Human coffee drinking: manipulation of concentration and caffeine dose.

In a residential research ward coffee drinking was studied in 9 volunteer human subjects with histories of heavy coffee drinking. A series of five experiments was undertaken to characterize adlibitum coffee consumption and to investigate the effects of manipulating coffee concentration, caffeine dose per cup, and caffeine preloads prior to coffee drinking. Manipulations were double-blind and scheduled in randomized sequences across days. When cups of coffee were freely available, coffee drinking tended to be rather regularly spaced during the day with intercup intervals becoming progressively longer throughout the day; experimental manipulations showed that this lengthening of intercup intervals was not due to accumulating caffeine levels. Number of cups of coffee consumed was an inverted U-shaped function of both coffee concentration and caffeine dose per cup; however, coffee-concentration and dose-per-cup manipulations did not produce similar effects on other measures of coffee drinking (intercup interval, time to drink a cup, within-day distribution of cups). Caffeine preload produced dose-related decreases in number of cups consumed. As a whole, these experiments provide some limited evidence for both the suppressive and the reinforcing effects of caffeine on coffee consumption. Examination of total daily coffee and caffeine intake across experiments, however, provides no evidence for precise regulation (i.e., titration) of coffee or caffeine intake.     

Cardiovascular reactivity, mood, and task performance in deprived and nondeprived coffee drinkers

Forty habitual, heavy coffee drinkers (M = 5.7 cups/day) participated in two experimental sessions. Participants were deprived of their morning coffee for one of the laboratory sessions, not deprived the other. During each session, subjects consumed 12 oz of caffeinated coffee, decaffeinated coffee, or caffeine-free herbal tea. Measurements of heart rate, blood pressure, mood, and catecholamine response to deprivation and consumption of the beverage, alone and in combination with challenging tasks, were made. This study found that caffeine continues to cause blood pressure increases with chronic, heavy consumption and that these effects do not appear to habituate with regular use. Subjects reacted to behavioral challenge with fewer negative mood effects if they had consumed caffeine or coffee. Mild caffeine deprivation was associated with symptoms of stress.     

Reinforcing effects of caffeine in coffee and capsules.

In a residential research ward the reinforcing and subjective effects of caffeine were studied under double-blind conditions in volunteer subjects with histories of heavy coffee drinking. In Experiment 1, 6 subjects had 13 opportunities each day to self-administer either a caffeine (100 mg) or a placebo capsule for periods of 14 to 61 days. All subjects developed a clear preference for caffeine, with intake of caffeine becoming relatively stable after preference had been attained. Preference for caffeine was demonstrated whether or not preference testing was preceded by a period of 10 to 37 days of caffeine abstinence, suggesting that a recent history of heavy caffeine intake (tolerance/dependence) was not a necessary condition for caffeine to function as a reinforcer. In Experiment 2, 6 subjects had 10 opportunities each day to self-administer a cup of coffee or (on different days) a capsule, dependent upon completing a work requirement that progressively increased and then decreased over days. Each day, one of four conditions was studied: caffeinated coffee (100 mg/cup), decaffeinated coffee, caffeine capsules (100 mg/capsule), or placebo capsules. Caffeinated coffee maintained the most self-administration, significantly higher than decaffeinated coffee and placebo capsules but not different from caffeine capsules. Both decaffeinated coffee and caffeine capsules were significantly higher than placebo capsules but not different from each other. In both experiments, subject ratings of "linking" of coffee or capsules covaried with the self-administration measures. These experiments provide the clearest demonstrations to date of the reinforcing effects of caffeine in capsules and in coffee.     

Effects of mental workload and caffeine on catecholamines and blood pressure compared to performance variations

Caffeine is characterised as a central nervous system stimulant, also affecting metabolic and cardiovascular functions. A number of studies have demonstrated an effect of caffeine on the excretion of catecholamines and their metabolites. Urinary epinephrine and norepinephrine have been shown to increase after caffeine administration. Similar trends were observed in our study in adrenaline (ADR) and noradrenaline (NORADR) levels and additionally a dose dependent effect of caffeine. The effect of caffeine on cognitive performance, blood pressure, and catecholamines was tested under resting conditions and under mental workload. Each subject performed the test after oral administration of 1 cup and then 3 cups of coffee. Root mean square error (RMSE) for the tracking task was continuously monitored. Blood pressure was also recorded before and after each stage of the experiment. Catecholamines were collected and measured for three different conditions as: at rest, after mental stress alone, after one dose of caffeine under stress, and after triple dose of caffeine under stress. Comparison of the performance of each stage with the resting conditions revealed statistically significant differences between group of smokers/coffee drinkers compared with the other two groups of non-coffee drinkers/non-smokers and non-smokers/coffee drinkers. There was no statistically significant difference between the last two groups. There was an increase of urine adrenaline with 1 cup of coffee and statistically significant increase of urine noradrenaline. Both catecholamines were significantly increased with triple dose of caffeine. Mental workload increased catecholamines. There was a dose dependent effect of caffeine on catecholamines.     

Self-Affirmation Reduces Biased Processing of Health-Risk Information

An experiment tested whether a positive experience (the endorsement and recall of one's past acts of kindness) would reduce biased processing of self-relevant health-risk information. Women college students (N = 66) who reported high or low levels of daily caffeine use were exposed to both risk-confirming and risk-disconfirming information about the link between caffeine consumption and fibrocystic breast disease (FBD). Participants were randomly assigned to complete an affirmation of their kindness via questionnaire or to a no-affirmation condition. Results indicated that the affirmation manipulation made frequent caffeine drinkers more open, less biased processors of risk-related information. Relative to frequent caffeine drinkers who did not affirm their kindness, frequent caffeine drinkers in the affirmation condition oriented more quickly to the risk-confirming information, rated the risk-confirming information as more convincing than the risk-disconfirming information, and recalled less risk-disconfirming information at a 1-week follow-up. They also reported greater perceived personal control over reducing their level of caffeine consumption. Although frequent caffeine drinkers in the affirmation condition initially reported lower intentions to reduce their caffeine consumption, there was no evidence that they were less likely to decrease their caffeine consumption at the follow-up. The possibility that positive beliefs and experiences function as self-regulatory resources among people confronting threats to health and well-being is discussed.     

Effects of phenobarbitol on aggressive behaviors in a program of required relaxation: A case study

A naturally occurring experiment of the effects of two dosage levels of phenobarbitol on aggressive behaviors in a program of required relaxation is described. A required relaxation program was initiated as a consequence for throwing and hitting by a 13-year-old developmentally disabled male resident of an institutional cottage. The resident had been receiving 50 mg of phenobarbitol twice per day to control seizure activity for two years prior to the introduction of this program. Aggressive behavior decreased from an average of 7.2 incidents a day during baseline to 1.7 per day after six weeks of the required relaxation program. Following several reported seizures, medical staff increased phenobarbitol dosage to 100 mg twice per day and hitting behavior increased beyond baseline levels. After five weeks at this dosage, medication was returned to 50 mg twice a day and hitting behavior returned quickly to the lower intervention levels, while seizure activity remained stable. All observations of behavior were collected during unstructured and regularly occurring events of the individual's daily life. These data suggested that changes in medication influenced observed changes in behavior.     

Impact of caffeine and psychological stress on blood pressure in black and white men

The purpose of this study was to examine the effects of caffeine and psychological stress on systolic blood pressure (SBP) and heart rate (HR) in 40 healthy Black and White male regular coffee drinkers. Half the subjects had a positive family history of hypertension (FH+), and half did not. The effects of 250 mg of caffeine versus placebo (3 mg) in decaffeinated coffee were compared in a within-subject, double-blind, cross-over design. SBP and HR were measured at rest, after caffeine ingestion, during mental arithmetic stress, and during recovery. Results confirmed previous findings with White men that a moderate dose of caffeine produced significant increases in SBP and little effect on HR and that the pressor effects of caffeine and stress combined additively. Contrary to expectations, no overall race or family history differences in SBP levels or in SBP reactivity were observed. FH+ Blacks, however, evidenced slower SBP recovery than Whites. Whites evidenced higher overall HR levels than blacks, but this difference was not specific to caffeine or to mental stress. Mechanisms of racial differences in reactivity underlying differential risk for hypertension are discussed, as well as the utility of caffeine as a pharmacologic probe for such differences.     

Co-occurrent use of cigarettes, alcohol, and coffee in healthy, community-living men and women

Previous studies have examined intra-individual aggregation in the use of cigarettes, alcohol, and coffee by examining the co-occurrent use of any pair of these three substances. A recent literature review failed to find a single investigation that studied use of all three in the same sample. In the present study, co-occurrent use of all three of these substances was examined in crossvalidated subsamples of 226 male and 245 female healthy, community-living, middle-class Americans. A log-linear analysis was used to compare the proportion of smokers, ex-smokers, and nonsmokers categorized as users of more or less amounts of coffee and alcohol. Although most of the intercorrelations were not strong, the results indicate that for both sexes, smokers and ex-smokers were more likely than nonsmokers to drink greater amounts of alcohol and coffee. Furthermore, for smokers, ex-smokers, and nonsmokers, a majority of individuals who reported drinking more alcohol also reported drinking more coffee. Interestingly, the coffee and alcohol consumption levels of ex-smokers resembled those of smokers more than those of nonsmokers. Also, ex-smokers reported drinking more wine and decaffeinated coffee than either smokers or nonsmokers. Finally, the number of cigarettes smoked per day (daily quantity) was positively related to total alcohol and coffee consumption in men, but not in women. Further studies are recommended to examine the role of individual differences in the development, maintenance, and modification of these three appetitive habits and their co-occurrence.     

Conditioning and the placebo effect: The effects of decaffeinated coffee on simple reaction time in habitual coffee drinkers

An experiment is reported in which reaction time was repeatedly assessed in six subjects (habitual coffee drinkers) up to 90 min after the administration of decaffeinated coffee (i.e. placebo), 250 mg caffeine in coffee and at equivalent times on control days. As predicted reaction time was shorter (but not significantly so) immediately after the administration of the two coffee preparations. This finding was taken to support the hypothesis that through a process akin to classical conditioning, drug effects may become associated with the cues that precede and are concurrent with their administration. The findings are critically assessed and related to previous studies. Finally, it is argued that the conditioning hypothesis can account for a number of clinical findings about the placebo response as observed in therapeutic trials.     

The effects of venlafaxine and cognitive behavioral therapy alone and combined in the treatment of co-morbid alcohol use-anxiety disorders

The effects of the antidepressant venlafaxine (VEN-225 mg daily) and transdiagnostic cognitive behavioral treatment (CBT) alone and in combination on alcohol intake in subjects with co-morbid alcohol use disorders (AUDs) and anxiety disorders were compared. Drinking outcomes and anxiety were assessed for 81 subjects treated for 11 weeks with one of 4 conditions: 1) VEN–CBT, 2) VEN-Progressive Muscle Relaxation therapy (PMR), 3) Placebo (PLC)-CBT and 4) a comparison group of PLC-PMR. For subjects who reported taking at least one dose of study medication, the Time × Group interaction was significant for percent days of heavy drinking and drinks consumed per day. For the measure of percent days heavy drinking, the paired comparison of PLC-CBT versus PLC-PMR group indicated that the PLC-CBT group had greater drinking reductions, whereas other groups were not superior to the comparison group. In Week 11, the proportion of subjects in the PLC-CBT group that had a 50% reduction from baseline in percent days heavy drinking was significantly greater than those in the comparison group. Of the 3 “active treatment” groups only the PLC-CBT group had significantly decreased heavy drinking when contrasted to the comparison group. This finding suggests that the transdiagnostic CBT approach of Barlow and colleagues may have value in the management of heavy drinking in individuals with co-morbid alcoholism and anxiety.     

Nicotine fading,self-monitoring and cigarette fading to produce cigarette abstinence or controlled smoking

This study developed and evaluated a smoking-treatment program. Twelve subjects were randomly assigned to one of two groups within a multiple baseline design. Subjects were first given a nicotine-fading and self-monitoring procedure for 3 weeks in which they changed their cigarette brands each week to ones containing progressively less nicotine and tar and plotted their daily intake of the two substances. Those subjects unable to quit smoking were then given a cigarette-fading procedure in which they systematically reduced the number of cigarettes smoked for 3 weeks. The study had two goals: (1) to achieve a reasonable percentage of abstinence; and (2) to reduce non-abstainers' smoking to a ‘safer’ level by having them smoke very low tar and nicotine cigarettes. The 12-month follow-up results revealed that 33% of the subjects were abstinent and all non-abstainers were smoking cigarettes lower in tar and nicotine than their baseline brands. Half the non-abstainers had decreased their smoking rate relative to baseline while the other half had increased. The subjects decreased their daily nicotine intake by 13.3 mg (81.6% reduction from baseline) and tar intake by 218.2 mg (85.5% reduction from baseline). These results suggest that the study's goals were achieved and that the non-aversive combined procedure could be used to treat not only habitual smokers but also those with cardiovascular and respiratory problems who cannot be treated by smoking-cessation procedures that use cigarette smoke as the aversive stimulus. Finally, a least-restrictive model for treating smoking is proposed and discussed.     

Drinking and cholinergic mechanisms in the abstinence after chronic barbital treatments

Male rats were treated with barbital in the drinking water for 32–33 weeks (intake 195 mg/kg/day). This treatment ended on day 0. On days 23–29, 1.5 mg/kg/day of atropine was given. The changes induced by the treatments alone or combined were recorded either as a sensitivity to hexobarbital in the brain determined with a threshold method or as water intake calculated on data obtained with weekly intervals. The hexobarbital threshold test indicated that the barbital treatment had induced a tolerance which at the time of the atropine treatment was variable. In the rats also given the atropine treatment this tolerance was after a delay of approx. 2 weeks more marked and less variable. The water intake in only barbital treated rats showed, compared with untreated controls, an increase which had a maximum on days 28–35. During the atropine treatment given on days 23–29 there was in the previously barbital treated rats no certain effect, but immediately after the end of treatment there was an approx. 25 per cent increase in water intake above that found in only barbital treated rats. No return to control levels was seen within a 14 weeks observation period. This increase resembled supersensitivity but did not correspond over time with the changes seen in hexobarbital sensitivity.     

Reducing cigarette smoking in a retarded adult: An application of self-management procedures

An attempt was made to reduce the overall number of cigarettes smoked per day with a mildly retarded adult. Self-monitoring was compared to self-monitoring plus self-graphing and goal setting procedures in reducing the number of cigarettes smoked. Self-monitoring plus self-graphing and goal setting was superior to self-monitoring alone when the goal was set at 15 cigarettes per day, but the actual number of cigarettes smoked increased when the goal was set at 12. The number of cigarettes smoked during all treatment conditions was lower than either baseline conditions. The therapist also reduced the patient's caffeine intake and switched the client's brand of cigarettes to a low “tar”/nicotine brand. The reduction in caffeine and “tar”/nicotine was related to a small and transient increase in somatic complaints and verbal abuse, as well as the complete elimination of nocturnal enuresis. Brand switching to low “tar”/nicotine cigarettes did not result in an increase in the number of cigarettes smoked per day.     

Gustatory responses during periods of controlled and ad lib cigarette smoking

Three psychophysical methods, differential sensitivity, perceived intensity, and degree of liking, were used to measure gustatory responses among nonsmokers and among smokers who were placed on 2-week schedules of increased and decreased cigarette consumption. Varying the smoking levels had little influence on the smokers’ sensitivity to the tastes of sucrose and sodium chloride. Throughout the experiments, nonsmokers were slightly more sensitive than smokers. Lower intensity ratings were ascribed to both compounds by smokers than by nonsmokers. Degree of liking of the test solutions was unrelated to smoking. A subsequent experiment showed that 45 nonsmokers were slightly, but not significantly, more sensitive than were 45 smokers to the tastes of sucrose, sodium chloride, citric acid, and quinine hydrochloride, with no differences in their sensitivity to the odor of 2-butanone and to the viscosity imparted by carrageenan gum. There was a slight inverse relationship between sensitivity and the number of cigarettes smoked per day. Smokers liked coffee significantly better and drank more cups per day than did nonsmokers. Few changes in body weight were observed, despite the smokers’ subjective assessment that their appetites and food intake were inversely related to the number of cigarettes smoked.     

A comparison of alcoholics whose drinking is totally uncontrolled and those whose drinking is mainly controlled

The analysis of drinking patterns of 77 married male alcoholics for the period of 12 months immediately following their intake into a treatment trial suggested the importance of a variable which has been neglected in the literature on alcohol dependence. Although only 3 had returned to a pattern of drinking which was, by their own and by their wives' accounts, totally controlled, there were wide individual differences amongst the remainder in the uniformity with which drinking was uncontrolled. Two extreme groups were identified: in 22 cases patients and their wives were agreed that drinking had been totally uncontrolled; in 14 cases patients and wives were agreed that drinking had been mainly controlled. There were no differences between these two groups in the amount of abstinence reported but there were major differences in other respects. Mainly controlled drinkers were more likely to think that they had no drinking problem or that their problem was of very recent origin, reported significantly fewer symptoms, were much less likely to be institutionalized during the 12 month period, were less likely to think of themselves as alcoholics and were less likely to express a preference for abstinence as a target. The hypothesis is suggested that this drinking pattern variable may serve as a differential predictor of successful outcome following abstinence-oriented or controlled drinking-oriented treatment.     

Hypertension risk and caffeine's effect on cardiovascular activity during mental stress in young men

Examined the cardiovascular effects of caffeine plus behavioral stress in men low versus high in risk of essential hypertension. Caffeine (3.3 mg/kg, equivalent to 2 to 3 cups of coffee) or placebo was given on alternate days to 19 low-risk men (negative for parental hypertension and low-normal resting blood pressure, BP) and 20 high-risk men (positive history, high-normal BP). Forty minutes later, each worked for 15 min on a demanding psychomotor task during which BP, cardiac output, and vascular resistance were determined. During rest, caffeine raised vascular resistance in both groups. During the task, it supra-additively increased the systolic BP response by enhancing the rise in cardiac output, producing equivalent BP rises in both groups. Due to the higher resting pressures of the high-risk men, caffeine plus the task resulted in 50% of these having transient BP of 140/90 mg Hg or greater. Caffeine in combination with mental stress may produce undesirable BP in those at risk for hypertension.     

Gasoline conservation: a procedure for measuring and reducing the driving of college students

The study sought to motivate college students to reduce the number of miles they drove each day and thus save gasoline. Students in two psychology classes were divided by class into two groups. The experimental group was offered various combinations of prizes such as cash, a tour of a mental-health facility, car servicing, and a university parking sticker for reducing driving. The value of the prize received was scaled in terms of per cent reduction in driving. The contrast group received no inducements. The condition in which the experimental group's mileage reduction was reinforced was counterbalanced by two baseline conditions. Several special recording procedures were used to reduce and detect the possibility of subjects altering their odometers, the source of the driving data. Experimental subjects reduced their average daily mileage by 20% relative to the initial baseline; the contrast group did not change. During the one-month reinforcement condition, the 12 experimental subjects saved some 170 gallons (worth $102) of gasoline.     

A company-based lottery to reduce the personal driving of employees

A company-based lottery was used to reduce the number of nonessential miles employees drove their personal cars each day and thereby save gasoline. Employees were divided into an experimental and a contrast group. The experimental design involved two conditions: (a) a baseline in which no consequences were attached to driving behavior, and (b) a month-long lottery in which the experimentals were rewarded for decreasing their percentage of average miles driven per day relative to their initial baseline average. The experimentals received an ABA order of conditions while the contrast group remained in baseline. The lottery condition consisted of four weekly lotteries and one grand drawing held at the end of the month. During the lottery condition, the experimentals reduced their average daily mileage by 11.6% relative to their initial baseline (7.85 miles per employee per day) while the contrast employees increased their average mileage by 21.2%. Both groups exceeded their initial baseline averages in the return to baseline. The study was almost cost-effective because the experimentals' gas savings ($75) was within $4 of the cost of motivating them to reduce their mileage ($79).     

Treatment‐seeking young adults from families with alcohol problems. What have they been through? What state are they in?

Aims: This study surveys the childhood experiences of treatment‐seeking young adult offspring of problem drinkers (AOPDs) and their psychological state at treatment baseline. Methods: Clients (N=502) entering a Danish nationwide treatment facility for young AOPDS completed the survey. Clients completed the Adult Children of Alcoholics Trauma Inventory, The Family Tree Questionnaire, the CORE–OM 34, Major Depression Inventory, and the Work and Social Adjustment Scale at treatment start. Results: A total of 48% of the clients' mothers and 75% of the clients' fathers were problem drinkers. Both parents were problem drinkers in 25% of cases, and 27% had at least one problem drinking stepparent. Mothers had on average drunk during 11.4 years of the clients' childhood (0–18 years). Fathers had on average drunk during 13.4 years; 46% knew or believed that at least one of their parents suffered from a psychiatric illness; 44% reported physical violence; 63% reported psychological abuse; and 38% had not spoken to anyone about their family's problem. A further 20% had only spoken to a parent or sibling. Conclusions/implications: The study highlights the high degree of variation in AOPD clients' childhood experiences and in their levels of distress, corresponding with studies of non clinical samples. The study offers a bleak image of the extent of parental drinking and of other negative factors in these clients' childhood homes, coupled with the finding that clients have often not spoken to others about their parents' drinking. Mentioning parental drinking to a counsellor is thus a potentially highly significant counselling event, demanding counsellor sensitivity and attention.     

Insulin and glucagon as determinants of body weight set point and microregulation in rats

Seven adult male rats were observed for body weight and microregulation (feeding, drinking, and running patterns) after manipulation of insulin and glucagon levels. They received three injections per day for 3 days each week of 3 U of protamine zinc insulin, .25 mg of zinc glucagon, 50 microgram of protamine zinc somatostatin (SRIF), or protamine zinc vehicle. Diabetes was then induced with an iv injection of streptozotocin (65 mg/kg), and the injection schedule was repeated after the full diabetic syndrome emerged. In all rats whose insulin levels were increased relative to glucagon levels, body weight increased; in those whose glucagon levels were increased relative to insulin levels, body weight decreased. All injections except vehicle reduced meal sizes in both normal and diabetic rats, but only insulin increased the frequency of feeding. These effects could be predicted by the glucostatic theory of food intake regulation and are thus interpreted as supportive of this theory. These results also support the hypothesis that the relative concentration of insulin to glucagon is a regulator of body weight set point.