Ketamine induces multiple individually distinct whole-brain functional connectivity signatures

Background

Ketamine has emerged as one of the most promising therapies for treatment-resistant depression. However, inter-individual variability in response to ketamine is still not well understood and it is unclear how ketamine's molecular mechanisms connect to its neural and behavioral effects.

Methods

We conducted a single-blind placebo-controlled study, with participants blinded to their treatment condition. 40 healthy participants received acute ketamine (initial bolus 0.23 mg/kg, continuous infusion 0.58 mg/kg/hr). We quantified resting-state functional connectivity via data-driven global brain connectivity and related it to individual ketamine-induced symptom variation and cortical gene expression targets.

Results

We found that: (i) both the neural and behavioral effects of acute ketamine are multi-dimensional, reflecting robust inter-individual variability; (ii) ketamine's data-driven principal neural gradient effect matched somatostatin (SST) and parvalbumin (PVALB) cortical gene expression patterns in humans, while the mean effect did not; and (iii) behavioral data-driven individual symptom variation mapped onto distinct neural gradients of ketamine, which were resolvable at the single-subject level.

Conclusions

These results highlight the importance of considering individual behavioral and neural variation in response to ketamine. They also have implications for the development of individually precise pharmacological biomarkers for treatment selection in psychiatry.

Funding

This study was supported by NIH grants DP5OD012109-01 (A.A.), 1U01MH121766 (A.A.), R01MH112746 (J.D.M.), 5R01MH112189 (A.A.), 5R01MH108590 (A.A.), NIAAA grant 2P50AA012870-11 (A.A.); NSF NeuroNex grant 2015276 (J.D.M.); Brain and Behavior Research Foundation Young Investigator Award (A.A.); SFARI Pilot Award (J.D.M., A.A.); Heffter Research Institute (Grant No. 1-190420) (FXV, KHP); Swiss Neuromatrix Foundation (Grant No. 2016-0111) (FXV, KHP); Swiss National Science Foundation under the framework of Neuron Cofund (Grant No. 01EW1908) (KHP); Usona Institute (2015 - 2056) (FXV).

Clinical trial number

NCT03842800.

Brain glutamate and sleep efficiency associations following a ketogenic diet intervention in individuals with Alcohol Use Disorder

Background

We previously showed that ketogenic diet (KD) was effective in curbing alcohol withdrawal and craving in individuals with alcohol use disorder (AUD). We hypothesized that the clinical benefits were due to improvements in sleep. To test this, we performed a secondary analysis on the KD trial data to (1) examine the effects of KD on total sleep time (TST) and sleep quality and (2) investigate the association between KD-induced alterations in cingulate glutamate concentration and changes in TST and sleep quality.

Methods

AUD individuals undergoing alcohol detoxification were randomized to receive KD (n=19) or standard American diet (SA; n=14) for three weeks. TST was measured weekly by self-report, GENEActive sleep accelerometer, and X4 Sleep Profiler ambulatory device. Sleep quality was assessed using subjectively ratings of sleep depth and restedness and Sleep Profiler (Sleep Efficiency [%]). Weekly ¹H magnetic resonance spectroscopy scans measured cingulate glutamate levels.

Results

TST was lower in KD than SA and increased with effect of time. Sleep depth, restedness, and Sleep Efficiency improved with time, but exhibited no effect of diet. In KD and SA combined, week 1 cingulate glutamate levels correlated positively with Sleep Efficiency, but not with TST.

Conclusions

Although cingulate glutamate levels correlated positively with Sleep Efficiency in week 1, KD-induced glutamate elevation did not produce significant sleep improvements. Rather, KD was associated with lower TST than SA. Given the well-established associations between sleep and alcohol relapse, longer follow up assessment of KD's impact on sleep in AUD is warranted.

Randomized controlled trial testing the effectiveness of adaptive "SMART" stepped-care treatment for adults with binge-eating disorder comorbid with obesity

This randomized controlled trial (RCT) tested effectiveness of adaptive SMART stepped-care treatment to "standard" behavioral weight loss (BWL [standard]) for patients with binge-eating disorder (BED) and obesity. One hundred ninety-one patients were randomly assigned to 6 months of BWL (standard; n = 39) or stepped care (n = 152). Within stepped care, patients started with BWL for 1 month; treatment responders continued BWL, whereas nonresponders switched to cognitive-behavioral therapy (CBT), and patients receiving stepped care were additionally randomized to weight-loss medication or placebo (double-blind) for the remaining 5 months. Independent assessments were performed reliably at baseline, throughout treatment, and posttreatment. Intent-to-treat (ITT) analyses of remission rates (zero binges/month) revealed that BWL (standard) and stepped care did not differ (74.4% vs. 66.5%); within stepped care, remission rates ranged 40.0% to 83.3%, with medication significantly superior to placebo (overall) and among nonresponders switched to CBT. Mixed-models analyses of binge-eating frequency revealed significant time effects, but BWL (standard) and stepped care did not differ; within stepped care, medication was significantly superior to placebo and among nonresponders switched to CBT. Mixed models revealed significant weight loss, but BWL (standard; 5.1% weight-loss) and stepped care (5.8% weight-loss) did not differ; within stepped care (range = 0.4% to 8.8% weight-loss), medication was significantly superior to placebo and among both responders continued on BWL and nonresponders switched to CBT. In summary, BWL (standard) and adaptive stepped-care treatments produced robust improvements in binge eating and weight loss in patients with BED/obesity. Within adaptive stepped care, weight-loss medication enhanced outcomes for BED/obesity. Implications for clinical practice and future adaptive designs are offered. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

A robust and reproducible connectome fingerprint of ketamine is highly associated with the connectomic signature of antidepressants

Over the past decade, various N-methyl-D-aspartate modulators have failed in clinical trials, underscoring the challenges of developing novel rapid-acting antidepressants based solely on the receptor or regional targets of ketamine. Thus, identifying the effect of ketamine on the brain circuitry and networks is becoming increasingly critical. In this longitudinal functional magnetic resonance imaging study of data from 265 participants, we used a validated predictive model approach that allows the full assessment of brain functional connectivity, without the need for seed selection or connectivity summaries. First, we identified a connectome fingerprint (CFP) in healthy participants (Cohort A, n = 25) during intravenous infusion of a subanesthetic dose of ketamine, compared to normal saline. We then demonstrated the robustness and reproducibility of the discovered ketamine CFP in two separate healthy samples (Cohort B, n = 22; Cohort C, n = 18). Finally, we investigated the ketamine CFP connectivity at 1-week post treatment in major depressive disorder patients randomized to 8 weeks of sertraline or placebo (Cohort D, n = 200). We found a significant, robust, and reproducible ketamine CFP, consistent with reduced connectivity within the primary cortices and within the executive network, but increased connectivity between the executive network and the rest of the brain. Compared to placebo, the ketamine CFP connectivity changes at 1 week predicted response to sertraline at 8 weeks. In each of Cohorts A-C, ketamine significantly increased connectivity in a previously identified antidepressant CFP. Investigating the brain connectivity networks, we successfully identified a robust and reproducible ketamine biomarker that is related to the mechanisms of antidepressants.

Naltrexone + Bupropion Combination for the Treatment of Binge-eating Disorder with Obesity: A Randomized, Controlled Pilot Study

PURPOSE

Binge-eating disorder (BED), the most prevalent eating disorder, is associated strongly with obesity and functional impairments. Few evidence-based treatments for BED exist; a pharmacotherapy effective in reducing both binge eating and weight needs to be identified. This placebo-controlled double-blind pilot RCT evaluated the acute effects of naltrexone + bupropion (NB) on BED with obesity and examined the longer-term effects through 6-month follow-up after the discontinuation of medication.

METHODS

Twenty-two adult patients with BED were randomized to receive 12 weeks of double-blind treatment with fixed-dose NB (naltrexone + bupropion XL 50/300 mg) or placebo. Independent (blinded) researcher-clinicians evaluated patients at major outcome time points (baseline, posttreatment, and 6-month follow-up after the treatment period); patients were also evaluated for the tracking of course/tolerability throughout treatments and at 3-month follow-up. Primary outcomes were changes from baseline in binge-eating frequency and percentage weight. Secondary outcomes were changes in eating-disorder psychopathology and depression.

FINDINGS

A total of 22 patients were enrolled (86.4% women; mean age, 50.4 years), with 77.3% of patients completing treatments; completion rates (NB, 83.3%; placebo, 70.0%) and adverse events did not differ significantly between NB and placebo. Analyses revealed significant reductions from baseline in binge-eating, eating-disorder psychopathology, depression, and weight during treatment, but these changes with NB did not differ significantly from those with placebo. The percentage of patients who attained 3% weight loss was significantly greater with NB than with placebo (45.5% vs 0%); weight-loss and binge-eating reductions were significantly correlated in the group that received NB. At 6-month follow-up, outcomes remained improved relative to baseline, with no significant differences between NB and placebo.

IMPLICATIONS

The findings from this pilot RCT suggest that NB was well-tolerated in these patients with BED and comorbid obesity. Most outcomes were not statistically different between NB and placebo. A larger-scale, adequately powered RCT is needed for determining the efficacy of NB in the treatment of BED. ClinicalTrials.gov identifier: NCT02317744.

The Barriers and Benefits to Developing Forensic Rotations for Psychiatry Residents

Psychiatry residents' experiences in forensic psychiatry vary greatly across the country, and many psychiatry programs meet the Accreditation Council for Graduate Medical Education requirements for a forensic experience through general psychiatry rotations (e.g., on a consult-liaison service) or classroom-based activities. Forensic clinical experiences during psychiatry residency are important for preparing future general psychiatrists for practice with justice-involved patients, generating interest in forensic psychiatry, and easing the transition from "healer to evaluator" for future fellows. Unfortunately, residency programs interested in expanding their forensic training may face many challenges because of current regulatory frameworks, the nature of forensic practice, and competing demands within residency training programs. This article describes these challenges, and the experience of the authors at one institution with developing a novel forensic experience in a criminal justice diversion setting. The authors conclude with some practical considerations for educators interested in developing forensic experiences at their institutions.

Sleep Perception and Misperception in Chronic Cocaine Users During Abstinence

Study Objectives

During abstinence, chronic cocaine users experience an objective worsening of sleep that is perceived as qualitatively improving. This phenomenon has been termed "occult insomnia." The objective of this study was to determine whether chronic cocaine users experience positive sleep state misperception during abstinence.

Methods

Forty-three cocaine-dependent persons were admitted to an inpatient research facility for 12 days and 11 nights to participate in a treatment study of modafinil. Polysomnographic sleep recordings were performed on study nights 3, 4, 10, and 11, when participants were on average 1 and 2 weeks abstinent from cocaine. Participants also completed sleep diary questionnaires every evening before bed and every morning upon awakening. Polysomnographic and sleep diary measurements of total sleep time, sleep latency, time awake after sleep onset, and time in bed after final awakening were compared.

Results

Chronic cocaine users accurately reported total sleep time after 1 week of abstinence but overreported total sleep time by an average of 40 min after 2 weeks of abstinence. Underestimating sleep latency and time spent awake after sleep onset were responsible for this difference.

Conclusions

Positive sleep state misperception is revealed in chronic cocaine users after 2 weeks of abstinence and is consistent with the previously identified "occult insomnia" in this population.

Schizophrenia is associated with a pattern of spatial working memory deficits consistent with cortical disinhibition

Schizophrenia is associated with severe cognitive deficits, including impaired working memory (WM). A neural mechanism that may contribute to WM impairment is the disruption in excitation-inhibition (E/I) balance in cortical microcircuits. It remains unknown, however, how these alterations map onto quantifiable behavioral deficits in patients. Based on predictions from a validated microcircuit model of spatial WM, we hypothesized two key behavioral consequences: i) increased variability of WM traces over time, reducing performance precision; and ii) decreased ability to filter out distractors that overlap with WM representations. To test model predictions, we studied N=27 schizophrenia patients and N=28 matched healthy comparison subjects (HCS) who performed a spatial WM task designed to test the computational model. Specifically, we manipulated delay duration and distractor distance presented during the delay. Subjects used a high-sensitivity joystick to indicate the remembered location, yielding a continuous response measure. Results largely followed model predictions, whereby patients exhibited increased variance and less WM precision as the delay period increased relative to HCS. Schizophrenia patients also exhibited increased WM distractibility, with reports biased toward distractors at specific spatial locations, as predicted by the model. Finally, the magnitude of the WM drift and distractibility were significantly correlated, indicating a possibly shared underlying mechanism. Effects are consistent with elevated E/I ratio in schizophrenia, establishing a framework for translating neural circuit computational model of cognition to human experiments, explicitly testing mechanistic behavioral hypotheses of cellular-level neural deficits in patients.

Computerized Cognitive Behavioral Therapy for Insomnia in a Community Health Setting

STUDY OBJECTIVES

Insomnia, though quite common in the general population, is especially prevalent among individuals with co-occurring mental illnesses, patients whose condition can be further exacerbated by insomnia and vice versa. For individuals taking one or more psychotropic medications, cognitive behavioral therapy for insomnia (CBT-I), the gold standard in insomnia treatment, is a particularly favorable option (vis-à-vis pharmacotherapy). However, CBT-I can be inaccessible for persons with low socioeconomic status, a group that includes many with psychiatric diagnoses. Computer-based delivery of CBT-I (cb-CBT-I) has the potential to be a cost-effective tool that could greatly improve accessibility for this at-risk demographic.

METHODS

Thirty-four participants with insomnia who were currently engaged in mental health care treatment were randomized to an active control group (sleep diary group; n = 16) or cb-CBT-I (n = 18) during weekly outpatient sessions over the course of 6 w. All participants completed sleep and activity logs at each appointment, whereas those in the cb-CBT-I group also completed one session of the cb-CBT-I program each week.

RESULTS

cb-CBT-I treatment was associated with lower scores (improved sleep) on the Pittsburgh Sleep Quality Index (PSQI). Post hoc tests demonstrated a between groups difference at week 6 (p = 0.02), with a statistically significant decrease in PSQI scores in the cb-CBT-I group (p = 0.0006) but not in the sleep diary group (p = 0.35).

CONCLUSIONS

cb-CBT-I improves sleep in individuals with insomnia and co-occurring mental illness. The significant improvements on the PSQI suggest that implementing a cb-CBT-I treatment in a community mental health center would be a simple and effective treatment for improving sleep over a short period of time.

COMMENTARY

A commentary on this article appears in this issue on page 161.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

Modafinil and sleep architecture in an inpatient-outpatient treatment study of cocaine dependence

OBJECTIVE

To determine whether the increase in slow-wave sleep associated with modafinil treatment in chronic cocaine users mediates improved clinical outcomes.

METHOD

57 cocaine dependent participants were randomized to receive modafinil 400mg or placebo daily during a period of inpatient treatment followed by six weeks of outpatient treatment. Participants underwent polysomnographic sleep recording during inpatient treatment prior to and after starting modafinil. Outpatient treatment consisted of weekly cognitive behavioral therapy. Contingency management was used to promote participation in treatment and research demands, including thrice weekly visits during the outpatient phase for urine toxicology screens and other assessments. The primary clinical outcome was the percent of urine toxicology screens that were negative for cocaine.

RESULTS

Modafinil treatment was associated with a higher mean percentage (52% vs. 26%) of cocaine-free urine screens (p=0.02) and an increase in N3 sleep time (p=0.002). The change in N3 sleep time mediated the higher rate of cocaine-free urine screens. Modafinil treatment was also associated with more consecutive days abstinent during outpatient treatment, greater survival of abstinence, higher daily rates of abstinence, and less sleep degradation typically associated with abstinence from chronic cocaine use.

CONCLUSIONS

Morning-dosed modafinil improves slow-wave sleep in abstinent cocaine users in the inpatient setting, and this effect is a statistical mediator of improved clinical outcomes associated with continued modafinil treatment. The high rates of abstinence achieved in this trial suggest that promoting healthy sleep physiology in an inpatient setting may be important in the effective treatment of cocaine dependence.

Association of Cigarette Smoking With Interpersonal and Self-Directed Violence in a Large Community-Based Sample

INTRODUCTION

Substance use is a major risk factor for various forms of violence, yet how cigarette smoking influences violence outcomes is incompletely understood. We investigated associations between cigarette smoking and three types of violence in a large, nationally representative, community-based sample.

METHODS

Adult subjects participating in both Wave 1 (2001-2002; N = 43 093) and Wave 2 (2004-2005; N = 34 653) of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC) were stratified by daily cigarette smoking status at Wave 1, and individuals with unchanged smoking status between waves were analyzed (nonsmokers [consisting of never and former daily smokers]: N = 22 529; daily smokers: N = 7442). We created composites of other- and self-directed violence and victimization occurring between Waves 1 and 2, and performed logistic regression models, controlling for psychiatric diagnoses, alcohol and substance use, and relevant demographic covariates.

RESULTS

Daily smokers at Wave 1 were 2.1 (95% CI: 1.5-3.0), 2.5 (2.1-2.9), and 1.7 (1.5-2.1) times more likely than nonsmokers to report self-directed violence, other-directed violence, or victimization between Waves 1 and 2, respectively. Former daily smokers were significantly less likely to report other-directed violence than individuals who were never daily smokers.

CONCLUSIONS

Daily cigarette smoking is temporally associated with multiple forms of violence compared to never and former cigarette smokers, even when common covariates associated with violence are controlled. Smoking status should be carefully controlled for in studies designed to identify risk factors for violence, and may be a useful component of violence risk assessment.

IMPLICATIONS

The findings suggest that cigarette smoking status should be carefully and systematically controlled for in studies of violence risk factors. The findings also support further investigation of the utility of cigarette smoking status for violence risk assessment, and whether smoking cessation strategies mitigate violence risk.

Ketamine-Induced Hallucinations

BACKGROUND

Ketamine, the NMDA glutamate receptor antagonist drug, is increasingly employed as an experimental model of psychosis in healthy volunteers. At subanesthetic doses, it safely and reversibly causes delusion-like ideas, amotivation and perceptual disruptions reminiscent of the aberrant salience experiences that characterize first-episode psychosis. However, auditory verbal hallucinations, a hallmark symptom of schizophrenia, have not been reported consistently in healthy volunteers even at high doses of ketamine.

SAMPLING AND METHODS

Here we present data from a set of healthy participants who received moderately dosed, placebo-controlled ketamine infusions in the reduced stimulation environment of the magnetic resonance imaging (MRI) scanner. We highlight the phenomenological experiences of 3 participants who experienced particularly vivid hallucinations.

RESULTS

Participants in this series reported auditory verbal and musical hallucinations at a ketamine dose that does not induce auditory hallucination outside of the scanner.

CONCLUSIONS

We interpret the observation of ketamine-induced auditory verbal hallucinations in the context of the reduced perceptual environment of the MRI scanner and offer an explanation grounded in predictive coding models of perception and psychosis - the brain fills in expected perceptual inputs, and it does so more in situations of altered perceptual input. The altered perceptual input of the MRI scanner creates a mismatch between top-down perceptual expectations and the heightened bottom-up signals induced by ketamine. Such circumstances induce aberrant percepts, including musical and auditory verbal hallucinations. We suggest that these circumstances might represent a useful experimental model of auditory verbal hallucinations and highlight the impact of ambient sensory stimuli on psychopathology.

Effects of endogenous and exogenous progesterone on emotional intelligence in cocaine-dependent men and women who also abuse alcohol

OBJECTIVE

As sex differences in substance dependence may impinge upon the perception and regulation of emotion, we assess emotional intelligence (EI) as a function of gender, menstrual cycle (MC) phase and hormonal changes in early abstinent cocaine-dependent individuals who abuse alcohol (CDA).

METHODS

Study 1: The Mayer, Salovey, and Caruso Emotional Intelligence Test (MSCEIT) was administered to 98 CDA (55 M/43 F) and 56 healthy (28 M/28 F) individuals. Performance in women was also assessed by MC phase. Study 2: The MSCEIT was administered to 28 CDA (19 M/9 F) who received exogenous progesterone (400 mg/day) versus placebo for 7 days (study 2).

RESULTS

Study 1: Healthy females were better than healthy males at facilitating thought and managing emotions. This gender discrepancy was not observed in the CDA group. Additionally, all women in the high compared with the low progesterone phase of their MC were better at managing their emotions. Study 2: Exogenous progesterone improved ability to facilitate thought in both males and females.

CONCLUSIONS

CDA women may be vulnerable to difficulties managing and regulating emotions. Gonadal hormones may contribute to this gender effect, as increases in both endogenous and exogenous progesterone improved selective aspects of EI.

Preliminary evidence for normalization of risk taking by modafinil in chronic cocaine users

Modafinil, a wake-promoting agent used to treat sleep disorders, is thought to enhance cognition. Although modafinil has shown promise as a pharmacotherapy for the treatment of cocaine dependence, it is unknown to what extent cognitive effects may play a role in such treatment. We examined the effect of modafinil on the Balloon Analogue Risk Task (BART), a behavioral measure in which higher scores are purported to reflect a greater propensity for risk-taking. Thirty cocaine dependent individuals, enrolled in a randomized clinical trial of modafinil 400mg (n=12) versus placebo (n=18), were administered the BART during the second week of inpatient treatment for cocaine dependence. A comparison cohort of healthy participants (n=19) performed the BART under similar conditions. Modafinil treatment was associated with significantly higher BART scores (p=0.01), which were comparable to scores in healthy persons. BART scores in placebo treated participants were much lower than previously reported in healthy participants, and lower than those observed in the comparison cohort. As propensity toward risk taking is typically associated with higher BART scores as well as increased risk for substance use, our findings may reflect a novel aspect of cognitive impairment related to chronic cocaine use. Notably, the low BART scores reflect highly suboptimal performance on the task, and the observed effect of modafinil may indicate a normalization of this impairment and have implications for treatment outcome.

Sex differences in guanfacine effects on drug craving and stress arousal in cocaine-dependent individuals

Currently, no FDA-approved medication exists for the treatment of cocaine use disorder. Furthermore, as women become increasingly more at risk for the consequences of cocaine addiction, the need to establish better-tailored treatment medications is paramount. We examine the effects of the alpha2 adrenergic agonist, guanfacine HCl, on responses to stress and drug cue in a group of cocaine-dependent men and women who also abuse alcohol and nicotine. Forty early abstinent treatment-seeking cocaine-dependent males and females were randomly assigned to receive either daily placebo (12 M/7 F) or guanfacine (2 or 3 mg) (15 M/6 F) for 3 weeks. In week 4, they participated in a laboratory experiment and were exposed to three 10-min guided imagery conditions (stress/stress, cue/cue, and stress/cue), one per day, consecutively in a random, counterbalanced order. Craving, negative emotion, anxiety, and cardiovascular function were assessed at baseline, immediately following imagery exposure, and at various recovery time points. Guanfacine significantly attenuated cocaine craving, alcohol craving, anxiety, and negative emotion following exposure to all three imagery conditions in females, but not males. Guanfacine did, however, reduce sympathetic tone as well as stress and cue-induced nicotine craving and systolic blood pressure (SBP) in both males and females. These findings highlight sex-specific effects of guanfacine on drug craving, anxiety, and negative mood with significant effects in women and not men. The findings suggest further evaluation of guanfacine in the treatment of cocaine use disorder with a specific focus on sex differences in treatment response.

The impact of NMDA receptor blockade on human working memory-related prefrontal function and connectivity

Preclinical research suggests that N-methyl-D-aspartate glutamate receptors (NMDA-Rs) have a crucial role in working memory (WM). In this study, we investigated the role of NMDA-Rs in the brain activation and connectivity that subserve WM. Because of its importance in WM, the lateral prefrontal cortex, particularly the dorsolateral prefrontal cortex and its connections, were the focus of analyses. Healthy participants (n=22) participated in a single functional magnetic resonance imaging session. They received saline and then the NMDA-R antagonist ketamine while performing a spatial WM task. Time-course analysis was used to compare lateral prefrontal activation during saline and ketamine administration. Seed-based functional connectivity analysis was used to compare dorsolateral prefrontal connectivity during the two conditions and global-based connectivity was used to test for laterality in these effects. Ketamine reduced accuracy on the spatial WM task and brain activation during the encoding and early maintenance (EEM) period of task trials. Decrements in task-related activation during EEM were related to performance deficits. Ketamine reduced connectivity in the DPFC network bilaterally, and region-specific reductions in connectivity were related to performance. These results support the hypothesis that NMDA-Rs are critical for WM. The knowledge gained may be helpful in understanding disorders that might involve glutamatergic deficits such as schizophrenia and developing better treatments.

Methylphenidate remediates error-preceding activation of the default mode brain regions in cocaine-addicted individuals

Many previous studies suggest the potential of psychostimulants in improving cognitive functioning. Our earlier pharmacological brain imaging study showed that intravenous methylphenidate (MPH) improves inhibitory control by altering cortico-striato-thalamic activations in cocaine-dependent (CD) individuals. Here we provide additional evidence for the effects of MPH in restoring cerebral activations during cognitive performance. Ten CD individuals performed a stop signal task (SST) during functional magnetic resonance imaging (fMRI) in two sessions, in which either MPH (0.5mg/kg body weight) or saline was administered intravenously. In the SST, a frequent go signal instructs participants to make a speeded response and a less frequent stop signal instructs them to withhold the response. Our previous work described increased activation of the precuneus/posterior cingulate cortex and ventromedial prefrontal cortex-regions of the default mode network (DMN)-before participants committed a stop error in healthy control but not CD individuals (Bednarski et al., 2011). The current results showed that, compared to saline, MPH restored error-preceding activations of DMN regions in CD individuals. The extent of the changes in precuneus activity was correlated with MPH-elicited increase in systolic blood pressure. These findings suggest that the influence of MPH on cerebral activations may extend beyond cognitive control and provide additional evidence warranting future studies to investigate the neural mechanisms and physiological markers of the efficacy of agonist therapy in cocaine dependence.

Relationship of resting brain hyperconnectivity and schizophrenia-like symptoms produced by the NMDA receptor antagonist ketamine in humans

N-methyl-D-aspartate glutamate receptor (NMDA-R) antagonists produce schizophrenia-like positive and negative symptoms in healthy human subjects. Preclinical research suggests that NMDA-R antagonists interfere with the function of gamma-aminobutyric acid (GABA) neurons and alter the brain oscillations. These changes have been hypothesized to contribute to psychosis. In this investigation, we evaluated the hypothesis that the NMDA-R antagonist ketamine produces alterations in cortical functional connectivity during rest that are related to symptoms. We administered ketamine to a primary sample of 22 subjects and to an additional, partially overlapping, sample of 12 subjects. Symptoms before and after the experimental session were rated with the Positive and Negative Syndrome Scale (PANSS). In the primary sample, functional connectivity was measured via functional magnetic resonance imaging almost immediately after infusion began. In the additional sample, this assessment was repeated after 45 min of continuous ketamine infusion. Global, enhanced functional connectivity was observed at both timepoints, and this hyperconnectivity was related to symptoms in a region-specific manner. This study supports the hypothesis that pathological increases in resting brain functional connectivity contribute to the emergence of positive and negative symptoms associated with schizophrenia.

The effects of exogenous progesterone on drug craving and stress arousal in cocaine dependence: impact of gender and cue type

AIMS

Exogenous progesterone has been shown to attenuate the rewarding effects of cocaine. However, its effects on provoked drug craving, stress arousal and cognitive performance has not been systematically investigated in cocaine dependent men and women. Thus, we conducted a double-blind placebo-controlled study assessing the efficacy of progesterone in reducing provoked drug craving, stress system arousal and improving cognitive performance in cocaine dependent men and women.

METHODS

Forty-two early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily doses of placebo (12M/9F) or micronized progesterone (12M/9F) (400 mg/day), for 7 days. Under experimental conditions, all subjects were exposed to three 5-min personalized guided imagery conditions (stress, cocaine cue, relaxing), one per day, consecutively in a random, counterbalanced order. Subjective craving, mood, hypothalamic-pituitary-adrenal (HPA) and cardiovascular output, and a cognitive measure of inhibitory control (Stroop Color Word Task) were assessed pre- and post imagery.

RESULTS

Progesterone relative to placebo significantly decreased cue-induced craving and cortisol responses and increased cue-induced ACTH. In addition, women but not men receiving progesterone reported lower ratings of negative emotion and higher ratings of relaxed mood following stress exposure. Improved Stroop performance was observed in all participants receiving progesterone, across all conditions.

CONCLUSIONS

Progesterone was selectively effective in reducing cocaine cue-induced but not stress-related cocaine craving as well as specific measures of the provoked arousal state. Findings suggest that progesterone's effects on drug craving and arousal are moderated by both the type of environmental cue exposure and gender.

A single-day paradigm of self-regulated human cocaine administration

Prior work by our group has shown the feasibility, safety, and validity of a multi-day, multi-dose paradigm of self-regulated cocaine administration in humans. The current work sought to consolidate these methods in a single-day design focused on reducing logistical complexity, decreasing research burden to human subjects, and increasing suitability for medication development designs.

METHODS

Eleven experienced cocaine users participated in a 6-hour, single-day design, consisting of one safety/eligibility and three experimental cocaine periods (during which subjects were allowed to self-administer 8, 16, and 32 mg/70 kg cocaine doses under a fixed-ratio 1:5 minute timeout schedule). Changes in cocaine-induced cardiovascular response, self-administration behavior, and subjective effects were assessed.

RESULTS

Procedures were well tolerated by participants, and no significant adverse events were noted. Significant (p < 0.05), changes in measures of cocaine self-administration (e.g., responses, infusions, interinfusion intervals, consumption, and plasma levels), cardiovascular response (HR), and subjective effects (“high”) were observed. In contrast, cocaine-induced increases in other vital signs (e.g., SBP, DBP) and subjective effect measures (e.g., paranoia) did not differ between doses.

CONCLUSIONS

These data support the safety, tolerability and validity of our single-day design. Depending on the application, such methods may afford advantages for assessing the self-regulation of cocaine administration behavior in humans (e.g., including medication development designs).

Night eating in obese treatment-seeking Hispanic patients with and without binge eating disorder

OBJECTIVE

To examine the frequency of night eating (NE) and its relation to binge eating disorder (BED), eating-disorder psychopathology, depression, and metabolic variables in treatment-seeking obese Hispanic men and women.

METHOD

A consecutive series of 79 obese monolingual Spanish-speaking-only Hispanic patients with BED (N = 40) and without BED (N = 39) were reliably assessed by bilingual research-clinicians using Spanish-language versions of semistructured interviews and measures.

RESULTS

Overall, 38% (N = 30) of the 79 patients reported regular NE (≥4 days/month). NE and BED were significantly associated; 70% (21/30) of NE versus 18% (9/49) of non-NE had BED. Patients with NE reported greater frequency of binge-eating and higher levels of eating-disorder psychopathology and depression than non-NE patients; group differences in eating disorder psychopathology and depression levels persisted after controlling for BED status. The NE and non-NE groups did not differ significantly in BMI or metabolic variables.

DISCUSSION

In obese treatment-seeking Hispanic patients, NE and BED were significantly associated and NE was associated with heightened eating-disorder psychopathology and depression even after controlling for BED status.

An examination of the food addiction construct in obese patients with binge eating disorder

OBJECTIVE

This study examined the psychometric properties of the Yale food addiction scale (YFAS) in obese patients with binge eating disorder (BED) and explored its association with measures of eating disorder and associated psychopathology.

METHOD

Eighty-one obese treatment-seeking BED patients were given the YFAS, structured interviews to assess psychiatric disorders and eating disorder psychopathology, and other pathology measures.

RESULTS

Confirmatory factor analysis revealed a one-factor solution with an excellent fit. Classification of "food addiction" was met by 57% of BED patients. Patients classified as meeting YFAS "food addiction" criteria had significantly higher levels of depression, negative affect, emotion dysregulation, eating disorder psychopathology, and lower self-esteem. YFAS scores were also significant predictors of binge eating frequency above and beyond other measures.

DISCUSSION

The subset of BED patients classified as having YFAS "food addiction" appear to represent a more disturbed variant characterized by greater eating disorder psychopathology and associated pathology.

Guanfacine effects on stress, drug craving and prefrontal activation in cocaine dependent individuals: preliminary findings

Cocaine dependence is associated with increased stress and drug cue-induced craving and physiological arousal but decreased prefrontal activity to emotional and cognitive challenge. As these changes are associated with relapse risk, we investigated the effects of α2 receptor agonist guanfacine on these processes. Twenty-nine early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily placebo or guanfacine (up to 3 mg) for four weeks. In a laboratory experiment, all patients were exposed to three 10-min guided imagery conditions (stress/stress, drug cue/drug cue, stress/drug cue), one per day, consecutively in a random, counterbalanced order. Subjective craving, anxiety and arousal as well as cardiovascular output were assessed repeatedly. Brain response to stress, drug cue and relaxing imagery was also assessed during a functional magnetic resonance (fMRI) imaging session. In the current study, guanfacine was found to be safe and well-tolerated. Lower basal heart rate and blood pressure was observed in the guanfacine versus placebo group. Guanfacine lowered stress and cue-induced nicotine craving and cue-induced cocaine craving, anxiety and arousal. The guanfacine group also showed increased medial and lateral prefrontal activity following stress and drug cue exposure compared with placebo. Data suggest further exploration of guanfacine is warranted in terms of its potential for reducing stress-induced and cue-induced drug craving and arousal.

Cortical GABA levels in primary insomnia

STUDY OBJECTIVES

GABA is increasingly recognized as an important neurotransmitter for the initiation and maintenance of sleep. We sought to measure cortical GABA content through proton magnetic resonance spectroscopy (MRS) in persons with and without primary insomnia, and relate brain GABA levels to polysomnographic sleep measures.

DESIGN

Two-group comparison study.

SETTING

Outpatient study at a university research clinic.

PARTICIPANTS

Non-medicated persons with primary insomnia (N = 16) and no sleep complaints (N = 17).

INTERVENTIONS

Participants kept sleep diaries and a regular time-in-bed schedule for 9 days, culminating in 2 consecutive nights of ambulatory polysomnography and a single proton MRS session. The main outcome measure was occipital GABA/creatine ratios; secondary measures included sleep measurements and relationship between polysomnographically measured time awake after sleep onset and occipital GABA content.

MEASUREMENTS AND RESULTS

The primary insomnia group was distinguished from persons with no sleep complaints on self-reported and polysomnographically measured sleep. The two groups did not differ in age, sex, body mass index, habitual bed- and wake-times, napping, use of caffeine, or use of cigarettes. Mean occipital GABA level was 12% higher in persons with insomnia than in persons without sleep complaints (P < 0.05). In both groups, GABA levels correlated negatively with polysomnographically measured time awake after sleep onset (P < 0.05).

CONCLUSIONS

Increased GABA levels in persons with insomnia may reflect an allostatic response to chronic hyperarousal. The preserved, negative relationship between GABA and time awake after sleep onset supports this notion, indicating that the possible allostatic response is adaptive.

Internalized weight bias in obese patients with binge eating disorder: associations with eating disturbances and psychological functioning

OBJECTIVE

Widespread bias against obese individuals may lead to the internalization of weight bias in obese persons. This study examined correlates of internalized weight bias (IWB) in obese patients with binge eating disorder (BED).

METHOD

One hundred treatment-seeking obese patients with BED were administered with the eating disorders examination interview and questionnaires assessing IWB, fat phobia, depression, and self-esteem.

RESULTS

The mean IWB score in this group of patients with BED was significantly greater than the mean IWB score observed previously in a community sample of overweight adults. IWB was positively associated with eating disorder psychopathology, fat phobia, and depression, and negatively associated with self-esteem. IWB made significant independent contributions to the variance in eating disorder psychopathology even after accounting for fat phobia, depression, and self-esteem.

DISCUSSION

Treatment-seeking obese patients with BED demonstrate high levels of IWB. IWB may contribute to the variance in eating disorder psychopathology in BED patients, beyond the contributions of fat phobia, depression, and self-esteem.

Prazosin effects on stress- and cue-induced craving and stress response in alcohol-dependent individuals: preliminary findings

BACKGROUND

Stress, alcohol cues, and dysregulated stress responses increase alcohol craving and relapse susceptibility, but few pharmacologic agents are known to decrease stress- and cue-induced alcohol craving and associated stress dysregulation in humans. Here we report findings from a preliminary efficacy study of the alpha-1 receptor antagonist, prazosin, in modulating these relapse-relevant factors in alcohol-dependent individuals.

METHODS

Seventeen early abstinent, treatment-seeking alcohol-dependent individuals (12 men and 5 women) were randomly assigned to receive either placebo or 16 mg daily prazosin in a double-blind, placebo-controlled manner over 4 weeks. During week 4, all patients participated in a 3-day laboratory experiment involving 5-minute guided imagery exposure to stress, alcohol cue, and neutral-relaxing/control conditions, 1 exposure per day, on consecutive days in a random, counterbalanced order. Alcohol craving, anxiety, negative emotion, cardiovascular measures, and plasma hypothalamic-pituitary-adrenal (HPA; cortisol, adenocorticotropic hormone) were assessed repeatedly in each session.

RESULTS

The prazosin group (n = 9) versus the placebo group (n = 8) showed significantly lower alcohol craving, anxiety, and negative emotion following stress exposure. The placebo group also showed significantly increased stress- and cue-induced alcohol craving, anxiety, negative emotion, and blood pressure (BP), as well as a blunted HPA response relative to the neutral condition, while the prazosin group showed no such increases in craving, anxiety, negative emotion, and BP, and no blunted HPA response to stress and alcohol cue exposure.

CONCLUSIONS

Prazosin appears efficacious in decreasing stress- and cue-induced alcohol craving and may normalize the stress dysregulation associated with early recovery from alcoholism. Further research to assess the efficacy of prazosin in reducing alcohol craving and stress-related relapse risk is warranted.

Exploring weight gain in year before treatment for binge eating disorder: a different context for interpreting limited weight losses in treatment studies

OBJECTIVE

To examine weight changes in obese patients with binge-eating disorder (BED) during the year before seeking treatment and to explore correlates of weight changes.

METHOD

Seventy-eight consecutive, treatment-seeking, obese BED patients were assessed with structured interviews and self-report questionnaires.

RESULTS

Overall, participants reported a mean weight gain of 15.1 pounds during the 12 months before treatment. This overall weight gain comprised remarkable heterogeneity, ranging from a 30-pound loss to a 53-pound gain. The subgroup of participants who reported gaining weight (76% of sample) reported gaining an average of 22.2 pounds during the 12 months before treatment. Weight change was associated with significantly more frequent binge eating and overeating during breakfasts.

DISCUSSION

Treatment-seeking obese patients with BED reported having gained substantial amounts of weight during the previous year. These findings provide an important context for interpreting the modest weight losses typically reported by treatment studies of BED.

A multistudy analysis of the effects of early cocaine abstinence on sleep

OBJECTIVE

To describe the sleep patterns of early cocaine abstinence in chronic users by polysomnographic and subjective measures.

METHODS

28 cocaine-dependent participants (ages 24-55) underwent polysomnographic sleep (PSG) recording on the 1st, 2nd and 3rd weeks of abstinence on a research dedicated inpatient facility. Objective measures of total sleep time, total REM time, slow wave sleep, sleep efficiency and a subjective measure (sleep quality) along with demographic data were collected from three different long term research studies over a five year period. Data were reanalysed to allow greater statistical power for comparisons.

RESULTS

Progressive weeks of abstinence had main effects on all assessed PSG sleep measures showing decreased total sleep time, REM sleep, stages 1 and 2 sleep, and sleep efficiency; increases in sleep onset and REM latencies and a slight increase in slow-wave sleep time were also present. Total sleep time and slow wave sleep were negatively associated with years of cocaine use. Total sleep time was positively associated with the amount of current ethanol use. Sex differences were found with females having more total REM time and an increase at a near significance level in slow wave sleep. Subjective measures were reported as improving with increasing abstinence over the same time period.

CONCLUSIONS

Chronic cocaine users show a general deterioration in objective sleep measures over a three-week period despite an increase in subjective overall sleep quality providing further evidence for "occult insomnia" during early cocaine abstinence.

Lucid dreaming and ventromedial versus dorsolateral prefrontal task performance

Activity in the prefrontal cortex may distinguish the meta-awareness experienced during lucid dreams from its absence in normal dreams. To examine a possible relationship between dream lucidity and prefrontal task performance, we carried out a prospective study in 28 high school students. Participants performed the Wisconsin Card Sort and Iowa Gambling tasks, then for 1 week kept dream journals and reported sleep quality and lucidity-related dream characteristics. Participants who exhibited a greater degree of lucidity performed significantly better on the task that engages the ventromedial prefrontal cortex (the Iowa Gambling Task), but degree of lucidity achieved did not distinguish performance on the task that engages the dorsolateral prefrontal cortex (the Wisconsin Card Sort Task), nor did it distinguish self-reported sleep quality or baseline characteristics. The association between performance on the Iowa Gambling Task and lucidity suggests a connection between lucid dreaming and ventromedial prefrontal function.

Gender-related influences of parental alcoholism on the prevalence of psychiatric illnesses: analysis of the National Epidemiologic Survey on Alcohol and Related Conditions

BACKGROUND

Offspring of individuals with alcoholism are at increased risk for psychiatric illness, but the effects of gender on this risk are not well known. In this study, we tested the hypothesis that the gender of the parent with alcoholism and the gender of offspring affect the association between parental alcoholism and offspring psychiatric illness.

METHOD

We analyzed the National Epidemiological Survey on Alcohol and Related Conditions (NESARC) data to examine the gender-specific prevalence of axis I and axis II disorders in 23,006 male and 17,368 female respondents with and without a history of paternal or maternal alcoholism. Adjusted odds ratios were calculated for the disorders based on gender and presence of maternal or paternal alcoholism.

RESULTS

Maternal or paternal alcoholism was associated with a higher prevalence of every disorder examined, regardless of the gender of offspring. Gender-related differences in prevalences were present in nearly all examined disorders, and the association between parental alcoholism and offspring psychiatric disorders was significantly different in men and women. These differences included stronger associations in female offspring of men with alcoholism (alcohol abuse without dependence); in female offspring of women with alcoholism (mania, nicotine dependence, alcohol abuse, and schizoid personality disorder); in male offspring of men with alcoholism (mania); and in male offspring of women with alcoholism (panic disorder).

CONCLUSIONS

Interactions between gender and parental alcoholism were specific to certain disorders but varied in their effects, and in general female children of women with alcoholism appear at greatest risk for adult psychopathology.

Normalizing effects of modafinil on sleep in chronic cocaine users

OBJECTIVE

The purpose of the present study was to determine the effect of morning-dosed modafinil on sleep and daytime sleepiness in chronic cocaine users.

METHOD

Twenty cocaine-dependent participants were randomly assigned to receive modafinil, 400 mg (N=10), or placebo (N=10) every morning at 7:30 a.m. for 16 days in an inpatient, double-blind randomized trial. Participants underwent polysomnographic sleep recordings on days 1 to 3, 7 to 9, and 14 to 16 (first, second, and third weeks of abstinence). The Multiple Sleep Latency Test was performed at 11:30 a.m., 2:00 p.m., and 4:30 p.m. on days 2, 8, and 15. For comparison of sleep architecture variables, 12 healthy comparison participants underwent a single night of experimental polysomnography that followed 1 night of accommodation polysomnography.

RESULTS

Progressive abstinence from cocaine was associated with worsening of all measured polysomnographic sleep outcomes. Compared with placebo, modafinil decreased nighttime sleep latency and increased slow-wave sleep time in cocaine-dependent participants. The effect of modafinil interacted with the abstinence week and was associated with longer total sleep time and shorter REM sleep latency in the third week of abstinence. Comparison of slow-wave sleep time, total sleep time, and sleep latency in cocaine-dependent and healthy participants revealed a normalizing effect of modafinil in cocaine-dependent participants. Modafinil was associated with increased daytime sleep latency, as measured by the Multiple Sleep Latency Test, and a nearly significant decrease in subjective daytime sleepiness.

CONCLUSIONS

Morning-dosed modafinil promotes nocturnal sleep, normalizes sleep architecture, and decreases daytime sleepiness in abstinent cocaine users. These effects may be relevant in the treatment of cocaine dependence.

Regulation of cocaine self-administration in humans: lack of evidence for loading and maintenance phases

BACKGROUND

In rodents, cocaine self-administration under a fixed-ratio schedule and with timeout intervals limited to the duration of the infusions is characterized by an initial burst of drug intake (loading) followed by more stable infusion rates (maintenance). We sought to examine whether similar phases might characterize self-regulated cocaine use in humans.

METHODS

31 Non-treatment seeking, cocaine dependent subjects participated in three (8, 16, and 32 mg/70 kg/infusion), self-regulated, 2-h cocaine self-administration sessions under a fixed-ratio 1, 5-min timeout schedule. Data were assessed for visual (e.g., by graphs of cumulative numbers of infusions) and statistical evidence of change in phase (by step-function analyses of individual infusion rates).

RESULTS

Graphs of cumulative infusions over time suggested a single, linear rate of self-administration over 2h at each cocaine dose. Statistical analyses of infusion data by generalized estimating equation (GEE) models also failed to support a loading/maintenance pattern (suggesting, if anything, the possibility of increasing infusion rates over time).

CONCLUSIONS

Our findings fail to support the existence of distinct loading and maintenance phases of self-regulated cocaine administration in humans at behaviorally relevant doses. Several factors may account for these observations including differences between humans and rodents in self-regulated drug intake.

Sex differences in sleep and sleep-dependent learning in abstinent cocaine users

Sleep and sleep-dependent learning are impaired in male cocaine users during abstinence, but for female users little is known. Cocaine dependent men (n=12) and women (n=14), and control participants (n=19) participated in this study of sleep and sleep-dependent learning. Cocaine users were assessed at 3, 10 and 20 days of abstinence and controls were studied over one night. Total sleep time, sleep efficiency and overnight motor learning were the main outcome measures. Cocaine dependent men compared to women exhibited deteriorations in sleep time, sleep efficiency, and overnight learning as abstinence progressed from 3 to 20 days. At abstinence day 3, cocaine dependent men and women were no different than control participants in the main outcomes. However, there were significant differences between cocaine men at abstinence day 20 and controls in sleep time and sleep-dependent learning, but no differences between controls and cocaine dependent women. There is growing evidence that sleep disturbances are associated with cocaine abuse and abstinence and have functional consequences that may be relevant to the development of effective treatments. The absence of sleep disturbances in women suggests a need to understand the mechanisms underlying these differences, as such knowledge could lead to novel therapies in cocaine dependence.

Subjective responses and cardiovascular effects of self-administered cocaine in cocaine-abusing men and women

This study aimed to examine sex differences in cocaine self-administration and cocaine-induced subjective and cardiovascular measures. The research was based on secondary analysis of data collected in our human laboratory in which subjects self-administered cocaine infusions (8, 16 and 32 mg/70 kg) over a 2-hour period under a fixed ratio 1, 5 minute time out schedule in three test sessions. Subjects were 10 women and 21 men with a history of either cocaine abuse or dependence who were not currently seeking treatment. Women and men self-administered similar amounts of cocaine. None of the subjective effects measures showed a significant main effect of sex during the cocaine self-administration session. Significant interactions were observed for subjective ratings of 'high' (sex x time) and 'stimulated' (sex x time x dose), with women reporting lower ratings over time/doses than men. Relative to men, cocaine produced dose- and time-dependent increases in feelings of hunger (i.e., reduced appetite suppression) in women. Systolic and diastolic blood pressures showed different patterns of change in men and women, with women showing less robust cocaine-induced increases than men. Taken together, these findings suggest that women and men may differ in their subjective and cardiovascular responses to self-administered cocaine. Further research that prospectively controls for hormonal influences upon these measures is needed.

Sleep architecture, cocaine and visual learning

BACKGROUND

Disturbances in sleep associated with chronic cocaine use may underlie abstinence-related cognitive dysfunction. We hypothesized that sleep-related cognitive function would be impaired in chronic cocaine users, and that this impairment would be associated with abstinence-related changes in sleep architecture.

METHODS

Twelve chronic cocaine users completed a 23-day in-patient study that included randomized, placebo-controlled, cocaine self-administration sessions. We report polysomnographic measurement of rapid eye-movement (REM) sleep and slow-wave activity, and performance on a visual texture discrimination task.

FINDINGS

Progressive abstinence from cocaine was associated with characteristic changes in REM sleep. REM sleep was shortest on nights following cocaine use and rebounded in the first week of abstinence before diminishing with progressive abstinence, following a pattern opposite that of slow-wave activity. Overnight visual learning was observed over the first night following 3 consecutive days of laboratory cocaine use; however, learning was not observed at 3 days or 17 days of abstinence. Across all points of abstinence, early-night slow-wave activity was associated strongly with non-deterioration of visual performance overnight. Furthermore, overnight enhancement of visual performance was predicted by the co-occurrence of sufficient early-night slow-wave activity and late night REM sleep, similar to results from studies in healthy subjects.

CONCLUSIONS

These results suggest that abstinence-associated sleep-dependent learning deficits are related to characteristic changes in sleep architecture, and promote the idea that treatments directed at sleep ('somno-tropic' treatments) could be helpful in offsetting physiological consequences of cocaine abstinence.

Altered levels of sex and stress steroid hormones assessed daily over a 28-day cycle in early abstinent cocaine-dependent females

RATIONALE

There is growing evidence of alterations in brain stress and reward circuits associated with cocaine dependence. Sex differences are also documented and sex steroid hormones have been linked to cocaine reinforcement.

OBJECTIVES

The current study therefore assessed daily fluctuations in stress and sex hormones in cocaine-dependent females compared with healthy females.

METHOD

Daily salivary samples of cortisol, progesterone, and estradiol were collected at waking across 28 days from 12 cocaine-dependent females receiving inpatient treatment and 10 healthy females. Participants also completed mood-rating scales each week corresponding to four phases of the menstrual cycle and cocaine craving was monitored in cocaine patients at each phase.

RESULTS

Cocaine-dependent females in their first month of abstinence demonstrated significantly higher levels of both cortisol and progesterone across the menstrual cycle and significantly lower estradiol/progesterone (E2/P) ratios compared to healthy controls. They also showed significantly increased negative mood compared with controls, but no variation in cocaine craving across the menstrual cycle.

CONCLUSIONS

Findings indicate altered stress and sex hormones suggestive of an overactive stress system during the first month of cocaine abstinence after chronic cocaine abuse. These increased levels of cortisol and progesterone could impact both abstinence-related symptoms such as negative mood and susceptibility to drug-seeking behavior in cocaine-dependent females.

Cocaine and sleep: early abstinence

Compulsive cocaine use is associated with a profound dysregulation of sleep. Perhaps the result of chronic use, a significant deterioration in sleep is apparent over the first 3 weeks of abstinence, with no indication of recovery. Interestingly, the diminished sleep is not accompanied by subjective reports of poor or worsening sleep. Rather, subjective reports actually improve over abstinence, while sleep-related cognitive performance declines. A mechanistic understanding of the apparent difference in objective and subjective measures is currently lacking. Here we review the relevant literature on cocaine use and sleep, and discuss the possible relevance of this sleep disturbance in relationship to the underlying disorder and its treatment.

Sex steroid hormones, stress response, and drug craving in cocaine-dependent women: implications for relapse susceptibility

Cocaine dependence is associated with an enhanced sensitivity to stress and drug craving. Increases in stress-induced craving and hypothalamic-pituitary-adrenal reactivity are also predictive of cocaine relapse outcomes. More important, sex differences in these responses have also been reported. To further understand the basis of the sex differences, the authors examined the influence of sex steroid hormones on subjective and physiological stress responses and drug craving in cocaine-dependent women. Women who had low progesterone levels (n=5) were compared with those with high progesterone levels (n=5) and with those with moderate levels of estradiol and progesterone (n=9) in their responses during exposure to stress, cocaine cues, and neutral imagery conditions. The high progesterone group showed significantly lower stress-induced and drug cue-induced cocaine craving ( p<.05) and reduced drug cue-induced anxiety levels ( p<.08) and lower drug cue-induced systolic and diastolic blood pressure levels compared with the low progesterone group. These data suggest that there are significant effects of sex steroid hormones on stress and drug cue-induced cocaine craving, anxiety, and cardiovascular responses. In particular, high progesterone during the midluteal phase of the cycle was associated with decreased stress-induced and drug cue-induced craving and decreased cue-induced anxiety and blood pressure responses. These findings are consistent with previous preclinical and clinical studies of progesterone's effects on the behavioral responses to cocaine and warrant further research to examine the effects of progesterone on stress-induced cocaine craving, stress arousal, and cocaine relapse susceptibility in women.

Sleep, sleep-dependent procedural learning and vigilance in chronic cocaine users: Evidence for occult insomnia

Sleep disturbance has been implicated in cocaine use; however, the nature of the disturbance and its potential effects on cognition and learning are largely unknown. Twelve chronic cocaine users completed a 23-day inpatient study that included randomized, placebo-controlled, cocaine self-administration sessions. Six subjects received cocaine on each of days 4-6 and placebo on days 18-20, the other six received cocaine on each of days 18-20 and placebo on days 4-6. Sleep was measured by polysomnography, the Nightcap sleep monitor, and self-reported measures. Simple and vigilance reaction times were measured daily; a motor-sequence test of procedural learning was administered four times. Electrophysiological measures of sleep showed a different pattern than self-reported sleep across cocaine administration and abstinence: total sleep time and sleep latency were at their worst by 14-17 days of abstinence while self-reported sleep was at its best. Vigilance correlated positively with electrophysiologically measured sleep and negatively with self-reported measures. Similarly, sleep-dependent procedural learning correlated with total sleep time and was impaired at 17 days abstinence relative to 2- and 3-days abstinence. Slow-wave activity was lowest at days 4-9 of abstinence and highest during use and days 10-17 of abstinence. With sustained abstinence, chronic cocaine users exhibit decreased sleep, impaired vigilance and sleep-dependent procedural learning, and spectral activity suggestive of chronic insomnia. However, they report subjectively improving sleep, indicating they are unaware of this "occult" insomnia. These results suggest the possibility of homeostatic sleep drive dysregulation in chronic cocaine users.

Self-reported paranoia during laboratory "binge" cocaine self-administration in humans

Cocaine-induced paranoia (CIP) has been extensively studied by retrospective interviews; however, only limited efforts have been made to further characterize CIP by human laboratory methods. We examined CIP in 28 healthy cocaine-dependent volunteers, who participated in 2-h, intravenous cocaine self-administration sessions at 8, 16, and 32 mg/70 kg doses, including 18 in a placebo-controlled design. Self-reports of paranoia showed significant main effects of cocaine dose (p=0.0002) and time (p=0.0003), and were statistically distinguishable from placebo at the two highest doses (16 and 32 mg). These effects were accounted for by a subgroup of vulnerable subjects in whom self-reports were consistent across dose and test-retest sessions. Subjects with CIP did not differ from those without CIP with respect to demographic, cocaine use, or cocaine self-administration variables. In conclusion, self-reports of CIP in the human lab are frequently endorsed, dose-dependent, and though variable between subjects, reproducible within subjects. Such methods may facilitate our understanding of the vulnerability to CIP in humans.

Interneuronal and peptidergic control of motor pattern switching in Aplysia

It has been proposed that a choice of specific behaviors can be mediated either by activation of behavior-specific higher order neurons or by distinct combinations of such neurons in different behaviors. We examined the role that two higher order neurons, CBI-2 and CBI-3, play in the selection of motor programs that correspond to ingestion and egestion, two stimulus-dependent behaviors that are generated by a single central pattern generator (CPG) of Aplysia. We found that CBI-2 could evoke either ingestive, egestive, or ambiguous motor programs depending on the regime of stimulation. When CBI-2 recruited CBI-3 firing via electrical coupling, the motor program tended to be ingestive. In the absence of CBI-3 activation, the program was usually egestive. When CBI-2 was stimulated to produce ingestive programs, hyperpolarization of CBI-3 converted the programs to egestive or ambiguous. When CBI-2 was stimulated to produce egestive or ambiguous programs, co-stimulation of CBI-3 converted them into ingestive. These findings are consistent with the idea that combinatorial commands are responsible for the choice of specific behaviors. Additional support for this view comes from the observations that appropriate stimulus conditions exist both for activation of CBI-2 together with CBI-3, and for activation of CBI-2 without a concomitant activation of CBI-3. The ability of CBI-3 to convert egestive and ambiguous programs into ingestive ones was mimicked by application of APGWamide, a neuropeptide that we have detected in CBI-3 by immunostaining. Thus combinatorial actions of higher order neurons that underlie pattern selection may involve the use of modulators released by specific higher order neurons.

Intrinsic and extrinsic modulation of a single central pattern generating circuit

Intrinsic and extrinsic neuromodulation are both thought to be responsible for the flexibility of the neural circuits (central pattern generators) that control rhythmic behaviors. Because the two forms of modulation have been studied in different circuits, it has been difficult to compare them directly. We find that the central pattern generator for biting in Aplysia is modulated both extrinsically and intrinsically. Both forms of modulation increase the frequency of motor programs and shorten the duration of the protraction phase. Extrinsic modulation is mediated by the serotonergic metacerebral cell (MCC) neurons and is mimicked by application of serotonin. Intrinsic modulation is mediated by the cerebral peptide-2 (CP-2) containing CBI-2 interneurons and is mimicked by application of CP-2. Since the effects of CBI-2 and CP-2 occlude each other, the modulatory actions of CBI-2 may be mediated by CP-2 release. Although the effects of intrinsic and extrinsic modulation are similar, the neurons that mediate them are active predominantly at different times, suggesting a specialized role for each system. Metacerebral cell (MCC) activity predominates in the preparatory (appetitive) phase and thus precedes the activation of CBI-2 and biting motor programs. Once the CBI-2s are activated and the biting motor program is initiated, MCC activity declines precipitously. Hence extrinsic modulation prefacilitates biting, whereas intrinsic modulation occurs during biting. Since biting inhibits appetitive behavior, intrinsic modulation cannot be used to prefacilitate biting in the appetitive phase. Thus the sequential use of extrinsic and intrinsic modulation may provide a means for premodulation of biting without the concomitant disruption of appetitive behaviors.