Melatonin for migraine prevention in children and adolescents: A randomized, double-blind, placebo-controlled trial after single-blind placebo lead-in.

BACKGROUND: Melatonin is effective for migraine prevention in adults. We hypothesized that melatonin would also be effective for migraine prevention in children and adolescents. METHODS: This was a randomized, double-blind trial of melatonin (3 mg or 6 mg) versus placebo for migraine prevention in 10-17 year-olds with 4-28/28 headache days at baseline. Participants were recruited from the UCSF Child & Adolescent Headache Program, UCSF child neurology clinic, and social media advertisements. Migraine diagnosis was confirmed by a headache specialist. Participants completed an 8-week single-blind placebo run-in. Those meeting randomization criteria (≥4 headache days and ≥23/28 electronic diary entries during weeks 5-8) were randomized 1:1:1 to placebo:melatonin 3 mg:melatonin 6 mg nightly for 8 weeks. The primary outcome measure was migraine days in weeks 5-8 of randomized treatment between melatonin (combined 6 mg + 3 mg) versus placebo. We aimed to enroll n = 210. RESULTS: The study closed early due to slow enrollment (n = 72). Two participants were in the single-blind phase when the study closed, therefore the meaningful n = 70. Sixteen percent (11/70) were lost to follow-up during the single-blind phase. An additional 21% (15/70) did not meet randomization criteria (<4 headache days: n = 5, <23/28 diary days: n = 7, both: n = 3). Sixty-three percent (44/70) were eligible to randomize, of whom 42 randomized (n = 14 per arm). Taking another preventive at enrollment (OR 8.3, 95% CI 1.01 to 68.9) was the only variable associated with meeting randomization criteria. Of those randomized, 91% (38/42) provided diary data in the final 4-weeks. However, given the amount of missing data, only those with ≥21/28 diary days were analyzed-7/14 (50%) in the placebo group, and 20/28 (71%) in the melatonin groups combined. Median (IQR) migraine/migrainous days in weeks 5-8 of double-blind treatment was 2 (1-7) in the placebo group versus 2 (1-12) in the melatonin groups combined; the difference in medians (95% CI for the difference) was 0 days (-9 to 3). There were no differences in adverse events between groups. CONCLUSIONS: When compared to recall at enrollment, headache days decreased across the single-blind placebo phase and the double-blind phase. There was no suggestion of superiority of melatonin; however, given the substantial portion of missing data, numerically higher in the placebo arm, and underpowering, this should not be interpreted as proof of inefficacy. Melatonin was generally well tolerated with no serious adverse events. Future migraine preventive trials in this age group may find this trial helpful for anticipating enrollment needs if using a single-blind placebo run-in. Enriching for those already on a migraine preventive may improve randomization rates in future trials, though would change the generalizability of results.

Headache in the Pediatric Population: Focus on Migraine.

Pediatric headache is a common condition with significant impact on quality of life and ability to function in academic, social, and extracurricular activities. Most pediatric patients seen in primary care and neurology clinics with headache have primary headache disorders. Diagnosis is largely based on clinical history. Imaging is rarely needed in the absence of red flag features. Careful diagnosis is important to guide appropriate treatment. Treatment focuses on a biopsychosocial model integrating lifestyle, pharmacologic and nonpharmacologic treatment modalities. As few therapies are approved in the pediatric population, treatments are often used off-label based on evidence extrapolated from adult studies. Outcomes vary over time but are generally favorable when headache disorders are diagnosed promptly and managed in a multidisciplinary setting.

Outcomes That Matter to Adolescents With Continuous Headache Due to Chronic Migraine and Their Parents: A Pilot Survey Study.

BACKGROUND AND OBJECTIVES: Children and adolescents with chronic migraine who have continuous headache may have high levels of headache-related disability but have largely been excluded from clinical trials. Understanding patient-valued treatment outcomes may facilitate future study design. The aim of this work was to identify patient-valued outcome measures for headache preventive treatments among adolescents with continuous headache due to chronic migraine and their parents. METHODS: Adolescents with an International Classification of Headache Disorders, 3rd edition diagnosis of chronic migraine, who had continuous headache and who were being cared for at a tertiary pediatric headache clinic, and their parents were surveyed to query the value of treatment outcomes in the domains of headache frequency, intensity, functional impact, and associated symptoms. Individual outcomes and categories of outcomes were ranked in order of preference using weighted average rank. Results were rounded to the degree of precision with which they were measured. RESULTS: The survey was completed by 55 adolescents and 60 parents of adolescents with continuous headache due to chronic migraine. Mean age of adolescents was 16 (SD 1, range 12-17) years. Median adolescent-reported duration of continuous headache was 24 (interquartile range [IQR] 12-39) months, and adolescents had tried a median of 2 (IQR 0-5) preventive medications, only 13% of which were perceived as helpful. Overall, the most valued individual outcome measure among both adolescents and parents was a decrease in frequency of more severe headaches; however, outcomes reflecting headache intensity were most valued by adolescents, while outcomes reflecting functional impact were most valued by parents. More than 60% of adolescents felt that it was more important to measure decrease in frequency and intensity of headaches in terms of severe headaches/spikes rather than total headache days. Among associated symptoms, improvement in brain fog was most highly valued by both adolescents and parents. DISCUSSION: The results of this study provide important information about which preventive treatment outcomes are valued by adolescents with continuous headache due to chronic migraine and their parents. Results suggest that adolescents value a decrease in frequency of severe headaches over a decrease in frequency of headache days overall. Generalizability may be limited because the surveyed population was being cared for at a tertiary pediatric headache clinic and generally had headache disorders that were refractory to treatment. These results may help guide future trial design in this population with continuous headache due to chronic migraine.

Acute and chronic management of posttraumatic headache in children: A systematic review.

OBJECTIVES: The goal of this paper is to provide a compilation of the evidence for the treatment of posttraumatic headache (PTH) in the pediatric population. Headache features and timing of therapy were considered. BACKGROUND: Headache is the most common symptom following mild traumatic brain injury (mTBI), affecting more than 80% of children and adolescents. It is unclear whether treatment for PTH should be tailored based on headache characteristics, particularly the presence of migraine features, and/or chronicity of the headache. METHODS: Systematic literature searches of PubMed, Embase, Scopus, and Cochrane databases (1985-2021, limited to English) were performed, and key characteristics of included studies were entered into RedCAP® (Prospero ID CRD42020198703). Articles and conference abstracts that described randomized controlled trials (RCTs), cohort studies, retrospective analyses, and case series were included. Participants included youth under 18 years of age with acute (<3 months) and persistent (≥3 months) PTH. Studies that commented on headache improvement in response to therapy were included. RESULTS: Twenty-seven unique studies met criteria for inclusion describing abortive pharmacologic therapies (9), preventative pharmacotherapies (5), neuromodulation (1), procedures (5), physical therapy and exercise (6), and behavioral therapy (2). Five RCTs were identified. Studies that focused on abortive pharmacotherapies were completed in the first 2 weeks post-mTBI, whereas other treatment modalities focused on outcomes 1 month to over 1-year post-injury. Few studies reported on migrainous features (7), personal history of migraine (7), or family history of migraine (3). CONCLUSIONS: There is limited evidence on the timing and types of therapies that are effective for treating PTH in the pediatric population. Prospective studies that account for headache characteristics and thoughtfully address the timing of therapies and outcome measurement are needed.

Benign paroxysmal torticollis: phenotype, natural history, and quality of life.

BACKGROUND: Benign paroxysmal torticollis (BPT) is characterized by attacks of head tilt associated with vomiting, irritability, and/or ataxia in early childhood. BPT is associated with migraine but risk factors are unknown. Impact on quality of life is also unknown. METHODS: Parents/caregivers of children with ongoing or resolved BPT participated in telephone interviews (n = 73). Those with ongoing BPT completed the Infant Toddler Quality of Life questionnaire (ITQoL). RESULTS: Median age of children at the time of interview was 2.9 years (range 0.25-23). BPT was ongoing in 52% (n = 38). Nineteen percent (n = 14) developed migraine (median age 9.25 years, range 2.5-23) and 63% (n = 46) developed another episodic syndrome associated with migraine. Proportion of patients who developed migraine was higher among those with certain migrainous symptoms during BPT attacks vs. those without: phonophobia (58 vs. 21%, p = 0.02), photophobia and phonophobia (55 vs. 23%, p = 0.05), and photophobia, phonophobia, and motion sensitivity (60 vs. 22%, p = 0.02). ITQoL results showed significant impact of BPT on quality of life. CONCLUSIONS: Children with BPT may develop migraine or other episodic syndromes associated with migraine. Presence of migrainous features during BPT episodes may increase likelihood of developing migraine. Though characterized as "benign," BPT can significantly impact children and families. IMPACT: Benign paroxysmal torticollis (BPT) is a rare condition of early childhood characterized by episodes of head tilt associated with vomiting, irritability, ataxia, pallor, and/or malaise. This cohort study describes the phenotypic spectrum of BPT, variable treatment, natural history and association with migraine, and impact on development and quality of life. Children with BPT may go on to develop migraine or episodic syndromes that may be associated with migraine; presence of migrainous features during attacks may increase odds of developing migraine. BPT can have significant impact on quality of life, demonstrated by findings from the Infant Toddler Quality of Life questionnaire.

Calcitonin Gene-Related Peptide Monoclonal Antibody Use for the Preventive Treatment of Refractory Headache Disorders in Adolescents.

BACKGROUND: Monoclonal antibodies to calcitonin gene-related peptide or its receptor have clinical trial evidence in adults with headache, but data are lacking in adolescents. The objective of this study was to describe the safety and efficacy of calcitonin gene-related peptide monoclonal antibody treatment in adolescents with chronic headache disorders. METHODS: We performed a retrospective multisite cohort study of patients less than 18 years of age who received a calcitonin gene-related peptide monoclonal antibody for headache prevention. Demographics, baseline headache characteristics, efficacy, and side effect data were collected. RESULTS: The study population comprised 112 adolescents who received at least one dose of a calcitonin gene-related peptide monoclonal antibody. Mean (S.D.; range) age at first dose was 15.9 years (1.4; 10.3 to 17.8). Ninety-four patients (83.9%) had chronic migraine, 12 (10.7%) had new daily persistent headache, and six (5.4%) had persistent post-traumatic headache. At baseline, the mean (S.D.) number of headache days per month was 26.9 (6.1) (n = 109) and headache was continuous in 75 of 111 (67.6%). At first follow-up visit there was a significant reduction in headache frequency compared with baseline (-2.0 days; 95% confidence interval, -0.8 to -3.2). Significant benefit was perceived by 29.5% of patients at first follow-up visit (n = 33/112) and 30.1% (n = 22/73) at second follow-up visit. A significant functional improvement was perceived by 31% of patients (n = 31/94) at the first follow-up visit and 22.4% (n = 15/67) at the second follow-up visit. The most common side effects were injection site reactions in 17.0% (n = 19) and constipation in 8.0% (n = 9). Five patients (4.5%) discontinued because of side effects. CONCLUSIONS: Side effects with calcitonin gene-related peptide monoclonal antibody treatment in adolescents were similar to those reported in adult trials. Calcitonin gene-related peptide monoclonal antibody treatment appears to benefit a proportion of adolescents with chronic refractory headache disorders.

Melatonin for Acute Treatment of Migraine in Children and Adolescents: A Pilot Randomized Trial.

OBJECTIVE: To determine what dose of melatonin is most effective for treating migraine acutely in children and adolescents. BACKGROUND: Acute migraine medications may not work for all patients and may cause side effects. Melatonin is effective for migraine prevention in adults and has been used acutely for procedural pain in children. Our goal was to determine whether a "high" or "low" dose of melatonin is more effective for treating migraine acutely in youth. METHODS: In this pilot, randomized, open-label, single-center, dose-finding trial, children and adolescents aged 4-17 years with episodic migraine were randomized to "high-dose" or "low-dose" dose melatonin (<40 kg: 4 mg vs. 1 mg; ≥40 kg: 8 mg vs. 2 mg). The primary outcome measure was change in mean pain score between time 0 and 2 hours. Secondary outcomes included 2-hour pain-relief and pain-freedom rates. RESULTS: Eighty-four participants (n = 42 per group) were enrolled in this study. Mean (SD) participant age was 11.8 (3.5) years and 55% (46/84) were female. Mean (SD) headache days/month was 5.6 (3.8). Sixty-six (79%) participants provided outcome data and were included in the analyses, n = 24 in the high-dose group and n = 22 in the low-dose group. The drop-out rate was 43% (18/42) in the high-dose group vs. 48% (20/42) in the low-dose group. Mean (SD) change in pain intensity at 2 hours was -2.7 (2.1) cm in the high-dose group vs. -2.3 (2.1) cm in the low-dose group (p = .581), a difference of 0.4 cm (95% CI: -1.17 to 1.92). Two-hour pain-freedom rate was 41% (7/17) vs. 27% (4/15) in the high-dose vs. low-dose groups (p = .415), and 2-hour pain-relief rate was 94% (16/17) vs. 80% (12/15), (p = .482). There were no serious adverse events. Napping occurred in the majority (67% (14/21) high dose vs. 47% (9/19) low dose). Higher mg/kg dose of melatonin and napping were each independently associated with greater headache benefit. CONCLUSIONS: As an acute treatment for pediatric migraine, both low and high doses of melatonin were associated with pain reduction; however, study drop-out was high. Higher dose and napping after treatment predicted greater benefit.

Pediatric Migraine: An Update.

This article outlines key features of diagnosis and treatment of migraine in children and adolescents. It emphasizes techniques that can be used by clinicians to optimize history taking in this population, as well as recognition of episodic conditions that may be associated with migraine and present in childhood. Acute treatment strategies include use of over-the-counter analgesics and triptan medications that have been approved by the US Food and Drug Administration for use in children and adolescents. Preventive treatment approach includes lifestyle modifications, behavioral strategies, and consideration of preventive medications with the lowest side effect profiles.

High School Start Time and Migraine Frequency in High School Students.

OBJECTIVE: To investigate whether later high school start time is associated with lower migraine frequency in high school students with migraine. BACKGROUND: Adequate sleep is thought to be important in managing adolescent migraine. The American Academy of Sleep Medicine recommends teenagers sleep ≥8 hours/night. Adolescents have a physiologically delayed sleep phase, going to bed, and waking later than children and adults. The American Academy of Pediatrics (AAP) accordingly recommends high schools start no earlier than 8:30 AM. METHODS: Cross-sectional observational study of U.S. high schoolers with migraine. Participants were recruited nationally using social media. Respondents attending high schools starting at 8:30 AM or later were compared to those attending earlier start time schools. The primary outcome was headache days/month. RESULTS: Two hundred and fifty-six subjects constituted the analysis set: 115 later group vs 141 earlier group. Age and sex did not differ. Mean (SD) self-reported headache days/month were 7 (5) vs 8 (7), respectively, (P = .985); mean difference (95% CI for the difference) was -0.8 (-2.3-0.7) days. Median (IQR) self-reported total hours of sleep/school night were: 5.6 (5.0-6.6) vs 5.6 (4.5-6.4), P = .058. Students attending later start time schools woke later (median [IQR] 6:38 AM [55 minutes] vs 6:09 AM [59 minutes], P < .0001) and left home later (median [IQR] 7:28 AM [28 minutes] vs 7:02 AM [60 minutes], P < .0001). Average commute time was also longer: 41 (21) minutes vs 28 (16), P < .0001. The vast majority in both groups reported missing breakfast at least once/week: 103/114 (90.4%) vs 128/141 (90.8%), P = .907. Hours of sleep did not correlate with headache days per month. CONCLUSION: High school start time does not have a large effect on headache frequency in high schoolers with migraine. Given the high variance in headache days/month observed in this study, a larger study would be needed to determine whether there might still be a small effect of starting high school at/after 8:30 AM. More research is needed to establish evidence-based recommendations about lifestyle factors in adolescent migraine management.

Natural history of pain associated with melanoma surgery.

INTRODUCTION: After excision of a primary malignant melanoma (MM), treatment of stage IB or higher MM consists of sentinel lymph node biopsy (SLNB). If malignant cells are identified, a complete lymph node dissection (CLND) can be performed. OBJECTIVE: To determine the natural history of pain and sensory changes after MM surgery. METHODS: We prospectively followed 39 patients (29 SLNB-only, 2 CLND-only, and 8 CLND preceded by SLNB) from before inguinal or axillary surgery through 6 months after surgery on measures of pain intensity, sensory symptoms, allodynia, and questionnaires of anxiety, depression, and catastrophizing. RESULTS: No patient had pain preoperatively. Ten days after surgery, 35% had surgical site pain after SLNB-only compared with 90% after CLND (P < 0.003); clinically meaningful pain (Visual Analogue Scale ≥ 30 mm/100 mm) was reported by 3% of patients after SLNB-only compared with 40% after CLND (P < 0.001). At 6 months, all SLNB-only patients were pain-free. By contrast, 4 of 7 in the SLNB + CLND group still had pain (P < 0.002). At 6 months, symptoms of altered sensation or numbness were reported by 32% and 42% of SLNB-only patients, and by 67% and 67% of patients undergoing CLND surgery (both P > 0.05). CONCLUSION: Acute pain is more common after CLND surgery. Undergoing SLNB followed by more invasive CLND surgery may increase the likelihood of pain at 6 months. Persistent sensory symptoms typical of those associated with nerve injury are more common after CLND. Surgery for MM is a good model for studying the natural history of postsurgical pain and sensory changes.

RReACT goes global: perils and pitfalls of constructing a global open-access database of registered analgesic clinical trials and trial results.

Eliminating publication bias requires ensuring public awareness of studies and access to results. Clinical trial registries provide basic trial information, but access to unbiased trial results is inadequate. Nearly all studies of trial registration and results reporting have been limited to the ClinicalTrials.gov registry. We analyzed trial registration, registry functionality, cross-registry harmonization, and results reporting on all 15 primary registries in the World Health Organization International Clinical Trials Registry Platform (ICTRP) for postherpetic neuralgia, painful diabetic neuropathy, and fibromyalgia. A total of 447 unique trials were identified, with 86 trials listed on more than one registry. A comprehensive search algorithm was used to find trial results in the peer-reviewed literature and the grey literature. Creating a global database of registered trials and trial results proved surprisingly difficult for several reasons: (1) ICTRP does not reliably identify trials listed on multiple registries, manual searches are necessary; (2) Searching ICTRP yields different results than searching individual registries; (3) Outcome measure descriptions for multiply registered trials vary between registries; (4) Registry-publication pairings are often inaccurate or incomplete; (5) Grey literature results are not permanent. Overall, only 46% of all trials had results available. Trials registered on ClinicalTrials.gov were significantly more likely to have results (52% vs. 18%, P<0.001), partly due to the ability to post results directly to the registry. In addition to the simple remedy of including trial registration numbers on all meeting abstracts and peer-reviewed papers, specific strategies are offered to facilitate identifying multiply registered studies and ensuring accurate pairing of results and publications.

Persistent postoperative pain and sensory changes following lymph node excision in melanoma patients: a topical review.

Studies on complications related to chronic nerve injury following sentinel lymph node biopsy (SLNB) and complete lymph node dissection (CLND) for melanoma are sparse. This review summarizes the existing literature on pain and neuropathic complications in melanoma patients undergoing SLNB with or without CLND. The Cochrane Central Register of Controlled Trials and the Embase and PubMed databases were searched. Full-text English language articles published before June 2013 were included. Prospective and retrospective studies assessing persistent (>1 month) sensory nerve injury, postoperative pain, neuropathic pain, and sensory disturbances following SLNB with or without CLND in melanoma patients were eligible. Nine studies (six prospective and three retrospective) including data for 3632 patients met our inclusion criteria. Outcome parameters were too heterogeneous to conduct a quantitative analysis, and few studies systematically evaluated pain and sensory abnormalities. Persistent postoperative pain was reported in 1-14% of patients following SLNB and in 6-34% following CLND and sensory abnormalities in 0.1-32 and 2-82%, respectively. In the one study that assessed the type of pain, neuropathic pain was suggested to explain persistent pain in 31-66% of patients with SLNB and 82-89% of patients with CLND. Sensory-nerve-related complications in melanoma patients seem to be less pronounced following SLNB compared with CLND. Prospective observational studies are necessary to identify predictors of persistent pain, to evaluate the prevalence and impact of pain and sensory abnormalities, and to develop strategies for prevention of long-term complications.

Discrepancies between registered and published primary outcome specifications in analgesic trials: ACTTION systematic review and recommendations.

The National Institutes of Health released the trial registry ClinicalTrials.gov in 2000 to increase public reporting and clinical trial transparency. This systematic review examined whether registered primary outcome specifications (POS; ie, definitions, timing, and analytic plans) in analgesic treatment trials correspond with published POS. Trials with accompanying publications (n = 87) were selected from the Repository of Registered Analgesic Clinical Trials (RReACT) database of all postherpetic neuralgia, diabetic peripheral neuropathy, and fibromyalgia clinical trials registered at ClinicalTrials.gov as of December 1, 2011. POS never matched precisely; discrepancies occurred in 79% of the registry-publication pairs (21% failed to register or publish primary outcomes [PO]). These percentages did not differ significantly between industry and non-industry-sponsored trials. Thirty percent of the trials contained unambiguous POS discrepancies (eg, omitting a registered PO from the publication, "demoting" a registered PO to a published secondary outcome), with a statistically significantly higher percentage of non-industry-sponsored than industry-sponsored trials containing unambiguous POS discrepancies. POS discrepancies due to ambiguous reporting included vaguely worded PO registration; or failing to report the timing of PO assessment, statistical analysis used for the PO, or method to address missing PO data. At best, POS discrepancies may be attributable to insufficient registry requirements, carelessness (eg, failing to report PO assessment timing), or difficulty uploading registry information. At worst, discrepancies could indicate investigator impropriety (eg, registering imprecise PO ["pain"], then publishing whichever pain assessment produced statistically significant results). Improvements in PO registration, as well as journal policies requiring consistency between registered and published PO descriptions, are needed.

Natural history of herpes zoster: late follow-up of 3.9 years (n=43) and 7.7 years (n=10).

Postherpetic neuralgia (PHN) is a common complication after herpes zoster (HZ). Subjects who completed a longitudinal observational 6-month study (4 visits) of the natural history of HZ were recontacted for 2 additional follow-up visits that included pain and sensory symptom assessment, quantitative sensory testing, capsaicin response test, and 3-mm punch skin biopsies in HZ-affected, mirror-image, and control skin sites. Forty-three subjects (14 with PHN at 6 months) of the original 94 subjects in the cohort were comprehensively assessed at a median 3.9 years after HZ onset (visit 5), and 10 subjects underwent a final assessment at a median 7.7 years after HZ onset (visit 6). At 3.9 years, none of the 29 subjects who had been pain free at 6 months had a recurrence of pain. Only 2 of the 14 subjects with PHN at 6 months still had pain at 3.9 years. One subject with PHN at 6 months was free of symptoms at 3.9 years but had very mild pain at 7.7 years. Sensory function continued on a path toward normalization, but was still abnormal in many subjects, especially those who met criteria for PHN at 6 months. Even at 7.7 years, reinnervation of HZ-affected skin was not apparent.

Interactive informed consent: randomized comparison with paper consents.

Informed consent is the cornerstone of human research subject protection. Many subjects sign consent documents without understanding the study purpose, procedures, risks, benefits, and their rights. Proof of comprehension is not required and rarely obtained. Understanding might improve by using an interactive system with multiple options for hearing, viewing and reading about the study and the consent form at the subject's own pace with testing and immediate feedback. This prospective randomized study compared the IRB-approved paper ICF for an actual clinical research study with an interactive presentation of the same study and its associated consent form using an iPad device in two populations: clinical research professionals, and patients drawn from a variety of outpatient practice settings. Of the 90 participants, 69 completed the online test and survey questions the day after the session (maximum 36 hours post-session). Among research professionals (n = 14), there was a trend (p = .07) in the direction of iPad subjects testing better on the online test (mean correct  =  77%) compared with paper subjects (mean correct = 57%). Among patients (n = 55), iPad subjects had significantly higher test scores than standard paper consent subjects (mean correct = 75% vs 58%, p < .001). For all subjects, the total time spent reviewing the paper consent was 13.2 minutes, significantly less than the average of 22.7 minutes total on the three components to be reviewed using the iPad (introductory video, consent form, interactive quiz). Overall satisfaction and overall enjoyment slightly favored the interactive iPad presentation. This study demonstrates that combining an introductory video, standard consent language, and an interactive quiz on a tablet-based system improves comprehension of research study procedures and risks.

Lower level of endogenous dopamine in patients with cocaine dependence: findings from PET imaging of D(2)/D(3) receptors following acute dopamine depletion.

OBJECTIVE: Previous positron emission tomography (PET) imaging studies have demonstrated that cocaine dependence is associated with a decrease in dopamine type 2 and 3 (D(2)/D(3)) receptor binding in cocaine-dependent individuals relative to healthy comparison subjects. However, given the nature of PET imaging, it is possible that the measured decrease in radiotracer binding results from an increase in baseline dopamine levels. The purpose of this study was to measure D(2)/D(3) receptors following acute dopamine depletion in cocaine-dependent volunteers relative to healthy comparison subjects. METHOD: Cocaine-dependent volunteers (N=15) and healthy matched comparison subjects (N=15) were scanned using PET, with the dopamine receptor radiotracer [(11)C]raclopride, at baseline and again following acute depletion of endogenous dopamine via alpha-methyl-para-tyrosine (AMPT) administration. Changes in radiotracer binding were measured in the subdivisions of the striatum (caudate, putamen, and ventral striatum) in addition to the striatum as a whole. RESULTS: Findings revealed that cocaine-dependent volunteers exhibited lower levels of endogenous dopamine relative to comparison subjects, which was measured as an increase in [(11)C]raclopride binding following AMPT administration. The increase in [(11)C]raclopride binding in the striatum was 11.1% (SD=4.4%) in healthy comparison subjects and 5.7% (SD=5.9%) in cocaine-dependent volunteers. Similar differences were seen in the subdivisions of the striatum. CONCLUSIONS: The decrease in striatal D(2)/D(3 )receptors associated with cocaine dependence cannot be attributed to higher levels of endogenous dopamine.