bluuebunny/crossref_metadata_2025 huggingface dataset:
Craving: what can be done to bring the insights of neuroscience, behavioral science and clinical science into synchrony
Authors: Meyer Roger E.
Published: March 2003

Alcohol self‐administration behavior is the common thread that is necessary to bring the insights of neuroscience, behavioral science and clinical science into synchrony around the concept of craving. Animal models should address the molecular and cellular changes that take place in behaviorally relevant brain regions of rats consequent to chronic self‐administration of ethanol. Animal models can focus on the biology of the anticipatory state in alcohol preferring/consuming rats, as well as studies of the effects of possible medications on this state in the animal model, on actual alcohol consuming behavior, and on the residual effects of chronic alcohol on the non‐human mammalian brain. In human studies of craving, cue‐reactivity in the absence of the opportunity to drink alcohol does not have the same salience as cue‐reactivity in which drinking is possible. Moreover, actual drinking behavior serves to validate self‐reports of craving. Studies of limited alcohol self‐administration in the laboratory are an essential element in screening new medications for the treatment of alcoholism. Studies to date suggest no adverse reaction to the participation of alcoholic subjects in limited alcohol self‐administration studies, but the research community should continue to monitor carefully the outcomes of alcohol‐dependent subjects who participate in this type of research, and efforts should always be made to encourage these subjects to enter active treatment. In outpatient clinical trials of new treatments for alcoholism, the assessment of craving should include queries regarding symptoms and signs of protracted abstinence such as sleep disturbances, as well as questions regarding situational craving. Field observations of alcoholics in their favorite drinking environments would contribute greatly to our understanding of the real‐world phenomenology of craving.
Research perspectives on alcohol craving: an overview
Authors: Lowman Cherry , Hunt Walter A. , Litten Raye Z. , Drummond D. Colin
Published: March 2003

This overview of the Addiction supplement on 'Research Perspectives on Alcohol Craving' has three objectives. The first is to familiarize readers with the variety of theoretical models relevant to craving and the definitions of craving generated by them that are discussed in the supplement. These include phenomenological models, classical and operant conditioning models, the incentive‐sensitization theory, a tonic‐phasic model of dopamine system regulation, cognitive social learning theory and the cognitive processing theory of craving. The second objective is to provide a brief summary of the methodological articles which focus as a whole more on what can be done than on what has been done in alcohol craving research. The final objective is to emphasize the potential importance of transdisciplinary research‐research that integrates components of different theoretical models‐for delineating the role of alcohol and drug craving in the complex biobehavioral process known as addiction. It is the hope of the guest editors (the authors of this overview) that the Addiction supplement and this introduction to it will contribute to development of a framework for future transdisciplinary research on alcohol craving.
Clinical perspectives for the study of craving and relapse in animal models
Authors: Li Ting‐Kai
Published: March 2003

Several major clinical models of alcoholism in which craving plays a role are summarized and key questions are raised regarding the course of craving in the emergence of alcoholism, how it varies in different stages of the disorder (e.g. active alcoholic, withdrawal, protracted abstinence) and what craving may contribute to major signs and symptoms of alcoholism. Turning to animal models, a plea is made for development of a standardized definition of human craving that can be represented and operationalized in animal models. Until there is scientific consensus on such a definition, four ways are elucidated in which animal model research can contribute to advances in our knowledge of human craving and the role it plays in addictive behavior: (1) engaging both basic and clinical researchers to identify parallel constructs of craving and predictors of craving for adoption in comparative human and animal model studies; (2) conducting exploratory research on craving in animal models using relapse to drinking as the dependent measure; (3) identifying mechanisms that underlie clinical signs and symptoms of alcoholism in animal models; and (4) identifying genetic models in basic research that account for variations in response to alcohol that may also occur in humans. This latter point is made in a discussion of the genetic contribution to voluntary alcohol consumption, the alcohol deprivation effect, tolerance and dependence, as illustrated by differences between alcohol‐preferring (P) rats and‐nonpreferring (NP) rats. The review concludes with four questions and issues that need to be among those that guide future research on craving.
A cognitive processing model of alcohol craving and compulsive alcohol use
Authors: Tiffany Stephen T. , Conklin Cynthia A.
Published: March 2003

Many addiction theories assume that craving plays a central role in the acquisition and maintenance of drug dependence. For example, craving is often depicted as the subjective experience of the motivational state directly responsible for all drinking in the alcoholic. Craving has two prominent features that must be explained by any viable model of craving. First, craving tends to be highly situationally specific, readily triggered by stimuli previously associated with drug use. Secondly, craving can persist well beyond the cessation of drinking in an alcoholic. Conventional theories typically address craving's cue specificity and persistence by invoking concepts of classical conditioning. These theories fall into two classes: those that emphasize withdrawal and those that focus on the positive‐incentive properties of drugs. Both types of theories assume that craving processes are represented by the concomitant activation of craving report, drug‐seeking and drug use, and specific patterns of autonomic responses. However, research fails to find more than modest relationships across these putative manifestations of craving. The cognitive processing model, described in this paper, offers a different view of craving's form and function and proposes that drug use can operate independently of the processes controlling craving. According to this model, addictive drug use is regulated by automatic cognitive processes, while craving represents the activation of non‐automatic processes. These non‐automatic processes are activated to either aid in completing interrupted drug use or block automatic drug‐use sequences. From this perspective, craving is neither irrelevant nor central to the alcoholic's drug use, but rather serves as a cognitive marker of processes that, only in some instance, may be associated with alcohol seeking and use. The research and treatment implications of this model's assumptions regarding drug use and craving processes are discussed.
Laboratory‐based assessment of alcohol craving in social drinkers
Authors: De Wit Harriet
Published: March 2003

Subjective feelings of craving for drugs and alcohol are hallmark symptoms of substance abuse and dependence, and they are thought to play a pivotal role in relapse to drug use. However, relatively little is known about the relationship between craving and overt drug‐seeking behavior or drug consumption. One way to investigate the relationship between self‐report measures of craving and objective measures of drug‐taking behavior is to investigate the degree to which they co‐vary in laboratory studies. In particular it may be informative to examine the degree to which these measures co‐vary after experimental manipulations that are expected to increase or decrease craving for, or use of, a drug. We review the results of several laboratory studies in which both self‐report measures of craving or desire for alcohol and alcohol consumption were measured, using subjects who were non‐problem social drinkers. The experimental manipulation used to increase craving and drug‐taking was the administration of a priming dose of alcohol. The manipulation that was intended to decrease craving and drug‐taking was administration of a dose of naltrexone, because of its use in the treatment for alcoholism. In most of these studies, self‐reported ratings of desire for alcohol were positively associated with consumption of alcohol. However, there were also instances in which one measure varied independently of the other, indicating that under certain circumstances they are controlled by separate factors. Laboratory‐based studies such as these may improve our understanding of how subjective reports of alcohol craving are related to objective measures of consumption.
Comments on craving
Authors: Shiffman Saul
Published: March 2003

This brief commentary addresses a few issues relevant to the conceptualization and assessment of craving. It begins by suggesting the utility of the analogy between craving and hunger, another often‐studied subjective experience with presumed motivational significance. It then proceeds to a discussion of procedures for assessing craving, highlighting the limitations of retrospective reports, and the potential utility of real‐time measures. Finally, building upon the findings of such real‐time measures, it suggests the need to differentiate tonic and phasic craving experiences.
Challenges in the manipulation, assessment and interpretation of craving relevant variables
Authors: Tiffany Stephen T. , Carter Brian L. , Singleton Edward G.
Published: March 2003

The nature of drug craving and its role in the addictive process is a contentious issue in the addiction sciences. There are numerous disputes regarding the definition, assessment, manipulation and interpretation of craving, and progress toward resolving the enigmas of craving confronts numerous conceptual and methodological challenges. Greater attention to certain fundamental principles of measurement and manipulation should generate immediate and substantial improvements in efforts to understand and control alcohol craving. This paper provides suggestions for enhancing the measurement of self‐reported alcohol craving and improving the manipulation of alcohol craving under controlled laboratory conditions. With regard to measurement, single‐item scales commonly employed in craving research tend to be handicapped by limited reliability and validity. Multi‐item craving scales are more likely to provide the accuracy required to accurately discriminate between different levels of craving across individuals or across different settings. Conceptual and practical considerations for the selection of multi‐item craving instruments are discussed. With regard to the manipulation of alcohol craving in the laboratory, recent meta‐analyses suggest that alcohol craving effects in such research may be relatively weaker than craving effects found in similar research with other addicts. Therefore, laboratory‐based investigations into the nature of alcohol craving should utilize procedures and assessments that are particularly sensitive to the detection of alcohol craving. This paper offers methodological recommendations for enhancing the magnitude of alcohol craving effects generated in laboratory research.
The measurement of drug craving
Authors: Sayette Michael A. , Shiffman Saul , Tiffany Stephen T. , Niaura Raymond S. , Martin Christopher S. , Schadel William G.
Published: March 2003

This paper reviews theoretical and methodological issues in the measurement of drug craving, with an emphasis on self‐report assessment. Despite the important role that craving plays in many research and clinical settings, the way in which the construct is conceptualized and measured rarely receives sufficient attention. Issues pertinent to conceptualizing craving are identified. Because there is no single perfect measure of craving, it is essential that researchers understand the limitations of each measure. Measurement performance concerns that affect the validity of different measures are reviewed. Non‐verbal assessment methods are also reviewed. Research factors that may help determine the optimal measures for a given study are highlighted. It is concluded that advances in assessment will proceed only when combined with additional research and a better theoretical understanding of craving.
Obsessive–compulsive aspects of craving: development of the Obsessive Compulsive Drinking Scale
Authors: Anton Raymond F.
Published: March 2003

“Craving” for alcohol needs improved definition and measurement. This review provides a rationale for considering at least certain aspects of craving as having obsessive and compulsive features. As such, there may be phenomenological, but not necessarily etiological, overlap with obsessive‐compulsive disorder. There are increasing data that suggest a neuroanatomical overlap between addiction/craving and obsessive‐compulsive symptoms. The self‐rated Obsessive Compulsive Drinking Scale (OCDS), based on the Yale‐Brown Obsessive Compulsive Scale for heavy drinking interview (YBOCS‐hd), was developed to assist in the examination of certain aspects of “craving” in alcoholics. The development, reliability, face validity, congruent validity and predictive validity of the OCDS are presented and discussed in this paper. The utility of the OCDS as a measurement tool in cognitive‐behavioral and pharmacological alcoholism treatment research is highlighted. The potential of this instrument as a research and clinical tool for the understanding and evaluation of alcohol dependence needs further evaluation.
Per capita alcohol consumption and all‐cause mortality in 14 European countries
Authors: Norström Thor
Published: March 2003

Aims. (1) To estimate the relationship between per capita alcohol consumption and male all‐cause mortality in 14 European countries. (2) To compare the estimates with predictions from the

U‐shaped curve at the aggregate level.

Data and method. The outcome measures comprised annual data, after 1950, on male mortality (all‐cause mortality and mortality from diseases) for the following age groups: 15 +, 15‐29, 30‐49, 50‐69 and 70 + years. Female mortality was included as a control variable. Alcohol sales were used as proxy for per capita consumption. The data were analysed using the Box‐Jenkins technique. The estimated alcohol effects were pooled within low‐, medium‐ and high‐consumption countries.

Results. For all‐cause mortality (15 +), the effect estimates were significantly positive in eight of the 14 countries. The effect on mortality of a 1‐litre increase in consumption tended to be stronger in low‐consumption countries (3% per litre) than in medium‐ and high‐consumption countries (1%). This pattern deviates from that predicted from the

U‐shaped curve. No significant impact of alcohol was found in the youngest age group when mortality from diseases was used as the outcome.

Conclusions. Increases in overall consumption seem to be associated with increases in total mortality. Differences in drinking patterns are discussed as a possible explanation for the variation between country groups in alcohol effect.
Alcohol and mortality: methodological and analytical issues in aggregate analyses
Authors: Norström Thor , Skog Ole‐Jørgen
Published: March 2003

This supplement includes a collection of papers that aim at estimating the relationship between per capita alcohol consumption and various forms of mortality, including mortality from liver cirrhosis, accidents, suicide, homicide, ischaemic heart disease, and total mortality. The papers apply a uniform methodological protocol, and they are all based on time series data covering the post‐war period in the present EU countries and Norway. In this paper we discuss various methodological and analytical issues that are common to these papers. We argue that analysis of time series data is the most feasible approach for assessing the aggregate health consequences of changes in population drinking. We further discuss how aggregate data may also be useful for judging the plausibility of individual‐level relationships, particularly those prone to be confounded by selection effects. The aggregation of linear and curvilinear risk curves is treated as well as various methods for dealing with the time‐lag problem. With regard to estimation techniques we find country specific analyses preferable to pooled cross‐sectional/time series models since the latter incorporate the dubious element of geographical co‐variation, and conceal potentially interesting variations in alcohol effects. The approach taken in the papers at hand is instead to pool the country specific results into three groups of countries that represent different drinking cultures; traditional wine countries of southern Europe, beer countries of central Europe and the British Isles and spirits countries of northern Europe. The findings of the papers reinforce the central tenet of the public health perspective that overall consumption is an important determinant of alcohol‐related harm rates. However, there is a variation across country groups in alcohol effects, particularly those on violent deaths, that indicates the potential importance of drinking patterns. There is no support for the notion that increases in per capita consumption have any cardioprotective effects at the population level.
Alcohol and suicide in 14 European countries
Authors: Ramstedt Mats
Published: March 2003

Aims. To test the hypothesis that a positive population‐level relationship between alcohol and suicide is more likely to be found in dry drinking cultures (as indicated by consumption level) than in wet drinking cultures.

Design. Gender‐ and age‐specific suicide rates in 14 western European countries were analysed in relation to per capita alcohol consumption employing the Box‐Jenkins technique for time series analysis. The country‐specific estimates were pooled into low‐, medium‐ and high‐consumption countries.

Measurements. Suicide mortality data for 5‐year age groups were converted into gender‐ and age‐specific mortality rates. Alcohol sales expressed as litres of 100% alcohol per year and inhabitants 15 years and older were used as a measure of alcohol consumption.

Findings. A positive and significant relationship between per capita consumption and gender‐ and age‐specific suicide rates was revealed most often in northern Europe and found least often in southern Europe. A stronger absolute alcohol effect for men was found only in northern Europe, whereas the relative alcohol effect was somewhat stronger for women in both northern and central Europe. Also, the suicide rate in younger age groups was more often significantly related to per capita consumption than suicide among the elder in northern and central Europe but not in southern Europe.

Conclusions. The population‐level association between alcohol and suicide is conditioned by cultural factors. In general, the suicide rate tends to be more responsive to changes in alcohol consumption in drinking cultures characterized by a low post‐war per capita consumption compared to drinking cultures with higher consumption levels. The findings give support to the hypothesis derived from previous theoretical and empirical work, suggesting that suicide and alcohol is more closely connected in dry cultures than in wet cultures.
Cannabis use: consistency and validity of self‐report, on‐site urine testing and laboratory testing
Authors: Buchan Betty J. , L. Dennis Michael , Tims Frank M. , Diamond Guy S.
Published: March 2003

Aims  To evaluate the agreement between adolescent self‐reported cannabis use, “on‐site” qualitative urine screening, and quantitative laboratory testing.

Design  A cross‐sectional study of intake and follow‐up data from 248 adolescents entering substance abuse treatment for cannabis use disorders (abuse or dependence). This is part of the multi‐site cooperative agreement Cannabis Youth Treatment study.

Setting  Data collected from adolescents randomly assigned to one of five outpatient treatments at four sites: Operation PAR, Inc., Florida; Chestnut Health Systems, Illinois; University of Connecticut Health Center, Connecticut; and Children's Hospital of Philadelphia, Pennsylvania.

Participants  The data represent 248 unique individuals from a sample of 297 adolescents ranging in age from 12 to 18 years.

Measurements  Prevalence, agreement, kappa, sensitivity, specificity, positive and negative predictive value.

Findings  The self‐report rates were higher at intake than either urine test (82.4% vs. 77.0% vs. 52.7%), but both lower and higher at the 3‐month follow‐up (55.5% vs. 70.0% vs. 47.3%) and 6‐month follow‐up (60.2% vs. 73.5% vs. 55.8%). The disagreements went in both directions and the kappa coefficients were only in the moderate range (0.4). Over two‐thirds of these frequent cannabis users tested positive when they said they had not used in 1 week and one‐third tested positive even though they said it had been more than 4 weeks since last use.

Conclusions  The findings suggest both the advantages of multiple sources of information and the need for further work on the latency of cannabis metabolites in clinical populations.
The Cannabis Youth Treatment (CYT) experiment: rationale, study design and analysis plans
Authors: Dennis Michael , Titus Janet C. , Diamond Guy , Donaldson Jean , Godley Susan H. , Tims Frank M. , Webb Charles , Kaminer Yifrah , Babor Thomas , Roebuck M. C. , Godley Mark D. , Hamilton Nancy , Liddle Howard , Scott Christy K. ,   The C. Y. T. Steering Committee
Published: March 2003

Aims  This paper provides a description of the rationale, study design, treatments and assessment procedures used in the Cannabis Youth Treatment (CYT) experiment.

Design  CYT was designed to (a) test the relative effectiveness, cost and benefit–cost of five promising treatment interventions under field conditions and (b) provide evidence based manual‐guided models of these interventions to the treatment field.

Setting  The study involved two community‐based treatment programs and two major medical centers.

Participants  Participants were 600 adolescents recruited from the regular intake who were between the ages of 12 and 18, had used marijuana in the past 90 days, and met one or more criteria of dependence or abuse.

Interventions  Participants were randomly assigned to one of five interventions: Motivational Enhancement Therapy (MET), Cognitive Behavioral Therapy (CBT), Family Support Network (FSN), Adolescent Community Reinforcement Approach (ACRA), or Multidimensional Family Therapy (MDFT).

Measurements  Self‐report data were collected at intake, 3, 6, 9 and 12 months post discharge using the Global Appraisal of Individual Needs (GAIN), as well as several supplemental self‐reports, collateral reports, urine testing, and service logs.

Findings  This paper reports on the study's implementation including the psychometric properties of the measures (alphas over 0.8), validity of self‐report (kappa over 0.6), high rates of treatment completion (81% completed two or more months), and high rates of follow‐up (over 94% per wave).

Conclusions  The feasibility of implementing the CYT manual‐guided treatment and quality assurance model in community‐based adolescent treatment programs is discussed.
Five outpatient treatment models for adolescent marijuana use: a description of the Cannabis Youth Treatment Interventions
Authors: Diamond Guy , Godley Susan H. , Liddle Howard A. , Sampl Susan , Webb Charles , Tims Frank M. , Meyers Robert
Published: March 2003

The five manual‐guided treatment models tested in the Cannabis Youth Treatment study funded by the Center for Substance Abuse Treatment are described. The five models include (a) a 6‐week intervention consisting of two sessions of individual motivational enhancement therapy plus three sessions of group cognitive behavioral therapy (MET/CBT5); (b) a 12‐week intervention consisting of two sessions of motivational enhancement therapy plus 10 sessions of group cognitive behavioral therapy treatment (MET/CBT12); (c) a 12‐week intervention consisting of MET/CBT12 plus the family support network (FSN), a multi‐component intervention that includes parent education, family therapy and case management; (d) a 12‐week intervention based on the adolescent community reinforcement approach (ACRA), an individual behavioral treatment approach designed to help adolescents and their parents reshape their environment and learn new skills; and (e) multi‐dimensional family therapy (MDFT), a multi‐faceted, developmentally and contextually oriented family‐based model targeting individual, family and social systems. For each model, we describe the treatment background and/or its empirical support, its theoretical underpinnings, its goals and proposed treatment mechanism and the structure and content of each treatment. Procedures used for maintaining treatment fidelity and monitoring quality assurance are also described. These interventions represent the first readily available, manual‐guided interventions to be evaluated in a large randomized field study for this population. Consequently, these manuals have the potential to advance treatment and research for adolescents with substance use disorders.
Tailoring cannabis dependence treatment for a diverse population
Authors: Steinberg Karen L. , Roffman Roger A. , Carroll Kathleen M. , Kabela Elise , Kadden Ronald , Miller Michael , Duresky David ,   The Marijuana Treatment Project Research Group
Published: March 2003

Accumulating evidence suggests that psychosocial treatment for cannabis dependence is effective. Earlier investigations were well designed and sought to evaluate efficacy of manual‐guided therapies with particular attention to protecting the independent variable. The Marijuana Treatment Project (MTP) represents an effort to build upon previous knowledge about cannabis dependence treatment through an evaluation of an integrative therapy, which was meant to allow for greater therapist latitude in its delivery, and to be more responsive to a potentially more diverse population of clients. The treatment intervention developed for delivery in the Marijuana Treatment Project (MTP) reflects an effort to find a true compromise between the needs of the scientific community to have clearly specified and measurable treatments, and the realities of the treatment community, which demand flexibility, appreciation of the multi‐determined nature of most problems, and individualized approaches. This paper will describe the clinical interventions used with the MTP participants, the theoretical rationale guiding their design and practical aspects related to implementation and treatment response.
Characteristics and problems of 600 adolescent cannabis abusers in outpatient treatment
Authors: Tims Frank M. , Dennis Michael L. , Hamilton Nancy , J. Buchan Betty , Diamond Guy , Funk Rod , Brantley Laura B.
Published: March 2003

Aims  Risk factors among adolescent substance abusers have been shown to correlate with substance use severity. Characteristics related to severity, such as demographic and family factors, peer influences, psychiatric co‐morbidity and HIV risk behaviors, are examined for a sample of adolescent cannabis users entering treatment.

Design  These data are from a clinical trial study utilizing blocked random assignment of clients to one of five treatment conditions. The study targeted adolescents entering outpatient treatment for primarily cannabis abuse or dependence.

Setting  Treatment and research facilities in four metropolitan areas of the US were used to recruit study participants. Treatment was delivered in outpatient drug‐free settings.

Participants  Participants were 600 clients, ages 12–18, admitted to outpatient substance abuse treatment programs for cannabis problems, 96% with DSM‐IV diagnoses of substance abuse or dependence, with the remaining 4% having at least one symptom of dependence plus significant problems indicating need for treatment.

Measurements  The Global Appraisal of Individual Needs (GAIN) was used to collect the information presented in this paper. The GAIN incorporates DSM‐IV criteria for substance use disorders, conduct disorder and attention deficit hyperactivity disorder, as well as dimensional (scale) measures for physical and mental health.

Findings  All participants reported at least one symptom of substance use disorders, and 46% met the DSM‐IV criteria for substance dependence, while 50% met criteria for a diagnosis of abuse. Only 20% of the participants perceived any need for help with problems associated with their drug or alcohol use. Clients participating in the study typically presented multiple problems at treatment entry, most often including conduct disorder, attention deficit hyperactivity disorder (ADHD), internal (mental) distress, and physical health distress. The co‐occurrence of conduct disorder and ADHD was found in 30% of the sample. Clients meeting criteria for substance dependence tended to have more co‐occurring problems and significantly less denial at admission.

Conclusions  The characteristics of this sample exemplify the complex nature of adolescent substance use and abuse among adolescents entering outpatient treatment programs. Patterns of co‐occurring problems are at rates comparable to those found in other clinical studies. Those with more severe substance use disorders tend to manifest more problems of social functioning, more mental health problems, and physical health problems. Implications of these findings are discussed in terms of treatment needs, challenges, and prognostic implications.
Treating juvenile offenders for marijuana problems
Authors: Webb Charles P. M. , Burleson Joseph A. , Ungemack Jane A.
Published: March 2003

Aims  This study investigated the characteristics and substance abuse treatment experience of two differentially defined groups of juvenileoffenders, those who were referred or otherwise involved with the legal system and those who reported recent criminal behavior.

Design  Six hundred adolescents from the Cannabis Youth Treatment (CYT) Project were classified by criminal justice system involvement and recentcriminal behavior. Multivariate and repeated‐measures techniques explored substance use frequency, substance use problems, psychologicaland social risk factors and treatment outcomes as functions of criminal status.

Findings  Adolescents reporting criminal justice system involvement were comparable to adolescents reporting no legal involvement. Adolescentsreporting past crime presented with heavier substance use, more substance use problems and greater psychological and environmentalrisks. Criminally active adolescents had greater reductions in substance use frequency and substance use problems during the course of treatment.

Conclusion  Juvenile offender status, whether defined by criminal justice system involvement or criminal behavior, does not seem to mitigatethe potential for adolescents to benefit from manual‐guided outpatient treatments.
Subtypes for classifying adolescents with marijuana use disorders: construct validity and clinical implications
Authors: Babor Thomas F. , Webb Charles , Burleson Joseph A. , Kaminer Yifrah
Published: March 2003

Aims  To evaluate the construct and predictive validity of six different subtyping classifications selected on the basis of their empirical support in the literature on adolescent substance abuse.

Methods  Typological data were collected from a heterogeneous sample of 600 adolescents presenting for marijuana treatment. The classification schemes were gender, onset age, family history, externalizing disorders, internalizing disorders and temperament. Subgroups were compared in terms of substance use frequency, substance abuse problems, social support for substance use, family conflict, school problems and negative peer associations.

Results  Each of the categorical classification schemes differentiated subtypes significantly on some or all of the construct validation measures after controlling for demographic factors, thereby indicating that each has valuable explanatory power from a theoretical perspective. Externalizing disorders, onset age, difficult temperament and internalizing disorders continued to add unique variance to discrimination after the effects of the other subtypes had been removed. At 12‐month follow‐up there were no differences between subtypes on substance use frequency, but adolescents with higher levels of externalizing disorders and internalizing disorders continued to experience more substance use problems.

Conclusion  Categorical subtypes may have particular relevance to the development of treatment interventions as well as prevention measures.
Gender differences in skeletal muscle fibre damage after eccentrically biased downhill running in rats
Authors: KOMULAINEN  , KOSKINEN  , KALLIOKOSKI  , TAKALA  , VIHKO
Published: March 2003

Specific antibodies against structural proteins of muscle fibres (actin, desmin, dystrophin) and extracellular matrix (fibronectin) were used to study the effect of eccentrically biased downhill running exercise (13,5°, 17 m min−1, 130 min) on the magnitude and properties of myofibre injury in the quadriceps femoris muscle of male and female rats. Muscle β‐glucuronidase activity, a quantitative indicator of muscle damage, showed clearly smaller increase in female than in male rats during the 4‐day period following exercise. A similar course of histopathological changes was observed in both sexes, although females showed slower and less marked changes than males. In males, discontinuous or even lost submembrane protein dystrophin staining was observed in some swollen fibres immediately after exercise, before the loss of desmin and staining of disorganized actin, i.e. before the disruption of the cytoskeletal system and the contractile apparatus. The observation that no dramatic changes in the microarchitecture of the muscle fibres were detected immediately or even 6 h after the exercise in females compared with males may indicate that the sarcolemma of the females might be strengthened against membrane damage by a still unknown stabilizing compound.
In vivo dynamics of human medial gastrocnemius muscle‐tendon complex during stretch‐shortening cycle exercise
Authors: Kubo K. , Kanehisa H. , Takeshita D. , Kawakami Y. , Fukashiro S. , Fukunaga T.
Published: March 2003

The purpose of this study was to investigate the dynamics of human muscle‐tendon complex (MTC) during stretch‐shortening cycle exercises through in vivo observation. A total of seven male subjects performed dorsi flexion followed by plantar flexion at two different frequencies, 0.3 Hz (slow) and 1.0 Hz (fast), in a toe‐standing position. The fascicle length (LF) of the medial gastrocnemius muscle during the movements was determined using a real‐time ultrasonography in vivo. The LF at the switching phase from dorsi to plantar flexion was significantly shorter in the fast exercise (54.4 ± 5.5 mm) than in the slow one (58.2 ± 5.4 mm), suggesting that the elongation of tendon structures at that time was significantly greater in the former than in the latter. Furthermore, at the initial stage of plantar flexion during the fast movement, the LF hardly changed with a rapid shortening of tendon structures at that time. The observed relation between MTC length and force showed that the behaviour of tendon structures contributed to 20.2 and 42.5% of the total amount of work completed during plantar flexion phase in the slow and fast movements, respectively. Thus, the present results suggest that tendon structures make the dynamics of MTC more efficient during stretch‐shortening cycle exercises by changing their lengths.
Forest elephant paths and movements at the Odzala National Park, Congo: the role of clearings and Marantaceae forests
Authors: VANLEEUWé HILDé , GAUTIER‐HION ANNIé
Published: March 2003

The role of forest clearings and Marantaceae forest on elephant movement at the Odzala National Park was studied by describing and mapping elephant paths. Three types of paths were distinguished based on their direction, length, width, elephant activity and the types of forests they cross. They were called boulevards, foraging paths, and clearing alleys. All paths explored were heavily used. Boulevards are used for travelling over long distances (up to 34 km) and for linking up rapidly favourite sites such as clearings. Foraging paths mainly run through the medium‐density Marantaceae forests which provide elephants with both herbaceous foods and tree fruit. Clearing alleys form a dense network of tracks around clearings. This network could be a result of an anti‐predatory monitoring behaviour of elephants before entering the clearings where they have long experienced heavy poaching. The heavy trampling which results from the elephant activity could contribute to the maintenance of clearings by preventing germination and seedling survival of the numerous seeds dispersed in their dung.
The influence of ants on the guild structure of Acacia insect communities in Mkomazi Game Reserve, north‐east Tanzania
Authors: KRÜGER OLIVER , McGAVIN GEORGE
Published: March 2003

A total of 41,099 insect specimens of 133 families and 492 morphospecies were collected from 31 trees of six species of Acacia in north‐east Tanzania, representing one of the largest insect samples ever analysed from a tropical savannah habitat. Herbivores (sapsuckers and chewers) and parasitoids had the highest diversity shares, whereas the highest biomass shares were obtained by phytophagous chewers, ants and predators. The percentage biomass of ants was correlated positively with the diversity share of sapsuckers and negatively with the diversity share of tourists. A positive correlation was found with the residual biomass share of phytophagous sapsuckers, indicating a protective function of ants for this guild. Diversity and abundance share was much higher in egg and coccoid parasitoids compared to larval parasitoids, probably due to predation by ants on larval parasitoids. Their low diversity supports the hypothesis of a decline towards the equator in ichneumonid diversity.
The impact of tourist hunting on large mammals in Tanzania: an initial assessment
Authors: Caro T. M , Pelkey N , Borner M , Severre E. L. M , Campbell K. L. I , Huish S. A , Ole Kuwai J , Farm B. P , Woodworth B. L
Published: March 2003

In Tanzania, where tourist hunting is employed as a conservation tool for habitat protection, information on population sizes and hunting offtake was used to assess the impact of tourist hunting on mammal densities. In general, tourist hunting pressure was unrelated to local population sizes, but for most species, animals were removed at a level of less than 10% of the local population size, suggesting that over‐exploitation was unlikely. Eland, however, and perhaps small antelope, bushbuck, kudu and reedbuck were hunted at levels which may be unsustainable in the long term. Analyses also identified areas of Tanzania with high levels of tourist hunting pressure, showed that, in certain areas, species with small population sizes such as eland could be declining as a result of tourist hunting, and suggested that current levels of lion and leopard offtake are too high. These findings, although preliminary, allow recommendations to be put forward for changing hunting quotas for certain species in particular areas of Tanzania.
Home‐range use, activity, and density of caracal in relation to prey density
Authors: Avenant N. L , Nel J. A. J
Published: March 2003

Two male and three female caracal Felis caracal were radio‐tracked over a 1‐year period in arid shrub on the west coast of South Africa, by day and night over at least 130 days for each caracal, and uninterrupted for up to 120 h at a time. These results, on short‐term use of space, were related to concurrent availability of prey. The use by caracal of specific plant communities showed a significant positive correlation to prey biomass of rodents. Males had much larger home‐ranges (26.9±0.75 km2) than females (7.39±1.68 km2). Male home‐ranges overlapped completely with those of females, whereas female ranges overlapped between 0 and 19%. Caracal were active by night and day; onset of activity was affected more by ambient temperature (TA) than photoperiod. Caracal were active significantly longer on nights colder than 20°C. Females ceased activity at TA > 20°C, males at TA > 22°C. Males foraged faster than females (667 vs. 312 m h−1) and moved more than twice the distance of females during an active period. Calculated density of caracal was between 0.23 and 0.47 km−2.
Wildlife–water quality interactions in the Serengeti National Park, Tanzania
Authors: GERETA EMMANUEL , WOLANSKI ERIC
Published: March 2003

Surveys of water quality in the surface waters in the Serengeti National Park were undertaken in both the wet and dry seasons of 1996. Most rivers were ponded, with ponds having a flushing time of 1 month in the wet season and zero flushing in the dry season. pH values varied spatially from extremely alkaline conditions (pH>10) in the southern plains to acidic conditions in the northern region (pH=5·9). In the southern plains at the end of the dry season the salinity of surface waters was high (5–17‰) while there was abundant surface water and the zebras and wildebeest had started to migrate away, a finding suggesting excessive salinity may be the trigger initiating the annual migration. Most surface waters were heavily eutrophicated as a result of animal dung. As a result, the dissolved oxygen concentration near the surface fluctuated widely between 1 and 200% of saturation, smaller values occurring deeper in the water column. Stirring and mechanical aeration by hippos, crocodiles and mammals crossing the rivers prevented the formation of anoxic conditions. The oxygen stress was measurably lessened in wetland‐fringed water bodies as a result of filtering. Light penetration was high (≥10 cm) in saline waters as a result of flocculation enhanced by bacteria and vegetation detritus, elsewhere the euphotic zone was less than 1 cm thick and the waters generally inhospitable to aquatic life. The discontinuity between wooded savanna and grassland coincides with the occurrence of alkaline, high salinity waters in the dry season.
Leaf temperature of desert sand dune plants: perspectives on the adaptability of leaf morphology
Authors: HEGAZY AHMAD , EL AMRY MAMDOUH
Published: March 2003

The leaf temperature of six annual and six perennial plant species was monitored during spring and summer on a sand dune ecosystem in the delta Mediterranean coast of Egypt. During winter, leaves of all tested perennial species attained temperatures higher than the air temperature at night and shortly after sunrise, with maximum leaf–air temperature differences reaching up to 8°C. The lowest differences were less than 1°C. Around noon, the leaves of several species attained temperatures lower than that of the air whereas others showed higher temperatures. The opposite was true during summer, when leaf temperatures were lower than air temperature. The maximum leaf–air temperature differences occurred after midnight towards sunrise and reached up to 10°C. The lowest differences were found around noon and were of less than 5°C. The annual plant species have more pronounced variations than perennials in their leaf temperatures during the night and for most of the day. The leaves were heated or cooled a few degrees above or below the air temperature. The results are discussed in relation to the morphological characters of the leaves. The variation in leaf temperature at different times of the day was significantly related to leaf morphology, specific leaf area, thickness, volume, leaf area index and the surrounding environment.
Some observations on the geomorphological impact of hippopotamus (Hippopotamus amphibius L.) in the Okavango Delta, Botswana
Authors: McCARTHY T. S. , ELLERY W. N. , BLOEM A.
Published: March 2003

The Okavango Delta is a large wetland system situated in northern Botswana. The hippopotamus forms an integral part of this dynamic ecosystem, as it exerts a catalytic effect on geomorphological change. In the distal reaches of the wetland, regular movement of hippos to feeding grounds results in the development of incised channels, which are kept clear of vegetation and act as nodes for swamp expansion. Hippos maintain pathways in backswamp areas, which lead to the development of new channel systems during channel avulsion. They create breaches in the vegetation levees which flank channels in the permanent swamps, causing diversion of water and sediment to backswamp areas. Their paths often lead to lakes in the permanent swamps. During channel avulsion, diversion of a channel into lakes may occur via these paths, which can result in lake closure.
Reproduction and survival of suricates (Suricata suricatta) in the southern Kalahari
Authors: Clutton‐Brock T. H. , Maccoll A. , Chadwick P. , Gaynor D. , Kansky R. , Skinner J. D.
Published: March 2003

In most respects, the demography of Kalahari suricates (Suricata suricatta) resembles that of other social mongooses. Average group size varies from four to nine, and groups typically include several mature females, of which one is responsible for the majority of breeding attempts. Breeding females show a postpartum oestrus; gestation is around 60 days; litter size is three to five pups at emergence and females rarely breed before the age of 24 months. In contrast, annual survival rates (0.20 for pups and 0.43 for animals over one year old) are lower than those recorded in other species. Breeding frequency is related to rainfall and breeding can cease altogether when rainfall is unusually low. In a year when this occurred, group size eroded rapidly and over 60% of groups became extinct. Total numbers were slow to recover during the following year because emigration by females was infrequent and new groups did not form in vacant ranges created by the extinction of groups. High rates of group extinction have been found in other cooperative breeders and may occur because breeding success and survival show inverse density dependence.
Seasonality of insect herbivory on the leaves of Neoboutonia macrocalyx in the Kibale National Park, Uganda
Authors: Kasenene J. M. , Roininen H.
Published: March 2003

The seasonality of herbivory on the leaves of Neoboutonia macrocalyx Pax. in Kibale Forest National Park, Uganda, was studied. A total of 2929 fallen leaves was collected during 15 months under randomly‐selected trees in three different habitats; natural forest and two selectively cut forest sites. The percentage of leaf area eaten and leaf size were estimated. Leaf herbivory was highly seasonal and correlated with rainfall in the previous 2 months, but less than 100 mm monthly rainfall had no effect. There was no correlation between leaf size and rainfall. Although Kibale Forest has two wet seasons, insect feeding on leaves had only one peak during the major rainy season from September to December. Three to four months after peak herbivory, leaves had very low rates of insect damage. Habitat had only a small effect on the amount of insect feeding. The sampling time accounted for 71% of variation in leaf herbivory. New leaves were formed continuously year‐round. The constant leaf production by Neoboutonia trees may be an adaptation to escape generalist herbivorous insects which might be synchronized with the major wet season when the leaf flush of the most other deciduous species occurs. Thus, the availability of fresh leaves is not acting as a regulating factor in seasonality of Neoboutonia herbivory.