Thomas J. Crowley

DSM-5 Criteria for Substance Use Disorders: Recommendations and Rationale

Since DSM-IV was published in 1994, its approach to substance use disorders has come under scrutiny. Strengths were identified (notably, reliability and validity of dependence), but concerns have also arisen. The DSM-5 Substance-Related Disorders Work Group considered these issues and recommended revisions for DSM-5. General concerns included whether to retain the division into two main disorders (dependence and abuse), whether substance use disorder criteria should be added or removed, and whether an appropriate substance use disorder severity indicator could be identified. Specific issues included possible addition of withdrawal syndromes for several substances, alignment of nicotine criteria with those for other substances, addition of biomarkers, and inclusion of nonsubstance, behavioral addictions.This article presents the major issues and evidence considered by the work group, which included literature reviews and extensive new data analyses. The work group recommendations for DSM-5 revisions included combining abuse and dependence criteria into a single substance use disorder based on consistent findings from over 200,000 study participants, dropping legal problems and adding craving as criteria, adding cannabis and caffeine withdrawal syndromes, aligning tobacco use disorder criteria with other substance use disorders, and moving gambling disorders to the chapter formerly reserved for substance-related disorders. The proposed changes overcome many problems, while further studies will be needed to address issues for which less data were available.

North Atlantic Deep Water cools the southern hemisphere

A standard explanation for coupling climate variations in the northern and southern hemispheres involves fluctuations in North Atlantic Deep Water (NADW) production. However, I suggest that the “NADW-Antarctic” connection may work opposite to that conjectured by many investigators; that is, when NADW production rates are high, southern hemisphere temperatures decrease rather than increase. The revised interpretation is consistent with observations and ocean modeling studies which demonstrate that, although upwelling of relatively warm NADW water around Antarctica promotes sea ice meltback, a second and more important negative feedback is also operating. In order to conserve volume, southward export of NADW across the equator is accompanied by import of an equivalent volume of considerably warmer water from shallower oceanic layers in the South Atlantic. The southern hemisphere loses heat as a result of this exchange. The hemispherically averaged net heat loss may be as high as 4 W/m², an amount comparable to a CO2 doubling. It is suggested that this more comprehensive view of the role of NADW may explain both decadal-scale variations in South Atlantic sea surface temperatures in this century and two significant problems in Pleistocene climatology: why southern hemisphere temperatures decreased before CO2 levels decreased at the end of the last interglacial and why southern hemisphere temperature changes precede changes in northern hemisphere ice volume. It is shown that when NADW production was reinitiated during the last interglacial (120,000 B.P.), high-latitude southern hemisphere temperatures decreased. The estimated magnitude of altered southern hemisphere heat export is comparable to the ice-age CO2 signal and may be able to account for the observed cooling even when CO2 levels were high. When cast into a frequency domain framework, this interpretation may also help explain why southern hemisphere temperatures lead global ice volume changes.

Substance use, abuse and dependence in adolescence: prevalence, symptom profiles and correlates

We present data on the lifetime prevalence of substance use, abuse and dependence in adolescents obtained through structured psychiatric interviews and self-report questionnaires. Most notably, we evaluate symptom profiles based on DSM-IV abuse and dependence criteria for tobacco, alcohol and marijuana, including a gender comparison. Participants are 3,072 adolescents (12-18 years) drawn from three community-based family samples in Colorado. Age trends suggest that substance use is a developmental phenomenon, which increases almost linearly from early to late adolescence. Substance use disorders are less common than experimentation in adolescence, but approximately 1 in 4 adolescents in the oldest cohorts meets criteria for abuse for at least one substance, and 1 in 5 meets criteria for substance dependence. By age 18 nearly 1 in 3 adolescents report daily smoking and 8.6% meet criteria for tobacco dependence. Although alcohol is the most commonly abused substance (10%), a slightly larger proportion of adolescents meet criteria for dependence on marijuana (4.3%) than alcohol (3.5%). Gender differences in prevalence of use more often show greater use in males than females. Males more frequently meet criteria for dependence on alcohol and marijuana in late adolescence, while females are more often nicotine dependent. A comparison of abuse and dependence symptom profiles shows some interesting variability across substances, and suggests that manifestations of a subset of symptoms are gender specific.

Medial orbitofrontal cortex gray matter is reduced in abstinent substance-dependent individuals.

BACKGROUND Chronic exposure to drugs of addiction induces cellular adaptations in orbitofrontal cortex (OFC) and associated limbic-prefrontal pathways that might underlie abuse-related behavior. A propensity to make risky decisions in spite of substantial negative consequences might be mediated by medial OFC dysfunction in substance-dependent individuals (SDI). We tested the hypothesis that medial OFC gray matter (GM) volume would be lower in SDI compared with control subjects. METHODS Nineteen SDI and 20 control subjects participated. The SDI were dependent on two or more substances, most often cocaine, amphetamine, and alcohol, with mean duration of abstinence 4.7, 2.4, and 3.2 years, respectively. High-resolution T1-weighted images were acquired on a 3-T magnetic resonance system. Image processing and analyses were conducted with voxel-based morphometry (VBM) implemented in Statistical Parametric Mapping (SPM) 5. Differences in regional GM volume were tested with an analysis of covariance model, co-varying for global GM and age. Statistical maps were set at p < .05, corrected for multiple comparisons. Medial OFC GM volume was correlated with behavioral performance on a modified gambling task. RESULTS There was lower GM volume specifically in bilateral medial OFC in SDI compared with control subjects. There was a small but significant correlation between medial OFC GM and persistence of playing high-risk decks on a modified gambling task. CONCLUSIONS This is the first study to use VBM with whole brain correction for multiple comparisons in SDI after prolonged abstinence. Reduced medial OFC GM might reflect long-term adaptations within the reward-learning circuit underlying pathological decision-making in substance dependence.

Depression in Substance-Dependent Delinquents

OBJECTIVE Depression often is comorbid with conduct disorder. The purpose of this study is to assess whether, among youths with conduct disorder, those with depression differ in other ways from those without depression. METHOD Ninety-nine delinquent boys (aged 13 through 19 years) were evaluated with the Diagnostic Interview Schedule for Children and other instruments. All boys had conduct disorder and substance use disorders. RESULTS Staff-rated and self-rated depression scores correlated significantly. Twenty-one boys had major depression and/or dysthymia. Depressed boys had more substance dependence diagnoses and were more likely to have attention-deficit hyperactivity disorder, posttraumatic stress disorder, and anxiety disorders, compared with the nondepressed boys. Depressed boys tended to develop conduct symptoms earlier than did the nondepressed boys. Depression scores did not change after at least 4 weeks of abstinence, for either depressed or nondepressed boys. CONCLUSIONS Depressed delinquents have more substance dependence diagnoses, tend to initiate behavioral problems at an earlier age, have increased anxiety and attentional problems, and more trauma effects, than nondepressed delinquents. Depression does not appear to be related to substance intoxication, since it is not alleviated after 4 weeks of abstinence. Such boys may require combined psychiatric and substance treatment.

Developmental epidemiology of drug use and abuse in adolescence and young adulthood: Evidence of generalized risk

Past studies highlight a narrowing gender gap and the existence of a shared etiology across substances of abuse; however, few have tested developmental models using longitudinal data. We present data on developmental trends of alcohol, tobacco, and marijuana use, abuse and dependence assessed during adolescence and young adulthood in a community-based Colorado twin sample of 1733 respondents through self-report questionnaires and structured psychiatric interviews. Additionally, we report on the rates of multiple substance use and disorders at each developmental stage, and the likelihood of a substance use disorder (SUD; i.e., abuse or dependence) diagnosis in young adulthood based on adolescent drug involvement. Most notably, we evaluate whether the pattern of multiple substance use and disorders and likelihood ratios across substances support a model of generalized risk. Lastly, we evaluate whether the ranked magnitudes of substance-specific risk match the addiction liability ranking. Substance use and SUDs are developmental phenomena, which increase from adolescence to young adulthood with few and inconsistent gender differences. Adolescents and young adults are not specialized users, but rather tend to use or abuse multiple substances increasingly with age. Risk analyses indicated that progression toward a SUD for any substance was increased with prior involvement with any of the three substances during adolescence. Despite the high prevalence of alcohol use, tobacco posed the greatest substance-specific risk for developing subsequent problems. Our data also confirm either a generalized risk or correlated risk factors for early onset substance use and subsequent development of SUDs.

Review of Twin and Adoption Studies of Adolescent Substance Use

OBJECTIVE To review studies of adolescent substance use and abuse with genetically informative designs. METHOD Twin and adoption studies of adolescent substance use were searched in Medline using keywords. RESULTS Of 19 studies that used adolescent samples, 18 examined initiation or use of substances and 1 examined abuse. Of the 7 retrospective studies using adult samples, 6 examined problematic behaviors such as substance dependence. Genetic and shared environmental influences on adolescent substance use are moderated by the specific substance, age, gender, specific contexts, religiousness, and region. There is some evidence for a common genetic influence on substance use across substances. Genetic influences on adolescent substance use may act through an influence on disinhibited behavior. Shared environment contributed to adolescent substance use consistently across all adolescent samples and common shared environmental influences influenced initiation into tobacco and alcohol use. While parental alcohol use had a small influence on adolescent shared environment, sibling influences were substantial. CONCLUSIONS Twin and adoption studies have increased our understanding of genetic and environmental influences on adolescent substance use and its initiation; however, more studies focusing on clinical syndromes of abuse and dependence are needed.

Effect of Drake and Panamanian Gateways on the circulation of an ocean model

Geologic studies indicate that prior to ∼40 Ma the Drake Passage was closed and the Central American Isthmus was open. The effect of these changes has been examined in an ocean general circulation model. Several sensitivity experiments were conducted, all with atmospheric forcing and other boundary conditions from the present climate, but with different combinations of closed and open gateways. In the first experiment, the only change involved closure of the Drake Passage. In agreement with earlier studies the barrier modified the geostrophic balance that now maintains the circumpolar flow in the southern ocean, with the net effect being decreased transport of the Antarctic Current and an approximate fourfold increase in outflow of Antarctic deep-bottom waters. The very large increase in Antarctic outflow suppresses North Atlantic Deep Water (NADW) formation. In addition to corroboration of results from earlier studies, our simulations provide several new insights into the role of a closed Drake Passage. A more geologically realistic closed Drake/open central American isthmus experiment produces essentially the same pattern of deepwater circulation from the first experiment, except that Antarctic outflow is about 20% less than the first experiment. The resultant unipolar deepwater circulation pattern for the second experiment is consistent with paleoceanographic observations from the early Cenozoic. A third experiment involved an open Drake and open central American isthmus. In this experiment, Antarctic outflow is diminished to slightly above present levels but NADW production is still low due to free exchange of low-salinity surface water between the North Pacific and North Atlantic. The low level of thermohaline overturn should have reduced oceanic productivity in the Oligocene (∼30 Ma), a result in agreement with geologic observations. Finally, simulations with an energy balance model demonstrate that the changes in surface heat flux south of 60°S due to breaching of the Drake barrier do not result in temperature changes large enough to have triggered Antarctic glaciation. This last result suggests that some other factor (CO2?) may be required for Antarctic ice sheet expansion in the Oligocene (∼30–34 Ma). Our results lend further support to the concept that even in the absence of changing boundary conditions due to ice sheet growth, variations in the geometry of the ocean basins can significantly influence ocean circulation patterns and the sediment record. The results also suggest that the primary polarities of the Cenozoic deepwater circulation may have been controlled by opening and closing of these two gateways.

Influences on adolescent substance dependence: conduct disorder, depression, attention deficit hyperactivity disorder, and gender

OBJECTIVE In adolescents, conduct disorder (CD), attention deficit hyperactivity disorder (ADHD), and depression are frequently comorbid with substance dependence (SD). We hypothesized that the prevalence and severity of CD, major depressive disorder (MDD), and ADHD would differ by gender, and that these conditions would associate differentially with severity of SD in males and females. METHODS We examined these issues, using standardized diagnostic interviews, in 285 male and 82 female adolescents referred for comorbid CD and SD. RESULTS Males and females did not differ significantly in severity of substance involvement, MDD, or ADHD, but males had more severe CD. MDD severity was the only variable significantly associated with SD severity for females, while for males, severity of CD combined with MDD and ADHD was significantly associated with SD severity. CONCLUSIONS Among referred adolescents, CD, MDD, and ADHD may all be important concomitants of SD in males, while in females, depression may be the primary variable related to SD.

The DSM-IV field trial for substance use disorders: major results

“Department of Psychiatry, Washington University School of Medicine, 4940 Children’s Place, Box 8134, St. Louis, MO 63110-1093. USA bDepartment of Psychiatry, Veterans Administration Hospital and University of California, 3350 LuJolla Village Dr., San Diego, CA 92161, USA EDepartment of Psychiatry, University of Vermont College of Medicine, Burlington, VT 05401, USA ‘University of Colorado Medical Center, Box C-268, 4200 E. 9th Ave., Denver, CO 80262, USA ‘VA Medical Center, 39th Woodland Ave.. Philadelphia, PA 19104, USA ‘Office of the Provost, University of Iowa, Jessup Hall III, Iowa City, IA 52242,