caffeine satisfies each criterion.
Primary Criteria Highly Controlled or Compulsive Use. This criterion is satisfied when &dquo;drug-taking behavior is driven by strong, often irresistible
~~~~~~~~~~~S~~~~~ M~ FM ~6 M~~~~~ &dquo;
Physical Dependence Just as caffeine choice can reflect a positive effect (i.e., &dquo;liking&dquo;) caffeine choice might also reflect an attempt to avoid a negative response (i.e., withdrawal symptoms). The withdrawal syndrome that accompanies abstinence after habitual use is the primary expression of physical dependence induced by a drug. In adults, caffeine withdrawal is sometimes followed by headache, sleepiness, laziness, and decreased alertness. In one study, the mean onset latency period of headache was 19 hours. 31,55 No similar syndrome has been described in children, even when &dquo;high&dquo; consumers were asked to eliminate dietary caffeine in a double-blind study of the effects of caffeine.’ Therefore, physical dependence in children may not occur or is less evident than in adults.
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747
urges.&dquo;&dquo; In the extreme, drugseeking may involve great risk (e.g., stealing, prostitution). For widely available substances, such as ethanol and nicotine, compulsive use reflects relative inability to quit despite repeated attempts. Adults and children appear to be able to give up caffeine either voluntarily or when medically necessary (e.g., fasting before and following surgery). Thus, caffeine does not satisfy the criterion of
compulsive use. Psychoactive Effects. Although some adults appear to recognize that at low doses caffeine improves their alertness, in general, results of most studies of the psychoactive properties of caffeine are equivocal. 67 A reasonable inference then is that caffeine has weak psychoactive properties. Drug-Reinforced Behavior. The section above, dealing with reinforcement, documents that students of drug dependency find little or no evidence that caffeine has reinforcing properties. In light of these perceptions, caffeine should not be viewed as reinforcing future consumption.
Secondary
Criteria
Among the additional (i.e., secondary, or minor) criteria of drug dependency are two sets of characteristics that define primary criteria. For example, one primary criterion, highly controlled or compulsive use, includes three secondary criteria: consumption despite harmful effects, relapse following abstinence, and recurrent drug cravings. The previous conclusion that caffeine consumption did not promote compulsive consumption based on decisions about each of these characteristics. Adults and children show no desire to consume caffeine at levels expected
was
to
promote
searched for,
748
dysphoria.1-3 Although no
report was found of
child’s
keeping with that impression. Cafat levels consumed by most
cravings for cafis there documentation of a high relapse rate following abstinence. The pattern of highest caffeine consumption in the moming is easily modified (consider all those people trying to minimize jet lag) and is not worthy of the term a
feine,
recurrent
feine,
nor
children, does not appear to produce adverse effects. REFERENCE 1. Morgan KJ,
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&dquo;
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