Milestones in the natural course of the onset of e-cigarette dependence among adolescents and young adults: Retrospective study

INTRODUCTION

There is considerable controversy about the development of dependence among e-cigarette users. This study describes the average amount of time using e-cigarettes before dependence milestones emerge and the differences in developing dependence between e-cigarette users who smoke cigarettes compared to those who do not.

METHODS

Adolescents and young adults aged 16-25 living in Canada were recruited into an online survey in 2021. Current (past-month) e-cigarette users completed 15 items assessing dependence from the Penn-State Electronic Cigarette Dependence Index and the E-cigarette Dependence Scale for a total of 12 behavioural (e.g., difficulty refraining from vaping) and 3 frequency (e.g., using e-cigarette daily, weekly, or monthly) indicators of dependence milestones. Number of years after e-cigarette onset at which the cumulative probability of attaining each milestone was 25 % was computed.

RESULTS

Among 1205 participants, most (80.6 %) were female, 73.7 % were Caucasian, and 49.7 % resided in Ontario. Ten of the 12 e-cigarette use milestones were attained by 25 % of respondents 2 years after starting vaping except for daily cigarette use (2.5 years after onset) and waking at night to vape (5.6 years after onset). Within the entire study population, frequency milestones (weekly, monthly, daily e-cigarette use) were attained faster by ever-smokers (hazard ratio compared to attainment by never-smokers: 1.12, 1.21, and 1.28 respectively), whereas for at least monthly users, behavioural milestones were attained faster by never-smokers.

DISCUSSION

Many current e-cigarette users developed symptoms of e-cigarette dependence between two and five years since onset. Never smokers may be at higher risk of becoming e-cigarette dependent since they attained e-cigarette dependence milestones faster than smokers.

Increasing popularity of waterpipe tobacco smoking and electronic cigarette use: Implications for oral healthcare

Cigarette smoking increases the risk of developing several systemic conditions including cancer, cardiovascular and pulmonary diseases. Cigarette smoking is also detrimental to oral health as it increases the incidence and severity of oral cancer, periodontal diseases and peri-implantitis, as well as impacting negatively on the dental patients' response to therapy. Therefore, consideration of smoking behavior and recommendation of smoking cessation are important parts of dental treatment planning. However, cigarettes are no longer the most popular form of tobacco use among adolescents in the United States and globally. In recent years, tobacco smoking using a waterpipe ("hookah," "shisha") and use of electronic cigarettes (ECIGs) has increased significantly. Thus, dental clinicians likely will treat more patients who are waterpipe and/or ECIG users. Yet, the literature on the health effects of waterpipe and ECIGs use is sparse. Both waterpipe and ECIGs deliver the dependence-producing drug nicotine. Waterpipe tobacco smoking has been associated with periodontitis, dry socket, premalignant lesions, and oral and esophageal cancer. The health effects of long-term ECIG use are unknown. The purpose of this review is to inform healthcare professionals about waterpipes and ECIGs, highlight emerging evidence on the biological effects of these increasingly popular tobacco products, and introduce perspectives for dental patient management and future research.

Now is the time to advocate for interventions designed specifically to prevent and control waterpipe tobacco smoking

Waterpipe tobacco usage is spreading rapidly worldwide, with reports of more youth being waterpipe users compared to adults. In many areas of the world, waterpipe usage surpasses cigarette smoking. Waterpipes and cigarettes are both mechanisms for inhalation of tobacco smoke and therefore have serious health consequences. However, because of the many differences between the two products, prevention and control strategies that have proven effective for cigarettes may not transfer readily to waterpipe. This report highlights the differences between waterpipes and cigarettes in toxicant exposure and physiologic effects, patterns of use, social norms, the extent of evidence, and the policy environment. There is little evidence to date around effective interventions for waterpipe prevention and control. The current state of evidence for intervention to curb or control waterpipe is at ground zero and critically needs attention from both scientists and policy makers. National and global efforts aimed at cigarette prevention have succeeded, particularly in developed countries. We suggest the time has come to harness what we know works for cigarette prevention and control and adapt it to tackle the growing epidemic of waterpipe tobacco use.

Waterpipe tobacco and cigarette smoking among university students in Jordan

SETTING

While waterpipe and cigarette smoking have been well studied in Syria and Lebanon, data from Jordan are limited.

OBJECTIVES

To characterize the relative prevalence of waterpipe tobacco and cigarette smoking among university students in Jordan, and to compare the demographic and environmental factors associated with each form of tobacco use.

DESIGN

We surveyed 1845 students randomly recruited from four universities in Jordan. We used multivariable logistic regression controlling for clustering of individuals within universities to determine associations between demographic and environmental covariates and waterpipe tobacco and cigarette use.

RESULTS

Waterpipe tobacco smoking rates were 30% in the past 30 days and 56% ever, while cigarette smoking rates were 29% in the past 30 days and 57% ever. Past 30-day waterpipe tobacco smoking rates were 59% for males and 13% for females. Females had substantially lower odds than males of being current waterpipe (OR 0.12, 95%CI 0.10-0.15) or cigarette (OR 0.08, 95%CI 0.05-0.14) smokers. Current cigarette smoking was more significantly associated with markers of high socio-economic status (SES) than waterpipe tobacco smoking.

CONCLUSION

Waterpipe tobacco smoking is as common as cigarette smoking among Jordanian university students. While cigarette smoking is consistently associated with high SES, waterpipe tobacco smoking is more evenly distributed across various populations.

Evaluating the acute effects of oral, non-combustible potential reduced exposure products marketed to smokers

BACKGROUND

Non-combustible potential reduced exposure products (PREPs; eg, Star Scientific's Ariva; a variety of other smokeless tobacco products) are marketed to reduce the harm associated with smoking. This marketing occurs despite an absence of objective data concerning the toxicant exposure and effects of these PREPs. Methods used to examine combustible PREPs were adapted to assess the acute effects of non-combustible PREPs for smokers.

METHODS

28 overnight abstinent cigarette smokers (17 men, 14 non-white) each completed seven, Latin-squared ordered, approximately 2.5 h laboratory sessions that differed by product administered: Ariva, Marlboro Snus (Philip Morris, USA), Camel Snus (RJ Reynolds, Winston-Salem, North Carolina, USA), Commit nicotine lozenge (GlaxoSmithKline; 2 mg), own brand cigarettes, Quest cigarettes (Vector Tobacco; delivers very low levels of nicotine) and sham smoking (ie, puffing on an unlit cigarette). In each session, the product was administered twice (separated by 60 min), and plasma nicotine levels, expired air CO and subjective effects were assessed regularly.

RESULTS

Non-combustible products delivered less nicotine than own brand cigarettes, did not expose smokers to CO and failed to suppress tobacco abstinence symptoms as effectively as combustible products.

CONCLUSIONS

While decreased toxicant exposure is a potential indicator of harm reduction potential, a failure to suppress abstinence symptoms suggests that currently marketed non-combustible PREPs may not be a viable harm reduction strategy for US smokers. This study demonstrates how clinical laboratory methods can be used to evaluate the short-term effects of non-combustible PREPs for smokers.

Exposure to secondhand smoke at home and in public places in Syria: a developing country's perspective

This study employs sensitive methods to address the issue of exposure to secondhand smoke among children and women in an understudied developing country setting (Syria). The study combines data collected by the Syrian Center for Tobacco Studies as part of two international studies conducted in 2006: the Secondhand Smoke Exposure among Women and Children study (Johns Hopkins) and the Global Air Monitoring Study (Roswell Park Cancer Institute). We employed objective measures (hair nicotine, and ambient household nicotine assessed by passive monitors) to assess children's and mothers' exposure to secondhand smoke at home, and used the TSI SidePak personal aerosol monitor to sample respirable suspended particles less than 2.5 microm diameter (PM(2.5)) in the air in public places (40 restaurants/cafés in Aleppo). In homes, the mean ambient nicotine level (+/- standard deviation, SD) was 2.24 +/- 2.77 microg/m(3). Mean level of hair nicotine was 11.8 ng/mg among children (n = 54), and was higher if the mother was a smoker (19.4 +/- 23.6 ng/mg) than nonsmoker (5.2 +/- 6.9 ng/mg) (p < .05). Mean hair nicotine among nonsmoking mothers (n = 23) was 1.17 +/- 1.56 ng/mg. Children's hair nicotine level was strongly correlated with ambient household nicotine and number of cigarettes smoked daily in the house (r = .54 and r = .50, respectively, p < .001), and also was related to having a father who smoked in the children's presence. In public places, average PM(2.5) in the monitored 40 hospitality venues was 464 microg/m(3) and correlated with smoker density measured as cigarettes-waterpipes/100 m(3) (r = .31, p = 0.049). Thus, children in Syria are exposed to high levels of secondhand smoke at home, in which mothers' smoking plays a major role. Also, levels of respirable hazardous particles are high in public hospitality venues, putting customers and workers at serious health risks. Efforts to limit exposure of children and women at home and to adopt clean air policies should become a public health priority in Syria and the Arab region.

Interventions for waterpipe smoking cessation

BACKGROUND

Waterpipe smoking is a traditional method of tobacco use, especially in the Eastern Mediterranean Region, but its use is now spreading throughout Europe and North America. It is smoked socially, often being shared between friends or family at home, or in dedicated bars and cafes that provide waterpipes to patrons. Because the smoke passes through a reservoir of water, waterpipe tobacco smoking is perceived as being less lethal than other methods of tobacco use. At least in some cultures, women and girls are more likely to use a waterpipe than to use other forms of tobacco, and it is popular among younger smokers. Accumulating evidence suggests that waterpipe smoking may be as addictive as other forms of tobacco use, and may carry similar or greater risks to health.

OBJECTIVES

To evaluate the effectiveness of tobacco cessation interventions for waterpipe users.

SEARCH STRATEGY

We searched the Cochrane Tobacco Addiction Review Group specialized register, in June 2007. We also searched MEDLINE, EMBASE, CINAHL and PsycINFO, using variant terms and spellings ('waterpipe' or 'narghile' or 'arghile' or 'shisha' or 'goza' or 'narkeela' or 'hookah' or 'hubble bubble'). We searched for trials, published or unpublished, in any language, and especially in regions where waterpipe use is widespread. We have also used our own existing bibliography, compiled from conducting an earlier exhaustive review of the literature on waterpipe smoking.

SELECTION CRITERIA

We sought randomized, quasi-randomized or cluster-randomized controlled trials of smoking cessation interventions for waterpipe smokers of any age or gender. The primary outcome of interest was abstinence from tobacco use, preferably sustained and biochemically verified, for at least six months from the start of the intervention.

DATA COLLECTION AND ANALYSIS

Each author intended to extract data and assess trial quality independently by standard Cochrane Collaboration methodologies, but no eligible trials were identified.

MAIN RESULTS

We found no completed intervention trials targeting waterpipe smokers. A pilot randomized controlled trial by the authors of this review is underway, and will be reported in future updates.

AUTHORS' CONCLUSIONS

Epidemiological and observational evidence suggests that waterpipe use is growing in popularity worldwide. It is widely and erroneously perceived to be less lethal than other forms of tobacco use. Women, girls, and young people are more likely to take up waterpipe smoking, especially in the Eastern Mediterranean Region. More research is needed on its addictive properties, and on the associated health risks, both for users and exposed non-smokers. Evidence-based information about waterpipe's addictive and harmful properties should be developed and disseminated in order to deglamourise and denormalise its use. High quality randomized trials are needed to guide treatment of waterpipe smoking.

The tobacco epidemic in Syria

BACKGROUND

The Syrian Center for Tobacco Studies (SCTS) was established in response to the smoking epidemic in Syria and lack of local knowledge and expertise to confront it.

OBJECTIVES

To (1) study tobacco use and local smoking practices using both qualitative and quantitative research methods; (2) develop and test an effective smoking cessation intervention for the Syrian environment; and (3) train Syrian researchers.

METHODS AND RESULTS

The Aleppo Household Survey involved a representative sample of adults in Aleppo (2038 subjects, 45.2% men, mean age 35.3 years, response rate 86%). The prevalence of cigarette smoking was 56.9% among men and 17.0% among women, while the prevalence of waterpipe smoking was 20.2% among men and 4.8% among women. Daily use predominated for cigarettes (29.0%), while the opposite was seen in waterpipe use with 10.6% smoking occasionally. Interest in quitting was greater for cigarette than waterpipe smokers (74.0% v 48.6%), while quit rates were higher for waterpipe compared to cigarettes (28.2% v 16.5%). In-depth ethnographic interviews with smokers show that smoking waterpipe is often viewed as an aesthetic enjoyable experience, while smoking cigarettes is viewed as a mundane anxiety-relieving addiction. Clinical laboratory studies reveal that both waterpipe and cigarette smokers in Syria are exposed to smoke toxicants and exhibit dependence symptoms.

CONCLUSIONS

All these data have been used iteratively to adapt smoking cessation interventions from developed countries to suit the local Syrian environment. Research conducted in the SCTS to date has provided a fertile training ground for Syrian researchers, as well as for the building of regional collaborations.

The time for tobacco industry sponsored PREP evaluation has arrived

Rigorous and objective industry funded evaluation of potential reduced exposure products will require innovation and flexibility, but must begin now

Standardizing questionnaire items for the assessment of waterpipe tobacco use in epidemiological studies

Lessons from surveillance of the smoking epidemic show that the lack of adequate attention to standardizing measures and instruments for epidemiological studies has negatively influenced our ability to assess spatial and secular trends in smoking worldwide. Waterpipe smoking, another hazardous form of tobacco use, is gaining popularity worldwide, with societies in the Eastern Mediterranean region (EMR) being most affected. Several research groups are currently investigating the epidemiology of waterpipe smoking among various populations in the EMR. Initial evidence shows that in contrast to usage patterns observed in adult cigarette smoking, waterpipe smoking is characterized mainly by intermittent and social use. As such, many measures that have been traditionally used for the study of usage patterns and dependence among adult cigarette smokers are uninformative for waterpipe smoking. Thus, the need to develop standardized measures and terminology for assessment of the epidemiology of waterpipe smoking in different populations is of paramount importance. As the monitoring of waterpipe smoking is in its infancy, the development of consensus measures should facilitate the initiation of effective surveillance that can guide public health response to this emerging epidemic.

Patterns of waterpipe use and dependence: implications for intervention development

Despite the dramatic increase of tobacco smoking via waterpipe in Arab societies, and the apparent potential of waterpipe use to produce tobacco-related disease, little is known about the pharmacological effects of this method of tobacco smoking, particularly its ability to support dependence. This review focuses on recent waterpipe research and current theories of dependence in an attempt to identify patterns of waterpipe use and features likely to reveal dependence. Recent work indicates that, relative to cigarette smoking, this form of tobacco use is characterized by more intermittent use, later age of onset, greater spread among women and lower interest in quitting or appreciation of addictive properties. Waterpipe use is associated with classic features of tobacco/nicotine dependence, as well as features unique to this tobacco use method. However, even shared features of dependence, such as craving and addiction-induced socio-cognitive behavioral changes, can be displayed differently in waterpipe users, indicating the need for waterpipe-specific research approaches. Preliminary evidence suggests that an important step toward dependence involves a transition from social to individual patterns of waterpipe use. Surveillance and research into factors affecting use and cessation of this tobacco use method should pave the way for the development of effective prevention and intervention strategies to curb the burgeoning waterpipe use epidemic.

Tobacco smoking using a waterpipe: a re-emerging strain in a global epidemic

CONTEXT

The global tobacco epidemic may kill 10 million people annually in the next 20-30 years, with 70% of these deaths occurring in developing countries. Current research, treatment, and policy efforts focus on cigarettes, while many people in developing regions (Asia, Indian subcontinent, Eastern Mediterranean) smoke tobacco using waterpipes. Waterpipes are increasing in popularity, and more must be learned about them so that we can understand their effects on public health, curtail their spread, and help their users quit.

OBJECTIVE

To conduct a comprehensive review regarding global waterpipe use, in order to identify current knowledge, guide scientific research, and promote public policy.

DATA SOURCES

A Medline search using as keywords "waterpipe", "narghile", "arghile", "shisha", "hookah", "goza", "hubble bubble" and variant spellings (for example, "hooka"; "hukka") was conducted. Resources compiled recently by members of GLOBALink were used.

STUDY SELECTION

Every identified published study related to waterpipe use was included.

DATA SYNTHESIS

Research regarding waterpipe epidemiology and health effects is limited; no published studies address treatment efforts. Waterpipe use is increasing globally, particularly in the Eastern Mediterranean Region, where perceptions regarding health effects and traditional values may facilitate use among women and children. Waterpipe smoke contains harmful constituents and there is preliminary evidence linking waterpipe smoking to a variety of life threatening conditions, including pulmonary disease, coronary heart disease, and pregnancy related complications.

CONCLUSIONS

More scientific documentation and careful analysis is required before the spread of waterpipe use and its health effects can be understood, and empirically guided treatment and public policy strategies can be implemented.

Factors related to frequency of narghile (waterpipe) use: the first insights on tobacco dependence in narghile users

AIMS

To evaluate factors related to level of narghile (waterpipe) use as a first step towards modeling tobacco dependence among narghile users.

DESIGN

Cross sectional survey done in 2003 using interviewer-administered anonymous questionnaires.

SETTING

Cafes/restaurants serving narghiles in Aleppo, Syria.

PARTICIPANTS

Narghile smokers (161 men and 107 women; mean age, 30.1 +/- 10.2, 161; age range, 18-68 years; response rate, 95.3%) randomly selected from the 17 cafes/restaurants sampled.

MEASUREMENTS

Frequency of narghile use (daily, weekly, monthly) was assessed as a function of several factors potentially indicative of dependence, including situational characteristics (where, when, and with whom smoking occurs; seasonality of use, and sharing of narghile), attitudes, and experience with quitting narghile use, escalation of use over time, future intentions regarding use, perception of being "hooked" on narghile, and cognitions/behaviors engaged in to support use (carrying one's own narghile; think of narghile when it is not available; considering narghile for selection of cafes/restaurants).

FINDINGS

Frequency of narghile use was strongly correlated with participant's subjective judgment of how hooked they are on narghile (coefficient, 0.5). Predictors of narghile use frequency according to multinomial logistic regression were: male gender, smoking mainly alone versus with others; smoking mainly at home versus outside; smoking more frequently since initiation, being hooked on narghile, carrying narghile, and considering it for cafe/restaurant choice.

CONCLUSIONS

Our data reveal two main domains of a tobacco dependence syndrome likely to be relevant to narghile; the first reflects the effects of nicotine contained in narghile tobacco, and is not very different from what is seen with other tobacco products, and the second is unique to narghile and is related mainly to its social dimension, with more intensive smokers showing an increasingly individual pattern of narghile smoking.

Characteristics of cigarette smoking and quitting among university students in Syria

BACKGROUND

No study to date in Syria has documented the smoking and quitting characteristics in a representative sample of university students, and this study aims to fill this void.

DESIGN

In 2003, a cross-sectional survey was carried out among students at Aleppo University using an interviewer-administered questionnaire. Overall, 587 students participated in the study (278 males, 309 females; mean age, 21.8 +/- 2.1 years; response rate, 98.8%). Experiences and attitudes related to smoking and quitting were assessed for two popular forms of tobacco use in Syria-cigarettes and narghile (waterpipe).

RESULTS

Current cigarette smoking was reported by 30.9% of male and 7.4% of female students and daily smoking by 24.8% of male and 5.2% of female students. Narghile smoking was seen among 25.5% of men and 4.9% of women, mostly on an occasional basis. More than half of current smokers (56%) believed they could quit cigarettes, 75.2% were interested in quitting, and 78% of those had made a quit attempt in the past year. Important correlates of cigarette smoking among students were being older, male, and smoking narghile, while being older and from a poorer family were associated with increased interest in quitting. Interestingly, peers' smoking was associated with current smoking among students, but inversely with their willingness to quit.

CONCLUSIONS

Cigarette smoking is mainly a problem of male students, whose narghile smoking is likely to be dramatically increasing as well, sometimes practiced as a substitute for cigarettes. The findings that most smokers in this sample are interested in quitting smoking and have tried unsuccessfully to do so indicate that cessation support for youths in this country is urgently needed.

Prevalence and characteristics of narghile smoking among university students in Syria

SETTING

Narghile (waterpipe) smoking is increasing in all Arab societies, but little is known about its pattern of use.

METHODS

In 2003, a cross-sectional survey was conducted among students at Aleppo University using an interviewer-administered questionnaire. A representative sample of 587 students participated (278 males, 309 females; mean age 21.8 +/- 2.1 years; response rate 98.8%).

RESULTS

Ever narghile smoking was seen among 62.6% of men and 29.8% of women, while current smoking was seen among 25.5% of men and 4.9% of women. Only 7.0% of the men used narghile daily. Age of initiation was 19.2 +/- 2.2 and 21.7 +/- 3.2 years for men and women, respectively (P < 0.001). The salient feature of narghile smoking was its social pattern, where most users initiated and currently smoked narghile with friends. Narghile and cigarette smoking were related among students, with narghile smoking most prevalent among daily cigarette smokers. Multivariate correlates of narghile smoking were being older, male, originating from the city, smoking cigarettes, having friends who smoke narghile, and coming from a household where a greater number of narghiles were smoked daily.

CONCLUSIONS

Narghile smoking is prevalent among university students in Syria, where it is mainly practiced by men, intermittently, and in the context of social activities with friends.

Adapting smoking cessation interventions for developing countries: a model for the Middle East

OBJECTIVE

To describe the rationale and methods for the development of culturally-sensitive smoking cessation interventions for primary care settings in developing countries.

RATIONALE

Smokers in the Middle East have great difficulty quitting. Effective smoking cessation programs are currently lacking in the Middle East, and the development of culturally sensitive programs is hindered by the dearth of standardized information regarding tobacco use and dependence in this region.

METHODS

Epidemiological and clinical laboratory methods are needed to determine the prevalence and patterns of tobacco use and nicotine dependence. One strategy is to adapt smoking cessation methods widely used in industrialized countries to the Syrian and Middle Eastern environment. In a recently initiated project, the Syrian Center for Tobacco Studies has been established to address these issues. Initial work is focusing on collecting formative data including key informant interviews, focus groups, and epidemiological surveys to assess smokers' use patterns, needs, and resources. Clinical laboratory techniques are also being applied to assess the physiological, behavioral, and subjective effects of local tobacco use methods, such as narghile (water pipe) smoking. These data will be used to help adapt existing smoking cessation interventions from industrialized countries to be evaluated in a randomized controlled trial.

CONCLUSION

There is a great need to develop and disseminate effective cessation interventions in low-income countries. Successful interventions will contribute to a culturally sensitive and sustainable regional tobacco control infrastructure. This paper describes one approach to the development of such an infrastructure that is currently underway in the Middle East.

Gender and smoking status-based analysis of views regarding waterpipe and cigarette smoking in Aleppo, Syria

BACKGROUND

Narghile (waterpipe) smoking is increasing across the Eastern Mediterranean region (EMR), though little is known about the social attitudes and perceptions related to this method of tobacco use, and how those attitudes and perceptions are influenced by gender.

METHODS

Data from two cross-sectional surveys conducted in 2003 in Aleppo, Syria, were used to examine these issues. Overall, 855 participants were included (439 men, 416 women; mean age, 24.4+/-7.1 years; response rate, 97%). The current analysis focuses on responses to four similar nine-item questions tapping perceptions related to narghile smoking by women or men, and cigarette smoking by women or men. Scores on the nine items were summed to yield a total score to gauge participants' perceptions about narghile and cigarette.

RESULTS

Generally, participants were less positive about women smoking relative to men smoking, and cigarette smoking relative to narghile smoking. Cigarette smoking by women was the behavior least associated with positive perceptions. Individuals who resided in the city, were economically better-off, and were Christian, had higher perception scores (i.e., more positive attitudes) toward all forms of smoking, whereas older and married participants had higher perception scores for narghile only. Smoking status of participants, especially narghile smoking, was also associated with more positive perceptions toward smoking in general.

CONCLUSIONS

We conclude that preliminary analysis shows that views on different forms of smoking in Syria differ by gender and smoking status.

Tobacco specific nitrosamines and potential reduced exposure products for smokers: a preliminary evaluation of Advance

OBJECTIVE

To develop a method for evaluating the carcinogen delivery of potential reduced exposure products (PREPs) like Advance, a PREP marketed to reduce smokers' exposure to one tobacco specific nitrosamine (TSN), NNK, a potent lung carcinogen.

DESIGN, SETTING, AND PARTICIPANTS

Latin square ordered, three condition, outpatient, crossover design with 12 smokers of light or ultra-light cigarettes (15 or more cigarettes/day). In each five day condition, participants either smoked own brand, Advance, or no cigarettes. Also, on the first and last day of each condition, participants smoked one cigarette in the laboratory.

MAIN OUTCOME MEASURES

Subject rated measures of tobacco/nicotine withdrawal, expired air carbon monoxide, urine concentrations of cotinine and NNAL (one TSN biomarker), puff volume, duration, number, and interpuff interval.

RESULTS

Relative to own brand, Advance produced similar withdrawal suppression, slightly lower carbon monoxide, equivalent cotinine, and 51% lower NNAL concentrations. The lowest cotinine and NNAL concentrations were observed in the no cigarette condition. Participants took fewer puffs when smoking Advance.

CONCLUSIONS

Past experience with PREPs that failed to reduce smoking's harm demonstrates the need for clinical methods in PREP evaluation. This study shows how assessing PREP induced changes in withdrawal and exposure to carbon monoxide, nicotine, and carcinogens may help predict PREP harm reduction potential. Adequate withdrawal suppression, slightly lower concentrations of carbon monoxide, and reduction of one TSN biomarker were observed for Advance. In the future, clinical methods like those described here may be valuable for evaluating PREPs before they are marketed publicly.

Acute effects of Advance: a potential reduced exposure product for smokers

OBJECTIVE

To examine the acute effects of Advance, a potential reduced exposure product (PREP) for smokers marketed as a means to reduce exposure to toxic gases and tobacco specific nitrosamines.

DESIGN, SETTING, PARTICIPANTS

Latin square ordered, three condition, laboratory based, crossover design with 20 smokers of light or ultra-light cigarettes (15 or more cigarettes/day). In each 2.5 hour condition, participants completed an 8-puff smoking bout from their own brand, Advance, or an unlit cigarette (that is, sham smoking) every 30 minutes for a total of four bouts.

MAIN OUTCOME MEASURES

Subject rated measures of tobacco/nicotine withdrawal; carbon monoxide (CO), and heart rate; plasma nicotine concentrations.

RESULTS

Relative to own brand, Advance produced similar withdrawal suppression and heart rate increase, lower CO boost, and higher plasma nicotine concentrations.

CONCLUSIONS

PREPs for smokers need to be evaluated using a comprehensive strategy that includes empirical examination of acute and long term effects. Adequate withdrawal suppression and potentially lower concentrations of CO associated with Advance use are positive factors, although higher nicotine concentrations do not constitute "reduced exposure". Overall, longer exposure periods are necessary to determine carcinogen delivery. PREP evaluation is complex and should be completed objectively.

Acute subjective and physiological responses to smoking in adolescents

AIMS

To determine the topography of cigarette smoking and the subjective and physiological effects of abstinence and nicotine in adolescents who smoke on a daily versus a non-daily basis.

DESIGN

Repeated measures experiment, non-blinded, involving a single test session.

SETTING

Human psychopharmacology laboratory.

PARTICIPANTS

Twenty-one daily and 21 non-daily adolescent cigarette smokers (21 females; 21 males; age 13-18 years) with life-time use greater than 10 cigarettes, responding to radio and print advertisements.

INTERVENTION

Overnight abstinence from cigarettes followed by smoking of a single cigarette furnished by the participant at test.

MEASUREMENTS

The Fagerstrom Test for Nicotine Dependence, saliva nicotine and cotinine, expired air carbon monoxide (CO), heart rate (HR), self-report scales and smoking topography. Most measurements were performed before and after smoking.

FINDINGS

Saliva nicotine, CO and HR increased, and self-reported intention and desire to smoke decreased, after smoking (p < 0.001). Fagerstrom scores indicated greater dependence and desire to smoke in daily than in non-daily smokers. HR increased substantially over pre-smoking levels in both groups. Puff topography did not differ between the groups, although collectively these participants appeared to take smaller and more puffs than adult smokers tested under similar conditions.

CONCLUSION

This study provides initial evidence that adolescent cigarette smokers self-administer physiologically active doses of nicotine very early in their smoking careers. Nicotine dependence in adolescents appears to be a function of the current frequency of cigarette use, and subjective-behavioral consequences of abstinence and smoking are evident even in non-daily smokers.

Withdrawal-suppressing effects of a novel smoking system: comparison with own brand, not own brand, and de-nicotinized cigarettes

Tobacco smoking is associated with many health risks, all of which are decreased by smoking cessation. Tobacco companies are marketing novel products (e.g., Phillip Morris' Accord, R.J. Reynolds' Eclipse) intended to reduce these risks. Evaluation of these products is necessary to determine if they increase, decrease, or fail to change smoking's health risks. This study examines the acute effects of the Accord system on cigarette smokers; the study extends a previous preliminary evaluation by controlling for the system's eight-puff/cigarette limit, smokers' brand preference, and the act of smoking. Smokers of light or ultra-light cigarette brands (> or = 10 cigarettes/day, 16 men and 16 women) participated in this within-subjects protocol. Prior to each of the four, Latin-square ordered, approximately 2.5-h sessions, subjects abstained from smoking for at least 8 h. In each session, subjects smoked eight puffs, at 30-min intervals, from either their own brand of cigarettes, a marketed brand that was not their own, de-nicotinized tobacco cigarettes, or the novel smoking system. Subjective and physiological effects were assessed regularly. Results confirmed previous observations that the withdrawal suppression, CO intake, and tachycardia produced by the novel system are all less than that produced by normally marketed cigarette brands, even controlling for the system's eight-puff limitation and for brand preference. Incomplete withdrawal suppression may increase smoking frequency, thus potentially offsetting any decreased risks associated with Accord use. Laboratory studies of the acute effects of novel smoking systems are an important part of a comprehensive evaluation program.

Effects of abstinence and smoking on information processing in adolescent smokers

RATIONALE

Although adolescent smokers appear to display some of the hallmark features of dependence, the biological and behavioral effects of smoking in this population are poorly understood.

OBJECTIVES

This study aimed to define empirically the effects of abstinence and smoking in adolescent smokers, using indices validated in adult smokers.

METHODS

Subjects were 16 young novice smokers (five male, 11 female), ages 14-18 years. A modified Stroop task measured the ability to inhibit attention to smoking-related cues; the classic Stroop task measured the ability to inhibit a pre-potent response (i.e. reading a word); a rapid information processing (RIP) task measured vigilance.

RESULTS

Abstinence increased and smoking decreased the intrusiveness of smoking cues. Parallel effects were seen in commission errors on the RIP task. These effects were restricted to heavier smokers (>11 cigarettes/day). Subjective withdrawal effects predicted the intrusiveness of smoking words during abstinence. The number of cigarettes smoked per day predicted the beneficial effect of smoking on the classic as well as modified Stroop tasks. The physiological effects of abstinence and smoking predicted RIP performance.

CONCLUSIONS

Abstinence impairs and smoking improves inhibitory information processing in young novice smokers in a manner similar to adult smokers. Daily frequency of smoking is a critical moderator of these effects.

Placebo control study of acute smokeless tobacco abstinence in young adult men

Tobacco use can lead to dependence, as indicated by withdrawal symptomatology during abstinence. In smokers, nicotine-free cigarettes suppress tobacco withdrawal, suggesting that non-nicotine stimuli may be relevant to tobacco dependence. This study examined non-nicotine factors in smokeless tobacco (SLT) withdrawal. SLT users used their own brand of SLT, nicotine-free SLT, or no SLT hourly in 3 approximately 4.5-hr sessions. Participant-rated measures of craving and desire to use SLT were elevated in the abstinence condition relative to the own-brand and nicotine-free conditions. Heart rate was significantly elevated in sessions in which participants' own brand was administered relative to the nicotine-free and abstinence conditions. These results support the notion that stimuli associated with tobacco use may have some withdrawal suppressing qualities, at least in the short term.

Initial tobacco use episodes in children and adolescents: current knowledge, future directions

Approximately three-quarters of adult tobacco users report that their first tobacco use occurred between ages 11 and 17, while many adults who do not regularly use tobacco report that they experimented with it as adolescents. Surprisingly little is known about the effects of these initial tobacco use episodes and their influence on adult tobacco use patterns. In particular, understanding the role that nicotine plays in these early tobacco use experiences may be important in understanding the development of regular tobacco use and concomitant nicotine dependence. One goal of this review is to summarize current knowledge regarding the effects of initial tobacco use episodes in adolescents and to discuss nicotine exposure in initial tobacco use episodes. Another goal is to outline a research agenda designed to learn more about initial tobacco use episodes and the effects of nicotine in children. An ethical rationale and some potential methods for this research agenda are presented.

Naltrexone alters subjective and psychomotor responses to alcohol in heavy drinking subjects

Preclinical studies support endogenous opioid system involvement in alcohol reinforcement and consumption; however, recent clinical trials and human laboratory studies have provided mixed findings of the effects of naltrexone (a non-selective opioid antagonist) on alcohol responses. This study used a within-subject design (n = 23) to investigate naltrexone effects (0, 50 and 100 mg qd) on subjective and psychomotor responses to alcohol (none, moderate, high) in heavy drinkers. Before alcohol administration, subjects reported decreased desire to drink alcohol when maintained on 50 mg compared with placebo naltrexone. Following alcohol administration, active naltrexone significantly increased subjective ratings of sedative, and unpleasant/sick effects and decreased ratings of liking, best effects and desire to drink. Naltrexone generally did not alter subjective or objective indicators of drunkenness. Finally, high doses of naltrexone and alcohol interacted to produce the greatest decreases in liking and best effects. Findings support the role of endogenous opioids as determinants of alcohol's effects and suggest that naltrexone may be particularly clinically useful in those treatment patients who continue to drink heavily.

Preliminary evaluation of a novel smoking system: effects on subjective and physiological measures and on smoking behavior

Tobacco companies are responding to public pressure to market less dangerous and aversive products by developing novel smoking systems. The short- and long-term effects of these systems must be evaluated to determine the risks inherent in their use. One such system, the Accord, uses a hand-held device to heat tobacco electronically and is marketed as a means to reduce second-hand smoke. In this study 10 cigarette smokers (> or = 10 cigarettes per day) were recruited to evaluate the short-term effects produced when using this system. Subjects abstained from smoking for at least 8 h before participating in two experimental sessions where they smoked either their usual brand or used the Accord at 30-min intervals for 2 hours. Subject-rated measures of tobacco withdrawal and craving, physiological measures, and smoking behavior were assessed within each session. Results show that, when using the Accord, the magnitude of smoking-induced craving reductions and the physiological effects of smoking were less, and puff volume and frequency were greater than when subjects smoked their own brand of cigarettes. The expired air carbon monoxide increases observed after smoking own brand cigarettes did not occur after using the Accord. The novel system does not provide maximal withdrawal suppression and produces little increase in expired air carbon monoxide; physiological data suggest that the novel system may deliver nicotine less efficiently than normally marketed cigarettes. Smokers using the Accord system may smoke more often or more intensely to compensate for decreased withdrawal suppression and/or nicotine delivery.

Smokers' sex and the effects of tobacco cigarettes: subject-rated and physiological measures

Smoking tobacco cigarettes results in characteristic subject-rated and physiological effects in regular tobacco smokers. Few reports have investigated potential sex differences in the physiological and subjective effects produced by tobacco smoking, though previous reports indicate that men and women differ in their tobacco smoking behavior. Sex differences in the subjective and/or physiological effects of smoking may help determine why women find quitting smoking more difficult than men and may help guide gender-specific treatment when planning smoking cessation. This laboratory study investigated sex differences in the subjective and physiological effects of cigarette smoking and smoking behavior in men (n = 38) and women (n = 30) before, during, and after they smoked two of their usual brand of cigarettes through a flowmeter-type puff topography measurement device. Results showed that the reduction in 'desire to smoke' produced by cigarette smoking was greater in women than in men, that the physiological effects of smoking were independent of smokers' sex, and that women take smaller and shorter puffs than men. These results suggest that women may be more sensitive than men to some of the subjective but not the physiological effects of smoking.

Relative potency of levo-alpha-acetylmethadol and methadone in humans under acute dosing conditions

levo-alpha-Acetylmethadol (LAAM) and methadone are full mu-opioid agonists used to treat opioid dependence. Current labeling indicates that LAAM is less potent than methadone. Clinical studies have not determined the relative potency of these drugs. This study compared the effects of acute doses of LAAM and methadone and also examined the ability of naloxone to reverse their effects. Five occasional opioid users received once weekly doses of either placebo, LAAM, or methadone (15, 30, or 60 mg/70 kg p.o.) in agonist exposure sessions and then received naloxone (1.0 mg/70 kg i.m.) 24, 72, and 144 h after agonist exposure. Subject-rated, observer-rated, and physiological measures were assessed regularly. Comparisons of physiological and subjective measures collected in agonist exposure sessions indicate that LAAM is not less potent than methadone under acute dosing conditions. For some measures, LAAM was significantly more potent. Three subjects who entered the study were withdrawn for safety reasons due to greater than anticipated and clinically relevant respiratory depression after receiving 60 mg of LAAM. Naloxone did not fully reverse the pupil constriction produced by 60 mg of LAAM. Acute agonist effects suggest that LAAM may be more potent than methadone and more potent than current labeling indicates. An accurate LAAM:methadone relative potency estimate will aid determination of adequate doses for opioid-dependent patients inducted onto LAAM and for methadone maintenance patients who choose to switch to more convenient thrice-weekly LAAM.

Induction with levomethadyl acetate: safety and efficacy

BACKGROUND

Levomethadyl acetate hydrochloride (known as LAAM) is a mu-opioid agonist approved for the treatment of opioid dependence. Clinical trials comparing LAAM and methadone have reported lower patient retention rates during LAAM induction; however, this may reflect dose and schedule differences. Few studies have systematically examined LAAM dose induction. This study compared induction with 3 different LAAM dosage levels.

METHODS

In a randomized, double-blind trial, male and female opioid-dependent patients (N = 180) were assigned to 1 of 3 LAAM doses. The low-dose (25 mg) induction was constant from the onset of treatment, the medium-dose (50 mg) induction lasted 7 days, and the high-dose (100 mg) induction lasted 17 days. Safety and efficacy were assessed on retention, urinalysis and self-reported drug use, symptoms, and patient ratings of medication adequacy.

RESULTS

The high-dose group had significantly fewer illicit opioid-positive urine samples in weeks 3 and 4 as compared with the low-dose group. The high-dose group had significantly lower self-reported heroin craving in weeks 2 and 3. All groups demonstrated significant decreases in illicit drug use, withdrawal symptoms, and depression. There were no between-group differences in retention; however, there was a trend (P = .08) for lower retention and a greater number of agonist adverse effects were observed in the high-dose group. Overall, LAAM doses were well tolerated by most patients.

CONCLUSION

Induction with low and medium LAAM doses can be safely and effectively achieved within 7 days. Induction with higher LAAM doses can be safely achieved within 17 days, but may result in greater rates of patient dropout and opioid agonist adverse effects. Therefore, higher doses should be approached more slowly.

Isoluminance and contingent color aftereffects

In the typical induction of the orientation-contingent color aftereffect (CCAE), the stimuli are composed of elements that differ in both color and luminance. Three experiments are reported that show that chromatic contrast between stimulus elements is insufficient for the induction of the orientation-CCAE and that luminance contrast is necessary. These experiments expand on previous research concerned with the role of luminance contrast in the induction of orientation-CCAEs by eliminating alternative explanations.

Dose-related efficacy of levomethadyl acetate for treatment of opioid dependence. A randomized clinical trial

OBJECTIVE

To compare the clinical efficacy of different doses of levomethadyl acetate hydrochloride (known as LAAM) in the treatment of opioid dependence.

DESIGN

A randomized controlled, double-blind, parallel group, 17-week study.

SETTING

Outpatient facilities at Johns Hopkins University Bayview Medical Center, Baltimore, Md.

PATIENTS

Opioid-dependent volunteers (N=180) applying to a treatment-research clinic.

INTERVENTION

Thrice-weekly (Monday/Wednesday/Friday) oral LAAM dose conditions of 25/25/35 mg, 50/50/70 mg, and 100/100/140 mg and nonmandatory counseling.

MAIN OUTCOME MEASURES

Retention in treatment, self-reported heroin use, and opioid-positive urine specimens.

RESULTS

Retention was independent of subjects' sex and dose. Self-reported heroin use decreased in a dose-related manner. At final assessment, patients in the high-dose condition reported using heroin 2.5 of 30 days as compared with 4.1 or 6.3 days for patients in the medium-dose and low-dose conditions, respectively (high dose vs low dose, P<.05); urinalysis results were similarly dose related. Overall, 20 (34%) of 59 patients in the high-dose condition remained opioid-abstinent for 4 consecutive weeks, as compared with 8 (14%) of 59 in the medium-dose and 7 (11%) of 62 in the low-dose conditions (P<.01). Self-report and urinalysis data are consistent with a greater than 90% reduction in illicit opioid use by the high-dose group relative to pretreatment levels.

CONCLUSION

Opioid substitution treatment with LAAM substantially reduces illicit opioid use. The clinical efficacy of LAAM is positively related to dose.

Controlled opioid withdrawal evaluation during 72 h dose omission in buprenorphine-maintained patients

Buprenorphine's clinical utility as an opioid dependence pharmacotherapy may be enhanced with less-than-daily dosing. This study assessed opioid withdrawal after an acute 72 h dose omission in buprenorphine-maintained patients (8 mg/day s.l.). Eight outpatients required to remain free of opioids, cocaine and benzodiazepines completed four double-blind, double-dummy, Latin-square ordered conditions. Test conditions of 8 or 16 mg s.l. buprenorphine were followed by 2 days of placebo dosing. Control conditions were buprenorphine maintenance (8 mg/day), to provide a reference for evaluation of placebo test days and naloxone administration (10 mg 70 kg i.m.) during 8 mg buprenorphine maintenance to assess withdrawal measure sensitivity. Subjective measures and pupil diameter were significantly influenced only by naloxone. The lack of subjective symptoms and physiological signs of opioid withdrawal during 72 h of acute dose omission supports the feasibility of less-than-daily dosing at buprenorphine doses of 8 mg/day in patients who have demonstrated an ability to remain drug-free for an extended period.

Human drug discrimination and multiple chemical sensitivity: caffeine exposure as an experimental model

Multiple chemical sensitivity is a controversial diagnosis. Rigorous, controlled, laboratory-based research can reduce this controversy and lead to potential clinical confirmatory tests. The literature on human caffeine discrimination provides a rigorous methodology that can address reports that patients who suffer multiple chemical sensitivity (MCS) are sensitive to usually well-tolerated chemical doses; the studies require patients to discriminate caffeine from placebo under double-blind conditions. Several issues relevant to the conduct of caffeine discrimination studies using MCS patients as subjects are addressed; these issues include study design, determination of safe and tolerable training doses, and discrimination training. Such research will benefit patients and clinicians dealing with a diagnosis of MCS.

Mecamylamine does not precipitate withdrawal in cigarette smokers

Mecamylamine is an antihypertensive that acts via nicotinic antagonism and has been suggested as an aid in smoking cessation. Nicotine dependent patients may not accept mecamylamine if it precipitates withdrawal, as it does in nicotine dependent rats. This study examined mecamylamine's effects using procedures designed to measure precipitated withdrawal symptoms in humans. Ten cigarette smokers (mean of 37.5 cigarettes/day) and ten non tobacco-using subjects participated in three 6-h sessions. After a 2-h baseline period in which smokers smoked one cigarette every 30 min, oral mecamylamine (0, 10, or 20 mg randomly ordered across sessions) was administered (double-blind). No smoking was allowed for the remainder of the session. Mecamylamine reduced blood pressure and increased heart rate relative to placebo in both the smokers and the non-tobacco users. No reliable direct subjective effects of mecamylamine were observed. Smokers' subjective reports of cigarette craving and tobacco withdrawal increased, and DSST performance was disrupted over the last 4 h of each session. Effects were independent of dose (placebo versus active). These results suggest that up to 20 mg mecamylamine will not precipitate nicotine withdrawal and that this medication would be acceptable for use in smoking cessation.

Buprenorphine's physical dependence potential: antagonist-precipitated withdrawal in humans

Buprenorphine is a partial mu opioid agonist with demonstrated efficacy in the treatment of opioid dependence. One potential advantage of buprenorphine over full mu opioid agonists is its reported low physical dependence profile. This study systematically examined physical dependence produced by maintenance with a clinically relevant dose of buprenorphine using antagonist challenge procedures. In this residential laboratory study, eight opioid-dependent volunteers maintained on 8 mg/day of sublingual buprenorphine were each challenged on independent occasions with placebo, i.m. naloxone (0.3, 1.0, 3.0 and 10.0 mg/70 kg) and p.o. naltrexone (0.3, 1.0 and 3.0 mg/70 kg) 14 hr after their daily buprenorphine dose using a repeated measures, cross-over design. Both naloxone and naltrexone precipitated time- and dose-dependent withdrawal, as evidenced by changes in subject-rated, observer-rated and physiological measures. Significant precipitated withdrawal occurred at 3.0 and 10 mg/70 kg i.m. of naloxone and 3.0 mg/70 kg p.o. of naltrexone. These results indicate that buprenorphine maintenance produces physical dependence and that i.m. naloxone and p.o. naltrexone produce equivalent effects in withdrawal precipitation under these conditions. Findings have implications for selection of antagonist doses for use in formulating combination agonist/antagonist medications and for use in transition of drug abusers from buprenorphine to antagonist maintenance therapies.

Buprenorphine treatment of opioid dependence: clinical trial of daily versus alternate-day dosing

Buprenorphine, a mu-opioid partial agonist, has demonstrated efficacy for the treatment of opioid dependence comparable to that of methadone. The clinical utility of buprenorphine would be enhanced if it could be dosed on a less than daily basis. The current study is a parallel-group outpatient clinical trial of daily versus alternate-day dosing with 8 mg sublingual (s.l.) buprenorphine. Participants were randomly assigned to daily (n = 51) or alternate-day (n = 48) schedules of active medication administration for an 11-week double-blind trial. Patients assigned to alternate-day buprenorphine received placebo every other day. Primary outcome measures were retention in treatment and urine specimens positive for opiates. Clinic attendance, dose adequacy ratings, withdrawal symptomatology, and urine specimens positive for cocaine were secondary outcome measures. Neither endpoint analysis with the intent-to-treat sample nor time course analysis with treatment completers revealed any statistically significant differences between the dosing schedules on any outcome measure. Examination of 95% confidence intervals suggested a non-significant trend for the daily dosing schedule to have superior clinical efficacy at the dose tested. Nevertheless, these results are generally consistent with previous studies of less than daily dosing with buprenorphine and support the conclusion that an alternate-day dosing schedule can be effective in and acceptable to a substantial portion of patients.

A placebo controlled clinical trial of buprenorphine as a treatment for opioid dependence

Large-scale placebo controlled clinical trials assessing the efficacy of medications for the treatment of drug dependence have generally been limited to alcohol, cocaine and nicotine dependent populations. The purpose of the present study was to assess the early (1-2 week) clinical effectiveness of buprenorphine versus placebo in an opioid dependent population. The study used a parallel-group design with a behavioral choice component to compare buprenorphine (a mu-opioid partial agonist) to placebo for the treatment of opioid dependence. Opioid dependent volunteer patients participated in a 14-day study to assess the effectiveness and patient acceptance of this new pharmacotherapy for the treatment of opioid dependence. Patients were randomly assigned to placebo (n = 60) or 2 mg (n = 60) or 8 mg (n = 30) daily sublingual buprenorphine. All doses were administered double-blind. On days 6-13 all patients could request a dose change, knowing that their new dose would be randomly chosen from the remaining 2 alternatives. Compared to placebo, patients given buprenorphine (independent of dose) showed greater time on initial dose, requested fewer dose changes, used less illicit opioids (assessed by urinalysis), and rated dose adequacy higher. These results demonstrate that a placebo controlled study with a behavioral choice component is an effective means of assessing the potential efficacy and acceptability of new pharmacotherapies for opioid dependence.

An associative interpretation of the indirect McCollough effect

Following an induction procedure in which a coloured grid is alternated with a square of a complementary colour, subjects report colour after-effects on both the grid orientation present during induction and the orthogonal non-induced grid orientation. The after-effect reported on the induced grid orientation is called the McCollough effect (ME). The after-effect reported on the non-induced grid orientation is called the indirect ME. There is evidence that the ME represents an instance of Pavlovian conditioning. The present results support a conditioning interpretation of the indirect ME and are inconsistent with interpretations of the indirect ME that attribute the phenomenon to special orthogonal coding mechanisms within the visual system.

Scanning and form-contingent color aftereffects

G. K. Humphrey, A. M. Herbert, L. A. Symons, and S. Kara (1994) and J. Broerse and P. Grimbeek (1994) suggested that the form-contingent color aftereffect reported by S. Siegel, L. G. Allan, and T. Eissenberg (1992) would not be obtained if Ss were instructed to scan the induction and assessment forms. The authors present data from Ss who were instructed to scan the forms. These scanning Ss displayed aftereffects that were no different from those described earlier by Siegel et al. Scanning Ss do display spatiotopic contingent color aftereffects.

The associative basis of contingent color aftereffects

According to a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimulus (grids) become associated with color. Contrary to this interpretation are reports that simple forms cannot be used to elicit illusory color and that the ME is not degraded by decreasing the grid-color correlation. The present results indicate: (a) Form stimuli can contingently elicit color aftereffects; (b) even a non-patterned stimulus--the lightness of a frame surrounding a colored area--can contingently elicit color aftereffects; (c) this frame lightness-contingent aftereffect, like the ME, persists for at least 24 hr; and (d) the frame lightness-contingent aftereffect can be used to demonstrate that correlational manipulations affect the ME, as they affect other types of conditional responses.

The associative basis of contingent color aftereffects

According to a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimulus (grids) become associated with color. Contrary to this interpretation are reports that simple forms cannot be used to elicit illusory color and that the ME is not degraded by decreasing the grid-color correlation. The present results indicate: (a) Form stimuli can contingently elicit color aftereffects; (b) even a non-patterned stimulus--the lightness of a frame surrounding a colored area--can contingently elicit color aftereffects; (c) this frame lightness-contingent aftereffect, like the ME, persists for at least 24 hr; and (d) the frame lightness-contingent aftereffect can be used to demonstrate that correlational manipulations affect the ME, as they affect other types of conditional responses.

Spatial contingency and the McCollough effect

On the basis of a conditioning analysis of the orientation-contingent color aftereffect (McCollough effect, ME), orientation stimuli become associated with simultaneously presented chromatic stimuli. This account suggests that decreasing the contingency between the grid orientation and color should decrease the strength of the aftereffect. Results of previous research indicate that decreasing the temporal contingency (by presenting homogeneous chromatic stimuli between presentations of chromatic grids) does not decrease the ME. However, it has been suggested that the appropriate contingency-degradation procedure would involve decreasing spatial (rather than temporal) contingency. That is, the illusion should be attenuated by extending the color beyond the confines of the grid. Contrary to this hypothesis, the results of the present experiments provide no evidence that decreasing the spatial contingency between grid and color decreases the ME; rather, the aftereffect is increased by such a manipulation.