Methadone maintenance dose modulates anterior cingulate glutamate levels in heroin-dependent individuals: A preliminary in vivo (1)H MRS study

Mu-opioid receptor agonists alter brain glutamate (GLU) levels in laboratory animals. This clinical study used proton magnetic resonance spectroscopy ((1)H MRS) to examine regional brain GLU levels during experimental manipulation of methadone (MTD) maintenance dose under double-blind, within-subject conditions in seven heroin-dependent volunteers. Subjects were scanned first at a high MTD dose (100 mg/day), underwent a 3-week outpatient MTD dose taper, and then were scanned again at a low MTD dose (10-25 mg/day; modified for participant comfort). Five age- and cigarette smoking-matched controls were scanned once. In vivo short echo time (TE = 22 ms), single voxel (1)H MRS data from midline pregenual anterior cingulate cortex (ACC) and thalamus (4.5 cm(3) each) were collected using PRESS on a 4-Tesla MRI system. Absolute metabolite levels were quantified. GLU levels in the ACC, but not the thalamus, were higher at the low relative to the high MTD dose in heroin-dependent subjects. No other metabolites differed by MTD dose, or between control vs. heroin-dependent subjects (at either MTD dose). GLU levels in the ACC were inversely related to the duration of cigarette smoking (controls) and heroin use (experimental group). Future studies are warranted to investigate the relationship between GLU levels during treatment (and detoxification), and withdrawal symptoms or relapse.

A population pharmacokinetic and pharmacodynamic modelling approach to support the clinical development of RBP-6000, a new, subcutaneously injectable, long-acting, sustained-release formulation of buprenorphine, for the treatment of opioid dependence

BACKGROUND AND OBJECTIVES

This study implemented pharmacokinetic/pharmacodynamic modelling to support the clinical development of RBP-6000, a new, long-acting, sustained-release formulation of buprenorphine for the treatment of opioid dependence. Such a formulation could offer advantages over existing buprenorphine pharmacotherapy by improving patient compliance and reducing the diversion of the product.

METHODS

A population pharmacokinetic model was developed using 36 opioid-dependent subjects who received single subcutaneous doses of RBP-6000. Another pharmacokinetic/pharmacodynamic model was developed using μ-opioid receptor occupancy (µORO) data to predict efficacy of RBP-6000 after repeated doses. It was also assessed how buprenorphine plasma concentrations were correlated with opioid withdrawal symptoms and hydromorphone agonist blockade data from 15 heroin-dependent subjects.

RESULTS

The resulting pharmacokinetic model accurately described buprenorphine and norbuprenorphine plasma concentrations. A saturable maximum effect (E max) model with 0.67 ng/mL effective concentration at 50 % of maximum (EC50) and 91 % E max best described µORO versus buprenorphine plasma concentrations. Linear relationships were found among µORO, withdrawal symptoms and blockade of agonist effects.

CONCLUSION

Previously published findings have demonstrated µORO ≥70 % is needed to achieve withdrawal suppression and blockade of opioid agonist subjective effects. Model simulations indicated that a 200 mg RBP-6000 dose should achieve 2–3 ng/mL buprenorphine average concentrations and desired efficacy.

Functional mu opioid receptor polymorphism (OPRM1 A(118) G) associated with heroin use outcomes in Caucasian males: A pilot study

BACKGROUND

Heroin's analgesic, euphoric and dependence-producing effects are primarily mediated by the mu opioid receptor (MOR). A single gene, OPRM1, encodes the MOR. The functional polymorphism A(118)G, located in exon 1 of the OPRM1 gene, results in anatomically-specific reductions in MOR expression, which may alter an individual's response to heroin. In prior studies 118G (rare allele) carriers demonstrated significantly greater opioid tolerance, overdose vulnerability, and pain sensitivity than 118AA homozygotes. Those findings suggest OPRM1 genotype may impact characteristics of heroin use.

METHODS

The present pilot study characterized the impact of OPRM1 genotype (rs1799971, 118G allele carriers vs. 118AA homozygotes) on heroin-use phenotypes associated with heroin dependence severity in a sample of male, Caucasian chronic heroin users (n = 86).

RESULTS

Results indicate that 118G allele carriers reported significantly more heroin use-related consequences and heroin-quit attempts, and were more likely to have sought treatment for their heroin use than 118AA homozygotes.

CONCLUSIONS

These preliminary findings, consistent with extant data, illustrate a role for OPRM1 allelic variation on heroin use characteristics, and provide support for considering genotype in heroin treatment and relapse prevention.

Effect of oral THC pretreatment on marijuana cue-induced responses in cannabis dependent volunteers

BACKGROUND

The current study tested whether oral Δ(9)-tetrahydrocannabinol (THC: 0-, 10-, and 20-mg) pretreatment would attenuate polysensory cue-induced craving for marijuana.

METHODS

Cannabis dependent participants (7 males and 7 females, who smoked on average 5.4 ± 1.1 blunts daily) completed 3 experimental sessions (oral THC pretreatment dose; counterbalanced order) using a placebo-controlled within-subject crossover design. During each session, participants completed a baseline evaluation and were first exposed to neutral cues then marijuana cues while physiological measures and subjective ratings of mood, craving, and drug effect were recorded.

RESULTS

Following placebo oral THC pretreatment, marijuana (vs. neutral) cues significantly increased ratings of marijuana craving (desire and urge to use, Marijuana Craving Questionnaire (MCQ)-Compulsivity scale), anxious mood and feeling hungry. Males also reported feeling more "Down" during marijuana cues relative to females. Pretreatment with oral THC (10-mg and/or 20-mg vs. placebo) significantly attenuated marijuana cue-induced increases in craving and anxiety but not hunger. Oral THC attenuation of the cue-induced increase in MCQ-Compulsivity ratings was observed in females only. Oral THC produced statistically (but not clinically) significant increases in heart rate and decreases in diastolic blood pressure, independent of cues.

CONCLUSIONS

These marijuana-cue findings replicate earlier results and further demonstrate that oral THC can attenuate selected effects during marijuana multi-cue exposure, and that some of these effects may be sex-related. Results of this study suggest oral THC may be effective for reducing marijuana cue-elicited (conditioned) effects. Further study is needed to determine whether females may selectively benefit from oral THC for this purpose.

Exploration of the telescoping effect among not-in-treatment, intensive heroin-using research volunteers

BACKGROUND

Addiction research literature suggests some demographic groups exhibit a later age of substance use initiation, more rapid escalation to dependence, and worse substance use-related outcomes. This 'telescoping' effect has been observed more often in females but has not yet been examined in not-in-treatment heroin users or racial subgroups.

METHODS

Not-in-treatment, intensive heroin-using adults screened for laboratory-based research studies (N=554; range 18-55 yr; mean age: 42.5 yr; 60.5% African American [AA]; 70.2% male) were included in this secondary analysis. A comprehensive drug history questionnaire assessed heroin-use characteristics and lifetime adverse consequences. We examined telescoping effects by racial and gender groups: Caucasian males and females; AA males and females.

RESULTS

Caucasian males initiated heroin use significantly later than AA males but this difference was not observed for age at intensive heroin use (≥3 times weekly). Caucasian males reported significantly more lifetime heroin use-related consequences, were more likely to inject heroin, and reported more-frequent past-month heroin use, but did not differ from AA males in lifetime heroin quit attempts or prior heroin treatment. Females, compared to males, reported later onset of initial and intensive use, but there was no gender-telescoping effect from initial to intensive heroin-use.

CONCLUSIONS

In this not-in-treatment sample, Caucasian males exhibited more rapid heroin-use progression and adverse consequences than AA males, i.e., within-gender, racial-group telescoping. Despite later-onset heroin use among females, there was no evidence of gender-related telescoping. Given the resurgence of heroin use, differential heroin-use trajectories across demographic groups may be helpful in planning interventions.

Causal pathways between impulsiveness, cocaine use consequences, and depression

AIMS

The present study examined whether lifetime cocaine use consequences mediate the relationship between trait impulsiveness and current depression symptoms among regular cocaine users.

METHODS

Regular cocaine users (N=108) were assessed using: Barratt Impulsiveness Scale subscales (non-planning, attentional, motor sub-scales) to measure trait impulsiveness; a standardized Drug History and Use Questionnaire to measure cocaine use and related consequences; and Beck Depression Inventory to measure current depression symptoms.

RESULTS

All impulsiveness subscales were positively associated with an earlier age of first cocaine use, a higher degree of current depression symptoms and a greater number of lifetime cocaine use consequences. In three separate simple mediation tests, lifetime cocaine use consequences partially mediated the relationship between each of the impulsiveness subscales (non-planning: R(2)=.42; attentional: R(2)=.40; motor: R(2)=.24) and current depression symptoms. Separate moderated mediation analyses failed to demonstrate an interaction between lifetime cocaine use and cocaine-related consequences predicting depression symptoms for the mediation models.

CONCLUSIONS

Cocaine-related consequences function in a more nuanced manner than just an outcome of impulsiveness or cocaine use, but as a pathway between trait impulsiveness and current depression symptoms.

Gender-specific predictors of retention and opioid abstinence during methadone maintenance treatment

AIMS

Retention in methadone maintenance treatment (MMT) for 1 year is associated with positive outcomes including opioid abstinence, however, most studies have not investigated gender differences. We hypothesized that predictors of retention and opioid abstinence would differ between men and women, and aimed to determine which factors best predict retention and abstinence for each gender.

METHODS

Data were available for 290 patients (173 M, 117 F) admitted to outpatient MMT. Regression analyses, stratified by gender, were conducted to identify unique predictors of MMT retention (<1 vs. >1 year) and opioid abstinence rate (proportion of opioid-free urine samples up to 1 year retention).

RESULTS

Gender did not significantly predict treatment retention (mean = 231 days, 39% retained > 1 year) or opioid abstinence (49% overall). For males, significant predictors of > 1-year retention were urine samples negative for opioids (odds ratio [OR] = 6.67) and cannabinoids (OR = 5.00) during the first month, and not cocaine dependent (OR = 2.70). Significant predictors of higher long-term opioid abstinence were first-month urine samples negative for opioids and cocaine metabolites. For females, significant predictors of >1-year retention were first-month urine samples negative for cocaine metabolites (OR = 4.00) and cannabinoids (OR = 9.26), and no history of sexual victimization (OR = 3.03). The only significant predictor of higher opioid abstinence rate was first-month opioid-free urine samples.

CONCLUSIONS

These findings indicate gender-specific predictors of MMT retention and opioid abstinence. Future studies on MMT outcomes should examine each gender separately, and consider unique pathways by which females and males adhere to, and benefit from MMT.

Predictors of buprenorphine initial outpatient maintenance and dose taper response among non-treatment-seeking heroin dependent volunteers

BACKGROUND

Buprenorphine (BUP) is effective for treating opioid use disorder. Individuals' heroin-use characteristics may predict their responses to BUP, which could differ during maintenance and dose-taper phases. If so, treatment providers could use pre-treatment characteristics to personalize level of individual care and possibly improve treatment outcomes.

METHODS

Non-treatment-seeking heroin-dependent volunteers (N=34) initiated outpatient BUP maintenance (8-mg/day) and submitted urine samples thrice weekly tested for opioids (non-contingent result). After completing three programmatically-related inpatient behavioral pharmacology experiments (while maintained on 8-mg/day BUP), participants were discharged and underwent a double-blind BUP dose taper (4-mg/day, 2-mg/day and 0-mg/day during weeks 1-3, respectively) with an opioid-abstinence incentive ($30 per consecutive opioid-negative urine specimen, obtained thrice weekly).

RESULTS

Participants who reported less pre-study (past-month) heroin use and shorter lifetime duration of heroin use were more likely to submit an opioid-negative urine sample during initial outpatient BUP maintenance. Participants who reported more lifetime heroin-quit attempts and provided any opioid-free urine sample during initial outpatient maintenance sustained longer continuous opioid-abstinence during the BUP dose taper. Participants who reported >3 lifetime quit attempts abstained from opioid use nearly one week longer (14 days vs. 8 days to opioid-lapse) and nearly half (46.7%) refrained from opioid use during dose taper.

CONCLUSIONS

Number of prior heroin quit attempts may predict BUP dose taper response and provide a metric for stratifying heroin-dependent individuals by relative risk for opioid lapse. This metric may inform personalized relapse prevention care and improve treatment outcomes.

Relationships of behavioral measures of frontal lobe dysfunction with underlying electrophysiology in cocaine-dependent patients

BACKGROUND AND OBJECTIVES

Despite evidence that frontal lobe functioning is impaired in cocaine-dependent individuals, relationships between behavioral measures of frontal dysfunction and electrophysiological measures of inhibition in cocaine use have not been explored.

METHODS

Using the Frontal Systems Behavior Scale (FrSBe), frontal dysfunction was assessed in a group of abstinent cocaine-dependent subjects (N = 49) and healthy controls (N = 32). Using transcranial magnetic stimulation (TMS) and evoked potential (EP)-based electrophysiological measures of inhibition, we assessed associations between these measures and FrSBe estimates of frontal dysfunction.

RESULTS

Patients had significantly higher FrSBe scores for executive dysfunction, disinhibition, and apathy than controls. Lower TMS-based resting motor thresholds (ie, hyperexcitability) were significantly associated with higher executive dysfunction scores in the patients.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Relationships between FrSBe scores and TMS-based measures highlight neurophysiological aberrations underlying frontal lobe dysfunction in cocaine abusers. TMS and EP measures may be useful probes of the intermediary steps between frontal lobe dysfunction and addictive behavior.

Cocaine behavioral economics: from the naturalistic environment to the controlled laboratory setting

BACKGROUND

We previously observed that behavioral economic factors predict naturalistic heroin seeking behavior that correlates with opioid seeking in the experimental laboratory. The present study sought to replicate and extend these prior findings with regular cocaine users.

METHODS

Participants (N=83) completed a semi-structured interview to establish income-generating and cocaine-purchasing/use repertoire during the past month. Questions addressed sources/amounts of income and expenditures; price (money and time) per purchase; and frequency/amounts of cocaine purchased and consumed. Naturalistic cocaine purchasing and use patterns were: (1) analyzed as a function of income quartile, (2) perturbed by hypothetical changes in cost factors to assess changes in purchasing/use habits, and (3) correlated with experimental cocaine seeking.

RESULTS

Income was positively related to naturalistic cocaine seeking/use pattern (i.e., income elastic), and behaviors were cost-efficient and sensitive to supply chain. Income was unrelated to proportional expenditure on cocaine (≈55%) but inversely related to food expenditure. In all hypothetical scenarios (changes in income or dealer, loss of income assistance from government or family/friends, and increasing arrest risk when purchasing), the high-income group reported they would continue to use more cocaine daily than other groups. Number of laboratory cocaine choices significantly correlated with cocaine purchase time (positively) and purity of cocaine (negatively) in the naturalistic setting.

CONCLUSIONS

These results replicate and extend findings with regular heroin users, demonstrate the importance of income, cost-efficiency and supply-mindedness in cocaine seeking/use, and suggest that this interview-based approach has good external validity.

Effect of experimental analogs of contingency management treatment on cocaine seeking behavior

BACKGROUND

Contingency management (CM) treatment is effective for treating cocaine dependence but further mechanistic studies of its efficacy are warranted. This study aimed to determine whether: (a) higher vs. lower predictable money amounts ($3 vs. $1; analogs of standard voucher-based CM) increase cocaine demand elasticity; and (b) probabilistic amounts matched for expected value with the $3-predictable amount (50% chance of $6; 25% chance of $12; and 12.5% chance of $24; analogs of prize CM) similarly affect cocaine choice.

METHODS

Each of 15 cocaine-dependent participants first completed a qualifying session to ensure that intranasal cocaine functioned as a reinforcer, then completed a 10-session, within-subject, randomized crossover study. During each of the 10 sessions, the participant responded on a progressive ratio schedule to earn units of cocaine (5-mg or 10-mg) and/or money (five monetary conditions above).

RESULTS

During the reinforcement qualifying session (10-mg vs. 0-mg units; no money alternative), cocaine choice was high. The $3-predictable amount significantly decreased cocaine choice relative to both the $1-predictable amount and the qualifying session. Cocaine-choices in the probabilistic conditions were similar to the $3 predictable condition.

CONCLUSIONS

These findings indicate that CM interventions targeted at reducing cocaine self-administration are more likely to succeed with higher value non-drug reinforcement.

Substance misuse following Roux-en-Y gastric bypass surgery

Post-bariatric surgery patients are overrepresented in substance abuse treatment, particularly those who have had the Roux-en-Y gastric bypass (RYGB) procedure. The severity of the substance use disorder (SUD; i.e., warranting inpatient treatment) and related consequences necessitate a better understanding of the variables associated with post-RYGB SUDs. This investigation assessed factors associated with post-RYGB substance misuse. Post-RYGB patients (N = 141; at least 24 months postsurgery) completed an online survey assessing variables hypothesized to contribute to post-RYGB SUDs. Fourteen percent of participants met criteria for postoperative substance misuse. Those with a lower percent total weight loss (%TWL) were more likely to endorse substance misuse. Family history of substance misuse was strongly associated with postoperative substance misuse. Eating-related variables including presurgical food addiction and postsurgical nocturnal eating, subjective hunger, and environmental responsiveness to food cues were also associated with a probable postoperative SUD. These findings have clinical utility in that family history of substance misuse can be easily assessed, and at-risk patients can be advised accordingly. In addition, those who endorse post-RYGB substance misuse appear to have stronger cognitive and behavioral responses to food, providing some support for the theory of behavioral substitution (or "addiction transfer").

BDNF Val(66)Met genotype is associated with drug-seeking phenotypes in heroin-dependent individuals: a pilot study

Brain-derived neurotrophic factor (BDNF) Val(66)Met genotype has been associated with neurobehavioral deficits. To examine its relevance for addiction, we examined BDNF genotype differences in drug-seeking behavior. Heroin-dependent volunteers (n = 128) completed an interview that assessed past-month naturalistic drug-seeking/use behaviors. In African Americans (n = 74), the Met allele was uncommon (carrier frequency 6.8%); thus, analyses focused on European Americans (n = 54), in whom the Met allele was common (carrier frequency 37.0%). In their natural setting, Met carriers (n = 20) reported more time- and cost-intensive heroin-seeking and more cigarette use than Val homozygotes (n = 34). BDNF Val(66)Met genotype predicted 18.4% of variance in 'weekly heroin investment' (purchasing time × amount × frequency). These data suggest that the BDNF Met allele may confer a 'preferred drug-invested' phenotype, resistant to moderating effects of higher drug prices and non-drug reinforcement. These preliminary hypothesis-generating findings require replication, but are consistent with pre-clinical data that demonstrate neurotrophic influence in drug reinforcement. Whether this genotype is relevant to other abused substances besides opioids or nicotine, or treatment response, remains to be determined.

Yohimbine increases opioid-seeking behavior in heroin-dependent, buprenorphine-maintained individuals

RATIONALE

In laboratory animals, the biological stressor yohimbine (α(2)-noradrenergic autoreceptor antagonist) promotes drug seeking. Human laboratory studies have demonstrated that psychological stressors can increase drug craving but not that stressors alter drug seeking.

OBJECTIVES

This clinical study tested whether yohimbine increases opioid-seeking behavior.

METHODS

Ten heroin-dependent, buprenorphine-stabilized (8 mg/day) volunteers sampled two doses of hydromorphone [12 and 24 mg IM in counterbalanced order, labeled drug A (session 1) and drug B (session 2)]. During each of six later sessions (within-subject, double-blind, randomized crossover design), volunteers could respond on a 12-trial choice progressive ratio task to earn units (1 or 2 mg) of the sampled hydromorphone dose (drug A or B) vs money ($2) following different oral yohimbine pretreatment doses (0, 16.2, and 32.4 mg).

RESULTS

Behavioral economic demand intensity and peak responding (O (max)) were significantly higher for hydromorphone 2 than 1 mg. Relative to placebo, yohimbine significantly increased hydromorphone demand inelasticity, more so for hydromorphone 1-mg units (P (max) = 909, 3,647, and 3,225 for placebo, 16.2, and 32.4 mg yohimbine doses, respectively) than hydromorphone 2-mg units (P (max) = 2,656, 3,193, and 3,615, respectively). Yohimbine produced significant but clinically modest dose-dependent increases in blood pressure (systolic ≈ 15 and diastolic ≈ 10 mmHg) and opioid withdrawal symptoms, and decreased opioid agonist symptoms and elated mood.

CONCLUSIONS

These findings concur with preclinical data by demonstrating that yohimbine increases drug seeking; in this study, these effects occurred without clinically significant subjective distress or elevated craving, and partly depended on opioid unit dose.

Validation of an online questionnaire measure of the relative reinforcing value of food

Laboratory methods and questionnaires to assess the relative reinforcing value of food (RRV-F) have been developed, but this is the first study to validate an online questionnaire measure of the RRV-F. Participants (281 college students) completed an online survey assessing demographic variables, food preferences, and the RRV-F. A subsample (n=21) also completed a laboratory food choice session. The online RRV-F instrument showed strong predictive validity for laboratory food choice behavior, convergent validity with overweight status, and discriminant validity with unrelated constructs (age, gender, height). Results suggest that online methodology is appropriate for assessing the RRV-F in a manner that is cost-effective, time-efficient, affords greater anonymity, and enables recruitment from larger samples over a broader geographic region.

Postsurgical patient-controlled opioid self-administration is greater in hospitalized abstinent smokers than nonsmokers

OBJECTIVE

To compare 24-hour postsurgical patient-controlled analgesia (PCA) in smokers and nonsmokers.

DESIGN

Patients completed a presurgical questionnaire inquiring about sleep, nicotine and other substance use, and comorbid disorders. Nicotine use was discontinued on hospital admission on the day of surgery. After morning surgery and (spinal) anesthesia recovery, each patient began opioid PCA with a device that limited dose frequency (morphine 1 mg equivalent units) using a lockout period (range, 6-10 minutes).

SETTING

Patients resided in the Orthopedic Unit at Henry Ford Hospital for the duration of the study.

PATIENTS

Cigarette smokers (n 5 13) and healthy nonsmokers (n 5 13) who completed the presurgical questionnaire were matched for age, gender, and type of surgery (hip vs knee replacement).

MAIN OUTCOME MEASURES

Postsurgical analgesic medication requests and denials were the primary measures.

RESULTS

In addition to group-matching variables, smokers (self-report of consuming 2-30 cigarettes per day [mean, 11.7]) and nonsmokers did not significantly differ in average weight, height, body mass index, surgery start time (about 9:45 AM), PCA start time (about 4 PM), or lockout interval (8.6 minutes). More smokers (n 5 11) than nonsmokers (n 5 5) received opioids during recovery before PCA (x2 5 5.85, p > 0.05). During PCA, smokers had significantly more injection denials [F(1,24) 5 4.65, p > 0.05] and fewer infusions per request [F(1,24) 5 6.74, p > 0.05] than nonsmokers. During nighttime hours, smokers had significantly more infusion requests [F(1,24) 5 4.41, p > 0.05] and more injection denials [F(1,24) 5 5.67, p > 0.03] than nonsmokers.

CONCLUSIONS

These data suggest that acute nicotine abstinence during hospitalization increases PCA opioid medication seeking but not consumption during postoperative recovery.

Motivational assessment of non-treatment buprenorphine research participation in heroin dependent individuals

BACKGROUND

Heroin abuse remains an important public health problem, particularly in economically disadvantaged areas. Insight into this problem is gained from interviewing addicted individuals. However, we lack systematic data on factors that motivate heroin users to participate in non-treatment research that offers both financial incentives (compensation) and non-financial incentives (e.g., short-term medication).

AIM

To better understand the relative importance of several types of personal motivations to participate in non-treatment buprenorphine research, and to relate self-motivations to social, economic, demographic and drug use factors.

METHODS

Heroin dependent volunteers (N=235 total; 57 female and 178 male; 136 African American, 86 Caucasian, and 13 Other) applied for non-therapeutic buprenorphine research in an urban outpatient setting from 2004 to 2008. We conducted a semi-structured behavioral economic interview, after which participants ranked 11 possible motivations for research participation.

RESULTS

Although the study was repeatedly described as non-treatment research involving buprenorphine, participants often ranked some treatment-related motivations as important (wanting to reduce/stop heroin use, needing a medication to get stabilized/detoxify). Some motivations correlated with income, heroin use, and years since marketing of buprenorphine. Two dimensions emerged from principal component analysis of motivation rankings: (1) treatment motivation vs. greater immediate needs and (2) commitment to trying alternatives vs. a more accepting attitude toward traditional interventions. In summary, heroin addicts' self-motivations to engage in non-therapeutic research are complex--they value economic gain but not exclusively or primarily--and relate to variables such as socioeconomic factors and drug use.

Heroin purchasing is income and price sensitive

Semi-structured interviews were used to assess behavioral economic drug demand in heroin dependent research volunteers. Findings on drug price, competing purchases, and past 30-day income and consumption, established in a previous study, are replicated. We extended these findings by having participants indicate whether hypothetical environmental changes would alter heroin purchasing. Participants (n = 109) reported they would significantly (p < .005) decrease heroin daily purchasing amounts (DPA) from past 30-day levels (M = $60/day) if: (a) they encountered a 33% decrease in income (DPA = $34), (b) family/friends no longer paid their living expenses (DPA = $32), or (c) they faced four-fold greater likelihood of police arrest at their purchasing location (DPA = $42). Participants in higher income quartiles (who purchase more heroin) show greater DPA reductions (but would still buy more heroin) than those in lower income quartiles. For participants receiving government aid (n = 31), heroin purchasing would decrease if those subsidies were eliminated (DPA = $28). Compared to participants whose urine tested negative for cocaine (n = 31), cocaine-positive subjects (n = 32) reported more efficient heroin purchasing, that is, they live closer to their primary dealer; are more likely to have heroin delivered or walk to obtain it (and less likely to ride the bus), thus reducing purchasing time (52 vs. 31 min, respectively); and purchase more heroin per episode. These simulation results have treatment and policy implications: Daily heroin users' purchasing repertoire is very cost-effective, more so for those also using cocaine, and only potent environmental changes (income reductions or increased legal sanctions) may impact this behavior.

Real-time functional MRI using pseudo-continuous arterial spin labeling

The first implementation of real-time acquisition and analysis of arterial spin labeling-based functional magnetic resonance imaging time series is presented in this article. The implementation uses a pseudo-continuous labeling scheme followed by a spiral k-space acquisition trajectory. Real-time reconstruction of the images, preprocessing, and regression analysis of the functional magnetic resonance imaging data were implemented on a laptop computer interfaced with the MRI scanner. The method allows the user to track the current raw data, subtraction images, and the cumulative t-statistic map overlaid on a cumulative subtraction image. The user is also able to track the time course of individual time courses and interactively selects a region of interest as a nuisance covariate. The pulse sequence allows the user to adjust acquisition and labeling parameters while observing their effect on the image within two successive pulse repetition times. This method is demonstrated by two functional imaging experiments: a simultaneous finger-tapping and visual stimulation paradigm, and a bimanual finger-tapping task.

Sustained release d-amphetamine reduces cocaine but not 'speedball'-seeking in buprenorphine-maintained volunteers: a test of dual-agonist pharmacotherapy for cocaine/heroin polydrug abusers

The aim of this study was to determine whether oral sustained release d-amphetamine (SR-AMP) reduces cocaine and opioid/cocaine combination ('speedball'-like) seeking in volunteers with current opioid dependence and cocaine dependence. Following outpatient buprenorphine (BUP) 8 mg/day stabilization without SR-AMP, eight participants completed a 3-week in-patient study with continued BUP 8 mg/day maintenance and double-blind ascending SR-AMP weekly doses of 0, 30, and 60 mg/day, respectively. After 3 days (Saturday-Monday) stabilization at each SR-AMP weekly dose (0, 15, or 30 mg administered at 0700 and 1225 each day), on Tuesday-Friday mornings (0900-1200 hours), participants sampled four drug combinations in randomized, counterbalanced order under double-blind, double-dummy (intranasal cocaine and intramuscular hydromorphone) conditions: cocaine (COC 100 mg+saline); hydromorphone (COC 4 mg+HYD 24 mg); 'speedball' (COC 100 mg+HYD 24 mg); and placebo (COC 4 mg+saline). Subjective and physiological effects of these drug combinations were measured. From 1230 to 1530 hours, participants could respond on a choice, 12-trial progressive ratio schedule to earn drug units (1/12th of total morning dose) or money units (US$2). SR-AMP significantly reduced COC, but not HYD or speedball, choices and breakpoints. SR-AMP also significantly reduced COC subjective (eg, abuse-related) effects and did not potentiate COC-induced cardiovascular responses. This study shows the ability of SR-AMP to attenuate COC self-administration, as well as its selectivity, in cocaine/heroin polydrug abusers. Further research is warranted to ascertain whether SR-AMP combined with BUP could be a useful dual-agonist pharmacotherapy.

A 14-year retrospective maternal report of alcohol consumption in pregnancy predicts pregnancy and teen outcomes

Detecting patterns of maternal drinking that place fetuses at risk for fetal alcohol spectrum disorders (FASDs) is critical to diagnosis, treatment, and prevention but is challenging because information on antenatal drinking collected during pregnancy is often insufficient or lacking. Although retrospective assessments have been considered less favored by many researchers due to presumed poor reliability, this perception may be inaccurate because of reduced maternal denial and/or distortion. The present study hypothesized that fetal alcohol exposure, as assessed retrospectively during child adolescence, would be related significantly to prior measures of maternal drinking and would predict alcohol-related behavioral problems in teens better than antenatal measures of maternal alcohol consumption. Drinking was assessed during pregnancy, and retrospectively about the same pregnancy, at a 14-year follow-up in 288 African-American women using well-validated semistructured interviews. Regression analysis examined the predictive validity of both drinking assessments on pregnancy outcomes and on teacher-reported teen behavior outcomes. Retrospective maternal self-reported drinking assessed 14 years postpartum was significantly higher than antenatal reports of consumption. Retrospective report identified 10.8 times more women as risk drinkers (≥ one drink per day) than the antenatal report. Antenatal and retrospective reports were moderately correlated and both were correlated with the Michigan Alcoholism Screening Test. Self-reported alcohol consumption during pregnancy based on retrospective report identified significantly more teens exposed prenatally to at-risk alcohol levels than antenatal, in-pregnancy reports. Retrospective report predicted more teen behavior problems (e.g., attention problems and externalizing behaviors) than the antenatal report. Antenatal report predicted younger gestational age at birth and retrospective report predicted smaller birth size; neither predicted teen IQ. These results suggest that if only antenatal, in-pregnancy maternal report is used, then a substantial proportion of children exposed prenatally to risk levels of alcohol might be misclassified. The validity of retrospective assessment of prior drinking during pregnancy as a more effective indicator of prenatal exposure was established by predicting more behavioral problems in teens than antenatal report. Retrospective report can provide valid information about drinking during a prior pregnancy and may facilitate diagnosis and subsequent interventions by educators, social service personnel, and health-care providers, thereby reducing the life-long impact of FASDs.

Just say "I don't": lack of concordance between teen report and biological measures of drug use

BACKGROUND

Prevalence estimates of illicit drug use by teens are typically generated from confidential or anonymous self-report. While data comparing teen self-report with biological measures are limited, adult studies identify varying degrees of under-reporting.

METHODS

Hair analyses for cocaine, opiates and marijuana were compared to confidential teen self- and parent-reported teen drug use in a longitudinal cohort of >400 high-risk urban teens and parents.

RESULTS

Both teens and parents substantially underreported recent teen cocaine and opiate use. However, compared with parents, teens were more likely to deny biomarker-verified cocaine use. Teen specimens (hair) were 52 times more likely to identify cocaine use compared with self-report. Parent hair analyses for cocaine and opiate use were 6.5 times and 5.5 times, respectively, more likely to indicate drug use than were parental self-report. The lack of concordance between self-report and bioassay occurred despite participant's knowledge that a "certificate of confidentiality" protected both teen and adult participants, and that the biological specimens would be tested for drugs.

CONCLUSIONS

These findings confirm prior reports of adult under-reporting of their own drug use while extending our understanding of teen's self-admitted drug use. The lack of concordance between teen self- or parent-reported teen drug use and biomarkers confirm our concerns that both teen- and parent-reported teen drug use is limited, at least for youth in high-risk urban settings. Methods of ascertainment other than self- or parent-report must be considered when health care providers, researchers and public health agencies attempt to estimate teen drug-use prevalence.

Effects of experimental Unemployment, Employment and Punishment analogs on opioid seeking and consumption in heroin-dependent volunteers

This study investigated the extent to which hydromorphone (HYD) choice and behavioral economic demand differed during experimental analogs of Unemployment (Drug Only: HYD and no money alternative), Employment (Drug or Money: HYD and $4 alternative), and Punishment (Drug Only+Money Loss: HYD only and $4 subtracted for each HYD choice), in the context of anticipated high vs. low post-session drug availability (HYD 24 mg vs. placebo). Eleven heroin-dependent, buprenorphine-stabilized (8 mg/day) volunteers first sampled two HYD doses (0 and 24 mg IM in randomized, counterbalanced order, labeled Drug A [session 1] and Drug B [session 2]). In each of the final six sessions, volunteers were given access to a 12-trial choice progressive ratio (PR) task and could work to receive HYD unit doses (2mg each); cumulative dose units earned were administered in a bolus injection after the work session. Before the PR task, volunteers were told which HYD dose (Drug A or B) would be available 3h after the PR-contingent injection. Relative to Unemployment (Drug Only), Employment (Drug or Money) and Punishment (Drug Only+Money Loss) each significantly suppressed HYD seeking (e.g., breakpoints). Employment and Punishment also reduced HYD behavioral economic demand, but via different mechanisms: Employment increased HYD price-elasticity, whereas Punishment decreased HYD demand intensity. Adjusting for the initial level difference (i.e., normalized demand), Employment significantly decreased P(max) (i.e., lower "essential value" of HYD) and O(max) (maximum HYD responding) compared to Punishment or Unemployment. These effects were not significantly altered by post-session drug availability.

Prenatal and postnatal cocaine exposure predict teen cocaine use

Preclinical studies have identified alterations in cocaine and alcohol self-administration and behavioral responses to pharmacological challenges in adolescent offspring following prenatal exposure. To date, no published human studies have evaluated the relation between prenatal cocaine exposure and postnatal adolescent cocaine use. Human studies of prenatal cocaine-exposed children have also noted an increase in behaviors previously associated with substance use/abuse in teens and young adults, specifically childhood and teen externalizing behaviors, impulsivity, and attention problems. Despite these findings, human research has not addressed prior prenatal exposure as a potential predictor of teen drug use behavior. The purpose of this study was to evaluate the relations between prenatal cocaine exposure and teen cocaine use in a prospective longitudinal cohort (n=316) that permitted extensive control for child, parent and community risk factors. Logistic regression analyses and Structural Equation Modeling revealed that both prenatal exposure and postnatal parent/caregiver cocaine use were uniquely related to teen use of cocaine at age 14 years. Teen cocaine use was also directly predicted by teen community violence exposure and caregiver negativity, and was indirectly related to teen community drug exposure. These data provide further evidence of the importance of prenatal exposure, family and community factors in the intergenerational transmission of teen/young adult substance abuse/use.