Construct validity of the abuse-dependence distinction as measured by DSM-IV criteria for different psychoactive substances

Psychometric modeling of abuse and dependence symptoms across six illicit substances indicates novel dimensions of misuse

AIMS

This study explored the factor structure of DSM III-R/IV symptoms for substance abuse and dependence across six illicit substance categories in a population-based sample of males.

METHOD

DSM III-R/IV drug abuse and dependence symptoms for cannabis, sedatives, stimulants, cocaine, opioids and hallucinogens from 4179 males born 1940-1970 from the population-based Virginia Adult Twin Study of Psychiatric and Substance Use Disorders were analyzed. Confirmatory factor analyses tested specific hypotheses regarding the latent structure of substance misuse for a comprehensive battery of 13 misuse symptoms measured across six illicit substance categories (78 items).

RESULTS

Among the models fit, the latent structure of substance misuse was best represented by a combination of substance-specific factors and misuse symptom-specific factors. We found no support for a general liability factor to illicit substance misuse.

CONCLUSIONS

Results indicate that liability to misuse illicit substances is drug class specific, with little evidence for a general liability factor. Additionally, unique dimensions capturing propensity toward specific misuse symptoms (e.g., tolerance, withdrawal) across substances were identified. While this finding requires independent replication, the possibility of symptom-specific misuse factors, present in multiple substances, raises the prospect of genetic, neurobiological and behavioral predispositions toward distinct, narrowly defined features of drug abuse and dependence.

Comparing factor, class, and mixture models of cannabis initiation and DSM cannabis use disorder criteria, including craving, in the Brisbane longitudinal twin study

Accumulating evidence suggests that the Diagnostic and Statistical Manual of Mental Disorders (DSM) diagnostic criteria for cannabis abuse and dependence are best represented by a single underlying factor. However, it remains possible that models with additional factors, or latent class models or hybrid models, may better explain the data. Using structured interviews, 626 adult male and female twins provided complete data on symptoms of cannabis abuse and dependence, plus a craving criterion. We compared latent factor analysis, latent class analysis, and factor mixture modeling using normal theory marginal maximum likelihood for ordinal data. Our aim was to derive a parsimonious, best-fitting cannabis use disorder (CUD) phenotype based on DSM-IV criteria and determine whether DSM-5 craving loads onto a general factor. When compared with latent class and mixture models, factor models provided a better fit to the data. When conditioned on initiation and cannabis use, the association between criteria for abuse, dependence, withdrawal, and craving were best explained by two correlated latent factors for males and females: a general risk factor to CUD and a factor capturing the symptoms of social and occupational impairment as a consequence of frequent use. Secondary analyses revealed a modest increase in the prevalence of DSM-5 CUD compared with DSM-IV cannabis abuse or dependence. It is concluded that, in addition to a general factor with loadings on cannabis use and symptoms of abuse, dependence, withdrawal, and craving, a second clinically relevant factor defined by features of social and occupational impairment was also found for frequent cannabis use.

COMT Val158Met modulates the effect of childhood adverse experiences on the risk of alcohol dependence

Genetic factors and childhood adverse experiences contribute to the vulnerability to alcohol dependence. However, empirical data on the interplay between specific genes and adverse experiences are few. The COMT Val158Met and DRD2/ANKK1 Taq1A genotypes have been suggested to affect both stress sensitivity and the risk for alcohol dependence. This study tested the hypothesis that genetic variation in COMT Val158Met and DRD2/ANKK1 Taq1A interacts with childhood adverse experiences to predict alcohol dependence. Male abstinent alcohol-dependent patients (n = 110) and age-matched healthy male controls (n = 99) were genotyped for the COMT Val158Met and the DRD2/ANKK1 Taq1A genotypes. Childhood adverse events were measured using three self-report questionnaires. Alcohol dependence severity, age of onset and duration of alcohol dependence were analyzed as secondary outcome measures. Statistical analysis involved logistic regression analysis and analysis of variance. Alcohol-dependent patients reported increased childhood adversity. The interaction between childhood adversity and the COMT Val158Met genotype added significantly to the prediction model. This gene-environment interaction was confirmed in the analysis of the secondary outcome measures, i.e. alcohol dependence severity, age of onset and duration of alcohol dependence. The DRD2/ANKK1 Taq1A genotype was not related to alcohol dependence, nor did it interact with childhood adversity in predicting alcohol dependence. This study provides evidence for a gene-environment interaction in alcohol dependence, in which an individual's sensitivity to childhood adverse experience is moderated by the COMT genotype. Exposed carriers of a low-activity Met allele have a higher risk to develop severe alcohol dependence than individuals homozygous for the Val allele.

Assessment of a modified DSM-5 diagnosis of alcohol use disorder in a genetically informative population

BACKGROUND

Proposed changes to the upcoming DSM-5 include the following: (i) combining criteria for DSM-IV alcohol abuse (AA) and alcohol dependence (AD) into 1 diagnostic category (alcohol use disorder [AUD]); (ii) exclusion of the "legal problems" (LP) criterion; and (iii) addition of a "craving" criterion. Few published studies empirically assess the potential consequences of the proposed changes.

METHODS

Using a population-based sample of twins assessed for lifetime AA/AD diagnoses, we explored phenotypic differences across DSM-IV and a modified DSM-5 diagnoses without craving because of its unavailability in the data set. We used factor analysis and item response theory (IRT) to evaluate the potential consequences of excluding the LP criterion from AUD and used twin modeling to examine genetic differences between DSM-IV and the modified DSM-5 diagnoses.

RESULTS

The prevalence of AUD was slightly higher than that of DSM-IV diagnoses. Individuals meeting DSM-IV or DSM-5 criteria, but not both, exhibit fewer comorbid diagnoses than those meeting both sets of criteria. Individuals meeting only DSM-5 criteria were slightly less severely affected than those meeting only DSM-IV criteria. Factor analysis indicated that the LP criterion loading is the lowest of all symptoms; IRT analysis suggested that this criterion has low discriminatory power. The genetic correlation between DSM-IV and DSM-5 diagnoses was slightly but significantly lower than unity.

CONCLUSIONS

The proposed DSM-5 AUD criteria are unlikely to result in significant changes in prevalence of diagnosed alcohol problems. However, it is unclear whether the new criteria represent a more valid diagnosis: new cases are no more severely affected than DSM-IV-only cases. Given the psychometric properties of LP, its exclusion should not negatively impact diagnostic validity. Similarly, the stable heritability across DSM-IV and DSM-5 diagnoses suggests that the proposed changes will not have substantial negative consequences in terms of familial influences, a key validator. These results provide equivocal empirical support for the proposed DSM-5 changes for AUDs.

Relationship of substance abuse to dependence in the U.S. general population

OBJECTIVE

The diagnostic categories of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, for substance abuse and dependence are commonly used in clinical work and research studies, but whether abuse and dependence represent two different syndromes has been debated. The purpose of this article is to investigate the relationship of substance abuse and dependence for cannabis, cocaine, stimulants and sedatives among lifetime users of these substances in the National Epidemiologic Survey on Alcohol and Related Conditions, a nationally representative survey conducted in 2001-2002.

METHOD

The multiple indicators multiple causes (MIMIC) model addresses three sets of relationships: those between (1) diagnostic criteria and latent factors, (2) latent factors and covariates, and (3) criteria and covariates. This approach allows for the detection of and compensation for noninvariance of the measurement of criteria across subgroups.

RESULTS

Compared with one-factor models, two-factor models (factors roughly corresponding to abuse and dependence) fit significantly better across all substances, with abuse and dependence factors highly correlated. The MIMIC model indicated that race/ethnicity, age, income, and marital status showed some differential relationships across substance groups, although most covariates showed similar associations to dependence and abuse factors. Noninvariance of criteria measurement by demographic covariates was most pronounced for cannabis abuse and dependence criteria.

CONCLUSIONS

The general relationship of abuse to dependence was consistent across substances. Results were equivocal on the value of retaining separate factors; therefore, investigating the relationships of specific genetic variants and treatment outcomes to dimensional indicators of abuse, dependence, and measures combining these criteria is warranted. Measurement of cannabis abuse and dependence criteria appears most affected by demographic characteristics.

Analyses related to the development of DSM-5 criteria for substance use related disorders: 2. Proposed DSM-5 criteria for alcohol, cannabis, cocaine and heroin disorders in 663 substance abuse patients

BACKGROUND

A number of changes have been proposed and investigated in the criteria for substance use disorders in DSM-5. However, although clinical utility of DSM-5 is a high priority, relatively little of the empirical evidence supporting the changes was obtained from samples of substance abuse patients.

METHODS

Proposed changes were examined in 663 patients in treatment for substance use disorders, evaluated by experienced clinicians using the Psychiatric Research Interview for Substance and Mental Disorders (PRISM). Factor and item response theory analysis was used to investigate the dimensionality and psychometric properties of alcohol, cannabis, cocaine and heroin abuse and dependence criteria, and craving.

RESULTS

The seven dependence criteria, three of the abuse criteria (hazardous use; social/interpersonal problems related to use; neglect of roles to use), and craving form a unidimensional latent trait for alcohol, cannabis, cocaine and heroin. Craving did not add significantly to the total information offered by the dependence criteria, but adding the three abuse criteria and craving together did significantly increase total information for the criteria sets associated with alcohol, cannabis and heroin.

CONCLUSION

Among adult patients in treatment for substance disorders, the alcohol, cannabis, cocaine and heroin criteria for dependence, abuse (with the exception of legal problems), and craving measure a single underlying dimension. Results support the proposal to combine abuse and dependence into a single diagnosis in the DSM-5, omitting legal problems. Mixed support was provided for the addition of craving as a new criterion, warranting future studies of this important construct in substance use disorders.

Are the symptoms of cannabis use disorder best accounted for by dimensional, categorical, or factor mixture models? A comparison of male and female young adults

Despite the consensus that criteria for cannabis abuse and dependence and symptoms of withdrawal are best explained by a single latent liability, it remains unknown whether alternative models provide a better explanation of these criteria. A series of latent factor, latent class, and hybrid factor mixture models were fitted to data from 872 recent cannabis users from the Minnesota Twin Family Study who completed Diagnostic and Statistical Manual of Mental Disorders (3rd ed., revised, and 4th ed.) diagnostic criteria for cannabis abuse, dependence, and symptoms of withdrawal. Despite theoretical appeal, results did not support latent class or factor mixture modeling. Instead, symptoms of abuse, dependence, and withdrawal were better summarized by a single latent factor Cannabis Use Disorder (CUD) for male and female young adults. An almost 2-fold sex difference in item endorsement was best explained by a single mean difference on the CUD factor, indicating that young men have a greater latent liability toward expressing CUD.

Psychometric modeling of cannabis initiation and use and the symptoms of cannabis abuse, dependence and withdrawal in a sample of male and female twins

BACKGROUND

Despite an emerging consensus that the DSM-IV diagnostic criteria for cannabis abuse and dependence are best represented by a single underlying liability, it remains unknown if latent class or hybrid models can better explain the data.

METHOD

Using structured interviews, 7316 adult male and female twins provided complete data on DSM-IV symptoms of cannabis abuse and dependence. Our aim was to derive a parsimonious, best-fitting cannabis use disorder (CUD) phenotype based on DSM-III-R/IV criteria by comparing an array of psychometric models (latent factor analysis, latent class analysis and factor mixture modeling) using full information maximum likelihood ordinal data methods in Mx.

RESULTS

We found little evidence to support population heterogeneity since neither latent class nor hybrid factor mixture models provided a consistently good fit to the data. When conditioned on initiation and cannabis use, the endorsement patterns of the abuse, dependence and withdrawal criteria were best explained by two latent factors for males and females. The first was a general CUD factor for which genetic effects explained 53-54% of the variance. A less interpretable second factor included a mix of cross-loading dependence and withdrawal symptoms.

CONCLUSIONS

This is the first study to compare competing measurement models to derive an empirically determined CUD phenotype. Commensurate with proposed changes to substance use disorders in the DSM-V, our results support an emerging consensus that a single CUD latent factor can more optimally assess the risk or liability underpinning correlated measures of use, abuse, dependence and withdrawal criterion.

Item response theory analysis of binge drinking and its relationship to lifetime alcohol use disorder symptom severity in an American Indian community sample

BACKGROUND

Item response theory (IRT) has been used to examine alcohol use disorder (AUD) symptoms and their psychometric properties but has not been previously applied to AUD symptoms from an American Indian sample.

METHODS

Lifetime DSM-IV AUD symptoms and binge drinking (5+ drinks men/4+ drinks women) at ≥1, ≥4, ≥8, and ≥15 days per month during the period of heaviest lifetime drinking criteria were assessed in 530 American Indian participants. Exploratory factor analysis was used to examine the factor structure of the 10 AUD symptoms and each alcohol consumption criterion. Two-parameter IRT models generated marginal maximum likelihood estimates for discrimination (a) and threshold (b) parameters for 10 DSM-IV AUD symptoms and each consumption criterion. Differential item functioning (DIF) analysis was used to assess AUD symptom severity in groups defined by gender and age at interview.

RESULTS

The AUD symptoms of "Withdrawal" and "Activities Given Up" were the most severe symptoms. "Tolerance" and "Social/Interpersonal Problems" were the least severe. All AUD symptoms fell on the moderate portion of the severity continuum, except "Withdrawal," which fell at the lower end of the severe portion. The consumption criterion of 5+/4+ (male/female) at ≥8 times per month demarcated the portion of the severity continuum where AUD symptoms began to occur at a probability of 50%. DIF analysis showed significant gender and age at interview differences for "Hazardous Use,""Tolerance," and "Activities Given Up," but not for the other AUD symptoms.

CONCLUSIONS

In this American Indian community sample, alcohol abuse and dependence did not represent distinct disorders. Only one AUD symptom was found outside the moderate portion of the underlying AUD severity continuum. Drinking 5+/4+ (male/female) drinks at a frequency of ≥8 times per month during the period of heaviest lifetime drinking was found to function well as both a risk and a diagnostic criterion for lifetime DSM-IV AUD. DSM-IV AUD symptom criteria, as currently assessed, may be limited in their ability to capture the full range of symptom severity of AUDs, at least in this high-risk population.

Assessing the dimensionality of lifetime DSM-IV alcohol use disorders and a quantity-frequency alcohol use criterion in the Australian population: a factor mixture modelling approach

AIMS

With the revision of the DSM-IV underway, two important research issues currently dominate the addiction literature: (a) how can the dimensionality of DSM-IV alcohol use disorders (AUD) diagnostic criteria best be described? and (ii) should a quantity-frequency alcohol use (QF) criterion be added to the existing diagnostic criteria set in the DSM-V? The current study addressed these aims by analysing lifetime data from a recent Australian population survey.

METHODS

Data from adults screened for lifetime DSM-IV AUD in the 2007 National Survey on Mental Health and Wellbeing (NSMHWB) were analysed (n = 5409). A series of alternative factor analytic, latent class and factor mixture or 'hybrid' models were used to assess the dimensionality of lifetime DSM-IV AUD diagnostic criteria and a lifetime QF criterion.

RESULTS

Examination of the goodness-of-fit indices revealed that a one-factor or a two-factor model, a three-class latent class model or a two-factor zero-class hybrid model, were all acceptable models for the data. A simple structure one-factor model was considered to be the most parsimonious and theoretically meaningful model, given the high correlation between the abuse and dependence factors (0.874) in the two-factor model. The inclusion of the QF criterion did not enhance the fit of the one-factor model.

CONCLUSIONS

Incorporating both dimensional and categorical conceptions of lifetime AUD did not provide substantial gains over a simple structure unidimensional model of AUD severity. The utility of a QF use criterion in helping to diagnose AUD is questionable. These findings should be of relevance to the DSM-5 substance use disorder workgroup.

Exploring the mediational role of coping motives for marijuana use in terms of the relation between anxiety sensitivity and marijuana dependence

This study evaluated the prediction that coping motives for marijuana use would mediate the relation between anxiety sensitivity and a marijuana dependence diagnosis after controlling for other co-occurring marijuana use motives. Participants were 136 current marijuana users (47.1% women; M(age)= 21.9, SD = 7.2). Results were consistent with a mediational effect, with the relation between anxiety sensitivity and marijuana dependence being explained by the addition of coping motives into the model. These results provide novel information related to the putative explanatory role of coping motives for marijuana use in the relation between anxiety sensitivity and marijuana dependence.

Social integration in young adulthood and the subsequent onset of substance use and disorders among a community population of urban African Americans

AIMS

This paper examines the association between social integration in young adulthood and the later onset of substance use and disorders through mid-adulthood. Design Data come from a community cohort of African Americans followed longitudinally from age 6-42 years with four assessment periods.

SETTING

The cohort all lived in the Woodlawn neighborhood of Chicago in 1966, an urban disadvantaged setting.

PARTICIPANTS

All Woodlawn first graders in 1966 were asked to participate; 13 families declined (n = 1242).

MEASUREMENT

Substance use was measured via interview at age 42 and includes the onset of alcohol and drug use disorders and the onset of cocaine/heroin use between ages 32 and 42 years. Social integration measures were assessed via interview at age 32 and include social roles (employee, spouse, parent), participation in religious and social organizations and a measure of overall social integration. Control variables were measured in childhood and later in the life course.

FINDINGS

Multivariate regression analyses suggest that unemployment, being unmarried, infrequent religious service attendance and lower overall social integration in young adulthood predict later adult-onset drug use disorders, but not alcohol use disorders once confounders are taken into consideration. Unemployment and lower overall social integration predict onset of cocaine/heroin use later in adulthood.

CONCLUSIONS

Results show meaningful onset of drug use and substance use disorders during mid-adulthood and that social integration in young adulthood seems to play a role in later onset of drug use and drug disorders, but not alcohol disorders.

Diagnosinstrument För Beroende och Missbruk

The Swedish National Board on Health and Welfare recommends that structured assessment instruments should be used in medical as well as in social treatment of substance misusers. These should be validated in a Swedish context. Instruments for diagnoses of dependence/abuse (DSM-IV) and dependence/harmful use (ICD-10) have been used in Sweden for many years, although not yet validated in Swedish. ADDIS, the Swedish version of the American SUDDS, is used in four Nordic countries and the most often used diagnostic instrument in Sweden. This article investigates the psychometric properties of ADDIS alcohol module, including discriminant and construct validity and internal consistency. The two main constructs in DSM – dependence and abuse – as well as the seven criteria for dependence and the four criteria for abuse are studied. Further, the value of each of the 44 specific items in ADDIS for capturing these criteria is studied. Two samples are explored: 1) a clinical sample (n = 349; incl. 129 women) and 2) a sample of 400 men convicted for driving while intoxicated. Mean age was the same (41 ys.). Using discriminant analyses on lifetime prevalence, the items correctly classify 94% of the cases in the two samples. Using one-factor principal component analysis to explore homogeneity of the combined samples, all 28 items on dependence and 15 of 18 items on abuse have loadings above 0,40 (R2 dependence = 0,46; abuse = 0,40). Separate analyses of the two samples, as well as on women, show similar results. Cronbach's alpha is excellent for dependence and satisfactory for abuse in all analyses. Analyses of specific criteria show satisfactory results on dependence and acceptable on abuse. Minor revisions are proposed to make ADDIS more user-friendly and to improve some specific items. In conclusion: ADDIS has acceptable to excellent discriminant and construct validity as well as internal consistency and captures the specific criteria of DSM-IV. It has the preconditions for sensitive assessment of alcohol use disorders in men and women.

The dimensionality of DSM-IV alcohol use disorders among adolescent and adult drinkers and symptom patterns by age, gender, and race/ethnicity

BACKGROUND

There is limited information on the validity of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) alcohol use disorders (AUD) symptom criteria among adolescents in the general population. The purpose of this study is to assess the DSM-IV AUD symptom criteria as reported by adolescent and adult drinkers in a single representative sample of the U.S. population aged 12 years and older. This design avoids potential confounding due to differences in survey methodology when comparing adolescents and adults from different surveys.

METHODS

A total of 133,231 current drinkers (had at least 1 drink in the past year) aged 12 years and older were drawn from respondents to the 2002 to 2005 National Surveys on Drug Use and Health. DSM-IV AUD criteria were assessed by questions related to specific symptoms occurring during the past 12 months. Factor analytic and item response theory models were applied to the 11 AUD symptom criteria to assess the probabilities of symptom item endorsements across different values of the underlying trait.

RESULTS

A 1-factor model provided an adequate and parsimonious interpretation for the 11 AUD criteria for the total sample and for each of the gender-age groups. The MIMIC model exhibited significant indication for item bias among some criteria by gender, age, and race/ethnicity. Symptom criteria for "tolerance,""time spent," and "hazardous use" had lower item thresholds (i.e., lower severity) and low item discrimination, and they were well separated from the other symptoms, especially in the 2 younger age groups (12 to 17 and 18 to 25). "Larger amounts,""cut down,""withdrawal," and "legal problems" had higher item thresholds but generally lower item discrimination, and they tend to exhibit greater dispersion at higher AUD severity, particularly in the youngest age group (12 to 17).

CONCLUSIONS

Findings from the present study do not provide support for the 2 separate DSM-IV diagnoses of alcohol abuse and dependence among either adolescents or adults. Variations in criteria severity for both abuse and dependence offer support for a dimensional approach to diagnosis which should be considered in the ongoing development of DSM-V.

Item response theory analysis of DSM-IV cannabis abuse and dependence criteria in adolescents

OBJECTIVE

To examine three aspects of adolescent cannabis problems: do DSM-IV cannabis abuse and dependence criteria represent two different levels of severity of substance involvement, to what degree do each of the 11 abuse and dependence criteria assess adolescent cannabis problems, and do the DSM-IV items function similarly across different adolescent populations?

METHOD

We examined 5,587 adolescents ages 11 to 19, including 615 youths in treatment for substance use disorders, 179 adjudicated youths, and 4,793 youths from the community. All of the subjects were assessed with a structured diagnostic interview. Item response theory was used to analyze symptom endorsement patterns.

RESULTS

Abuse and dependence criteria were not found to represent different levels of severity of problem cannabis use in any of the samples. Among the 11 abuse and dependence criteria, problems cutting down and legal problems were the least informative for distinguishing problem users. Two dependence criteria and three of the four abuse criteria indicated different severities of cannabis problems across samples.

CONCLUSIONS

We found little evidence to support the idea that abuse and dependence are separate constructs for adolescent cannabis problems. Furthermore, certain abuse criteria may indicate severe substance problems, whereas specific dependence items may indicate less severe problems. The abuse items in particular need further study. These results have implications for the refinement of the current substance use disorder criteria for DSM-V.

Reliability of use, abuse, and dependence of four types of inhalants in adolescents and young adults

Inhalants, as a class of drugs, consists of heterogeneous substances that increase the probability of many serious illnesses and death. Research on inhalant abuse has lagged behind other drugs partly because of the need for a diagnostic instrument of different types of inhalants. This study was conducted to obtain reliability estimates for the new Substance Abuse Module DSM-IV inhalants diagnoses for four types of inhalants: aerosols, gases, nitrites, and solvents as well as different diagnostic configurations of inhalant-related criteria. Participants were 162 community sample adolescents or young adults (mean age=20.3 years, S.D.=2.4). Two-thirds of the sample was male and 83.3% was Caucasian. Kappas and intraclass correlation coefficients were computed to estimate test-retest reliabilities. Results suggested (a) abuse was more common than dependence (34.6% versus 12.3%), (b) reliabilities of abuse criteria and diagnosis were good to excellent across subtypes, and (c) reliabilities of dependence criteria and diagnoses were poor to good across subtypes. Alternative configurations of DSM-IV criteria that were consistent with previous research on adolescents provided excellent reliabilities across subtypes of inhalants. Moreover, 11.1% of participants experienced inhalants withdrawal.

Factor and item-response analysis DSM-IV criteria for abuse of and dependence on cannabis, cocaine, hallucinogens, sedatives, stimulants and opioids

AIMS

This paper explored, in a population-based sample of males, the factorial structure of criteria for substance abuse and dependence, and compared qualitatively the performance of these criteria across drug categories using item-response theory (IRT).

DESIGN

Marginal maximum likelihood was used to explore the factor structure of criteria within drug classes, and a two-parameter IRT model was used to determine how the difficulty and discrimination of individual criteria differ across drug classes.

PARTICIPANTS

A total of 4234 males born from 1940 to 1974 from the population-based Virginia Twin Registry were approached to participate.

MEASUREMENTS

DSM-IV drug use, abuse and dependence criteria for cannabis, sedatives, stimulants, cocaine and opiates.

FINDINGS

For each drug class, the pattern of endorsement of individual criteria for abuse and dependence, conditioned on initiation and use, could be best explained by a single factor. There were large differences in individual item performance across substances in terms of item difficulty and discrimination. Cocaine users were more likely to have encountered legal, social, physical and psychological consequences.

CONCLUSIONS

The DSM-IV abuse and dependence criteria, within each drug class, are not distinct but best described in terms of a single underlying continuum of risk. Because individual criteria performed very differently across substances in IRT analyses, the assumption that these items are measuring equivalent levels of severity or liability with the same discrimination across different substances is unsustainable. Compared to other drugs, cocaine usage is associated with more detrimental effects and negative consequences, whereas the effects of cannabis and hallucinogens appear to be less harmful. Implications for other drug classes are discussed.

Pancreatitis: prevalence and risk factors among male veterans in a detoxification program

OBJECTIVES

To determine the prevalence of pancreatitis and associated risk factors among heavy-drinking veterans.

METHODS

At a large Veterans Administration Outpatient Detoxification Program (ODP) that systematically collects risk information, 1409 black and white male veterans with International Classification of Diseases, Ninth Revision codes for alcohol abuse enrolling in the ODP from January 2002 to December 2003 were identified. Among these patients, pancreatitis at any time (before the ODP admission or occurring through June 2005) was identified using International Classification of Diseases, Ninth Revision codes. Cases were verified by chart review. Logistic regression analyses were used for multivariable analyses.

RESULTS

Overall, history of smoking (89.6%) and current or past drug use (90.1%) were very common, whereas intravenous drug use (22.3%) was less so. Although 87 (6.2%) subjects had pancreatitis codes (acute, 50; chronic, 15; both, 22), chart review verified only 42 cases (acute, 29; chronic, 5; both, 8) for a 3% prevalence. Alcohol appeared to be the definite etiology in 39 of these 42 patients. In bivariate analyses, patients with pancreatitis were older, had more substance abuse admissions, reported a significantly heavier current alcohol use, and lower drug dependence (each P < 0.05). In multivariable models, alcoholic pancreatitis was associated positively with age (odds ratio, 1.08; 95% confidence interval, 1.04-1.12) and number of substance abuse admissions (odds ratio, 1.08; 95% confidence interval, 0.995-1.18; P = 0.06).

CONCLUSIONS

In this high-risk population of heavy drinkers, the prevalence of pancreatitis is at least 3%. Our study provides preliminary data regarding potential cofactors for pancreatitis in heavy drinkers.

Is there heterogeneity among syndromes of substance use disorder for illicit drugs?

The use of DSM criteria to evaluate liability to substance use disorders (SUDs) and to identify SUD phenotypes may not provide the sensitivity required to identify genes associated with vulnerability to SUDs. The purpose of this study is to evaluate a number of basic aspects of substance use that may be more proximal than full SUDs to risk genes, some of which may thus have greater potential utility as phenotypes in subsequent molecular genetic analyses. In this paper we present results from the first stage of our planned analyses, focusing on how individual symptoms of abuse and dependence may be used to create alternate phenotypes for SUDs. Specifically, we used factor analysis and biometrical modeling on each symptom of illicit substance abuse and dependence within different types of substances, and compared and contrasted factor patterns and heritabilities across the different substances. These analyses were carried out using a population-based sample of 3372 male-male twin pairs from the Vietnam Era Twin Registry who participated in the Harvard Twin Study of Substance Abuse. We obtained extensive data from these participants on substance use and SUDs via telephone interview in 1992, including data on the illicit substances: opiates, cocaine, cannabis, sedatives, stimulants, and psychedelics. The results indicate that: A) although a one-factor model assuming a single underlying liability for abuse and dependence symptoms and behaviors can be rejected for most substances, there is no uniform support for a two-factor model differentiating between abuse versus dependence; B) patterns of symptoms or behaviors reported by substance users vary across substances; C) not all symptoms or behaviors contribute equally to the presentation of an SUD; and D) the heritability of symptoms or behaviors of substance users varies both within and between substances. These results represent important first steps in facilitating the search for SUD-risk genes in subsequent high-throughput molecular genetic analyses by providing alternate phenotypes that may have both optimal validity and increased heritability.

Methamphetamine and alcohol abuse and dependence symptoms: associations with affect lability and impulsivity in a rural treatment population

The present study examined associations between impulsivity and affect lability and methamphetamine and alcohol abuse and dependence symptoms in a rural inpatient treatment population (N=235). Thirty-two percent of participants reported methamphetamine use in the past 90 days prior to admission. Amphetamine use disorders were found to be more common among younger participants whereas alcohol use disorders were more common among older and Native American participants. After controlling for age, gender, use frequency, and injection use, impulsivity but not affect lability was associated with methamphetamine abuse but not dependence symptoms. Lability but not impulsivity was associated with alcohol dependence but not abuse symptoms after controlling for age, gender, and use frequency. Consistent with past epidemiological studies, results indicate that methamphetamine use is a prominent problem facing rural substance use treatment facilities. Affect lability and impulsivity are associated with methamphetamine and alcohol-related problems in this population.

Reinforcement-based therapy: 12-month evaluation of an outpatient drug-free treatment for heroin abusers

This controlled study examined the efficacy of reinforcement-based therapy (RBT) for producing enhanced abstinence outcomes over 12 months in opioid-dependent patients exiting a brief residential detoxification. Patients were randomly assigned upon completing their medically managed taper (i.e., detoxification) to RBT (N=66) or usual care (N=64) referral to community treatment programs. The 6-month RBT program offered an array of abstinence-based incentives including rent payment for recovery housing, program-led recreational activities and skills training for procuring employment. RBT produced significantly higher self-report and urinalysis-confirmed rates of abstinence from opioids and cocaine relative to usual care at 1 (42% versus 15%) and 3 (38% versus 17%) months during treatment but not at 6 or 12 months after enrollment. The RBT but not the usual care group showed significant increases in the number of days worked and the amount of legal income earned at 3, 6 and 12 months. The results of this randomized study suggest that an intensive reinforcement-based therapy that includes abstinence-based recovery housing is a promising approach; however, further research is needed to determine the role of treatment intensity and the specific efficacy of RBT's component parts.

Craving and withdrawal as core symptoms of alcohol dependence

There is ongoing debate regarding the validity of the distinction of alcohol abuse and dependence, the distinction between normality and alcohol abuse, and the absence of craving in the DSM-IV classification of alcohol use disorders. In this study, we examine the discriminant validity of the DSM-IV alcohol use disorder diagnoses in three different populations (98 patients from an alcohol treatment service, 68 nontreatment-seeking heavy drinkers, and 75 psychiatric outpatients). We compare the results of the DSM-IV classification with an alternative classification that requires craving and withdrawal for the diagnosis of dependence and at least two DSM-IV abuse-dependence symptoms for the diagnosis of abuse: the Craving Withdrawal Model (CWM). Although the total prevalence of any alcohol use disorder did not differ between DSM-IV and CWM, the distinction between normality and abuse and between abuse and dependence was better for the CWM categories.

Compulsive smoking: the development of a Rasch homogeneous scale of nicotine dependence

The unidimensionality of nicotine dependence has not been established firmly yet. The aim of this study was to assess the dimensionality of nicotine dependence, preferably meeting the strict assumptions of the Rasch model. First, we examined the validity of the Fagerström Test for Nicotine Dependence (FTND) [Br. J. Addict. 86 (1991) 1119.] in 1525 smokers who participated in a national survey considering smoking behavior. Two factors were found, suggesting that the FTND does not measure a unidimensional construct. Factor analysis of 19 other dependence items in 512 smokers resulted in four factors of which three were interpretable: compulsive smoking, social problems due to smoking, and physical dependence. We focused on smoking compulsivity. This factor turned out to consist of a four-item Rasch homogeneous scale. Two items of the FTND with face validity of smoking compulsivity were found to fit into the scale. The results of Rasch analysis were in support of a continuum of compulsivity. Difficulty refraining from smoking in places where it is forbidden was found to indicate highest compulsivity. Several correlates with smoking compulsivity were found. We conclude that compulsive smoking is one important dimension of nicotine dependence, which may account for the considerable relapse of this disorder.

The discriminant validity of alcohol use disorder in well-functioning men with hazardous alcohol use

The purpose of this study was to establish the discriminant validity of alcohol use disorder (AUD) diagnoses within a population of well-functioning male heavy drinkers. A group of 57 subjects with a consumption of at least 28 alcoholic units (AU)/week was recruited from wine-tasting clubs. Within this group, a comparison was made between those individuals who met the criteria of AUD and those who did not. We compared the subjective and objective health status and drinking habits of both groups. No significant differences were found between the individuals with AUD and those without AUD, or between individuals with alcohol dependence and those without AUD, except for their drinking pattern. These findings raise doubt of the discriminant validity of AUD diagnoses in well-educated heavy wine drinkers.

Possible age-associated bias in reporting of clinical features of drug dependence: epidemiological evidence on adolescent-onset marijuana use

AIMS

To probe recent evidence on apparent excess occurrence of marijuana dependence when marijuana smoking starts in adolescence.

DESIGN AND PARTICIPANTS

A national sample of recent-onset marijuana users was identified within public data files of the National Household Survey on Drug Abuse (NHSDA), 1995-98 (1,866 adolescents and 762 adults).

MEASUREMENTS

Marijuana dependence was assessed via seven standardized questions about its clinical features, such as being unable to cut down. Multivariate response models (GLM/GEE and MIMIC) were used to evaluate adolescent excess risk and possible item biases.

FINDINGS

Among people who had just started to use marijuana, clinical features of marijuana dependence occurred twice as often among adolescents compared to adults, even with statistical adjustment for other covariates (P < 0.01 from GLM/GEE). MIMIC analyses suggest that adolescent-onset users have somewhat higher levels of marijuana dependence, and they also provide evidence of age-associated response bias for some but not all clinical features of marijuana dependence. That is, even with level of marijuana dependence held constant, adolescent recent-onset users were more likely than adults to report being unable to cut down (P = 0.01) and tolerance (P = 0.029).

CONCLUSION

Nosologic, methodological and substantive reasons for observed age-related excess in occurrence of marijuana dependence problems among early onset users deserve more attention in future research.