Associations between regular cannabis use and brain resting-state functional connectivity in adolescents and adults

BACKGROUND/AIM

Cannabis use is highly prevalent in adolescents; however, little is known about its effects on adolescent brain function.

METHOD

Resting-state functional magnetic resonance imaging was used in matched groups of regular cannabis users (N = 70, 35 adolescents: 16-17 years old, 35 adults: 26-29 years old) and non-regular-using controls (N = 70, 35 adolescents/35 adults). Pre-registered analyses examined the connectivity of seven major cortical and sub-cortical brain networks (default mode network, executive control network (ECN), salience network, hippocampal network and three striatal networks) using seed-based analysis methods with cross-sectional comparisons between user groups and age groups.

RESULTS

The regular cannabis use group (across both age groups), relative to controls, showed localised increases in connectivity only in the ECN analysis. All networks showed localised connectivity differences based on age group, with the adolescents generally showing weaker connectivity than adults, consistent with the developmental effects. Mean connectivity across entire network regions of interest (ROIs) was also significantly decreased in the ECN in adolescents. However, there were no significant interactions found between age group and user group in any of the seed-based or ROI analyses. There were also no associations found between cannabis use frequency and any of the derived connectivity measures.

CONCLUSION

Regular cannabis use is associated with changes in connectivity of the ECN, which may reflect allostatic or compensatory changes in response to regular cannabis intoxication. However, these associations were not significantly different in adolescents compared to adults.

Increased low-frequency brain responses to music after psilocybin therapy for depression

BACKGROUND

Psychedelic-assisted psychotherapy with psilocybin is an emerging therapy with great promise for depression, and modern psychedelic therapy (PT) methods incorporate music as a key element. Music is an effective emotional/hedonic stimulus that could also be useful in assessing changes in emotional responsiveness following PT.

METHODS

Brain responses to music were assessed before and after PT using functional Magnetic Resonance Imaging (fMRI) and ALFF (Amplitude of Low Frequency Fluctuations) analysis methods. Nineteen patients with treatment-resistant depression underwent two treatment sessions involving administration of psilocybin, with MRI data acquired one week prior and the day after completion of psilocybin dosing sessions.

RESULTS

Comparison of music-listening and resting-state scans revealed significantly greater ALFF in bilateral superior temporal cortex for the post-treatment music scan, and in the right ventral occipital lobe for the post-treatment resting-state scan. ROI analyses of these clusters revealed a significant effect of treatment in the superior temporal lobe for the music scan only. Voxelwise comparison of treatment effects showed relative increases for the music scan in the bilateral superior temporal lobes and supramarginal gyrus, and relative decreases in the medial frontal lobes for the resting-state scan. ALFF in these music-related clusters was significantly correlated with intensity of subjective effects felt during the dosing sessions.

LIMITATIONS

Open-label trial. Relatively small sample size.

CONCLUSIONS

These data suggest an effect of PT on the brain's response to music, implying an elevated responsiveness to music after psilocybin therapy that was related to subjective drug effects felt during dosing.

Effects of Kisspeptin on Sexual Brain Processing and Penile Tumescence in Men With Hypoactive Sexual Desire Disorder: A Randomized Clinical Trial

IMPORTANCE

The human physiological sexual response is crucial for reward, satisfaction, and reproduction. Disruption of the associated neurophysiological pathways predisposes to low sexual desire; the most prevalent psychological form is hypoactive sexual desire disorder (HSDD), which affects 8% of men but currently has no effective pharmacological treatment options. The reproductive neuropeptide kisspeptin offers a putative therapeutic target, owing to emerging understanding of its role in reproductive behavior.

OBJECTIVE

To determine the physiological, behavioral, neural, and hormonal effects of kisspeptin administration in men with HSDD.

DESIGN, SETTING, AND PARTICIPANTS

This double-blind, 2-way crossover, placebo-controlled randomized clinical trial was performed at a single academic research center in the UK. Eligible participants were right-handed heterosexual men with HSDD. Physiological, behavioral, functional magnetic resonance imaging (fMRI), and hormonal analyses were used to investigate the clinical and mechanistic effects of kisspeptin administration in response to visual sexual stimuli (short and long video tasks). The trial was conducted between January 11 and September 15, 2021, and data analysis was performed between October and November 2021.

INTERVENTIONS

Participants attended 2 study visits at least 7 days apart, in balanced random order, for intravenous infusion of kisspeptin-54 (1 nmol/kg/h) for 75 minutes or for administration of a rate-matched placebo.

MAIN OUTCOMES AND MEASURES

Changes in (1) brain activity on whole-brain analysis, as determined by fMRI blood oxygen level-dependent activity in response to visual sexual stimuli during kisspeptin administration compared with placebo, (2) physiological sexual arousal (penile tumescence), and (3) behavioral measures of sexual desire and arousal.

RESULTS

Of the 37 men randomized, 32 completed the trial. Participants had a mean (SD) age of 37.9 (8.6) years and a mean (SD) body mass index of 24.9 (5.4). On viewing sexual videos, kisspeptin significantly modulated brain activity in key structures of the sexual-processing network on whole-brain analysis compared with placebo (mean absolute change [Cohen d] = 0.81 [95% CI, 0.41-1.21]; P =  .003). Furthermore, improvements in several secondary analyses were observed, including significant increases in penile tumescence in response to sexual stimuli (by up to 56% more than placebo; mean difference = 0.28 units [95% CI, 0.04-0.52 units]; P = .02) and behavioral measures of sexual desire-most notably, increased happiness about sex (mean difference = 0.63 points [95% CI, 0.10-1.15 points]; P = .02).

CONCLUSIONS AND RELEVANCE

Collectively, this randomized clinical trial provides the first evidence to date showing that kisspeptin administration substantially modulates sexual brain processing in men with HSDD, with associated increases in penile tumescence and behavioral measures of sexual desire and arousal. These data suggest that kisspeptin has potential as the first pharmacological treatment for men with low sexual desire.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN17271094.

OR17-5 Kisspeptin Increases Penile Tumescence and Sexual Brain Processing in Men with Hypoactive Sexual Desire Disorder

Background

Hypoactive Sexual Desire Disorder (HSDD) is associated with dysfunctional brain activation in regions governing sexual responses, resulting in a deficiency or absence of sexual desire with marked distress. It is of major clinical importance given it affects 8% of men with detrimental effects on quality of life, interpersonal relationships and fertility, but so far has no licensed treatment options. The reproductive neuropeptide kisspeptin offers a putative therapeutic target owing to its emerging role in modulating reproductive behaviour in animal models and healthy men. However, there are no studies examining its effects in HSDD. To address this, we performed the first clinical study of kisspeptin in men with HSDD.

Methods

We examined the effects of kisspeptin administration (vs placebo) on brain activity during short and long erotic video tasks using functional MRI in 32 men with HSDD (mean ±SEM age 37.9 ±1.5 y, BMI 24.9 ±1.0 kg/m2). The short video task used 20-second segments of erotic video with non-erotic video as control. During the long video task, participants viewed a continuous eight-minute erotic video. To provide functional and behavioural relevance for the associated fMRI brain responses during the long erotic video, simultaneous penile tumescence and subjective level of arousal were recorded. Participants also completed psychometric and behavioural questionnaires. Standard analysis methods were used for fMRI data from the short videos task, and the long videos task used regressors derived from the subjective arousal and penile tumescence data. The statistical threshold used for both was Z=2.3, p < 0.05 (cluster-corrected).

Results

In response to visual erotic stimuli, kisspeptin administration significantly increased penile tumescence during the long video task compared to placebo, with kisspeptin increasing penile tumescence by 56% at six-minutes (p=0.002). In addition, kisspeptin increased participant-reported happiness about sex (p=0.02). During both video tasks, kisspeptin significantly modulated brain activity compared to placebo in key structures of the sexual-processing network, providing a mechanistic pathway for the increases in physiological and behavioural measures. In response to short erotic videos, kisspeptin enhanced left middle frontal gyrus and left anterior cingulate activity, and decreased activity in bilateral parahippocampus (all p<0.05). During the long video task, kisspeptin enhanced right fusiform gyrus and bilateral visual cortex activity, and decreased left frontal pole, right posterior cingulate and bilateral precuneus activity (all <0.05). Additionally, we observed positive correlations between the effects of kisspeptin on aforementioned brain activity and psychometric parameters of sexual desire and arousal (all p<0.01).

Conclusion

Collectively, we demonstrate for the first time that kisspeptin administration in men with HSDD increases penile tumescence and psychometric measures of sexual desire and arousal by modulating sexual brain processing. Taken together, our data suggest that kisspeptin-based therapeutics may offer a novel, effective and much-needed clinical strategy for men with HSDD.

Presentation: Sunday, June 12, 2022 12:00 p.m. - 12:15 p.m.

PMON214 Kisspeptin Restores Sexual and Attraction Brain Processing in Women with Hypoactive Sexual Desire Disorder

Introduction

Sexual desire is a key component of the sexual response model. Absence or deficiency of sexual desire can lead to marked distress or interpersonal difficulty, termed 'hypoactive sexual desire disorder' (HSDD). HSDD is the most common female sexual health complaint worldwide, affecting 10% of women. Despite its detrimental impact on psychological well-being and quality of life, treatment options are currently limited. The hormone kisspeptin is a key endogenous activator of the reproductive endocrine axis, with emerging roles in sexual and emotional behaviour, and thus could serve as a novel treatment option in women with HSDD.

Hypothesis

Kisspeptin restores sexual brain processing in women with HSDD.

Methods

To test our hypothesis, we performed a randomized, double-blind, two-way crossover, placebo-controlled study in 32 (mean age ± SEM 29.2±1.2 years; BMI 23.1±0.5 kg/m2) premenopausal women with HSDD using psychometric assessments, functional neuroimaging, and hormonal assessments to investigate the effects of kisspeptin administration on brain activity, in response to erotic stimuli (erotic videos) and facial attraction (face images of varying attractiveness). Study visits were undertaken in the early follicular phase of the menstrual cycle.

Results

Kisspeptin administration resulted in an increase in self-reported ratings of feeling 'sexy', compared to placebo, measured using the Sexual Arousal and Desire Inventory (t [32] =2.27, P=0.03). On functional MRI, kisspeptin administration deactivated the left inferior frontal gyrus and activated the postcentral and supramarginal gyrus in response to erotic videos (Z=2.3, P< 0.05). Kisspeptin administration deactivated the secondary somatosensory cortex (Z=2.3, P<0.05) and enhanced activation in the posterior cingulate cortex on viewing male faces, which correlated with a reduction in self-reported sexual aversion (r=0.476, P=0.005). Kisspeptin resulted in a mean increase in LH of 2.75 iU/L (F(1, 62) = 6.084, P=0.02) and FSH of 0.37 iU/L (F(1, 62) = 4.030, P=0.05) across the 75-minute duration of the study, with no effect observed on downstream circulating estradiol, progesterone or testosterone levels.

Interpretation of results and conclusionsDeactivation of the left inferior frontal gyrus by kisspeptin administration likely serves to reduce the internal monologue and response inhibition. Furthermore, kisspeptin's deactivation of the secondary somatosensory cortex can reduce a woman's focus on herself, her body image, and related negative thoughts, thus augmenting her judgement of male facial attractiveness. Finally, kisspeptin's actions in the posterior cingulate cortex can serve to increase feelings of romantic love and reward processing, thereby reducing sexual aversion and increasing sexual desire. Collectively these brain changes provide mechanistic insights for the observed increase in sexual desire and attraction during kisspeptin administration in women with HSDD.

These behavioural and mechanistic findings in women with HSDD lay the foundations for clinical applications for kisspeptin in psychosexual disorders.

Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

RF01 | PMON43 Melanocortin-4 Receptor Agonism Enhances Sexual Brain Processing in Women with Hypoactive Sexual Desire Disorder

Introduction

Hypoactive sexual desire disorder (HSDD) is characterized by a persistent deficiency of sexual fantasies and desire for sexual activity, causing marked distress or interpersonal difficulty. It is the most prevalent female sexual health problem worldwide, affecting approximately 1 in 10 women, but has limited treatment options despite its substantial health, social, and economic burden. Melanocortin-4 receptor (MC4R) agonists have emerged as a promising therapy for women with HSDD, although, to date, their mechanism of action is unknown. This study aims to use functional MRI to delineate the reproductive neuroendocrine pathways involved and elucidate how MC4R agonists treat HSDD in women.

Methods

We conducted a randomized, double-blinded, placebo-controlled, crossover clinical study, using psychometric, functional neuroimaging and hormonal analyses, to assess the effects of MC4R agonism on sexual brain processing in 31 premenopausal women with HSDD. Participants attended on two occasions, receiving either a subcutaneous injection of an MC4R agonist (Bremelanotide 1.75 mg), or placebo, at each study visit, thereby acting as their own controls.

Results

31 randomized women were included (mean age 32 years, mean duration of HSDD 41 months). MC4R agonism significantly increased self-reported sexual desire for up to 24-hours post administration, compared to placebo (P=0.007). During functional neuroimaging, MC4R agonism enhanced cerebellar and supplementary motor area activity, as well as deactivating the secondary somatosensory cortex, specifically in response to visual erotic videos, compared to placebo (Z=2.3, P<0.05). In addition, MC4R agonism enhanced functional connectivity between the amygdala-insula and amygdala-thalamus during prolonged visual erotic stimuli, compared to placebo (P=0.025). MC4R agonism resulted in a mean increase in LH of 1.1 iU/L (F [1,58] = 13.38, P=0.0005), and FSH of 0.35 iU/L (F [1,60] = 10.97, P=0.0016) across the 300-minute duration of the study, with no effect observed on circulating estradiol or progesterone levels.

Interpretation of results and conclusions:We demonstrate that MC4R agonism deactivates the secondary somatosensory cortex which can reduce the detrimental self-monitoring process often observed in HSDD, thereby increasing sexual desire. Furthermore, cerebellar and supplementary motor area activation by MC4R agonism are associated with increased sexual arousal and sexual motor imagery respectively. Finally, MC4R agonism enhanced functional connectivity between key limbic structures which can be disrupted in HSDD.

In summary, these data identify the previously undescribed neural substrates and connections through which MC4R agonism modulates sexual brain processing to increase sexual desire. These findings provide mechanistic insight for the action of MC4R agonism in sexual behaviour and are relevant to ongoing therapeutic development for HSDD and for MC4R agonist development more widely.

Trial registration: ClinicalTrials.gov identifier NCT04179734.Funding: Investigator-sponsored study funded by AMAG Pharmaceuticals Inc, MRC and NIHR.

Presentation: Saturday, June 11, 2022 1:00 p.m. - 1:05 p.m., Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.

Melanocortin 4 receptor agonism enhances sexual brain processing in women with hypoactive sexual desire disorder

BACKGROUND

Hypoactive sexual desire disorder (HSDD) is characterized by a persistent deficiency of sexual fantasies and desire for sexual activity, causing marked distress and interpersonal difficulty. It is the most prevalent female sexual health problem globally, affecting approximately 10% of women, but has limited treatment options. Melanocortin 4 receptor (MC4R) agonists have emerged as a promising therapy for women with HSDD, through unknown mechanisms. Studying the pathways involved is crucial for our understanding of normal and abnormal sexual behavior.

METHODS

Using psychometric, functional neuroimaging, and hormonal analyses, we conducted a randomized, double-blinded, placebo-controlled, crossover clinical study to assess the effects of MC4R agonism compared with placebo on sexual brain processing in 31 premenopausal heterosexual women with HSDD.

RESULTS

MC4R agonism significantly increased sexual desire for up to 24 hours after administration compared with placebo. During functional neuroimaging, MC4R agonism enhanced cerebellar and supplementary motor area activity and deactivated the secondary somatosensory cortex, specifically in response to visual erotic stimuli, compared with placebo. In addition, MC4R agonism enhanced functional connectivity between the amygdala and the insula during visual erotic stimuli compared with placebo.

CONCLUSION

These data suggest that MC4R agonism enhanced sexual brain processing by reducing self-consciousness, increasing sexual imagery, and sensitizing women with HSDD to erotic stimuli. These findings provide mechanistic insight into the action of MC4R agonism in sexual behavior and are relevant to the ongoing development of HSDD therapies and MC4R agonist development more widely.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04179734.

FUNDING

This is an investigator-sponsored study funded by AMAG Pharmaceuticals Inc., the Medical Research Council (MRC) (MR/T006242/1), and the National Institute for Health Research (NIHR) (CS-2018-18-ST2-002 and RP-2014-05-001).

Effects of Kisspeptin Administration in Women With Hypoactive Sexual Desire Disorder: A Randomized Clinical Trial

IMPORTANCE

Despite being the most common female sexual health complaint worldwide, current treatment options for hypoactive sexual desire disorder (HSDD) are limited in their safety and effectiveness. The hormone kisspeptin is a key endogenous activator of the reproductive hormonal axis with additional emerging roles in sexual and emotional behavior; however, its effects in women with HSDD are unknown.

OBJECTIVE

To test the hypothesis that kisspeptin enhances sexual and attraction brain processing in women with HSDD.

DESIGN, SETTING, AND PARTICIPANTS

This randomized clinical trial was double-masked and placebo controlled with a 2-way crossover. The trial was conducted in a university research setting in the UK from October 2020 to April 2021. Eligible participants were premenopausal women with HSDD. Functional neuroimaging, psychometric, and hormonal analyses were employed to investigate the effects of kisspeptin administration on brain processing, in response to erotic stimuli (erotic videos) and facial attraction (face images of varying attractiveness). Data were analyzed from May to December 2021.

INTERVENTIONS

A 75-minute intravenous infusion of kisspeptin-54 (1 nmol/kg/h) vs equivalent-rate placebo infusion.

MAIN OUTCOMES AND MEASURES

Blood oxygen level-dependent responses across the whole brain and regions of interest during kisspeptin vs placebo administration in response to erotic and facial attraction stimuli.

RESULTS

Of the 40 participants who were randomized, 32 women completed both kisspeptin and placebo visits, with a mean (SE) age of 29.2 (1.2) years. Kisspeptin administration resulted in modulations in sexual and facial attraction brain processing (deactivation of the left inferior frontal gyrus: Z max, 3.76; P = .01; activation of the right postcentral and supramarginal gyrus: Z max, 3.73; P < .001; deactivation of the right temporoparietal junction: Z max 4.08; P = .02). Furthermore, positive correlations were observed between kisspeptin-enhanced hippocampal activity in response to erotic videos, and baseline distress relating to sexual function (r = 0.469; P = .007). Kisspeptin's enhancement of posterior cingulate cortex activity in response to attractive male faces also correlated with reduced sexual aversion, providing additional functional significance (r = 0.476, P = .005). Kisspeptin was well-tolerated with no reported adverse effects.

CONCLUSIONS AND RELEVANCE

These findings lay the foundations for clinical applications for kisspeptin in women with HSDD.

TRIAL REGISTRATION

ISRCTN trial registry identifier: ISRCTN17271094.

Individual and combined effects of cannabidiol and Δ9-tetrahydrocannabinol on striato-cortical connectivity in the human brain

BACKGROUND

Cannabidiol (CBD) and Δ⁹-tetrahydrocannabinol (THC) are the two major constituents of cannabis with contrasting mechanisms of action. THC is the major psychoactive, addiction-promoting, and psychotomimetic compound, while CBD may have opposite effects. The brain effects of these drugs alone and in combination are poorly understood. In particular, the striatum is implicated in the pathophysiology of several psychiatric disorders, but it is unclear how THC and CBD influence striato-cortical connectivity.

AIMS

To examine effects of THC, CBD, and THC + CBD on functional connectivity of striatal sub-divisions (associative, limbic and sensorimotor).

METHOD

Resting-state functional Magnetic Resonance Imaging (fMRI) was used across two within-subjects, placebo-controlled, double-blind studies, with a unified analysis approach.

RESULTS

Study 1 (N = 17; inhaled cannabis containing 8 mg THC, 8 mg THC + 10 mg CBD or placebo) showed strong disruptive effects of both THC and THC + CBD on connectivity in the associative and sensorimotor networks, but a specific effect of THC in the limbic striatum network which was not present in the THC + CBD condition. In Study 2 (N = 23, oral 600 mg CBD, placebo), CBD increased connectivity in the associative network, but produced only relatively minor disruptions in the limbic and sensorimotor networks.

OUTCOMES

THC strongly disrupts striato-cortical networks, but this effect is mitigated by co-administration of CBD in the limbic striatum network. Oral CBD administered has a more complex effect profile of relative increases and decreases in connectivity. The insula emerges as a key region affected by cannabinoid-induced changes in functional connectivity, with potential implications for understanding cannabis-related disorders, and the development of cannabinoid therapeutics.

Theory of medical scoring systems and a practical method to evaluate Asian elephant (Elephas maximus) foot health in European zoos

Several established models in human and veterinary medicine exist to evaluate an individual health or disease status. Many of these seem unsuitable for further epidemiological research aimed at discovering underlying influential factors. As a case example for score development and choice, the present study analyses different approaches to scoring the foot health of Asian elephants (Elephas maximus) living in European facilities. Sum scores with varying degree of detail, and without or with a weighting method, were compared using descriptive statistics, ie kurtosis, skewness, Shannon entropy, total redundancy, their maximum and their actual ranges. With increasing score complexity, a higher level of differentiation was reached. In parallel, the distribution of score frequencies in the population shifted systematically: with the least complex scoring model the pattern indicated a severely unhealthy population with an opposite skew to a hypothetically healthy population, whereas the most complex scoring model indicated a mildly affected population with a skew corresponding to that expected for a healthy population. We propose the latter, in the form of the Particularised Severity Score (ParSev), which accounts for every nail and pad individually and weights the sub-scores by squaring, as the most relevant score for further investigations, either in assessing changes within an elephant population over time, or correlating foot health in epidemiological studies to potentially influencing factors. Our results emphasise the relevance of choosing appropriate scoring models for welfare-associated evaluations, due to implications for the applicability as well as the perceived welfare status of the test population.

Choosing successful managers. Participative selection can help

The attitude and behavior of first line managers can greatly influence the success of any health care organization. Managers directly affect 90 to 95 percent of the workers in a hospital. This article offers a specific description of a new process that allows staff to participate in management selection. The author shows how the process, which is a truly participative form of management, increases the success potential of new health care managers.