Brain mGlu5 Is Linked to Cognition and Cigarette Smoking but Does Not Differ From Control in Early Abstinence From Chronic Methamphetamine Use.

BACKGROUND: The group-I metabotropic glutamate receptor subtype 5 (mGlu5) has been implicated in methamphetamine exposure in animals and in human cognition. Because people with methamphetamine use disorder (MUD) exhibit cognitive deficits, we evaluated mGlu5 in people with MUD and controls and tested its association with cognitive performance. METHODS: Positron emission tomography was performed to measure the total VT of [18F]FPEB, a radiotracer for mGlu5, in brains of participants with MUD (abstinent from methamphetamine for at least 2 weeks, N = 14) and a control group (N = 14). Drug use history questionnaires and tests of verbal learning, spatial working memory, and executive function were administered. Associations of VT with methamphetamine use, tobacco use, and cognitive performance were tested. RESULTS: MUD participants did not differ from controls in global or regional VT, and measures of methamphetamine use were not correlated with VT. VT was significantly higher globally in nonsmoking vs smoking participants (main effect, P = .0041). MUD participants showed nonsignificant weakness on the Rey Auditory Verbal Learning Task and the Stroop test vs controls (P = .08 and P = .13, respectively) with moderate to large effect sizes, and significantly underperformed controls on the Spatial Capacity Delayed Response Test (P = .015). Across groups, Rey Auditory Verbal Learning Task performance correlated with VT in the dorsolateral prefrontal cortex and superior frontal gyrus. CONCLUSION: Abstinent MUD patients show no evidence of mGlu5 downregulation in brain, but association of VT in dorsolateral prefrontal cortex with verbal learning suggests that medications that target mGlu5 may improve cognitive performance.

Distribution of insulin in primate brain following nose-to-brain transport.

Introduction: Nose-to-brain (N2B) insulin delivery has potential for Alzheimer's disease (AD) therapy. However, clinical implementation has been challenging without methods to follow N2B delivery non-invasively. Positron emission tomography (PET) was applied to measure F-18-labeled insulin ([18F]FB-insulin) from intranasal dosing to brain uptake in non-human primates following N2B delivery. Methods: [18F]FB-insulin was prepared by reacting A1,B29-di(tert-butyloxycarbonyl)insulin with [18F]-N-succinimidyl-4-fluorobenzoate. Three methods of N2B delivery for [18F]FB-insulin were compared - delivery as aerosol via tubing (rhesus macaque, n = 2), as aerosol via preplaced catheter (rhesus macaque, n = 3), and as solution via preplaced catheter (cynomolgus macaque, n = 3). Following dosing, dynamic PET imaging (120 min) quantified delivery efficiency to the nasal cavity and whole brain. Area under the time-activity curve was calculated for 46 regions of the cynomolgus macaque brain to determine regional [18F]FB-insulin levels. Results: Liquid instillation of [18F]FB-insulin by catheter outperformed aerosol methods for delivery to the subject (39.89% injected dose vs 10.03% for aerosol via tubing, 0.17% for aerosol by catheter) and subsequently to brain (0.34% injected dose vs 0.00020% for aerosol via tubing, 0.05% for aerosol by catheter). [18F]FB-insulin was rapidly transferred across the cribriform plate to limbic and frontotemporal areas responsible for emotional and memory processing. [18F]FB-insulin half-life was longer in olfactory nerve projection sites with high insulin receptor density compared to the whole brain. Discussion: The catheter-based liquid delivery approach combined with PET imaging successfully tracked the fate of N2B [18F]FB-insulin and is thought to be broadly applicable for assessments of other therapeutic agents. This method can be rapidly applied in humans to advance clinical evaluation of N2B insulin as an AD therapeutic. Highlights for: [18F]FB-insulin passage across the cribriform plate was detected by PET.Intranasal [18F]FB-insulin reached the brain within 13 min.[18F]FB-insulin activity was highest in emotional and memory processing regions.Aerosol delivery was less efficient than liquid instillation by preplaced catheter.Insulin delivery to the cribriform plate was critical for arrival in the brain.

Brief communication: ß-cell function influences dopamine receptor availability.

We aim to identify physiologic regulators of dopamine (DA) signaling in obesity but previously did not find a compelling relationship with insulin sensitivity measured by oral-minimal model (OMM) and DA subtype 2 and 3 receptor (D2/3R) binding potential (BPND). Reduced disposition index (DI), a ß-cell function metric that can also be calculated by OMM, was shown to predict a negative reward behavior that occurs in states of lower endogenous DA. We hypothesized that reduced DI would occur with higher D2/3R BPND, reflecting lower endogenous DA. Participants completed PET scanning, with a displaceable radioligand to measure D2/3R BPND, and a 5-hour oral glucose tolerance test to measure DI by OMM. We studied 26 age-similar females without (n = 8) and with obesity (n = 18) (22 vs 39 kg/m2). Reduced DI predicted increased striatal D2/3R BPND independent of BMI. By accounting for ß-cell function, we were able to determine that the state of insulin and glucose metabolism is pertinent to striatal D2/3R BPND in obesity. Clinical Trial Registration Number: NCT00802204.

Lack of consistent sex differences in D-amphetamine-induced dopamine release measured with [18F]fallypride PET.

RATIONALE: Sex differences in the dopaminergic response to psychostimulants could have implications for drug abuse risk and other psychopathology involving the dopamine system, but human data are limited and mixed. OBJECTIVES: Here, we sought to investigate sex differences in dopamine release after oral D-amphetamine administration. METHODS: We used [18F]fallypride positron emission tomography (PET) to measure the change in dopamine D2/3 receptor availability (%ΔBPND, an index of dopamine release) between placebo and D-amphetamine sessions in two independent datasets containing a total of 39 females (on either hormonal birth control n = 18, postmenopausal n = 10, or studied in the first 10 days of their menstrual cycle n = 11) and 37 males. RESULTS: Using both a priori anatomical regions of interest based on previous findings and voxelwise analyses, we failed to consistently detect broad sex differences in D-amphetamine-induced dopamine release. Nevertheless, there was limited evidence for greater right ventral striatal dopamine release in young adult males relative to similarly aged females, but this was not consistently observed across samples. Plasma estradiol did not correlate with dopamine release and this measure did not differ in females on and off hormonal birth control. CONCLUSIONS: While our finding in young adults from one dataset of greater %ΔBPND in males is partially consistent with a previously published study on sex differences in D-amphetamine-induced dopamine release, our data do not support the presence of consistent widespread sex differences in this measure of dopamine release.

[18F]fallypride characterization of striatal and extrastriatal D2/3 receptors in Parkinson's disease.

Parkinson's disease (PD) is characterized by widespread degeneration of monoaminergic (especially dopaminergic) networks, manifesting with a number of both motor and non-motor symptoms. Regional alterations to dopamine D2/3 receptors in PD patients are documented in striatal and some extrastriatal areas, and medications that target D2/3 receptors can improve motor and non-motor symptoms. However, data regarding the combined pattern of D2/3 receptor binding in both striatal and extrastriatal regions in PD are limited. We studied 35 PD patients off-medication and 31 age- and sex-matched healthy controls (HCs) using PET imaging with [18F]fallypride, a high affinity D2/3 receptor ligand, to measure striatal and extrastriatal D2/3 nondisplaceable binding potential (BPND). PD patients completed PET imaging in the off medication state, and motor severity was concurrently assessed. Voxel-wise evaluation between groups revealed significant BPND reductions in PD patients in striatal and several extrastriatal regions, including the locus coeruleus and mesotemporal cortex. A region-of-interest (ROI) based approach quantified differences in dopamine D2/3 receptors, where reduced BPND was noted in the globus pallidus, caudate, amygdala, hippocampus, ventral midbrain, and thalamus of PD patients relative to HC subjects. Motor severity positively correlated with D2/3 receptor density in the putamen and globus pallidus. These findings support the hypothesis that abnormal D2/3 expression occurs in regions related to both the motor and non-motor symptoms of PD, including areas richly invested with noradrenergic neurons.

Nigrostriatal and Mesolimbic D2/3 Receptor Expression in Parkinson's Disease Patients with Compulsive Reward-Driven Behaviors.

The nigrostriatal and mesocorticolimbic dopamine networks regulate reward-driven behavior. Regional alterations to mesolimbic dopamine D2/3 receptor expression are described in drug-seeking and addiction disorders. Parkinson's disease (PD) patients are frequently prescribed D2-like dopamine agonist (DAgonist) therapy for motor symptoms, yet a proportion develop clinically significant behavioral addictions characterized by impulsive and compulsive behaviors (ICBs). Until now, changes in D2/3 receptor binding in both striatal and extrastriatal regions have not been concurrently quantified in this population. We identified 35 human PD patients (both male and female) receiving DAgonist therapy, with (n = 17) and without (n = 18) ICBs, matched for age, disease duration, disease severity, and dose of dopamine therapy. In the off-dopamine state, all completed PET imaging with [18F]fallypride, a high affinity D2-like receptor ligand that can measure striatal and extrastriatal D2/3 nondisplaceable binding potential (BPND). Striatal differences between ICB+/ICB- patients localized to the ventral striatum and putamen, where ICB+ subjects had reduced BPND In this group, self-reported severity of ICB symptoms positively correlated with midbrain D2/3 receptor BPND Group differences in regional D2/3 BPND relationships were also notable: ICB+ (but not ICB-) patients expressed positive correlations between midbrain and caudate, putamen, globus pallidus, and amygdala BPNDs. These findings support the hypothesis that compulsive behaviors in PD are associated with reduced ventral and dorsal striatal D2/3 expression, similar to changes in comparable behavioral disorders. The data also suggest that relatively preserved ventral midbrain dopaminergic projections throughout nigrostriatal and mesolimbic networks are characteristic of ICB+ patients, and may account for differential DAgonist therapeutic response.SIGNIFICANCE STATEMENT The biologic determinants of compulsive reward-based behaviors have broad clinical relevance, from addiction to neurodegenerative disorders. Here, we address biomolecular distinctions in Parkinson's disease patients with impulsive compulsive behaviors (ICBs). This is the first study to image a large cohort of ICB+ patients using positron emission tomography with [18F]fallypride, allowing quantification of D2/3 receptors throughout the mesocorticolimbic network. We demonstrate widespread differences in dopaminergic networks, including (1) D2-like receptor distinctions in the ventral striatum and putamen, and (2) a preservation of widespread dopaminergic projections emerging from the midbrain, which is associated with the severity of compulsive behaviors. This clearly illustrates the roles of D2/3 receptors and medication effects in maladaptive behaviors, and localizes them specifically to nigrostriatal and extrastriatal regions.

Florbetapir-PET ß-amyloid imaging and associated neuropsychological trajectories in survivors of critical illness: A case series.

PURPOSE: Cognitive impairment resembling Alzheimer's disease is common in survivors of critical illness. We hypothesized that Intensive Care Unit (ICU) survivors with cognitive impairment would have significant amyloid and designed a pilot study to explore this relationship. MATERIALS AND METHODS: A pilot, case series of a convenience sample of 14 adult medical and surgical ICU survivors, in a clinical neuroradiology clinic. Patients underwent cognitive testing at 3months, 1year, 4years, and 6years after hospital discharge with the Repeatable Battery for the Assessment of Neuropsychological Status. They received a single PET scan using amyloid PET imaging (florbetapir F18) 2 to 4years after their ICU stay. RESULTS: Amyloid (defined as a Standard Uptake Value ratio or SUVr >1.10) was present in 2 of 14 (14%) individuals, both of whom demonstrated significant cognitive impairment yet no consistent decline over time. Of the 6 impaired patients (RBANS<78), 4 (66.7%) were amyloid negative. CONCLUSIONS: It is feasible to assess ICU survivors with amyloid imaging. In this small sample, most patients with cognitive impairment were negative on amyloid PET imaging, which raises the possibility that ICU survivors may experience a unique form of dementia not driven by an amyloid related mechanism.

Therapeutic D2/3 receptor occupancies and response with low amisulpride blood concentrations in very late-onset schizophrenia-like psychosis (VLOSLP).

OBJECTIVE: Antipsychotic drug sensitivity in very late-onset schizophrenia-like psychosis (VLOSLP) is well documented, but poorly understood. This study aimed to investigate blood drug concentration, D2/3 receptor occupancy and outcome in VLOSLP during open amisulpride prescribing, and compare this with Alzheimer's disease (AD). METHODS: Blood drug concentration, prolactin, symptoms and extrapyramidal side-effects (EPS) were serially assessed during dose titration. [18 F]fallypride imaging was used to quantify D2/3 receptor occupancy. Average steady-state amisulpride concentration (Caverage, ng/ml) was estimated by incorporating pharmacokinetic (PK) data into an existing population PK model (25 AD participants, 20 healthy older people). RESULTS: Eight patients (target 20) were recruited (six women; 76 + - 6 years; six treatment compliant; five serially sampled; three with paired imaging data). Mean + - SD symptom reduction was 74 ± 12% (50-100 mg/day; 92.5 + -39.4 ng/ml). Mild EPS emerged at 96 ng/ml (in AD, severe EPS, 50 mg/day, 60 ng/ml). In three participants, imaged during optimal treatment (50 mg/day; 41-70 ng/ml), caudate occupancy was 44-59% (58-74% in AD across a comparable Caverage). CONCLUSIONS: Despite the small sample size, our findings are highly relevant as they suggest that, as in AD, 50 mg/day amisulpride is associated with >40% occupancy and clinically relevant responses in VLOSLP. It was not possible to fully characterise concentration-occupancy relationships in VLOSLP, and it is thus unclear whether the greater susceptibility of those with AD to emergent EPS was accounted for by increased central drug access. Further investigation of age- and diagnosis-specific threshold sensitivities is warranted, to guide amisulpride prescribing in older people, and therapeutic drug monitoring studies offer a potentially informative future approach. Copyright © 2017 John Wiley & Sons, Ltd.

Ventral striatal network connectivity reflects reward learning and behavior in patients with Parkinson's disease.

A subgroup of Parkinson's disease (PD) patients treated with dopaminergic therapy develop compulsive reward-driven behaviors, which can result in life-altering morbidity. The mesocorticolimbic dopamine network guides reward-motivated behavior; however, its role in this treatment-related behavioral phenotype is incompletely understood. Here, mesocorticolimbic network function in PD patients who develop impulsive and compulsive behaviors (ICB) in response to dopamine agonists was assessed using BOLD fMRI. The tested hypothesis was that network connectivity between the ventral striatum and the limbic cortex is elevated in patients with ICB and that reward-learning proficiency reflects the extent of mesocorticolimbic network connectivity. To evaluate this hypothesis, 3.0T BOLD-fMRI was applied to measure baseline functional connectivity on and off dopamine agonist therapy in age and sex-matched PD patients with (n = 19) or without (n = 18) ICB. An incentive-based task was administered to a subset of patients (n = 20) to quantify positively or negatively reinforced learning. Whole-brain voxelwise analyses and region-of-interest-based mixed linear effects modeling were performed. Elevated ventral striatal connectivity to the anterior cingulate gyrus (P = 0.013), orbitofrontal cortex (P = 0.034), insula (P = 0.044), putamen (P = 0.014), globus pallidus (P < 0.01), and thalamus (P < 0.01) was observed in patients with ICB. A strong trend for elevated amygdala-to-midbrain connectivity was found in ICB patients on dopamine agonist. Ventral striatum-to-subgenual cingulate connectivity correlated with reward learning (P < 0.01), but not with punishment-avoidance learning. These data indicate that PD-ICB patients have elevated network connectivity in the mesocorticolimbic network. Behaviorally, proficient reward-based learning is related to this enhanced limbic and ventral striatal connectivity. Hum Brain Mapp 39:509-521, 2018. © 2017 Wiley Periodicals, Inc.

Caloric Restriction-Induced Decreases in Dopamine Receptor Availability are Associated with Leptin Concentration.

OBJECTIVE: It has been previously reported that early after Roux-en-Y-gastric bypass, dopamine (DA) type 2 and 3 receptor (D2/3R) binding potential (BPND ) was decreased from preoperative levels. The current study aimed to determine whether calorie restriction without weight loss modifies D2/3R BPND and whether such changes are explained by neuroendocrine regulation. METHODS: Fifteen females with obesity (BMI = 39 ± 6 kg/m2 ) were studied before and after ∼10 days of a very-low-calorie-diet (VLCD). Outcome measures included fasting insulin, leptin, acyl ghrelin, and glucose, and insulin sensitivity and disposition index were estimated using the oral-minimal model (OMM) method. Participants underwent positron emission tomography scanning with the displaceable radioligand [18 F]fallypride to estimate available regional D2/3R levels. Regions of interest included the caudate, putamen, ventral striatum, hypothalamus, and substantia nigra (SN). RESULTS: With the VLCD, weight decreased slightly (-3 kg). Insulin, glucose, and leptin decreased significantly, but there was no change in acyl ghrelin or measures from OMM. SN D2/3R BPND decreased significantly, with trends toward decreased levels in the remaining regions. The decrease in leptin concentration strongly predicted the change in D2/3R BPND in all regions (all P ≤ 0.004). CONCLUSIONS: In obesity, reductions in regional D2/3R availability after VLCD are suggestive of increased endogenous DA competing with the radioligand. Changes in regional D2/3R availability were associated with decreases in leptin concentrations that occurred before clinically significant weight loss.

A Population Approach to Guide Amisulpride Dose Adjustments in Older Patients With Alzheimer's Disease.

OBJECTIVE: We have previously reported high dopamine D2/3 receptor occupancies at low amisulpride concentrations in older people with Alzheimer's disease (AD), during off-label treatment of AD-related psychosis. This post hoc analysis explored pharmacokinetic (concentration) and pharmacodynamic (prolactin, D2/3 occupancy) contributions to symptom reduction and extrapyramidal side effects (EPS) to inform AD-specific dose adjustments. METHODS: Population pharmacokinetic-pharmacodynamic models were developed by combining pharmacokinetic data from a phase 1 study in 20 healthy older people with pharmacokinetic prolactin, [¹8F]fallypride D2/3 receptor imaging, and clinical outcome data from 28 older patients prescribed open amisulpride (25-75 mg/d) to treat AD-related psychosis. Model predictions were used to simulate dose-response and dose-EPS. RESULTS: Symptom reduction (delusions) was associated with amisulpride concentration (P = 1.3e-05) and D2/3 occupancy (P < .01, caudate, putamen, thalamus). Model predictions suggested that across concentrations of 40-100 ng/mL, and occupancies of 40% to 70% in the caudate and thalamus and 30% to 60% in the putamen, there was a 50% to 90% probability of response and < 30% probability of EPS. Simulations, based on concentration-delusions and concentration-EPS model outputs, showed that 50 mg/d of amisulpride was the appropriate dose to achieve this target range in those aged > 75 years; increasing the dose to 75 mg/d increased the risk of EPS, particularly in those aged > 85 years of low body weight. CONCLUSIONS: These findings argue strongly for the consideration of age- and weight-based dose adjustments in older patients with AD-related psychosis and indicate that 50 mg/d of amisulpride may be both the minimal clinically effective dose and, in those aged > 75 years, the maximally tolerated dose.

Mesocorticolimbic hemodynamic response in Parkinson's disease patients with compulsive behaviors.

BACKGROUND: PD patients treated with dopamine therapy can develop maladaptive impulsive and compulsive behaviors, manifesting as repetitive participation in reward-driven activities. This behavioral phenotype implicates aberrant mesocorticolimbic network function, a concept supported by past literature. However, no study has investigated the acute hemodynamic response to dopamine agonists in this subpopulation. OBJECTIVES: We tested the hypothesis that dopamine agonists differentially alter mesocortical and mesolimbic network activity in patients with impulsive-compulsive behaviors. METHODS: Dopamine agonist effects on neuronal metabolism were quantified using arterial-spin-labeling MRI measures of cerebral blood flow in the on-dopamine agonist and off-dopamine states. The within-subject design included 34 PD patients, 17 with active impulsive compulsive behavior symptoms, matched for age, sex, disease duration, and PD severity. RESULTS: Patients with impulsive-compulsive behaviors have a significant increase in ventral striatal cerebral blood flow in response to dopamine agonists. Across all patients, ventral striatal cerebral blood flow on-dopamine agonist is significantly correlated with impulsive-compulsive behavior severity (Questionnaire for Impulsive Compulsive Disorders in Parkinson's Disease- Rating Scale). Voxel-wise analysis of dopamine agonist-induced cerebral blood flow revealed group differences in mesocortical (ventromedial prefrontal cortex; insular cortex), mesolimbic (ventral striatum), and midbrain (SN; periaqueductal gray) regions. CONCLUSIONS: These results indicate that dopamine agonist therapy can augment mesocorticolimbic and striato-nigro-striatal network activity in patients susceptible to impulsive-compulsive behaviors. Our findings reinforce a wider literature linking studies of maladaptive behaviors to mesocorticolimbic networks and extend our understanding of biological mechanisms of impulsive compulsive behaviors in PD. © 2017 International Parkinson and Movement Disorder Society.

Therapeutic window of dopamine D2/3 receptor occupancy to treat psychosis in Alzheimer's disease.

See Caravaggio and Graff-Guerrero (doi:10.1093/awx023) for a scientific commentary on this article.Antipsychotic drugs, originally developed to treat schizophrenia, are used to treat psychosis, agitation and aggression in Alzheimer's disease. In the absence of dopamine D2/3 receptor occupancy data to inform antipsychotic prescribing for psychosis in Alzheimer's disease, the mechanisms underpinning antipsychotic efficacy and side effects are poorly understood. This study used a population approach to investigate the relationship between amisulpride blood concentration and central D2/3 occupancy in older people with Alzheimer's disease by combining: (i) pharmacokinetic data (280 venous samples) from a phase I single (50 mg) dose study in healthy older people (n = 20, 65-79 years); (ii) pharmacokinetic, 18F-fallypride D2/3 receptor imaging and clinical outcome data on patients with Alzheimer's disease who were prescribed amisulpride (25-75 mg daily) to treat psychosis as part of an open study (n = 28; 69-92 years; 41 blood samples, five pretreatment scans, 19 post-treatment scans); and (iii) 18F-fallypride imaging of an antipsychotic free Alzheimer's disease control group (n = 10, 78-92 years), to provide additional pretreatment data. Non-linear mixed effects modelling was used to describe pharmacokinetic-occupancy curves in caudate, putamen and thalamus. Model outputs were used to estimate threshold steady state blood concentration and occupancy required to elicit a clinically relevant response (>25% reduction in scores on delusions, hallucinations and agitation domains of the Neuropsychiatric Inventory) and extrapyramidal side effects (Simpson Angus Scale scores > 3). Average steady state blood levels were low (71 ± 30 ng/ml), and associated with high D2/3 occupancies (65 ± 8%, caudate; 67 ± 11%, thalamus; 52 ± 11%, putamen). Antipsychotic clinical response occurred at a threshold concentration of 20 ng/ml and D2/3 occupancies of 43% (caudate), 25% (putamen), 43% (thalamus). Extrapyramidal side effects (n = 7) emerged at a threshold concentration of 60 ng/ml, and D2/3 occupancies of 61% (caudate), 49% (putamen) and 69% (thalamus). This study has established that, as in schizophrenia, there is a therapeutic window of D2/3 receptor occupancy for optimal treatment of psychosis in Alzheimer's disease. We have also shown that occupancies within and beyond this window are achieved at very low amisulpride doses in Alzheimer's disease due to higher than anticipated occupancies for a given blood drug concentration. Our findings support a central pharmacokinetic contribution to antipsychotic sensitivity in Alzheimer's disease and implicate the blood-brain barrier, which controls central drug access. Whether high D2/3 receptor occupancies are primarily accounted for by age- or disease-specific blood-brain barrier disruption is unclear, and this is an important future area of future investigation, as it has implications beyond antipsychotic prescribing.

Variability in paralimbic dopamine signaling correlates with subjective responses to d-amphetamine.

Subjective responses to psychostimulants vary, the basis of which is poorly understood, especially in relation to possible cortical contributions. Here, we tested for relationships between participants' positive subjective responses to oral d-amphetamine (dAMPH) versus placebo and variability in striatal and extrastriatal dopamine (DA) receptor availability and release, measured via positron emission tomography (PET) with the radiotracer (18)F-fallypride. Analyses focused on 35 healthy adult participants showing positive subjective effects to dAMPH measured via the Drug Effects Questionnaire (DEQ) Feel, Like, High, and Want More subscales (Responders), and were repeated after inclusion of 11 subjects who lacked subjective responses. Associations between peak DEQ subscale ratings and both baseline (18)F-fallypride binding potential (BPnd; an index of D2/D3 receptor availability) and the percentage change in BPnd post dAMPH (%ΔBPnd; a measure of DA release) were assessed. Baseline BPnd in ventromedial prefrontal cortex (vmPFC) predicted the peak level of High reported following dAMPH. Furthermore, %ΔBPnd in vmPFC positively correlated with DEQ Want More ratings. DEQ Want More was also positively correlated with %ΔBPnd in right ventral striatum and left insula. This work indicates that characteristics of DA functioning in vmPFC, a cortical area implicated in subjective valuation, are associated with both subjective high and incentive (wanting) responses. The observation that insula %ΔBPnd was associated with drug wanting converges with evidence suggesting its role in drug craving. These findings highlight the importance of variability in DA signaling in specific paralimbic cortical regions in dAMPH's subjective response, which may confer risk for abusing psychostimulants.

Single-dose Live Oral Cholera Vaccine CVD 103-HgR Protects Against Human Experimental Infection With Vibrio cholerae O1 El Tor.

BACKGROUND: No licensed cholera vaccine is presently available in the United States. Cholera vaccines available in other countries require 2 spaced doses. A single-dose cholera vaccine that can rapidly protect short-notice travelers to high-risk areas and help control explosive outbreaks where logistics render 2-dose immunization regimens impractical would be a major advance.PXVX0200, based on live attenuated Vibrio cholerae O1 classical Inaba vaccine strain CVD 103-HgR, elicits seroconversion of vibriocidal antibodies (a correlate of protection) within 10 days of a single oral dose. We investigated the protection conferred by this vaccine in a human cholera challenge model. METHODS: Consenting healthy adult volunteers, 18-45 years old, were randomly allocated 1:1 to receive 1 oral dose of vaccine (approximately 5 × 10(8) colony-forming units [CFU]) or placebo in double-blind fashion. Volunteers ingested approximately 1 × 10(5) CFU of wild-type V. cholerae O1 El Tor Inaba strain N16961 10 days or 3 months after vaccination and were observed on an inpatient research ward for stool output measurement and management of hydration. RESULTS: The vaccine was well tolerated, with no difference in adverse event frequency among 95 vaccinees vs 102 placebo recipients. The primary endpoint, moderate (≥3.0 L) to severe (≥5.0 L) diarrheal purge, occurred in 39 of 66 (59.1%) placebo controls but only 2 of 35 (5.7%) vaccinees at 10 days (vaccine efficacy, 90.3%; P < .0001) and 4 of 33 (12.1%) vaccinees at 3 months (vaccine efficacy, 79.5%; P < .0001). CONCLUSIONS: The significant vaccine efficacy documented 10 days and 3 months after 1 oral dose of PXVX0200 supports further development as a single-dose cholera vaccine. CLINICAL TRIALS REGISTRATION: NCT01895855.

Individual differences in timing of peak positive subjective responses to d-amphetamine: Relationship to pharmacokinetics and physiology.

Rate of delivery of psychostimulants has been associated with their positive euphoric effects and potential addiction liability. However, information on individual differences in onset of d-amphetamine's effects remains scarce. We examined individual differences in the time to peak subjective and physiological effects and the pharmacokinetics/pharmacodynamics of oral d-amphetamine. We considered two independent studies that used different dosing regimens where subjects completed the drug effects questionnaire at multiple time points post d-amphetamine. Based on the observation of distinct individual differences in time course of drug effects questionnaire "feel", "high", and "like" ratings (DEQH+L+F) in Study 1, subjects in both studies were categorized as early peak responders (peak within 60 minutes), late peak responders (peak > 60 minutes) or nonresponders; 20-25% of participants were categorized as early peak responders, 50-55% as late peak responders and 20-30% as nonresponders. Physiological (both studies) and plasma d-amphetamine (Study 1) were compared among these groups. Early peak responders exhibited an earlier rise in plasma d-amphetamine levels and more sustained elevation in heart rate compared to late peak responders. The present data illustrate the presence of significant individual differences in the temporal pattern of responses to oral d-amphetamine, which may contribute to heightened abuse potential.

The neurobiological basis of binge-eating disorder.

Relatively little is known about the neuropathophysiology of binge-eating disorder (BED). Here, the evidence from neuroimaging, neurocognitive, genetics, and animal studies are reviewed to synthesize our current understanding of the pathophysiology of BED. Binge-eating disorder may be conceptualized as an impulsive/compulsive disorder, with altered reward sensitivity and food-related attentional biases. Neuroimaging studies suggest there are corticostriatal circuitry alterations in BED similar to those observed in substance abuse, including altered function of prefrontal, insular, and orbitofrontal cortices and the striatum. Human genetics and animal studies suggest that there are changes in neurotransmitter networks, including dopaminergic and opioidergic systems, associated with binge-eating behaviors. Overall, the current evidence suggests that BED may be related to maladaptation of the corticostriatal circuitry regulating motivation and impulse control similar to that found in other impulsive/compulsive disorders. Further studies are needed to understand the genetics of BED and how neurotransmitter activity and neurocircuitry function are altered in BED and how pharmacotherapies may influence these systems to reduce BED symptoms.

Caudate asymmetry is related to attentional impulsivity and an objective measure of ADHD-like attentional problems in healthy adults.

Case-control studies comparing ADHD with typically developing individuals suggest that anatomical asymmetry of the caudate nucleus is a marker of attention deficit hyperactivity disorder (ADHD). However, there is no consensus on whether the asymmetry favors the right or left caudate nucleus in ADHD, or whether the asymmetry is increased or decreased in ADHD. The current study aimed to clarify this relationship by applying a dimensional approach to assessing ADHD symptoms that, instead of relying on clinical classification, utilizes the natural behavioral continuum of traits related to ADHD. Structural T1-weighted MRI was collected from 71 adults between 18 and 35 years and analyzed for caudate asymmetry. ADHD-like attentional symptoms were assessed with an objective measure of attentional problems, the ADHD score from the Test of Variables of Attention (TOVA). Impulsivity, a core feature in ADHD, was measured using the Barratt Impulsiveness Scale, a self-report measure that assesses attentional, non-planning, and motor features of impulsivity. We found that larger right relative to left caudate volumes correlated with both higher attentional impulsiveness and worse ADHD scores on the TOVA. Higher attentional impulsiveness also correlated with worse ADHD scores, establishing coherence between the objective measure and the self-report measure of attentional problems. These results suggest that a differential passage of information through frontal-striatal networks may produce instability leading to attentional problems. The findings also demonstrate the utility of a dimensional approach to understanding structural correlates of ADHD symptoms.

Diarrhea, bacteremia and multiorgan dysfunction due to an extraintestinal pathogenic Escherichia coli strain with enteropathogenic E. coli genes.

A 55-year-old man with well-controlled HIV had severe diarrhea for 3 weeks and developed multiorgan dysfunction and bacteremia due to Escherichia coli. The genome of the patient's isolate had features characteristic of extraintestinal pathogenic E. coli and genes distantly related to those defining enteropathogenic E. coli.