A preliminary investigation of the acute effects of delta-9-tetrahydrocannabinol on pain and opioid attentional bias among persons with opioid use disorder.

INTRODUCTION: Attentional bias (AB) is believed to be an important factor in the development and maintenance of both opioid use disorder (OUD) and chronic pain. Cannabis and its main psychoactive constituent, delta-9-tetrahydrocannabinol (THC), produce analgesic effects via processes that are potentially relevant to AB and is commonly used by persons with OUD. This exploratory study investigated if THC influences AB towards pain and opioid cues individuals with OUD. METHODS: Using a within-subject, crossover design, 27 adults receiving methadone were randomly assigned to receive single doses of oral THC (10 mg, 20 mg administered as dronabinol) or placebo across three, 5-h sessions. During each session, a visual probe task was used to measure AB to pain and opioid cues at baseline and 120 min post-THC administration. RESULTS: Mixed-effects models examined main effects of THC dose, time, and their interaction across all participants; findings were then stratified by methadone dose (low dose <90 mg/day and high dose ≥90 mg/day). Among individuals receiving high doses of methadone, a significant interaction was observed such that AB towards opioids increased following 10 mg THC administration and decreased following 20 mg THC administration. Additionally, participants receiving low doses of methadone showed significant increases in the variability of opioid-related AB post THC administration. CONCLUSION: We provide preliminary evidence showing that THC may cause dose-dependent effects on selective attention for opioid cues among methadone patients. These results underscore the need for further clinical investigation into the effects of cannabinoids and other substances with potential analgesic and addictive properties among persons with OUD.

Blood pressure changes during ketamine infusion for the treatment of depression.

OBJECTIVE: This study aimed to examine blood pressure changes during ketamine infusion for depression and exploring the factors associated with these changes. METHOD: This study is a retrospective chart-review of patients with depression undergoing ketamine infusion at Yale Psychiatry Hospital during a 7-year period. Blood pressure (BP) was recorded every 10 min during the infusion. Surges in systolic and diastolic blood pressure (SBP, DBP), along with severe hypertension events, were analyzed in relation to patient demographics. RESULTS: A total of 138 patients received a total of 2342 infusions. SBP and DBP peaked at 40 min after the start of the infusion with a mean change of 16.0 (SD: 11.2) and 11.0 mmHg (SD: 8.45) respectively. Severe hypertension was observed in 17 patients (12.5%) and 23 infusion sessions (0.98%), occuring more frequently during the first three infusions (43.4%). Age (OR = 1.04 [1.02,1.05], p-value <0.001) was significantly associated with a surge in SBP and all patients with a past medical history of hypertension experienced a BP surge during their infusions. CONCLUSION: Ketamine infusions can cause significant blood pressure increases, particularly in older and hypertensive patients, highlighting the need for careful cardiovascular monitoring to mitigate risks during treatment.

Disentangling negative and positive symptoms in schizophrenia and autism spectrum disorder.

Autism spectrum disorder (ASD) and schizophrenia (SZ) share traits, especially in social skills and negative symptoms, and to a lesser degree positive symptoms. Differential diagnosis can be challenging and discerning expressive and experiential negative symptoms may provide knowledge with potential diagnostic and functional relevance that can guide treatment. Two exploratory factor analyses (EFA) were conducted to reveal the underlying dimensions of negative and positive symptoms using the Positive and Negative Syndrome Scale (PANSS), the Scale for the Assessment of Positive Symptoms & Negative Symptoms (SAPS/SANS) and the Autism Diagnostic Observation Schedule-Generic (ADOS-G). Three factors emerged from the negative symptom EFA (70.5 % variance): NF1) Expressive Negative; NF2) Experiential Negative; and NF3) Preoccupation, Absorption & Expressive Affective Flattening. Three positive factors emerged (68.6 % variance): PF1) Hallucinations-Delusions; PF2) Grandiosity; and PF3) Thought Disorder-ADOS positive Symptoms. SZ showed higher PF1 scores, and ASD had higher PF3 scores. No differences between groups were observed in the negative factors. Across groups, all negative factors were inversely associated with quality of life. Only NF1 and NF2 and PF1 were detrimentally related to social functioning. A discriminant function analysis using all factors classified correctly 84.4 % of participants, with PF1, NF1 followed by NF2 being the best predictors of diagnosis. Expressive negative followed by Experiential negative symptoms are of diagnostic value independent of and beyond SZ-related positive symptoms and are related with detrimental functioning. Findings confirm the need to distinctively target negative symptoms, and specific SZ-related and ASD-related positive symptoms, and especially the use of several assessment tools for diagnostic classification.

Smartband-based smoking detection and real-time brief mindfulness intervention: findings from a feasibility clinical trial.

BACKGROUND: Smartbands can be used to detect cigarette smoking and deliver real time smoking interventions. Brief mindfulness interventions have been found to reduce smoking. OBJECTIVE: This single arm feasibility trial used a smartband to detect smoking and deliver brief mindfulness exercises. METHODS: Daily smokers who were motivated to reduce their smoking wore a smartband for 60 days. For 21 days, the smartband monitored, detected and notified the user of smoking in real time. After 21 days, a 'mindful smoking' exercise was triggered by detected smoking. After 28 days, a 'RAIN' (recognize, allow, investigate, nonidentify) exercise was delivered to predicted smoking. Participants received mindfulness exercises by text message and online mindfulness training. Feasibility measures included treatment fidelity, adherence and acceptability. RESULTS: Participants (N=155) were 54% female, 76% white non-Hispanic, and treatment starters (n=115) were analyzed. Treatment fidelity cutoffs were met, including for detecting smoking and delivering mindfulness exercises. Adherence was mixed, including moderate smartband use and low completion of mindfulness exercises. Acceptability was mixed, including high helpfulness ratings and mixed user experiences data. Retention of treatment starters was high (81.9%). CONCLUSIONS: Findings demonstrate the feasibility of using a smartband to track smoking and deliver quit smoking interventions contingent on smoking.

Sex differences in the acute effects of oral THC: a randomized, placebo-controlled, crossover human laboratory study.

RATIONALE: Recent reports have shown increased cannabis use among women, leading to growing concerns about cannabis use disorder (CUD). While there is preclinical evidence suggesting biological sex influences cannabinoid effects, human research remains scant. We investigated sex differences in the acute response to oral tetrahydrocannabinol (THC) in humans. METHODS: 56 healthy men and women with prior exposure to cannabis but no history of CUD participated in a randomized, placebo-controlled, human laboratory study where they received a single 10 mg dose of oral THC (dronabinol). Subjective psychoactive effects were assessed by the visual analog scale of "high", psychotomimetic effects by the Clinician-Administered Dissociative Symptoms Scale and Psychotomimetic States Inventory, verbal learning and memory by Rey Auditory Verbal Learning Test (RAVLT), and physiological effects by heart rate. Outcomes were regularly measured on the test day, except for the RAVLT, which was assessed once. Peak differences from baseline were analyzed using a nonparametric method for repeated measures. RESULTS: Oral THC (10 mg) demonstrated significant dose-related effects in psychotomimetic and physiological domains, but not in RAVLT outcomes. A notable interaction between THC dose and sex emerged concerning the subjective "high" scores, with women reporting heightened sensations (p = 0.05). No other significant effects of sex and THC dose interaction were observed. CONCLUSION: Oral THC (10 mg) yields similar acute psychotomimetic and physiological effects across sexes, but women may experience a pronounced subjective psychoactive effect. Further research is needed to identify individual vulnerabilities and facilitate tailored interventions addressing CUD. CLINICALTRIALS: GOV REGISTRATION: https://clinicaltrials.gov/study/NCT02781519?term=Ranganathan&intr=THC&rank=3 .

Psychological flexibility as a mechanism of change in psilocybin-assisted therapy for major depression: results from an exploratory placebo-controlled trial.

Several phase II studies have demonstrated that psilocybin-assisted therapy shows therapeutic potential across a spectrum of neuropsychiatric conditions, including major depressive disorder (MDD). However, the mechanisms underlying its often persisting beneficial effects remain unclear. Observational research suggests that improvements in psychological flexibility may mediate therapeutic effects. However, no psychedelic trials to date have substantiated this finding in a clinical sample. In an exploratory placebo-controlled, within-subject, fixed-order study, individuals with moderate to severe MDD were administered placebo (n = 19) followed by psilocybin (0.3 mg/kg) (n = 15) 4 weeks later. Dosing sessions were embedded within a manualized psychotherapy that incorporated principles of Acceptance and Commitment Therapy. Depression severity, psychological flexibility, mindfulness, and values-congruent living were measured over a 16-weeks study period. Psychological flexibility, several facets of mindfulness, and values-congruent living significantly improved following psilocybin and were maintained through week 16. Additionally, improvements in psychological flexibility and experiential acceptance were strongly associated with reductions in depression severity following psilocybin. These findings support the theoretical premise of integrating psilocybin treatment with psychotherapeutic platforms that target psychological flexibility and add to emerging evidence that increasing psychological flexibility may be an important putative mechanism of change in psilocybin-assisted therapy for MDD and potentially, other mental health conditions.

Psilocybin pulse regimen reduces cluster headache attack frequency in the blinded extension phase of a randomized controlled trial.

BACKGROUND: In a recent randomized, double-blind, placebo-controlled study, we observed a nonsignificant reduction of attack frequency in cluster headache after pulse administration of psilocybin (10 mg/70 kg, 3 doses, 5 days apart each). We carried out a blinded extension phase to consider the safety and efficacy of repeating the pulse regimen. METHODS: Eligible participants returned to receive a psilocybin pulse at least 6 months after their first round of study participation. Participants kept headache diaries starting two weeks before and continuing through eight weeks after the first drug session. Ten participants completed the extension phase and all ten were included in the final analysis. RESULTS: In the three weeks after the start of the pulse, cluster attack frequency was significantly reduced from baseline (18.4 [95% confidence interval 8.4 to 28.4] to 9.8 [4.3 to 15.2] attacks/week; p = 0.013, d' = 0.97). A reduction of approximately 50% was seen regardless of individual response to psilocybin in the first round. Psilocybin was well-tolerated without any unexpected or serious adverse events. DISCUSSION: This study shows a significant reduction in cluster attack frequency in a repeat round of pulse psilocybin administration and suggests that prior response may not predict the effect of repeated treatment. To gauge the full potential of psilocybin as a viable medicine in cluster headache, future work should investigate the safety and therapeutic efficacy in larger, more representative samples over a longer time period, including repeating the treatment. CLINICAL TRIALS REGISTRATION: NCT02981173.

The relationship of pain intensity and opioid craving with delayed methadone dose: A preliminary study of individuals with opioid use disorder.

AIMS: Despite a strong theoretical link between opioid craving and pain, little is known about the temporal relationship between pain and craving and the acute experience of pain in the context of methadone treatment. Using a cross-over design, the current study evaluated the time course of pain and craving and objective experience of pain as a function of the last methadone dose. METHODS: Participants (n = 20) presented for the study in the morning and either received methadone dose as scheduled or delayed dose until the afternoon. During the 4-h study visit, participants completed a series of tasks, including repeated assessment of pain and craving at 0, +40, +70, +130, +160 and +240 min and a cold pressor test (CPT) at +15 and +220 min. RESULTS: Separate mixed model results demonstrated no effect of dosing condition on craving; however, there was a significant dosing condition by time interaction (F(5,209) = 3.38, P = .006) such that pain increased over time in the delayed methadone condition but decreased in time in the scheduled methadone condition. A mixed model predicting self-reported pain revealed a three-way interaction between dosing condition, craving and time (F(5,197) = 2.39, P = .039) explained by a positive association between craving and pain at each time point (except 240 min) in delayed condition (P-range = .004-.0001). A separate mixed model on CPT data indicated a significant condition by time interaction such that pain threshold decreased in the delayed, but not scheduled, condition (F(1,57) = 4.01, P = .050). CONCLUSIONS: These preliminary findings highlight the potential for increased risks after even a short delay in receiving a methadone dose.

Differences in diagnostic rules used to determine borderline personality disorder impact prevalence and associations with clinically relevant variables: Findings from the National Epidemiologic Survey on Alcohol and Related Conditions-III.

Borderline personality disorder (BPD) is a serious and understudied mental health condition associated with profound personal and public health consequences. Methodological differences in characterizing BPD may limit understanding the scope of the disorder's prevalence and effect. For example, using different diagnostic rules for BPD can affect apparent prevalence, comorbidity, and clinical presentation. This study examined how differences in diagnostic rules used to assign BPD diagnosis impacted its prevalence and associations with clinically relevant variables (e.g., demographics, comorbidity, treatment-seeking). Participants were a nationally representative sample of 36,309 noninstitutionalized U.S. adults. All variables were assessed via clinical interview (Alcohol Use Disorder and Associated Disabilities Interview Schedule-5). Six diagnostic rules determined BPD status. We used frequencies to examine prevalence rates of and associations between BPD and other clinical variables, and logistic regressions to examine the associations between each BPD variable and the other outcomes. The prevalence of BPD ranged widely-from 0.5% to 11.4%-per the diagnostic rule used. Associations between BPD diagnosis and various outcomes and clinical variables generally remained stable across all diagnostic rules, though effects became more extreme as diagnostic rules became more restrictive. Additionally, meaningful differences emerged as a function of the number of items used (30 vs. 18 items) even with no other changes to diagnostic rules. The field examining BPD and associated problem behaviors should critically consider how to most effectively characterize BPD to understand these problems more accurately and optimize the generalizability of findings. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Sex Differences in the Acute Effects of Oral THC: A Randomized, Placebo-Controlled, Crossover Human Laboratory Study.

Rationale: Recent reports have shown increased cannabis use among women, leading to growing concerns about cannabis use disorder (CUD). Some evidence suggests a faster progression to addiction in women, known as the "telescoping effect." While there is preclinical evidence suggesting biological sex influences cannabinoid effects, human research remains scant. We investigated sex differences in the response to oral tetrahydrocannabinol (THC) in humans. Methods: 56 healthy men and women with prior exposure to cannabis but no history of CUD participated in a randomized, placebo-controlled, human laboratory study where they received a single 10 mg dose of oral THC (dronabinol). Subjective psychoactive effects were assessed by the visual analog scale of "high", psychotomimetic effects by the Clinician-Administered Dissociative Symptoms Scale and Psychotomimetic States Inventory, verbal learning and memory by Rey Auditory Verbal Learning Test (RAVLT), and physiological effects by heart rate. Outcomes were regularly measured on the test day, except for the RAVLT, which was assessed once. Peak differences from baseline were analyzed using a nonparametric method for repeated measures. Results: Oral THC demonstrated significant dose-related effects in psychotomimetic and physiological domains, but not in RAVLT outcomes. A notable interaction between THC dose and sex emerged concerning the subjective "high" scores, with women reporting heightened sensations (p=0.05). No other significant effects of sex and THC dose interaction were observed. Conclusion: Oral THC yields similar psychotomimetic and physiological effects across sexes, but women may experience a pronounced subjective psychoactive effect. Further research is needed to identify individual vulnerabilities and facilitate tailored interventions addressing CUD.

Brief report: The influence of childhood trauma on the effects of delta-9-tetrahydrocannabinol in persons with opioid use disorder.

BACKGROUND AND OBJECTIVES: Childhood trauma (CT) increases addiction vulnerability. We examined CT's impact on delta-9-tetrahydrocannabinol (THC) effects. METHODS: This is a post-hoc analysis of a randomized, placebo-controlled, crossover trial investigating the effects of oral THC (10, 20 mg) among 25 persons receiving methadone for opioid use disorder (OUD). RESULTS: Greater CT was associated with lower aversive effects from higher THC doses (20 mg) (p = .006). DISCUSSION AND CONCLUSIONS: CT may reduce the subjective aversive effects of THC, potentially leading to greater cannabis use in individuals with OUD. SCIENTIFIC SIGNIFICANCE: These findings offer insights into THC's risks versus benefits in OUD subgroups and emphasize assessing CT in OUD treatment and research.

The regional pattern of age-related synaptic loss in the human brain differs from gray matter volume loss: in vivo PET measurement with [11C]UCB-J.

PURPOSE: Aging is a major societal concern due to age-related functional losses. Synapses are crucial components of neural circuits, and synaptic density could be a sensitive biomarker to evaluate brain function. [11C]UCB-J is a positron emission tomography (PET) ligand targeting synaptic vesicle glycoprotein 2A (SV2A), which can be used to evaluate brain synaptic density in vivo. METHODS: We evaluated age-related changes in gray matter synaptic density, volume, and blood flow using [11C]UCB-J PET and magnetic resonance imaging (MRI) in a wide age range of 80 cognitive normal subjects (21-83 years old). Partial volume correction was applied to the PET data. RESULTS: Significant age-related decreases were found in 13, two, and nine brain regions for volume, synaptic density, and blood flow, respectively. The prefrontal cortex showed the largest volume decline (4.9% reduction per decade: RPD), while the synaptic density loss was largest in the caudate (3.6% RPD) and medial occipital cortex (3.4% RPD). The reductions in caudate are consistent with previous SV2A PET studies and likely reflect that caudate is the site of nerve terminals for multiple major tracts that undergo substantial age-related neurodegeneration. There was a non-significant negative relationship between volume and synaptic density reductions in 16 gray matter regions. CONCLUSION: MRI and [11]C-UCB-J PET showed age-related decreases of gray matter volume, synaptic density, and blood flow; however, the regional patterns of the reductions in volume and SV2A binding were different. Those patterns suggest that MR-based measures of GM volume may not be directly representative of synaptic density.

Cognitive training for children with ADHD: composite cognitive score outcome in a randomized controlled trial.

PURPOSE OF THE ARTICLE: Cognitive training for Attention Deficit/Hyperactivity Disorder (ADHD) has shown promising, although mixed results. In post-hoc analyses, we evaluate effects of cognitive training using a novel composite cognition score as the outcome for children attending at least 16 sessions of training, dose-response of training and associations between symptoms and cognitive functioning. MATERIALS AND METHODS: Children (age 6-13) with ADHD were randomized to intervention (n = 26) or control (n = 34). For the current analysis, we restricted the intervention group to children, who completed at least 16 sessions of cognitive training (n = 26) and examined a dose response within that group. RESULTS: Cognition improved significantly in the intervention, but not control group. Amount of the completed training sessions correlated significantly with the amount of cognitive improvement. CONCLUSION: Variations in dose and frequency of training may be an important source of the variance in previous studies.

Protocol description for a randomized controlled trial of fMRI neurofeedback for tics in adolescents with Tourette Syndrome.

This article describes the protocol for a randomized, controlled clinical trial of a neurofeedback (NF) intervention for Tourette Syndrome (TS) and chronic tic disorder. The intervention involves using functional magnetic resonance imaging (fMRI) to provide feedback regarding activity in the supplementary motor area: participants practice controlling this brain area while using the feedback as a training signal. The previous version of this NF protocol was tested in a small study (n = 21) training adolescents with TS that yielded clinically promising results. Therefore, we plan a larger trial. Here we describe the background literature that motivated this work, the design of our original neurofeedback study protocol, and adaptations of the research study protocol for the new trial. We focus on those ideas incorporated into our protocol that may be of interest to others designing and running NF studies. For example, we highlight our approach for defining an unrelated brain region to be trained in the control group that is based on identifying a region with low functional connectivity to the target area. Consistent with a desire for transparency and open science, the new protocol is described in detail here prior to conducting the trial.

Naltrexone/bupropion for binge-eating disorder: A randomized, double-blind, placebo-controlled trial.

OBJECTIVE: Binge-eating disorder (BED) is a prevalent psychiatric disorder associated with obesity. Few evidence-based treatments exist for BED, particularly pharmacological options. This study tested the efficacy of naltrexone/bupropion for BED. METHODS: A randomized, double-blind, placebo-controlled, 12-week trial tested naltrexone/bupropion for BED with and without obesity. Eighty-nine patients (70.8% women, 69.7% White, mean age 45.7 y, mean BMI 35.1 kg/m2 , 77.5% with BMI ≥ 30 kg/m2 ) were randomized to placebo (n = 46) or naltrexone/bupropion (n = 43), with randomization stratified by obesity status and gender; 92.1% completed post-treatment assessments. RESULTS: Mixed models of binge-eating frequency revealed significant reductions that did not differ significantly between naltrexone/bupropion and placebo. Logistic regression of binge-eating remission rates revealed that naltrexone/bupropion and placebo did not differ significantly. Obesity status did not predict, or moderate, binge-eating outcomes considered either continuously or categorically. Mixed models revealed that naltrexone/bupropion was associated with significantly greater percentage weight loss than placebo. Logistic regression revealed that naltrexone/bupropion had significantly higher rates of attaining ≥5% weight loss than placebo (27.9% vs. 6.5%). Obesity status did not predict or moderate weight-loss outcomes. CONCLUSIONS: Naltrexone/bupropion did not demonstrate effectiveness for reducing binge eating relative to placebo but showed effectiveness for weight reduction in patients with BED. Obesity status did not predict or moderate medication outcomes.

Delta-9-tetrahydrocannabinol modulates pain sensitivity among persons receiving opioid agonist therapy for opioid use disorder: A within-subject, randomized, placebo-controlled laboratory study.

The opioid and cannabinoid receptor systems are inextricably linked-overlapping at the anatomical, functional and behavioural levels. Preclinical studies have reported that cannabinoid and opioid agonists produce synergistic antinociceptive effects. Still, there are no experimental data on the effects of cannabinoid agonists among humans who receive opioid agonist therapies for opioid use disorder (OUD). We conducted an experimental study to investigate the acute effects of the delta-9-tetrahydrocannabinol (THC) among persons receiving methadone therapy for OUD. Using a within-subject, crossover, human laboratory design, 25 persons on methadone therapy for OUD (24% women) were randomly assigned to receive single oral doses of THC (10 or 20 mg, administered as dronabinol) or placebo, during three separate 5-h test sessions. Measures of experimental and self-reported pain sensitivity, abuse potential, cognitive performance and physiological effects were collected. Mixed-effects models examined the main effects of THC dose and interactions between THC (10 and 20 mg) and methadone doses (low-dose methadone defined as <90 mg/day; high dose defined as >90 mg/day). Results demonstrated that, for self-reported rather than experimental pain sensitivity measures, 10 mg THC provided greater relief than 20 mg THC, with no substantial evidence of abuse potential, and inconsistent dose-dependent cognitive adverse effects. There was no indication of any interaction between THC and methadone doses. Collectively, these results provide valuable insights for future studies aiming to evaluate the risk-benefit profile of cannabinoids to relieve pain among individuals receiving opioid agonist therapy for OUD, a timely endeavour amidst the opioid crisis.

Discriminating cocaine use from other sympathomimetics using wearable electrocardiographic (ECG) sensors.

BACKGROUND: Our group has established the feasibility of using on-body electrocardiographic (ECG) sensors to detect cocaine use in the human laboratory. The purpose of the current study was to test whether ECG sensors and features are capable of discriminating cocaine use from other non-cocaine sympathomimetics. METHODS: Eleven subjects with cocaine use disorder wore the Zephyr BioHarness™ 3 chest band under six experimental (drug and non-drug) conditions, including 1) laboratory, intravenous cocaine self-administration, 2) after a single oral dose of methylphenidate, 3) during aerobic exercise, 4) during tobacco use (N=7 who smoked tobacco), and 5) during routine activities of daily inpatient living (unit activity). Three ECG-derived feature sets served as primary outcome measures, including 1) the RR interval (i.e., heart rate), 2) a group of ECG interval proxies (i.e., PR, QS, QT and QTc intervals), and 3) the full ECG waveform. Discriminatory power between cocaine and non-cocaine conditions for each of the three outcomes measures was expressed as the area under the receiver operating characteristics (AUROC) curve. RESULTS: All three outcomes successfully discriminated cocaine use from unit activity, exercise, tobacco, and methylphenidate conditions with a mean AUROC values ranging from 0.66 to 0.99 and with least squares means values all statistically different/higher than 0.5 among all subjects [F(3, 99) = 3.38, p =0.02] and among those with tobacco use [F(4, 84) = 5.39, p = 0.0007]. CONCLUSIONS: These preliminary results support discriminatory power of wearable ECG sensors for detecting cocaine use.

Sub-acute effects of psilocybin on EEG correlates of neural plasticity in major depression: Relationship to symptoms.

BACKGROUND: Evidence suggests that serotonergic psychedelics (e.g. psilocybin), have rapid-acting and long-lasting antidepressant effects after a single dose. However, the mechanism underlying these effects remain unclear. One proposed mechanism is that these drugs promote neuroplasticity. However, this has not been conclusively demonstrated in humans. AIMS: We hypothesized that relative to placebo, psilocybin would: (1) increase electroencephalographic (EEG) correlates of neuroplasticity, (2) reduce depression symptoms, and (3) changes in EEG would correlate with improvements in depression. METHODS: In this double-blind, placebo-controlled, within-subject study, individuals with major depressive disorder (MDD; n = 19) were administered placebo followed by psilocybin (0.3 mg/kg) in a fixed order (placebo, followed by psilocybin 4 weeks later). EEG indices of neuroplasticity (tetanus-induced long-term potentiation) as assessed via auditory evoked theta (4-8 Hz) power and measures of depression (GRID Hamilton Rating Scale for Depression-17 (GRID-HAM-D-17)) were measured at several time-points after placebo and psilocybin (24 h and 2 weeks after each session). RESULTS: EEG theta power doubled in amplitude 2 weeks after a single psychedelic dose of psilocybin but not after placebo. Further, improvements in depression symptoms 2 weeks after psilocybin were correlated with increases in theta power. CONCLUSIONS: The increased theta power observed represents evidence of sustained changes in the brain following psilocybin. Given the correlation with enhancement in depressive symptoms, changes in theta may represent an EEG biomarker of the sustained effects of psilocybin, and may shed light on potential mechanisms of psilocybin's antidepressant effect. Taken together, these results complement the emerging notion that psilocybin, and perhaps other psychedelics, can produce long-term alterations in neuroplasticity.

Relationships of in vivo brain norepinephrine transporter and age, BMI, and gender.

Previous research reported an age-related decline in brain norepinephrine transporter (NET) using (S, S)-[11C]O-methylreboxetine ([11C]MRB) as a radiotracer. Studies with the same tracer have been mixed in regard to differences related to body mass index (BMI). Here, we investigated potential age-, BMI-, and gender-related differences in brain NET availability using [11C]MRB, the most selective available radiotracer. Forty-three healthy participants (20 females, 23 males; age range 18-49 years), including 12 individuals with normal/lean weight, 15 with overweight, and 16 with obesity were scanned with [11C]MRB using a positron emission tomography (PET) high-resolution research tomograph (HRRT). We evaluated binding potential (BPND ) in brain regions with high NET availability using multilinear reference tissue model 2 (MRTM2) with the occipital cortex as a reference region. Brain regions were delineated with a defined anatomic template applied to subjects' structural MR scans. We found a negative association between age and NET availability in the locus coeruleus, raphe nucleus, and hypothalamus, with a 17%, 19%, and 14% decrease per decade, respectively, in each region. No gender or BMI relationships with NET availability were observed. Our findings suggest an age-related decline, but no BMI- or gender-related differences, in NET availability in healthy adults.

Preliminary study of the interactive effects of THC and ethanol on self-reported ability and simulated driving, subjective effects, and cardiovascular responses.

RATIONALE: Drug- and alcohol-related motor vehicle accidents are a leading cause of morbidity and mortality worldwide. Compared to alcohol, less is known about the effects of cannabis on driving and even less about their combined effects. OBJECTIVE: To characterize the combined and separate effects of ethanol and tetrahydrocannabinol (THC) on perceived ability to drive, subjective effects, and simulated driving. METHODS: In a within-subject (crossover), randomized, placebo-controlled, double-blind, 2 × 2 design, the effects of oral THC (10 mg [dronabinol] or placebo) and low-dose intravenous ethanol (clamped at BAC 0.04% or placebo) on perceived ability to drive, simulated driving (standard deviation of lateral position [SDLP]), subjective effects (e.g., "high"), and physiological effects (e.g., heart rate) were studied in healthy humans (n = 18). RESULTS: Subjects reported reductions in perceived ability to drive (THC < ethanol < combination) which persisted for ~ 6 h (placebo = ethanol, THC < combination). Ethanol and THC produced synergistic effects on heart rate, significant differences compared to either drug alone on perceived ability to drive and feeling states of intoxication (e.g., high), as well increases in SDLP compared to placebo. CONCLUSIONS: Perceived ability to drive is reduced under the influence of THC against the backdrop of blood alcohol levels that are below the legal limit. People should be aware that the effects of oral THC on driving may persist for up to six hours from administration. Findings are relevant to the increasingly common practice of combining alcohol and cannabinoids and the effects on driving.