Dopamine dysregulation syndrome in Parkinson's disease: a systematic review of published cases

G Protein-Coupled Receptors (GPCRs)-Mediated Calcium Signaling in Ovarian Cancer: Focus on GPCRs activated by Neurotransmitters and Inflammation-Associated Molecules

G-coupled protein receptors (GCPR) involve several signaling pathways, some of them being coupled with intracellular calcium (Ca²⁺) mobilization. GPCRs were involved in migration, invasion and metastasis of different types of cancers, including ovarian cancer. Many studies have discussed the essential contribution of GPCRs activated by steroid hormones in ovarian cancer. However, ovarian cancer is also associated with altered signals coming from the nervous system, the immune system or the inflammatory environment, in which GPCRs are ‘sensing’ these molecular signals. Many studies have been oriented so far on ovarian cell lines (most of them being of human cell lines), and only few studies based on animal models or clinical studies have been devoted to the expression changes or functional role of GPCRs in ovarian cancer. In this paper, we review the alterations of GPCRs activated by neurotransmitters (muscarinic receptors, serotonin receptors, dopamine receptors, adrenoceptors) or inflammation-associated molecules (bradykinin receptors, histamine receptors, chemokine receptors) in ovarian cancer and we discuss their potential as histological biomarkers.

Deep brain stimulation for the treatment of drug addiction

Drug addiction represents a significant public health concern that has high rates of relapse despite optimal medical therapy and rehabilitation support. New therapies are needed, and deep brain stimulation (DBS) may be an effective treatment. The past 15 years have seen numerous animal DBS studies for addiction to various drugs of abuse, with most reporting decreases in drug-seeking behavior with stimulation. The most common target for stimulation has been the nucleus accumbens, a key structure in the mesolimbic reward pathway. In addiction, the mesolimbic reward pathway undergoes a series of neuroplastic changes. Chief among them is a relative hypofunctioning of the prefrontal cortex, which is thought to lead to the diminished impulse control that is characteristic of drug addiction. The prefrontal cortex, as well as other targets involved in drug addiction such as the lateral habenula, hypothalamus, insula, and subthalamic nucleus have also been stimulated in animals, with encouraging results. Although animal studies have largely shown promising results, current DBS studies for drug addiction primarily use stimulation during active drug use. More data are needed on the effect of DBS during withdrawal in preventing future relapse. The published human experience for DBS for drug addiction is currently limited to several promising case series or case reports that are not controlled. Further animal and human work is needed to determine what role DBS can play in the treatment of drug addiction.

Dopamine dysregulation syndrome in non-Parkinson's disease patients: a systematic review

OBJECTIVES

To explore the presence of dopamine dysregulation syndrome in non-Parkinson's disease patients receiving dopamine replacement therapy.

METHODS

Electronic searches were conducted of Medline, Embase, PsycINFO and PreMedline to capture articles related to dopamine misuse or factitious disorder combined with the presence of dopamine replacement therapy or a non-Parkinson's disease population. In total, 430 articles were reviewed and studies that addressed dopamine dysregulation syndrome in non-Parkinson's disease patients were included.

RESULTS

Nine case reports were identified.

CONCLUSIONS

The pathophysiology underlying dopamine dysregulation syndrome has been thoroughly explored with numerous mechanisms posited. What remains unclear is whether dopamine dysregulation syndrome is a phenomenon specific to Parkinson's disease, as indicated in the proposed diagnostic criteria. A more useful predictor of susceptibility to dopamine dysregulation syndrome may be temperamental traits such as novelty seeking and impulsivity, which overlap with predisposing factors for an addiction disorder.

"Pseudo-syndromes" associated with Parkinson disease, dementia, apathy, anxiety, and depression

PURPOSE OF REVIEW

Physicians treating patients with Parkinson disease must evaluate not only motor symptoms but also acquire expertise in assessing the complex behavioral features that often accompany the disease, such as dementia, apathy, anxiety, and depression.

RECENT FINDINGS

There is a risk of diagnostic confusion and error because many of the behavioral and motor symptoms accentuate, overlap, or mimic each other.

SUMMARY

Awareness of potential diagnostic pitfalls and "pseudo-syndromes" should lead to more accurate clinical assessment and better care for our patients.

Dopamine dysregulation syndrome induced by proxy

Dopamine dysregulation syndrome is a rare complication of Parkinson's disease (PD) treatment. We present a 70-year-old woman with a long-standing PD and a clinical picture compatible with dopaminergic dysregulation, which was ultimately revealed to be induced by her companion. Patient's exuberant choreiform dyskinesia led to a potential financial advantage when performed outside the hospital but excessive dopamine intake also occurred during hospital admission, without any obvious reward for the abuser. Even in cases where there is no place for a definitive diagnosis, deceptive behaviours must be identified as their management is based on psychological and social support in parallel to the adjustment of PD therapy.

Factors to Consider in the Selection of Dopamine Agonists for Older Persons with Parkinson's Disease

Dopamine agonists (DAs) are frequently used in the management of Parkinson's disease (PD), a complex multisystem disorder influenced substantially by age-related factors. Over 80% of PD patients present after age 60 years and may have clinical features exacerbated by age-related comorbidities or decline in physiological compensatory mechanisms. Pharmacotherapy for motor symptoms in older persons is more likely to involve exclusive use of levodopa combined with a peripheral decarboxylase inhibitor throughout the course of the illness. Non-ergot DAs, such as pramipexole, rotigotine and ropinirole, may be used as de novo monotherapy for the control of motor symptoms in older persons, although they are less efficacious than levodopa therapy. DAs may also be considered as adjunct therapy in older persons when motor symptoms are no longer adequately controlled by levodopa or when motor fluctuations and dyskinesia appear. DAs may be used cautiously in older persons with cognitive impairment and orthostatic hypotension but should be avoided when there is a history or risk of psychosis or impulse control disorders.

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.

Impact of Cognitive Profile on Impulse Control Disorders Presence and Severity in Parkinson's Disease

Background: Impulse control disorders (ICDs) and related behaviors are frequent in Parkinson's disease (PD). Mild cognitive impairment (PD-MCI) and dementia (PDD), both characterized by heterogeneous cognitive phenotypes, are also commonly reported in PD. However, the frequency and severity of ICD within PD cognitive states is unknown.

Methods: Three hundred and twenty-six PD patients completed a comprehensive neuropsychological assessment and were classified as PD-MCI, PDD, or without cognitive alterations (PD-NC). The Minnesota impulsive disorders interview was used to ascertain the presence (ICD+) or absence (ICD–) of ICD. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale was used to assess ICD severity. A subsample of 286 patients evaluated with the same cognitive tasks was selected in order to investigate the characteristics of ICD in PD cognitive phenotypes.

Results: ICDs were present in 55% of PD-NC, in 50% of PD-MCI, and in 42% of PDD patients. Frequencies of ICD+ with attentive (ICD+: 20% vs. ICD–: 4%; p = 0.031) and executive impairments (ICD+: 44% vs. ICD–: 30%; p = 0.027) were higher in the PD-MCI and PDD subgroups, respectively. As expected, no differences were observed in the PD-NC. PD-MCI with attentive impairments presented higher percentage of ICD+ with deficits in the Trail Making Test B-A but not in the Digit Span Sequencing task. In PDD, executive failures concerned Similarities task (ICD+: 67%; ICD–: 29%; p = 0.035), with no differences between ICD+ and ICD– in the Stroop task.

Conclusions: Prevalence and severity of ICDs and related behaviors do not differ in PD with different cognitive states. However, ICD+ are more likely to show deficits, respectively in attentive and in executive domains, specifically in the Trail Making Test B-A task for the attention and working memory domain in PD-MCI and in the Similarities task for the executive function domain in PDD. Prospective studies should evaluate if these tests can be used as screening tool for ICDs in PD.

French validation of the questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS)

INTRODUCTION

The management of impulse control disorders (ICDs) in Parkinson's disease (PD) relies on their early identification, allowing adjustment of antiparkinsonian treatment before these manifestations lead to major social, financial or legal consequences. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) is an English-developed and -validated PD-specific rating scale constructed to support the rating of ICDs and related disorders and the assessment of changes in symptom severity over time, but it has not to date been validated in French.

METHODS

We conducted an observational, multicenter, cross-sectional study among a subset of patients (n = 280) from the Drug Interacting with Genes in PD (DIG-PD) cohort, aiming to assess psychometric properties of the French version of QUIP-RS: acceptability, internal consistency, factor analysis, reproductibility and hypotheses testing. In addition to this scale, the following measures were applied: MDS-Unified Parkinson's Disease Rating Scale, Mini-Mental State Examination, Frontal Assessment Behavior, and Ardouin Scale of Behavior in Parkinson's Disease (ASBPD).

RESULTS

Cronbach's alpha coefficient was 0.72 and ranged from 0.25 to 0.55. Regarding test-retest reliability and inter-rater reliability, the Lin concordance coefficient for items was higher than 0.58. The correlations between QUIP-RS and ASBPD were moderate to high except for dopaminergic addiction and hobbyism (r = 0.41 and 0.40 respectively, p < 0.001). No clinically significant correlation was found between QUIP-RS total score (and items) and other scales.

CONCLUSION

The French version of the QUIP-RS appears to be a valid, reliable, and precise instrument for the assessment of ICDs and related disorders in PD. REGISTRATION NUMBER: clinicaltrials.gov number NCT01564992.

Dopamine and addiction: what have we learned from 40 years of research

Among the neurotransmitters involved in addiction, dopamine (DA) is clearly the best known. The critical role of DA in addiction is supported by converging evidence that has been accumulated in the last 40 years. In the present review, first we describe the dopaminergic system in terms of connectivity, functioning and involvement in reward processes. Second, we describe the functional, structural, and molecular changes induced by drugs within the DA system in terms of neuronal activity, synaptic plasticity and transcriptional and molecular adaptations. Third, we describe how genetic mouse models have helped characterizing the role of DA in addiction. Fourth, we describe the involvement of the DA system in the vulnerability to addiction and the interesting case of addiction DA replacement therapy in Parkinson's disease. Finally, we describe how the DA system has been targeted to treat patients suffering from addiction and the result obtained in clinical settings and we discuss how these different lines of evidence have been instrumental in shaping our understanding of the physiopathology of drug addiction.

Nutritional modulation of the intestinal microbiota; future opportunities for the prevention and treatment of neuroimmune and neuroinflammatory disease

The gut-brain axis refers to the bidirectional communication between the enteric nervous system and the central nervous system. Mounting evidence supports the premise that the intestinal microbiota plays a pivotal role in its function and has led to the more common and perhaps more accurate term gut-microbiota-brain axis. Numerous studies have identified associations between an altered microbiome and neuroimmune and neuroinflammatory diseases. In most cases, it is unknown if these associations are cause or effect; notwithstanding, maintaining or restoring homeostasis of the microbiota may represent future opportunities when treating or preventing these diseases. In recent years, several studies have identified the diet as a primary contributing factor in shaping the composition of the gut microbiota and, in turn, the mucosal and systemic immune systems. In this review, we will discuss the potential opportunities and challenges with respect to modifying and shaping the microbiota through diet and nutrition in order to treat or prevent neuroimmune and neuroinflammatory disease.

Pharmacological insights into impulsive-compulsive spectrum disorders associated with dopaminergic therapy

Impulsive-compulsive spectrum disorders are associated with dopamine agonist therapy in some patients. These untoward outcomes occur with direct-acting, full and partial agonists at D2 dopamine family receptors. The disorders typically emerge during chronic treatment, and exhibit common features that are independent of the neurological or psychiatric pathology for which the initial therapy was indicated. It is well-documented that the brain is 'plastic', changing in response to alterations to internal factors (e.g., disease processes), as well as external factors (e.g., therapies). The complexities of these clinical scenarios have eluded a clear depiction of the neurobiology for impulsive-compulsive spectrum disorders and engendered considerable debate regarding the mechanistic underpinnings of the disorders. In this opinion, we use pharmacological concepts related to homeostatic compensation subsequent to chronic receptor activation to provide a unifying construct. This construct helps explain the occurrence of impulsive-compulsive spectrum disorders across disease states, and during therapy with full and partial agonists.

Impulse control and related disorders in Parkinson's disease

Neuropsychiatric disorders are common among patients with Parkinson's disease and may appear in any stage of the disease. However, these disorders often go undiagnosed and receive insufficient treatment. Observations in recent years have revealed that dopamine replacement therapy may lead to the development or worsening of conditions, such as gambling disorder, compulsive sexual behavior, compulsive buying and binge eating, in addition to punding and dopamine dysregulation syndrome. The pathophysiology of these disorders seems to be related to abnormal dopaminergic stimulation of the basal regions of the basal ganglia, especially via nigro-mesolimbic pathways. The aim of the present study was to perform a literature review on impulsivity, impulse control disorders and related conditions among patients with Parkinson's disease, with emphasis on their epidemiology, clinical characteristics and treatment.

The Outcome of Dopamine Dysregulation Syndrome in Parkinson's Disease: A Retrospective Postmortem Study

Introduction

We have performed a retrospective analysis of the frequency and relation to treatment of dopamine dysregulation syndrome (DDS) using the Queen Square Brain Bank (QSBB) database.

Methods

A search of the QSBB database for consecutive cases donated between 2005 and 2016 with a pathological diagnosis of Parkinson's disease was performed.

Results

DDS was present in 8.8% of cases, was more prevalent in males, and was associated with younger age of onset, longer disease duration, and more dopa-induced dyskinesias. Treatment approaches for DDS included: reduction of levodopa, reduction/cessation of dopamine agonist (DA), and initiation of infusion therapies. DDS had completely resolved in just over half the patients. DA peak l-dopa equivalent daily dose (LEDD) was higher in patients who failed to achieve remission.

Conclusion

This is the first study to provide data on the course of DDS until death. Treatment strategies consisted mainly of reduction of dopaminergic treatment, and, despite the majority of patients showing some improvement, half remained symptomatic. Successful treatment was associated with a lower l-dopa dosage at death.

Delusions in Parkinson's Disease: A Systematic Review of Published Cases

Delusions in Parkinson's disease (PD) are thought to be associated with disease progression and cognitive impairment. However, this symptom description is not consistent in the literature and there is a suggestion that different subgroups of psychotic patients occur in PD, which we aimed to clarify. Case reports were identified through a systematic search of databases (PUBMED, EMBASE, PsychInfo). Cases with isolated delusions were compared to those with both delusions and hallucinations. We identified 184 cases of delusions in PD. Delusions were primarily paranoid in nature (83%) and isolated in 50%. Those with isolated delusions had an earlier onset of PD (46 years vs 55 years), higher rates of impulse control disorders (40.2 vs 10.3%), dopamine dysregulation (29.9 vs 11.3%) and lower rates of cognitive impairment (8.0 vs 26.8%). There is unexpected heterogeneity amongst cases of delusional psychosis, that cannot adequately be explained by existing models of PD psychosis.