Neural response to visual sexual cues in dopamine treatment-linked hypersexuality in Parkinson's disease

The relationship between Parkinson's disease and sexual hyperactivity secondary to drug treatment: A systematic review

INTRODUCTION

This review addresses the prevalence of hypersexual behavior in Parkinson's patients and the underlying neurobiological mechanisms, identifying risk and protective factors, comparing incidence among different treatments, and proposing recommendations for management and prevention.

OBJECTIVE

To conduct a review on the relationship between Parkinson's disease and hypersexual behavior as a result of pharmacological treatment.

METHODOLOGY

The search strategy, guided by PRISMA and PICOS criteria, focuses on the correlation between Parkinson's disease and hypersexual behavior due to pharmacological treatment. Utilizing databases like PubMed and Proquest, studies from the last 10 years in English or Spanish were selected, emphasizing clinical trials with Parkinson's patients under treatment. Inaccessible, irrelevant, or mixed-sample studies were excluded. The Cochrane Scale assessed the risk of bias.

RESULTS

Out of 122 records, 103 remained after eliminating duplicates; 48 were reviewed, and ultimately, 6 studies met the inclusion criteria for analysis.

CONCLUSIONS

Synthesizing the risk and protective factors linked to hypersexual behavior in Parkinson's patients receiving pharmacological treatment underscores the critical need for early detection and incorporation of these factors into clinical care. The suggested guidelines for managing and preventing hypersexual behavior in these patients carry substantial practical implications.

Imaging of impulse control disorders in Parkinson's disease

Impulse control disorders (ICD) are frequent and cumbersome behavioral disorders in patients with Parkinson's disease (PD). Understanding their pathophysiological underpinnings is crucial. Molecular imaging using positron emission tomography (PET) and single-photon emission computed tomography (SPECT) clearly indicates preexisting vulnerability and abnormal sensitization of the pre- and postsynaptic dopaminergic system. Functional magnetic resonance imaging (fMRI) studies reveal abnormal connectivity within the reward system involving the ventral striatum and orbitofrontal cortex. These alterations pinpoint the dysfunction of reinforcement learning in ICD, which is biased toward the overvaluation of reward and underestimation of risk, and the deficit in inhibitory control mechanisms related to abnormal connectivity within and between the limbic and the associative and motor networks.

A qualitative study exploring the clinical phenomenology and impact of hypersexuality in patients with Parkinson's Disease

Hypersexuality (HS) is a complex yet underreported phenomenon in Parkinson's disease (PD), profoundly impacting patients' lives. This study aims to systematically investigate the clinical phenomenology and manifestations of HS using qualitative methodologies. This phenomenological qualitative research study employed semi-structured interviews to examine hypersexuality and its impact among nine English-speaking individuals with PD. Participants were recruited from clinical settings and met specific inclusion criteria, including clinically diagnosed PD, reported hypersexuality post-PD diagnosis, and no cognitive impairment. The study adhered to ethical standards, with written informed consent obtained from all participants. Nine patients with PD (six males, mean age 61.7 ± 13.3 years, and three females, mean age 64.3 ± 5.7 years) participated. The mean age of PD onset was 51.4 ± 12.5 years, while HS onset was 54.1 ± 11.5 years, ranging from 35 to 68 years. Eight of the nine patients were in monogamous relationships. Qualitative analysis revealed ten themes. Clinical manifestations included increased preoccupation with sex, heightened desire, and altered behaviors like risk-taking. Sexual practices varied, with increased urges not necessarily leading to more frequent sex with partners; instead, behaviors like masturbation and promiscuity were common. Emotional formulations ranged from negative to neutral, influenced by whether patients internalized or externalized their hypersexuality. Insight varied, with some patients viewing HS as natural and others seeing it as conflicting with their values. Control over HS was mixed, with efforts to manage behaviors influenced by personal or external factors. The impact on life was predominantly negative, affecting marital closeness, family dynamics, social interactions, work efficiency, and physical health. Patients perceived mostly negative feelings from their partners regarding HS. Stigma was significant, including personal shame, social concealment, and discomfort discussing HS with health professionals. Barriers to seeking help included communication deficits, professional neglect, and stigma. Despite challenges, patients expressed a desire for better guidance and open discussions with health professionals to manage HS. This study uncovered the profound impact of HS on various facets of life such as quality of life, work, and personal relationships, elucidating the emotional distress and societal challenges faced by patients. This preliminary study on hypersexuality in neurological disorders suggests multiple avenues for future research.

Hypersexuality in neurological disorders: A systematic review

BACKGROUND

Hypersexuality (HS) accompanying neurological conditions remains poorly characterized despite profound psychosocial impacts. Objective We aimed to systematically review the literature on HS in patients with neurological disorders. Study selection and analysis We conducted a systematic review to identify studies that reported HS in neurological disorders. HS was defined as a condition characterized by excessive and persistent preoccupation with sexual thoughts, urges, and behaviors that cause significant distress or impairment in personal, social, or occupational functioning. Data on demographics, assessment techniques, associated elements, phenotypic manifestations, and management strategies were also extracted. Findings The final analysis included 79 studies on HS, encompassing 32 662 patients across 81 cohorts with neurological disorders. Parkinson's disease was the most frequently studied condition (55.6%), followed by various types of dementia (12.7%). Questionnaires were the most common assessment approach for evaluating HS, although the techniques varied substantially. Alterations in the dopaminergic pathways have emerged as contributing mechanisms based on the effects of medication cessation. However, standardized treatment protocols still need to be improved, with significant heterogeneity in documented approaches. Critical deficiencies include risks of selection bias in participant sampling, uncontrolled residual confounding factors, and lack of blinded evaluations of reported outcomes. Conclusions and clinical implications Despite growth in the last decade, research on HS remains limited across neurological conditions, with lingering quality and methodological standardization deficits. Key priorities include advancing assessment tools, elucidating the underlying neurobiology, and formulating management guidelines.

PROSPERO REGISTRATION NUMBER

CRD42017036478.

A circuit-based approach to modulate hypersexuality in Parkinson's disease

AIM

Impulse-control disorder is a common neuropsychiatric complication in Parkinson's disease (PD) under dopamine replacement therapy. Prior studies tested the balance between enhanced desire towards reward and cognitive control deficits, hypothesized to be biased towards the former in impulse control disorders. We provide evidence for this hypothesis by measuring behavioral and neural patterns behind the influence of sexual desire over response inhibition and tools towards functional restoration using repetitive transcranial stimulation in patients with hypersexuality as predominant impulsive disorder.

METHODS

The effect of sexual cues on inhibition was measured with a novel erotic stop-signal task under on and off dopaminergic medication. Task-related functional and anatomical connectivity models were estimated in 16 hypersexual and 17 nonhypersexual patients with PD as well as in 17 healthy controls. Additionally, excitatory neuromodulation using intermittent theta-burst stimulation (sham-controlled) was applied over the pre-supplementary motor area in 20 additional hypersexual patients with PD aiming to improve response inhibition.

RESULTS

Compared with their nonhypersexual peers, patients with hypersexuality recruited caudate, pre-supplementary motor area, ventral tegmental area, and anterior cingulate cortex while on medication. Reduced connectivity was found between pre-supplementary motor area and caudate nucleus in hypersexual compared with nonhypersexual patients (while medicated), a result paralleled by compensatory enhanced anatomical connectivity. Furthermore, stimulation over the pre-supplementary motor area improved response inhibition in hypersexual patients with PD when exposed to sexual cues.

CONCLUSION

This study, therefore, has identified a specific fronto-striatal and mesolimbic circuitry underlying uncontrolled sexual responses in medicated patients with PD where cortical neuromodulation halts its expression.

Exploring the underlying mechanisms of drug-induced impulse control disorders: a pharmacovigilance-pharmacodynamic study

INTRODUCTION

Impulse control disorders (e.g. pathological gambling, hypersexuality) may develop as adverse reactions to drugs. Pathogenetic hypotheses have mainly focused on D3-receptor agonism, and switching to alternatives with different pharmacologic mechanisms represents a common management strategy. Nonetheless, treatment failure is common and gaining pathophysiological insights is needed.

AIM

We aimed to identify targets potentially contributing to pathologic impulsivity.

METHOD

We performed a pharmacovigilance-pharmacodynamic study on dopamine agonists and antipsychotics using the Food and Drug Administration Adverse Event Reporting System (January 2004-December 2021). We estimated disproportionate reporting using the Bayesian information component. Using online public databases (IUPHAR, ChEMBL, PDSP, DrugBank), we calculated drug occupancies. To identify the targets potentially contributing to impulsivity, we fitted univariate regression models interpolating information components and occupancies within dopamine agonists and antipsychotics. Sensitivity analyses were performed to check for the robustness of the results.

RESULTS

Among 19 887 reports of impulsivity, 5898 recorded an antipsychotic, and 3100 a dopamine agonist. The more robust signals concerned aripiprazole (N = 3091; median information component [95% confidence interval] = 4.51[4.45-4.55]) and brexpiprazole (229; 4.00[3.78-4.16]) for antipsychotics, pergolide (105; 5.82[5.50-6.06]) and pramipexole (2009; 5.43[5.36-5.48]) for dopamine agonists. Robust, significant positive associations between drug occupancy and impulsivity reporting were found for D3 within dopamine agonists (beta = 1.52; P-value = 0.047) and 5-HT1a within antipsychotics (1.92, 0.029).

CONCLUSION

Our results supported the role of D3-receptor agonism in inducing impulsivity in dopamine receptor agonists and identified a potential role of 5-HT1a receptor agonism in antipsychotics. Investigating these receptors may drive towards a better management of drug-induced impulsivity.

Neural correlates of impulsive compulsive behaviors in Parkinson's disease: A Japanese retrospective study

BACKGROUND

Impulsive compulsive behaviors (ICBs) often disturb patients with Parkinson's Disease (PD), of which impulse control disorder (ICD) and dopamine dysregulation syndrome (DDS) are two major subsets. The nucleus accumbens (NAcc) is involved in ICB; however, it remains unclear how the NAcc affects cortical function and defines the different behavioral characteristics of ICD and DDS.

OBJECTIVES

To identify the cortico-striatal network primarily involved in ICB and the differences in these networks between patients with ICD and DDS using structural and resting-state functional magnetic resonance imaging.

METHODS

Patients with PD were recruited using data from a previous cohort study and divided into those with ICB (ICB group) and without ICB (non-ICB group) using the Japanese version of the Questionnaire for Impulsive Compulsive Disorders in Parkinson's Disease (J-QUIP). From these two groups, we extracted 37 pairs matched for age, sex, disease duration, and levodopa equivalent daily dose of dopamine agonists. Patients with ICB were further classified as having ICD or DDS based on the J-QUIP subscore. General linear models were used to compare gray matter volume and functional connectivity (FC) of the NAcc, caudate, and putamen between the ICB and non-ICB groups and between patients with ICD and those with DDS.

RESULTS

We found no significant differences in gray matter volumebetween the ICB and non-ICB groups or between patients with ICD and those with DDS. Compared with the non-ICB group, the FC of the right NAcc in the ICB group was lower in the bilateral ventromedial prefrontal cortex and higher in the left middle occipital gyrus. Furthermore, patients with DDS showed higher FC between the right putamen and left superior temporal gyrus and higher FC between the left caudate and bilateral middle occipital gyrus than patients with ICD. In contrast, patients with ICD exhibited higher FC between the left NAcc and the right posterior cingulate cortex than patients with DDS.

CONCLUSIONS

The functionally altered network between the right NAcc and ventromedial prefrontal cortex was associated with ICB in PD. In addition, the surrounding cortico-striatal networks may differentiate the behavioral characteristics of patients with ICD and those with DDS.

A motivation model of sex addiction - Relevance to the controversy over the concept

An integrative model of sexual addiction is presented, involving a combination of models based upon (i) incentive motivation theory and (ii) the dual organisation of the control of behavior. The model is related to ongoing arguments about the validity of the notion of addiction when applied to sexual behavior. It is suggested that the evidence strongly favors the viability of an addiction model of sex. Strong similarities to the classical addiction to hard drugs are observed and features can be better understood with the help of the model. These include tolerance, escalation and withdrawal symptoms. It is argued that other candidates for accounting for the phenomena, such as obsessive-compulsive behavior, faulty impulse control, high drive and hypersexuality do not fit the evidence. The role of dopamine is central to the model. The model's relevance to stress, abuse, development, psychopathy, fantasy, sex differences, evolutionary psychology and the interaction with drug-taking is shown.

Neural correlates of risky decision making in Parkinson’s disease patients with impulse control disorders

Some patients with Parkinson's disease (PD) experience impulse control disorders (ICDs), characterized by deficient voluntary control over impulses, drives, or temptations regarding excessive hedonic behavior. The present study aimed to better understand the neural basis of impulsive, risky decision making in PD patients with ICDs by disentangling potential dysfunctions in decision and outcome mechanisms. We collected fMRI data from 20 patients with ICDs and 28 without ICDs performing an information gathering task. Patients viewed sequences of bead colors drawn from hidden urns and were instructed to infer the majority bead color in each urn. With each new bead, they could choose to either seek more evidence by drawing another bead (draw choice) or make an urn-inference (urn choice followed by feedback). We manipulated risk via the probability of bead color splits (80/20 vs. 60/40) and potential loss following an incorrect inference ($10 vs. $0). Patients also completed the Barratt Impulsiveness Scale (BIS) to assess impulsivity. Patients with ICDs showed greater urn choice-specific activation in the right middle frontal gyrus, overlapping the dorsal premotor cortex. Across all patients, fewer draw choices (i.e., more impulsivity) were associated with greater activation during both decision making and outcome processing in a variety of frontal and parietal areas, cerebellum, and bilateral striatum. Our findings demonstrate that ICDs in PD are associated with differences in neural processing of risk-related information and outcomes, implicating both reward and sensorimotor dopaminergic pathways.

Inhibitory framing in hypersexual patients with Parkinson's disease. An fMRI pilot study

Hypersexuality in medicated patients with PD is caused by an increased influence of motivational drive areas and a decreased influence of inhibitory control areas due to dopaminergic medication. In this pilot study, we test a newly developed paradigm investigating the influence of dopaminergic medication on brain activation elicited by sexual pictures with and without inhibitory contextual framing. Twenty PD patients with and without hypersexuality were examined with fMRI either OFF or ON standardized dopaminergic medication. The paradigm consisted of a priming phase where either a neutral context or an inhibitory context was presented. This priming phase was either followed by a sexual or a neutral target. Sexual, compared to neutral pictures resulted in a BOLD activation of various brain regions implicated in sexual processing. Hypersexual PD patients showed increased activity compared to PD controls in these regions. There was no relevant effect of medication between the two groups. The inhibitory context elicited less activation in inhibition-related areas in hypersexual PD, but had no influence on the perception of sexual cues. The paradigm partially worked: reactivity of motivational brain areas to sexual cues was increased in hypersexual PD and inhibitory contextual framing lead to decreased activation of inhibitory control areas in PD. We could not find a medication effect and the length of the inhibitory stimulus was not optimal to suppress reactivity to sexual cues. Our data provide new insights into the mechanisms of hypersexuality and warrant a replication with a greater cohort and an optimized stimulus length in the future.

Neural and behavioral correlates of sexual stimuli anticipation point to addiction-like mechanisms in compulsive sexual behavior disorder

BACKGROUND AND AIMS

Compulsive sexual behavior disorder (CSBD) is characterized by persistent patterns of failure to control sexual impulses resulting in repetitive sexual behavior, pursued despite adverse consequences. Despite previous indications of addiction-like mechanisms and the recent impulse-control disorder classification in the International Classification of Diseases (ICD-11), the neurobiological processes underlying CSBD are unknown.

METHODS

We designed and applied a behavioral paradigm aimed at disentangling processes related to anticipation and viewing of erotic stimuli. In 22 male CSBD patients (age: M = 38.7, SD = 11.7) and 20 healthy male controls (HC, age: M = 37.6, SD = 8.5), we measured behavioral responses and neural activity during functional magnetic resonance imaging (fMRI). The main outcomes were response time differences between erotic and non-erotic trials and ventral striatum (VS) activity during anticipation of visual stimuli. We related these outcomes with each other, to CSBD diagnosis, and symptom severity.

RESULTS

We found robust case-control differences on behavioral level, where CSBD patients showed larger response time differences between erotic and non-erotic trials than HC. The task induced reliable main activations within each group. While we did not observe significant group differences in VS activity, VS activity during anticipation correlated with response time differences and self-ratings for anticipation of erotic stimuli.

DISCUSSION AND CONCLUSIONS

Our results support the validity and applicability of the developed task and suggest that CSBD is associated with altered behavioral correlates of anticipation, which were associated with ventral striatum activity during anticipation of erotic stimuli. This supports the idea that addiction-like mechanisms play a role in CSBD.

Action and emotion perception in Parkinson's disease: A neuroimaging meta-analysis

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The neural substrates for action and emotion perception deficits in PD are still unclear.

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We addressed this issue via coordinate-based meta-analyses of previous fMRI data.

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PD patients exhibit decreased response in the basal ganglia.

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PD patients exhibit a trend toward decreased response in the parietal areas.

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PD patients exhibit a trend toward increased activation in the posterior cerebellum.

Patients with Parkinson disease (PD) may show impairments in the social perception. Whether these deficits have been consistently reported, it remains to be clarified which brain alterations subtend them. To this aim, we conducted a neuroimaging meta-analysis to compare the brain activity during social perception in patients with PD versus healthy controls. Our results show that PD patients exhibit a significantly decreased response in the basal ganglia (putamen and pallidum) and a trend toward decreased activity in the mirror system, particularly in the left parietal cortex (inferior parietal lobule and intraparietal sulcus). This reduced activation may be tied to a disruption of cognitive resonance mechanisms and may thus constitute the basis of impaired others’ representations underlying action and emotion perception. We also found increased activation in the posterior cerebellum in PD, although only in a within-group analysis and not in comparison with healthy controls. This cerebellar activation may reflect compensatory mechanisms, an aspect that deserves further investigation. We discuss the clinical implications of our findings for the development of novel social skill training programs for PD patients.

Diagnostic Difficulties and Treatment Challenges of a Young Patient With Severe Acute Psychosis and Complete Recovery

First break psychosis in young adults is sometimes presented as a dichotomous model of organic or substance-induced etiology or a primary psychiatric disorder on the schizophrenia spectrum and related disorders. In this case of a young adult with a typical age of onset for psychotic symptoms also presenting with cannabis use, excessive vaping, history of COVID-19 illness, pineal cyst, and extreme elevation of blood pressure, the diagnostic certainty decreases. Increased risk of progression to schizophrenia in individuals with cannabis use disorder and genetic loading has been extensively reported in the literature. Clinicians may face significant diagnostic and treatment challenges when managing a patient with severe psychotic symptoms. For the clinicians acutely managing such patients facing these exact questions of unknown certainty in progression to full-blown schizophrenia, we highlight a case of severe acute psychosis and complete recovery on a first-generation antipsychotic and mood stabilizer. 

Impulse control disorders, dopamine dysregulation syndrome and sex dysfunction in Parkinson's disease

Hypersexuality (HS), characterized by an aberrant, compulsive and inappropriate sexual drive, is an underreported and undermanaged complication of the treatment with dopamine agonists in patients with Parkinson's disease (PD). HS is part of the spectrum of impulse control disorders (ICDs). The failure to control these addictive behaviors is distressing for the patient and it is associated with important consequences. Reports of the prevalence of HS showed different results, due to the lack of standardized diagnostic criteria, but also due to the embarrassment or guilt feelings that patients experience regarding their sexual behaviors. Overall, it is considered that HS may occur in 1.92-22.8% of PD patients and the main risk factors involved could be male sex and genetic susceptibility. The pathophysiology of HS is unknown, but several degenerative mechanisms were proposed, involving dopaminergic, serotoninergic and noradrenergic pathways in cerebral regions responsive for planning and rewarding. There are no standardized tools for the assessment of HS in PD patients; however, several scales and questionnaires were developed with the aim of screening and rating the severity of ICDs, including HS. The management of HS is challenging. Discontinuation or reducing the dopaminergic treatment was effective in some cases, but it might lead to worsening of the motor function. A multidisciplinary approach is mandatory to manage the other associated aspects, such as psychological and social consequences of HS.

Concomitant Othello syndrome and impulse control disorders in a patient with Parkinson’s disease: A case report

BACKGROUND

Othello syndrome (OS) is characterized by delusional beliefs concerning the infidelity of a spouse or sexual partner, which may lead to extreme behaviors. Impulse control disorders refer to behaviors involving repetitive, excessive, and compulsive activities driven by an intense desire. Both OS and impulse control disorders in Parkinson’s disease (PD) may be side effects of dopamine agonists. At present, there are only a few case reports and studies related to PD with concomitant OS and impulse control disorders.

CASE SUMMARY

We describe a 70-year-old male patient with PD, OS, and impulse control disorders, who presented with a six-month history of the delusional belief that his wife was having an affair with someone. He began to show an obvious increase in libido presenting as frequent masturbation. He had been diagnosed with PD ten years earlier and had no past psychiatric history. In his fourth year of PD, he engaged in binge eating, which lasted approximately one year. Both OS and hypersexuality were alleviated substantially after a reduction of his pramipexole dosage and a prescription of quetiapine.

CONCLUSION

Given its potential for severe consequences, OS should be identified early, especially in patients undergoing treatment with dopamine agonists.

Imaging Cognitive Impairment and Impulse Control Disorders in Parkinson's Disease

Dementia and mild forms of cognitive impairment as well as neuropsychiatric symptoms (i. e., impulse control disorders) are frequent and disabling non-motor symptoms of Parkinson's disease (PD). The identification of changes in neuroimaging studies for the early diagnosis and monitoring of the cognitive and neuropsychiatric symptoms associated with Parkinson's disease, as well as their pathophysiological understanding, are critical for the development of an optimal therapeutic approach. In the current literature review, we present an update on the latest structural and functional neuroimaging findings, including high magnetic field resonance and radionuclide imaging, assessing cognitive dysfunction and impulse control disorders in PD.

Analysis of Impulse Control Disorders (ICDs) and Factors Associated with Their Development in a Parkinson's Disease Population

Parkinson's Disease (PD) is a neurodegenerative disease in which non-motor symptoms may appear before motor phenomena, which include Impulse Control Disorders (ICDs). The objective of this study is to identify factors associated with the development of ICDs in PD. An analytical, cross-sectional study was conducted using clinical records from patients diagnosed with PD, both genders, from 40 to 80 years old. Clinical and demographic data were collected: 181 patients were recruited; 80 of them showed PD and ICDs, and they constituted the study group, whereas 101 patients with PD without ICDs constituted the control reference group. The duration of PD was longer in the group with ICDs (p < 0.008), and all patients showed at least one ICD: binge eating (61.29%), compulsive shopping (48.75%), hypersexuality (23.75%), gambling behavior (8.75%), and punding (3.75%). After logistic regression analysis, only the use of dopamine agonists remained associated with ICDs (p < 0.001), and the tremorgenic form was suggested to be a protective factor (p < 0.001). Positive associations were observed between the rigid-akinetic form and compulsive shopping (p < 0.007), between male and hypersexuality (p < 0.018), and between dopamine agonists and compulsive shopping (p < 0.004), and negative associations were observed between motor fluctuations and compulsive shopping (p < 0.031), between Deep Brain Stimulation and binge eating (p < 0.046), and between levodopa consumption and binge eating (p < 0.045). Binge eating, compulsive shopping, and hypersexuality were the most frequent ICDs. Complex forms and motor complications of PD were associated with the development of ICDs.

Neural Representation of Costs and Rewards in Decision Making

Decision making is crucial for animal survival because the choices they make based on their current situation could influence their future rewards and could have potential costs. This review summarises recent developments in decision making, discusses how rewards and costs could be encoded in the brain, and how different options are compared such that the most optimal one is chosen. The reward and cost are mainly encoded by the forebrain structures (e.g., anterior cingulate cortex, orbitofrontal cortex), and their value is updated through learning. The recent development on dopamine and the lateral habenula's role in reporting prediction errors and instructing learning will be emphasised. The importance of dopamine in powering the choice and accounting for the internal state will also be discussed. While the orbitofrontal cortex is the place where the state values are stored, the anterior cingulate cortex is more important when the environment is volatile. All of these structures compare different attributes of the task simultaneously, and the local competition of different neuronal networks allows for the selection of the most appropriate one. Therefore, the total value of the task is not encoded as a scalar quantity in the brain but, instead, as an emergent phenomenon, arising from the computation at different brain regions.

Effects of tDCS on reward responsiveness and valuation in Parkinson's patients with impulse control disorders

Parkinson's disease (PD) patients with impulse control disorders (ICD) frequently report hypersensitivity to rewards. However, a few studies have explored the effectiveness of modulation techniques on symptoms experienced by these patients. In this study, we assessed the effect of anodal tDCS over the DLPFC on reward responsiveness and valuation in PD patients with ICD. 43 participants (15 PD patients with ICD, 13 PD without ICD, and 15 healthy matched controls) were asked to perform a reward-craving test employing both explicit (self-ratings of liking and wanting) and implicit (heart rate and skin conductance response) measures, as well as two temporal discounting tasks with food and money rewards. Each participant performed the experimental tasks during active anodal tDCS of the left dorsolateral prefrontal cortex (DLPFC), anodal tDCS of the primary motor cortex (M1), and sham tDCS. Results showed increased wanting and a steeper temporal discounting of rewards in PD with ICD compared to the other groups. Moreover, we found that PD without ICD exhibit reduced liking for rewards. tDCS results capable to modulate the altered intensity of PD patients' liking, but not wanting and temporal discounting of rewards in PD patients with ICD. These findings confirm that alterations in reward responsiveness and valuation are characteristics of impulse control disorders in patients with PD but suggest that anodal tDCS over the left DLPFC is not capable to influence these processes. At the same time, they provide new insight into affective experience of rewards in PD.

Aberrant Salient and Corticolimbic Connectivity in Hypersexual Parkinson's Disease

Introduction: Impulse control disorders (ICDs) represent a side effect of dopaminergic medication in Parkinson's disease (PD). Patients experience an excessive desire toward natural rewards paired with uncontrolled actions. Yet, the precise neural and behavioral mechanisms associated with ICDs and, importantly, each specific subdomain remain unclear. We aim to decipher resting-state and corticolimbic functional connectivity in PD patients with and without hypersexual ICD. Materials and Methods: Seventeen PD patients with hypersexuality (PD+HS) and 15 PD patients without hypersexuality (PD-HS) underwent two sessions (with and without medication) of resting-state functional magnetic resonance imaging and were compared with 17 healthy controls. Dual-regression independent component analyses extracted salience, sensorimotor, default-mode, and central executive networks. Seed-based functional connectivity with three striatal subdivisions (motor, associative, and limbic) was obtained and significant changes were correlated with key impulsivity and inhibitory measures. Results: Enhanced salience network (SN) activity represented by a significant rise in the right inferior frontal gyrus was found in PD+HS compared with PD-HS. Connectivity analyses revealed a functional disconnection between associative and limbic striatum with precuneus and superior parietal lobe in PD+HS, some connections explained by abnormal sexual behavior and inhibition in PD+HS. Conclusions: Hypersexual ICD is associated with enhanced SN signaling and corticolimbic disconnections, including striatal associative and limbic loops that contribute to altered control of sexually driven behavior and overall severity in PD and ICD.

Clinical implications for dopaminergic and functional neuroimage research in cognitive symptoms of Parkinson's disease

Evidence from dopaminergic image and cerebral blood flow/metabolism images have shed light on symptomatology of cognitive aspects in brain physiology of healthy human as well as patients with Parkinson's disease. Cognitive impairment in Parkinson's disease is characterized by executive, visuospatial, attentional disturbances. Dopaminergic system includes triadic parallel pathways. The mesostriatal pathway consist of posterolateral putamen and motor areas, the mesocortical pathway of dorsal caudate nucleus and dorsolateral prefrontal cortex, and the mesolimbic pathway of ventral striatum, anterior cingulate cortex. The mesocortical pathway is responsible for the executive function which may change by administration of dopaminergic medication. The mesolimbic pathway is associated with motivation and reward prediction which may result in depression or apathy when dopamine level was suboptimal, impulse control disorder and punding when dopamine was over the optimal level. Abnormal brain metabolism/perfusion related to cognitive impairment in Parkinson's disease are relatively reduced activity located in frontal and parietal association areas and relatively increased activity in the cerebellum. In the anterior brain, the mesocortical pathway, is responsible for verbal memory and executive function, which originates with caudate dopaminergic system and account for mild cognitive impairment of Parkinson's disease. The posterior brain system which includes the parietal, temporal, and occipital cortices, is responsible for the memory and visuospatial function, and related to cholinergic dysfunction and possibly glucocerebrosidase gene variants, relating to dementia in Parkinson's disease. The role of cerebellum in Parkinson's disease remains unclear but emerging evidence suggests that it may relate to the sequencing detection and affective symptoms. The dual syndrome hypothesis is helpful for understanding the mechanism of cognitive impairment in Parkinson's disease and optimal symptom management.

Sexual Disorders and Quality of Life in Parkinson's Disease

Introduction

Sexual disorders are the most neglected nonmotor symptoms in Parkinson's disease (PD). Although doctors seek greater priority to motor manifestations, which are the basis for the diagnosis of PD, the nonmotor symptoms deserve to be highlighted as much as the motor problems because of their strong presence and discomfort in the patients, causing the important impairment in the quality of life (QoL) of the individual with PD.

Aim

Provide the prevalence of sexual disorders among patients with PD and alert the medical profession to investigate and be familiar with problems related to QoL and sexual disorders in PD.

Methods

This is a large literature review on sexual disorders in PD and impaired QoL.

Main Outcome Measures

Sexual disorders in PD and prevalence between genders have been described in epidemiological studies. Neuroanatomy, pathophysiology, risk factors, QoL, and etiologies were reviewed.

Results

The estimate of the prevalence of sexual dysfunction in the form of compulsive sexual behavior in PD is higher in men by 5.2% than in women by 0.5%. This diagnosis is a determinant of intense and persistent suffering and is related to several health problems of a social, economic, personal, family, psychological, and occupational nature, which can even culminate in sexual abuse. It is most commonly associated with the use of drugs commonly used in PD therapy in 98.1% of cases. In addition to this serious public health problem, another common condition of sexual dysfunction occur with the decreased libido by loss of the neurotransmitter dopamine proper of the pathophysiology of PD.

Conclusion

The presence of sexual disorders in PD should be tracked and monitored because of its harmful consequences, whether due to increased sexual behavior or associated psychological distress, as well as the impacts on QoL. Early recognition and adequate treatment of PD in its fullness and richness of associated symptoms are essential for improving QoL.

Santa Rosa Malcher CM, Roberto da Silva Gonçalves Oliveira K, Fernandes Caldato MC, et al. Sexual Disorders and Quality of Life in Parkinson's Disease. Sex Med 2021;9:100280.

Management of psychiatric disorders in Parkinson's disease : Neurotherapeutics - Movement Disorders Therapeutics

Affective disorders (depression and anxiety), psychosis, impulse control disorders, and apathy are common and sometimes disabling psychiatric conditions in Parkinson disease (PD). Psychiatric aspects of PD are associated with numerous adverse outcomes, yet in spite of this and their high frequency, there remains incomplete understanding of epidemiology, presentation, risk factors, neural substrate, and management strategies. Psychiatric features are typically co- or multimorbid, and there is great intra- and interindividual variability in presentation [1]. The neuropathophysiological changes that occur in PD, as well as the association between PD treatment and particular psychiatric disorders, suggest a neurobiological contribution to many psychiatric symptoms. There is evidence that psychiatric disorders in PD are still under-recognized and undertreated, and although psychotropic medication use is common, randomized controlled trials demonstrating efficacy and tolerability are largely lacking. Future research on neuropsychiatric complications in PD should be oriented toward determining modifiable correlates or risk factors, and most importantly, establishing efficacious and well-tolerated treatment strategies.

Incentive-driven decision-making networks in de novo and drug-treated Parkinson's disease patients with impulsive-compulsive behaviors: A systematic review of neuroimaging studies

BACKGROUND

In Parkinson's disease (PD), impulsive-compulsive behaviors (ICBs) may develop as side-effect of dopaminergic medications. Abnormal incentive-driven decision-making, which is supported by the cognitive control and motivation interaction, may represent an ICBs signature. This systematic review explored whether structural and/or functional brain differences between PD patients with vs without ICBs encompass incentive-driven decision-making networks.

METHODS

Structural and functional neuroimaging studies comparing PD patients with and without ICBs, either de novo or medicated, were included.

RESULTS

Thirty articles were identified. No consistent evidence of structural alteration both in de novo and medicated PD patients were found. Differences in connectivity within the default mode, the salience and the central executive networks predate ICBs development and remain stable once ICBs are fully developed. Medicated PD patients with ICBs show increased metabolism and cerebral blood flow in orbitofrontal and cingulate cortices, ventral striatum, amygdala, insula, temporal and supramarginal gyri. Abnormal ventral striatum connectivity with anterior cingulate cortex and limbic structures was reported in PD patients with ICBs.

DISCUSSION

Functional brain signatures of ICBs in PD encompass areas involved in cognitive control and motivational encoding networks of the incentive-driven decision-making. Functional alterations predating ICBs may be related to abnormal synaptic plasticity in these networks.

The glucagon-like peptide-1 receptor agonist, exendin-4, reduces sexual interaction behaviors in a brain site-specific manner in sexually naïve male mice

Besides reducing food intake and controlling energy balance, glucagon-like peptide-1 (GLP-1) suppresses the reinforcing properties of palatable foods and addictive drugs. This reduction in reward involves activation of GLP-1 receptors (GLP-1R) within areas processing natural and artificial rewards, including the laterodorsal tegmental area (LDTg), ventral tegmental area (VTA) and nucleus accumbens (NAc) shell. These areas are part of a neurocircuitry mediating reward from addictive drugs and natural rewards including sexual behaviors. The male sexual encounter with a female includes three different stages: a pre-sexual interaction phase with social behaviors, which is followed by a sexual interaction phase with mounting and intromission of the female, and ends with a post-sexual interaction phase characterized by self-grooming behaviors. Albeit GLP-1 modulates reward, the influence of GLP-1R activation on sexual interaction is unknown. Thus, we infused the GLP-1R agonist, exendin-4 (Ex4), into sub-regions of the reward neurocircuitry in sexually naïve male mice and recorded their novel interaction with an estrus female. We found that Ex4 into the LDTg, posterior VTA or NAc shell reduces pre-sexual interaction behaviors and activation of GLP-1R in the LDTg or posterior VTA decreases sexual interaction behaviors. Contrarily, Ex4 infusion into anterior VTA does not influence these behaviors. Furthermore, self-grooming behaviors are not influenced by activation of GLP-1R in the aforementioned areas. These data highlight that activation of GLP-1R in reward-related areas reduces different aspects of the sexual interaction chain and further supports a role of the GLP-1R in social behaviors.

The role of dopaminergic and serotonergic transmission in the processing of primary and monetary reward

Natural rewards such as erotic stimuli activate common neural pathways with monetary rewards. In human studies, the manipulation of dopamine and serotonin play an important role in the processing of monetary rewards with less understood on its role on erotic stimuli. In this study, we investigate the neuromodulatory effects of dopaminergic and serotonergic transmission in the processing of erotic versus monetary visual stimuli. We scanned one hundred and two (N = 102) healthy volunteers using functional magnetic resonance imaging while performing a modified version of the well-validated monetary incentive delay task consisting of erotic, monetary and neutral visual stimuli. We show a role for enhanced central dopamine and lowered central serotonin levels in increasing activity in the right caudate and left anterior insula during anticipation of erotic relative to monetary rewards in healthy controls. We further show differential activation in the anticipation of natural versus monetary rewards with the former associated with ventromesial and dorsomesial activity and the latter with dorsal cingulate, striatal and anterior insular activity. These findings are consistent with preclinical and clinical findings of a role for dopaminergic and serotonergic mechanisms in the processing of natural rewards. Our study provides further insights into the neural substrates underlying reward processing for natural primary erotic rewards and yields importance for the neurochemical systems of addictive disorders including gambling disorder.

From apathy to addiction: Insights from neurology and psychiatry

The tendency to engage in addictive behaviors has long been tied to the actions of the dopamine system. Early theories were based on the fact that all addictive drugs and behaviors (such as gambling) increase dopamine levels in the striatum, and the evidence that dopamine signaled reward or reward prediction error. However, with a changing emphasis of addiction away from purely pharmacological models that emphasize tolerance and withdrawal, towards one of behavioral dyscontrol, is there still a place for abnormal dopamine signaling in addiction? Here we recast the dopamine theory of addiction based on the idea that tonic dopamine may index a continuous phenotype that goes from apathy to impulsivity and compulsivity. Higher tonic dopamine signaling would make individuals vulnerable to drug reinforcement and cue-induced craving. We relate this to computational models of dopamine signaling, and review clinical and neuroimaging evidence from Parkinson's Disease, schizophrenia and bipolar disorder in support of this model.

Linking brain activity during sequential gambling to impulse control in Parkinson's disease

Dopaminergic treatment may impair the ability to suppress impulsive behaviours in patients with Parkinson's disease, triggering impulse control disorders. It is unclear how dopaminergic medication affects the neural networks that contribute to withholding inappropriate actions. To address this question, we mapped task-related brain activity with whole-brain functional magnetic resonance imaging at 3 Tesla in 26 patients with Parkinson's disease. Patients performed a sequential gambling task while being ON and OFF their regular dopaminergic treatment. During a gambling round, patients repeatedly decided between the option to continue with gambling and accumulate more monetary reward under increasing risk or the option to bank the current balance and start a new round. 13 patients had an impulse control disorder (ICD + group). These patients did not differ in risk-taking attitude during sequential gambling from 13 patients without impulse control disorder (ICD - group), but they displayed differences in gambling-related activity in cortico-subcortical brain areas supporting inhibitory control. First, the ICD + group showed reduced "continue-to-gamble" activity in right inferior frontal gyrus and subthalamic nucleus. Second, the individual risk-attitude scaled positively with "continue-to-gamble" activity in right subthalamic nucleus and striatum in the ICD - group only. Third, ICD + patients differed in their functional neural responses to dopaminergic treatment from ICD - patients: dopaminergic therapy reduced functional connectivity between inferior frontal gyrus and subthalamic nucleus during "continue-to-gamble" decisions and attenuated striatal responses towards accumulating reward and risk. Together, the medication-independent (trait) and medication-related (state) differences in neural activity may set a permissive stage for the emergence of impulse control disorders during dopamine replacement therapy in Parkinson's disease.

MRI of Motor and Nonmotor Therapy-Induced Complications in Parkinson's Disease

Levodopa therapy remains the most effective drug for the treatment of Parkinson's disease, and it is associated with the greatest improvement in motor function as assessed by the Unified Parkinson's Disease Rating Scale. Dopamine agonists have also proven their efficacy as monotherapy in early Parkinson's disease but also as adjunct therapy. However, the chronic use of dopaminergic therapy is associated with disabling motor and nonmotor side effects and complications, among which levodopa-induced dyskinesias and impulse control behaviors are the most common. The underlying mechanisms of these disorders are not fully understood. In the last decade, classic neuroimaging methods and more sophisticated techniques, such as analysis of gray-matter structural imaging and functional magnetic resonance imaging, have given access to anatomical and functional abnormalities, respectively, in the brain. This review presents an overview of structural and functional brain changes associated with motor and nonmotor therapy-induced complications in Parkinson's disease. Magnetic resonance imaging may offer structural and/or functional neuroimaging biomarkers that could be used as predictive signs of development, maintenance, and progression of these complications. Neurophysiological tools, such as theta burst stimulation and transcranial magnetic stimulation, might help us to integrate neuroimaging findings and clinical features and could be used as therapeutic options, translating neuroimaging data into clinical practice. © 2020 International Parkinson and Movement Disorder Society.

Recurrent Episodes of Paraphilic Behavior Possibly Associated With Olanzapine and Aripiprazole Treatment in a Patient With Schizophrenia

BACKGROUND

Hypersexual and paraphilic disorders have been frequently associated with concomitant psychiatric disorders, including schizophrenia. A growing number of published cases has recently indicated that hypersexual behavior may also arise in conjunction with treatment with second-generation antipsychotics. Although hypersexuality has been acknowledged as a possible side effect of antipsychotic treatment with partial dopamine agonists, including aripiprazole, only very few cases of olanzapine-associated hypersexuality have been reported in the literature.

CASE PRESENTATION

A 29-year-old man presented with delusions of persecution and reference, auditory hallucinations, and negative symptoms, and was diagnosed with paranoid-hallucinatory schizophrenia. One and a half months after initiation of antipsychotic treatment with olanzapine, he developed compulsive sexual behavior and paraphilia, without signs of akathisia. After olanzapine discontinuation, a full remission of the hypersexual behavior was noted within one week, and treatment was switched to risperidone. Due to hyperprolactinemia, adjunct treatment with low-dose aripiprazole was initiated and a severe recurrence of identical hypersexual behavior occurred. The hypersexual behavior resolved completely within a week after aripiprazole discontinuation.

CONCLUSION

This case illustrates that hypersexuality may be a rare adverse effect of treatment with second-generation antipsychotics. Although aripiprazole is a drug with a well-established risk for hypersexuality, the question of whether a causal association between hypersexuality and olanzapine exists remains currently unresolved. As the currently limited amount of available evidence precludes any definitive conclusions, additional research is warranted to delineate the possible neurobiological substrates of hypersexual and paraphilic disorders in patients treated with second-generation antipsychotics.

Disrupted salience network dynamics in Parkinson's disease patients with impulse control disorders

BACKGROUND

Dynamic functional network analysis may add relevant information about the temporal nature of the neurocognitive alterations in PD patients with impulse control disorders (PD-ICD). Our aim was to investigate changes in dynamic functional network connectivity (dFNC) in PD-ICD patients, and topological properties of such networks.

METHODS

Resting state fMRI was performed on 16 PD PD-ICD patients, 20 PD patients without ICD and 17 healthy controls, whose demographic, clinical and behavioral scores were assessed. We conducted a group spatial independent component analysis, sliding window and graph-theory analyses.

RESULTS

PD-ICD patients, in contrast to PD-noICD and HC subjects, were engaged across time in a brain configuration pattern characterized by a lack of between-network connections at the expense of strong within-network connections (State III) in temporal, frontoinsular and cingulate cortices, all key nodes of the salience network. Moreover, this increased maintenance of State III in PD-ICD patients was positively correlated with the severity of impulsivity and novelty seeking as measured by specific scales. While in State III, these patients also exhibited increased local efficiency in all the aforementioned areas.

CONCLUSIONS

Our findings show for the first time that PD-ICD patients have a dynamic functional engagement of local connectivity involving the limbic circuit, leading to the inefficient modulation in emotional processing and reward-related decision-making. These results provide new insights into the pathophysiology of ICD in PD patients and indicate that the dFC study of fMRI could be a useful biomarker to identify patients at risk to develop ICD.

Functional inhibitory control dynamics in impulse control disorders in Parkinson's disease

BACKGROUND

Impulse control disorders related to alterations in the mesocorticolimbic dopamine network occur in Parkinson's disease (PD). Our objective was to investigate the functional neural substrates of reward processing and inhibitory control in these patients.

METHODS

Eighteen PD patients with impulse control disorders, 17 without this complication, and 18 healthy controls performed a version of the Iowa Gambling Task during functional magnetic resonance scanning under 3 conditions: positive, negative, and mixed feedback. Whole-brain contrasts, regions of interest, time courses, functional connectivity analyses, and brain-behavior associations were examined.

RESULTS

PD patients with impulse control disorders exhibited hyperactivation in subcortical and cortical regions typically associated with reward processing and inhibitory control compared with their PD and healthy control counterparts. Time-course analyses revealed that only PD patients with impulse control disorders exhibited stronger signal intensity during the initial versus final periods of the negative-feedback condition in bilateral insula, and right ventral striatum. Interestingly, hyperactivation of all the examined right-lateralized frontostriatal areas during negative feedback was positively associated with impulse control disorder severity. Importantly, positive associations between impulse control disorder severity and regional activations in the right insula and right inferior frontal gyrus, but not the right subthalamic nucleus, were mediated by functional connectivity with the right ventral striatum.

CONCLUSIONS

During a reward-based task, PD patients with impulse control disorders showed hyperactivation in a right-lateralized network of regions including the subthalamic nucleus that was strongly associated with impulse control disorder severity. In these patients, the right ventral striatum in particular played a critical role in modulating the functional dynamics of right-lateralized inhibitory-control frontal regions when facing penalties. © 2019 International Parkinson and Movement Disorder Society.

A Neurobehavioral Approach to Addiction: Implications for the Opioid Epidemic and the Psychology of Addiction

Two major questions about addictive behaviors need to be explained by any worthwhile neurobiological theory. First, why do people seek drugs in the first place? Second, why do some people who use drugs seem to eventually become unable to resist drug temptation and so become "addicted"? We will review the theories of addiction that address negative-reinforcement views of drug use (i.e., taking opioids to alleviate distress or withdrawal), positive-reinforcement views (i.e., taking drugs for euphoria), habit views (i.e., growth of automatic drug-use routines), incentive-sensitization views (i.e., growth of excessive "wanting" to take drugs as a result of dopamine-related sensitization), and cognitive-dysfunction views (i.e., impaired prefrontal top-down control), including those involving competing neurobehavioral decision systems (CNDS), and the role of the insula in modulating addictive drug craving. In the special case of opioids, particular attention is paid to whether their analgesic effects overlap with their reinforcing effects and whether the perceived low risk of taking legal medicinal opioids, which are often prescribed by a health professional, could play a role in the decision to use. Specifically, we will address the issue of predisposition or vulnerability to becoming addicted to drugs (i.e., the question of why some people who experiment with drugs develop an addiction, while others do not). Finally, we review attempts to develop novel therapeutic strategies and policy ideas that could help prevent opioid and other substance abuse.

Demographic and psychiatric correlates of compulsive sexual behaviors in gambling disorder

BACKGROUND AND AIMS

Gambling disorder (GD) and compulsive sexual behavior (CSB) may commonly co-occur. Yet, the psychiatric correlates of these co-occurring disorders are an untapped area of empirical scrutiny, limiting our understanding of appropriate treatment modalities for this dual-diagnosed population. This study examined the demographic and clinical correlates of CSB in a sample of treatment-seeking individuals with GD (N = 368) in São Paulo, Brazil.

METHODS

Psychiatrists and psychologists conducted semi-structured clinical interviews to identify rates of CSB and other comorbid psychiatric disorders. The Shorter PROMIS Questionnaire was administered to assess additional addictive behaviors. The TCI and BIS-11 were used to assess facets of personality. Demographic and gambling variables were also assessed.

RESULTS

Of the total sample, 24 (6.5%) met diagnostic criteria for comorbid CSB (GD + CSB). Compared to those without compulsive sexual behaviors (GD - CSB), individuals with GD + CSB were more likely to be younger and male. No differences in gambling involvement emerged. Individuals with GD + CSB tended to have higher rates of psychiatric disorders (depression, post-traumatic stress disorder, and bulimia nervosa) and engage in more addictive behaviors (problematic alcohol use, drug use, and exercise) compared to GD - CSB. Those with GD + CSB evidenced less self-directedness, cooperativeness, self-transcendence, and greater motor impulsivity. Logistic regression showed that the predictors of GD + CSB, which remained in the final model, were being male, a diagnosis of bulimia, greater gambling severity, and less self-transcendence.

DISCUSSION AND CONCLUSION

Given those with GD + CSB evidence greater psychopathology, greater attention should be allocated to this often under studied comorbid condition to ensure adequate treatment opportunities.

The Neuropsychiatry of Parkinson Disease: A Perfect Storm

Affective disorders, cognitive decline, and psychosis have long been recognized as common in Parkinson disease (PD), and other psychiatric disorders include impulse control disorders, anxiety symptoms, disorders of sleep and wakefulness, and apathy. Psychiatric aspects of PD are associated with numerous adverse outcomes, yet in spite of this and their frequent occurrence, there is incomplete understanding of epidemiology, presentation, risk factors, neural substrate, and management strategies. Psychiatric features are typically multimorbid, and there is great intra- and interindividual variability in presentation. The hallmark neuropathophysiological changes that occur in PD, plus the association between exposure to dopaminergic medications and certain psychiatric disorders, suggest a neurobiological basis for many psychiatric symptoms, although psychological factors are involved as well. There is evidence that psychiatric disorders in PD are still under-recognized and undertreated and although psychotropic medication use is common, controlled studies demonstrating efficacy and tolerability are largely lacking. Future research on neuropsychiatric complications in PD should be oriented toward determining modifiable correlates or risk factors and establishing efficacious and well-tolerated treatment strategies.

Resting state oscillations suggest a motor component of Parkinson's Impulse Control Disorders

OBJECTIVES

Impulse control disorders (ICDs) in Parkinson's disease (PD) have been associated with cognitive impulsivity and dopaminergic dysfunction and treatment. The present study tests the neglected hypothesis that the neurofunctional networks involved in motor impulsivity might also be dysfunctional in PD-ICDs.

METHODS

We performed blind spectral analyses of resting state electroencephalographic (EEG) data in PD patients with and without ICDs to probe the functional integrity of all cortical networks. Analyses were performed directly at the source level after blind source separation. Discrete differences between groups were tested by comparing patients with and without ICDs. Gradual dysfunctions were assessed by means of correlations between power changes and clinical scores reflecting ICD severity (QUIP score).

RESULTS

Spectral signatures of ICDs were found in the medial prefrontal cortex, the dorsal anterior cingulate and the supplementary motor area, in the beta and gamma bands. Beta power changes in the supplementary motor area were found to predict ICDs severity.

CONCLUSION

ICDs are associated with abnormal activity within frequency bands and cortical circuits supporting the control of motor response inhibition.

SIGNIFICANCE

These results bring to the forefront the need to consider, in addition to the classical interpretation based on aberrant mesocorticolimbic reward processing, the issue of motor impulsivity in PD-ICDs and its potential implications for PD therapy.

Wait and you shall see: sexual delay discounting in hypersexual Parkinson's disease

Patients with Parkinson's disease may develop impulse control disorders under dopaminergic treatments. Impulse control disorders include a wide spectrum of behaviours, such as hypersexuality, pathological gambling or compulsive shopping. Yet, the neural systems engaged in specific impulse control disorders remain poorly characterized. Here, using model-based functional MRI, we aimed to determine the brain systems involved during delay-discounting of erotic rewards in hypersexual patients with Parkinson's disease (PD+HS), patients with Parkinson's disease without hypersexuality (PD - HS) and controls. Patients with Parkinson's disease were evaluated ON and OFF levodopa (counterbalanced). Participants had to decide between two options: (i) wait for 1.5 s to briefly view an erotic image; or (ii) wait longer to see the erotic image for a longer period of time. At the time of decision-making, we investigated which brain regions were engaged with the subjective valuation of the delayed erotic reward. At the time of the rewarded outcome, we searched for the brain regions responding more robustly after waiting longer to view the erotic image. PD+HS patients showed reduced discounting of erotic delayed rewards, compared to both patients with Parkinson's disease and controls, suggesting that they accepted waiting longer to view erotic images for a longer period of time. Thus, when using erotic stimuli that motivate PD+HS, these patients were less impulsive for the immediate reward. At the brain system level, this effect was paralleled by the fact that PD+HS, as compared to controls and PD - HS, showed a negative correlation between subjective value of the delayed reward and activity of medial prefrontal cortex and ventral striatum. Consistent with the incentive salience hypothesis combining learned cue-reward associations with current relevant physiological state, dopaminergic treatment in PD+HS boosted excessive 'wanting' of rewards and heightened activity in the anterior medial prefrontal cortex and the posterior cingulate cortex, as reflected by higher correlation with subjective value of the option associated to the delayed reward when ON medication as compared to the OFF medication state. At the time of outcome, the anterior medial prefrontal/rostral anterior cingulate cortex showed an interaction between group (PD+HS versus PD - HS) and medication (ON versus OFF), suggesting that dopaminergic treatment boosted activity of this brain region in PD+HS when viewing erotic images after waiting for longer periods of time. Our findings point to reduced delay discounting of erotic rewards in PD+HS, both at the behavioural and brain system levels, and abnormal reinforcing effect of levodopa when PD+HS patients are confronted with erotic stimuli.10.1093/brain/awy298_video1awy298media15983845074001.

Impulse Control Disorders in Parkinson's Disease. A Brief and Comprehensive Review

Impulse control and related disorders (ICDs-RD) encompasses a heterogeneous group of disorders that involve pleasurable behaviors performed repetitively, excessively, and compulsively. The key common symptom in all these disorders is the failure to resist an impulse or temptation to control an act or specific behavior, which is ultimately harmful to oneself or others and interferes in major areas of life. The major symptoms of ICDs include pathological gambling (PG), hypersexualtiy (HS), compulsive buying/shopping (CB) and binge eating (BE) functioning. ICDs and ICDs-RD have been included in the behavioral spectrum of non-motor symptoms in Parkinson's disease (PD) leading, in some cases, to serious financial, legal and psychosocial devastating consequences. Herein we present the prevalence of ICDs, the risk factors, its pathophysiological mechanisms, the link with agonist dopaminergic therapies and therapeutic managements.

Effect of Sex Hormones on Brain Connectivity Related to Sexual Function in Perimenopausal Women: A Resting-State fMRI Functional Connectivity Study

BACKGROUND

Perimenopause is associated with increased risk of depression, vasomotor symptoms, and sexual dysfunction.

AIMS

To explore the effect of sex hormones on the functional connectivity (FC) of different brain regions related to sexual function in perimenopausal women.

METHODS

32 premenopausal women (mean age, 47.75 ± 1.55 years) and 25 perimenopausal women (mean age, 51.60 ± 1.63 years) underwent sex hormone level measurements and resting-state fMRI.

MAIN OUTCOME MEASURES

Serum levels of sex hormones, including prolactin (PRL), follicle-stimulating hormone (FSH), luteotropic hormone (LH), estradiol (E2), free testosterone (free-T), and progesterone (P), were measured. 10 brain regions related to sexual function were selected according to a meta-analysis, and FCs of the selected regions of interest were calculated as Pearson's correlation coefficient.

RESULTS

Compared with premenopausal women, perimenopausal women showed increased FC between the right area 13 (A13_r) and the right medial superior frontal gyrus (mSFG), between the left dorsal granular insula (dIg_L) and the right superior frontal gyrus (SFG) (Gaussian random field-corrected at the voxel level, P < .001, and cluster level, P < .025). Furthermore, the PRL level was negatively correlated with the FC of A13_R with the right mSFG and the FC of dIg_L with the right SFG.

CLINICAL TRANSLATION

These findings may be applicable to assessing brain dysfunction with FC changes in women approaching menopause.

STRENGTHS & LIMITATIONS

This study is the first to evaluate a direct relationship between sex hormone levels and brain FC changes in women approaching menopause. Sexual function was not assessed, which may weaken the conclusions related to sexual function.

CONCLUSIONS

The results show that women approaching menopause suffered from aberrant intrinsic FC in regions related to sexual function, and reveal a direct relationship between serum sex hormone levels and FC changes related to sexual function. Lu W, Guo W, Cui D, et al. Effect of Sex Hormones on Brain Connectivity Related to Sexual Function in Perimenopausal Women: A Resting-State fMRI Functional Connectivity Study. J Sex Med 2019;16:711-720.

Unmasking neurobiological commonalities between addictive disorders and impulse control disorders in Parkinson’s disease

Changes in reward circuitry have been studied extensively in substance and behavioural addictions. However, comparatively little is known about the neurobiology underlying impulse control disorders (ICDs) in Parkinson's disease, which show roughly similar risk factors and behavioural presentations to both stimulant and behavioural addictions. ICDs occur in a subset of susceptible patients with Parkinson's disease (PD) following intake of dopamine replacement therapy (DRT). These behavioural disorders often have debilitating effects on a patient's quality of life and increase caregiver burden. This comprehensive review examined findings of 40 neuroimaging studies of ICDs in PD to determine (a) whether there are putative neurobiological commonalities between traditional substance and behavioural addictions and DRT-induced ICD in PD and (b) opportunities for future studies to advance current neurobiological understanding of the phenomenon. Results revealed that strikingly similar (a) deficits in dopaminergic receptor expression, (b) connectivity changes in corticostriatal circuitry and (c) neural responses to cue exposure are observed in both ICDs in PD and addictive disorders. These findings point to the value of adopting a transdiagnostic approach when studying addicted populations and pave the way for demystifying this peculiar, often-devastating phenomenon in PD that has so far proven extremely difficult to treat and predict with any precision.

Functional imaging studies of Impulse Control Disorders in Parkinson's disease need a stronger neurocognitive footing

Impulse control disorders (ICDs) in Parkinson's disease (PD) are associated with dopaminergic dysfunction and treatment, but have no satisfactory therapeutic solution. While studies assessing the neurofunctional bases of ICDs are important for advancing our understanding and management of ICDs, they remain sparse and inconsistent. Based on a systematic analysis of the neuroimaging literature, the present review pinpoints various abnormalities beyond the mesocorticolimbic circuit that supports reward processing, suggesting possible dysfunction at the sensorimotor, executive and affective levels. We advocate that: 1) Future studies should use more sophisticated psychological models and behavioral designs that take into account the potentially multifaceted aspect of ICDs; this would allow a more accurate assessment of the underlying neurocognitive processes, which are not all dependent on the dopaminergic system. 2) Future neuroimaging studies should rely more strongly on task-based, event-related analyses to disentangle the various mechanisms that can be dysfunctional in ICDs. We believe these guidelines constitute a prerequisite towards distinguishing causes, correlates and individual susceptibility factors of PD patients with ICDs.

Disruption of Multiple Distinctive Neural Networks Associated With Impulse Control Disorder in Parkinson's Disease

The phenomenon of impulsivity in Parkinson's disease appears as an arduous side effect of dopaminergic therapy with potentially detrimental consequences for the life of the patients. Although conceptualized as a result of non-physiologic chronic dopaminergic stimulation, recent advances speculate on combined disruption of other networks as well. In the search for neuroanatomical correlates of this multifaceted disturbance, this study employs two distinct, well-defined tasks of close association to motor inhibition and decision-making impulsivity, Go/No Go and Delay discounting. The fMRI and functional connectivity analysis in 21 Parkinson's disease patients, including 8 patients suffering from severe impulse control disorder, and 28 healthy controls, revealed in impulsive Parkinson's disease patients not only decreased fMRI activation in the dorsolateral prefrontal cortex and bilateral striatum, but also vast functional connectivity changes of both caudate nuclei as decreased connectivity to the superior parietal cortex and increased connectivity to the insular area, clearly beyond the commonly stated areas, which indicates that orbitofronto-striatal and mesolimbic functional disruptions are not the sole mechanisms underlying impulse control disorder in Parkinson's disease. Ergo, our results present a refinement and synthesis of gradually developing ideas about the nature of impulsive control disorder in Parkinson's disease—an umbrella term encompassing various behavioral deviations related to distinct neuronal networks and presumably neurotransmitter systems, which greatly exceed the previously envisioned dopaminergic pathways as the only culprit.

Impulse Control Behaviors in Parkinson's Disease: Drugs or Disease? Contribution From Imaging Studies

Impulse control behaviors (ICB) are recognized as non-motor complications of dopaminergic medications in patients with Parkinson's disease (PD). Compelling evidence suggests that ICB are not merely due to the PD-related pathology itself. Several risk factors have been identified, either demographic, clinical, genetic or neuropsychological. Neuroimaging studies have yielded controversial results regarding ICB correlates in PD and still it is not clear whether they can be triggered by the PD biology or the dopaminergic treatment stimulation. We provided an overview of the imaging studies that offered the most relevant insights into the debate about the role of drugs and disease in ICB pathophysiology. Understanding neural correlates and potential predisposing factors of these severe neuropsychiatric symptoms will be crucial to guide clinical practice and to foster preventive strategies.