Dopamine-induced nonmotor symptoms of Parkinson's disease

Validation of the Non-Motor Symptoms Scale for Parkinson's Disease of Persian Version

Objective

We aimed to assess the validity and reliability of the Persian version of the NonMotor Symptoms Scale (NMSS) in Iranian patients with PD.

Methods

This cross-sectional study was conducted in patients with PD. After the cross-cultural adaptation of the NMSS, the acceptability, reliability, precision, and validity of the Persian NMSS were evaluated. For this purpose, in addition to NMSS, we used the following measures: Scales for Outcomes in Parkinson's Disease (SCOPA)-Autonomic (SCOPA-AUT), SCOPA-Sleep, Beck's Depression Inventory (BDI) questionnaire, Parkinson's Disease Questionnaire-8 questions (PDQ-8), SCOPA-Motor, SCOPA-Psychiatric Complications (SCOPA-PC), SCOPA-Cognition (SCOPA-COG), Mini-Mental State Examination (MMSE), Hoehn and Yahr Staging (H and Y), and Unified Parkinson Disease Rating Scale (UPDRS).

Results

186 patients were enrolled (mean age 64.46 ± 9.9 years; disease duration 5.59 ± 3.99 years; 118 (63.4%) male; mean NMSS score 52.01 ± 38.54). Neither the floor effect (2.7%) nor the ceiling effect (0.5%) was seen in NMSS total score. Cronbach's alpha of total NMSS was 0.84. The test-retest reliability was 0.93 for the NMSS total and 0.81-0.96 for domains. The standard error of measurement (SEM) was lower than half of the standard deviation for NMSS total and all domains. NMSS total showed a high correlation with UPDRS I (r_s = 0.84), UPDRS II (r_s = 0.58), PDQ-8 (r_s = 0.61), BDI (r_s = 0.71), SCOPA-sleep (r_s = 0.60), and SCOPA AUT (r_s = 0.66). NMSS has an acceptable discriminative validity based on disease duration and severity of disease according to H and Y staging.

Conclusion

The Persian NMSS is a valid and reliable measure for evaluating the burden of nonmotor symptoms in Iranian patients with PD.

The PPN and motor control: Preclinical studies to deep brain stimulation for Parkinson's disease

The pedunculopontine nucleus (PPN) is the major part of the mesencephalic locomotor region, involved in the control of gait and locomotion. The PPN contains glutamatergic, cholinergic, and GABAergic neurons that all make local connections, but also have long-range ascending and descending connections. While initially thought of as a region only involved in gait and locomotion, recent evidence is showing that this structure also participates in decision-making to initiate movement. Clinically, the PPN has been used as a target for deep brain stimulation to manage freezing of gait in late Parkinson's disease. In this review, we will discuss current thinking on the role of the PPN in locomotor control. We will focus on the cytoarchitecture and functional connectivity of the PPN in relationship to motor control.

Diffusion Tensor Imaging Reveals Deep Brain Structure Changes in Early Parkinson's Disease Patients with Various Sleep Disorders

Parkinson’s disease (PD) is a progressive age-related movement disorder caused by dopaminergic neuron loss in the substantia nigra. Diffusion-based magnetic resonance imaging (MRI) studies—namely, diffusion tensor imaging (DTI)—have been performed in the context of PD, either with or without the involvement of sleep disorders (SDs), to deepen our understanding of cerebral microstructural alterations. Analyzing the clinical characteristics and neuroimaging features of SDs in early PD patients is beneficial for early diagnosis and timely invention. In our present study, we enrolled 36 early PD patients (31 patients with SDs and 5 patients without) and 22 healthy controls. Different types of SDs were assessed using the Rapid Eye Movement Sleep Behavior Disorder Questionnaire—Hong Kong, Epworth Sleepiness Scale, International Restless Legs Scale and PD Sleep Scale-2. Brain MRI examinations were carried out in all the participants, and a region-of-interest (ROI) analysis was used to determine the DTI-based fractional anisotropy (FA) values in the substantia nigra (SN), thalamus (Thal) and hypothalamus (HT). The results illustrate that SDs showed a higher prevalence in the early PD patients than in the healthy controls (86.11% vs. 27.27%). Early PD patients with nighttime problems (NPs) had longer courses of PD than those without (5.097 ± 2.925 vs. 2.200 ± 1.095; p < 0.05), and these patients with excessive daytime sleepiness (EDS) or restless legs syndrome (RLS) had more advanced Hoehn and Yahr stages (HY stage) than those without (1.522 ± 0.511 and 1.526 ± 0.513, respectively; both p < 0.05). Compared with the early PD patients without probable rapid eye movement sleep behavior disorder (pRBD), those with pRBD had longer courses, more advanced HY stages and worse motor and non-motor symptoms of PD (course(years), 3.385 ± 1.895 vs. 5.435 ± 3.160; HY stages, 1.462 ± 0.477 vs. 1.848 ± 0.553; UPDRS, 13.538 ± 7.333 vs. 21.783 ± 10.766; UPDRS, 6.538 ± 1.898 vs. 7.957 ± 2.345; all p < 0.05). In addition, the different number of SD types in early PD patients was significantly inversely associated with the severity of damage in the SN and HT. All of the early PD patients with various SDs had injuries in the SN, in whom the damage was more pronounced in patients with NP than those without. Moreover, early PD patients with NP, RLS or pRBD had worse degrees of HT damage than those without. The current study demonstrated the pathophysiological features and neuroimaging changes in early PD patients with various types of sleep disorders, which will help in early diagnosis and therapy.

Influence of Clinical Markers of Dopaminergic Behaviors on Depressive Symptoms During Withdrawal in Cocaine Users

Background: During cocaine withdrawal, transient depressive symptoms that do not meet the criteria for depression, but promote relapse, are frequently observed. Their temporality could evoke a role of dopamine, especially since the underlying mechanism of these depressive symptoms is not well understood. We hypothesized that variation in the dopaminergic activity profile, modeled from clinical markers, could be implicated in the development of depressive symptoms during cocaine withdrawal. Methods: We compared patients reporting depressive symptoms (RDS+) or not (RDS-) during cocaine withdrawal. We evaluated dopaminergic activity through indirect clinical markers based on the known dopaminergic behaviors. A combined criterion was constructed for hyper and hypo dopaminergic models according to the O'Brien method and illustrated by the Hedges' effect-size and forest-plot graph. A multidimensional factorial analysis was carried out to determine which parameters discriminate RDS+/RDS- patients. Results: 313 patients were included, and 77% reported depressive symptoms during cocaine withdrawal. Hyperdopaminergic variables used to discriminate the two groups had a large overall effect size (-0.669) and included psychotic symptoms (-0.524), hallucinations (-0.548), and delusions (-0.528). The overall effect of the hypodopaminergic component was considerable (-0.604) with a large effect size for the severity of dependence (-0.616), withdrawal symptoms (-0.578), and anhedonia (-0.528). The combined model including hyperdopaminergic and hypodopaminergic components had the largest effect size (-0.785). Conclusion: The dopaminergic activities profile, assessed by indirect clinical markers, seems to characterize patients with depressive symptoms very well during cocaine withdrawal. RDS+ patients reported moreover higher levels of psychotic symptoms and more severe cocaine use disorder than RDS-.

Flash Electroretinography Parameters and Parkinson's Disease

BACKGROUND

Parkinson's disease (PD) is known to affect retinal structure and activity. As such, retinal evaluations may be used to develop objective and possibly early PD diagnostic tools.

OBJECTIVE

The aim of this study was to investigate the effects of Parkinson's disease (PD) manifestation and treatment on retinal activity.

METHODS

Data were collected on 21 participants diagnosed with PD, including the number of medications taken, clinical scales and flash electroretinography (fERG) measurements, under light-adapted and dark-adapted conditions. The fERG parameters measured included a-wave and b-wave amplitude and implicit time (i.e., latency). First, we investigated correlations between symptom measure scores and the fERG parameters. Next, we divided participants into two groups based on their antiparkinsonian medication load and analyzed differences between these groups' fERG parameters.

RESULTS

fERG parameters were strongly correlated with a number of clinical variables, including motor and non-motor symptoms and age at PD onset. Photoreceptor cell implicit time was longer among participants taking one or less antiparkinsonian medication as compared to those taking two or more. However, overall there was not strong evidence of a relationship between the number of antiparkinsonian medications taken and the fERG parameters.

CONCLUSION

Findings suggest that fERG may be a useful, non-intrusive measure of retinal, and, perhaps overall CNS function, in PD. However, additional studies in larger samples are needed to clarify this association.

Agitation and impulsivity in mid and late life as possible risk markers for incident dementia

To identify knowledge gaps regarding new-onset agitation and impulsivity prior to onset of cognitive impairment or dementia the International Society to Advance Alzheimer's Research and Treatment Neuropsychiatric Syndromes (NPS) Professional Interest Area conducted a scoping review. Extending a series of reviews exploring the pre-dementia risk syndrome Mild Behavioral Impairment (MBI), we focused on late-onset agitation and impulsivity (the MBI impulse dyscontrol domain) and risk of incident cognitive decline and dementia. This scoping review of agitation and impulsivity pre-dementia syndromes summarizes the current biomedical literature in terms of epidemiology, diagnosis and measurement, neurobiology, neuroimaging, biomarkers, course and prognosis, treatment, and ongoing clinical trials. Validations for pre-dementia scales such as the MBI Checklist, and incorporation into longitudinal and intervention trials, are needed to better understand impulse dyscontrol as a risk factor for mild cognitive impairment and dementia.

The Parkinson's phenome-traits associated with Parkinson's disease in a broadly phenotyped cohort

In order to systematically describe the Parkinson's disease phenome, we performed a series of 832 cross-sectional case-control analyses in a large database. Responses to 832 online survey-based phenotypes including diseases, medications, and environmental exposures were analyzed in 23andMe research participants. For each phenotype, survey respondents were used to construct a cohort of Parkinson's disease cases and age-matched and sex-matched controls, and an association test was performed using logistic regression. Cohorts included a median of 3899 Parkinson's disease cases and 49,808 controls, all of European ancestry. Highly correlated phenotypes were removed and the novelty of each significant association was systematically assessed (assigned to one of four categories: known, likely, unclear, or novel). Parkinson's disease diagnosis was associated with 122 phenotypes. We replicated 27 known associations and found 23 associations with a strong a priori link to a known association. We discovered 42 associations that have not previously been reported. Migraine, obsessive-compulsive disorder, and seasonal allergies were associated with Parkinson's disease and tend to occur decades before the typical age of diagnosis for Parkinson's disease. The phenotypes that currently comprise the Parkinson's disease phenome have mostly been explored in relatively small purpose-built studies. Using a single large dataset, we have successfully reproduced many of these established associations and have extended the Parkinson's disease phenome by discovering novel associations. Our work paves the way for studies of these associated phenotypes that explore shared molecular mechanisms with Parkinson's disease, infer causal relationships, and improve our ability to identify individuals at high-risk of Parkinson's disease.

Genetic variability of inflammation and oxidative stress genes does not play a major role in the occurrence of adverse events of dopaminergic treatment in Parkinson's disease

BACKGROUND

Inflammation and oxidative stress are recognized as important contributors to Parkinson's disease pathogenesis. As such, genetic variability in these pathways could have a role in susceptibility for the disease as well as in the treatment outcome. Dopaminergic treatment is effective in management of motor symptoms, but poses a risk for motor and non-motor adverse events. Our aim was to evaluate the impact of selected single-nucleotide polymorphisms in genes involved in inflammation and oxidative stress on Parkinson's disease susceptibility and the occurrence of adverse events of dopaminergic treatment.

METHODS

In total, 224 patients were enrolled, and their demographic and clinical data on the disease course were collected. Furthermore, a control group of 146 healthy Slovenian blood donors were included for Parkinson's disease' risk evaluation. Peripheral blood was obtained for DNA isolation. Genotyping was performed for NLRP3 rs35829419, CARD8 rs2043211, IL1β rs16944, IL1β rs1143623, IL6 rs1800795, CAT rs1001179, CAT rs10836235, SOD2 rs4880, NOS1 rs2293054, NOS1 rs2682826, TNF-α rs1800629, and GPX1 rs1050450. Logistic regression was used for analysis of possible associations.

RESULTS

We observed a nominally significant association of the IL1β rs1143623 C allele with the risk for Parkinson's disease (OR = 0.59; 95%CI = 0.38-0.92, p = 0.021). CAT rs1001179 A allele was significantly associated with peripheral edema (OR = 0.32; 95%CI = 0.15-0.68; p = 0.003). Other associations observed were only nominally significant after adjustments: NOS1 rs2682826 A allele and excessive daytime sleepiness and sleep attacks (OR = 1.75; 95%CI = 1.00-3.06, p = 0.048), SOD2 rs4880 T allele and nausea/vomiting (OR = 0.49, 95%CI = 0.25-0.94; p = 0.031), IL1β rs1143623 C allele and orthostatic hypotension (OR = 0.57, 95%CI = 0.32-1.00, p = 0.050), and NOS1 rs2682826 A allele and impulse control disorders (OR = 2.59; 95%CI = 1.09-6.19; p = 0.032). We did not find any associations between selected polymorphisms and motor adverse events.

CONCLUSIONS

Apart from some nominally significant associations, one significant association between CAT genetic variability and peripheral edema was observed as well. Therefore, the results of our study suggest some links between genetic variability in inflammation- and oxidative stress-related pathways and non-motor adverse events of dopaminergic treatment. However, the investigated polymorphisms do not play a major role in the occurrence of the disease and the adverse events of dopaminergic treatment.

The 5-HT2A Receptor (5-HT2AR) Regulates Impulsive Action and Cocaine Cue Reactivity in Male Sprague-Dawley Rats

Impulsivity and the attentional orienting response to cocaine-associated cues (cue reactivity) promote relapse in cocaine-use disorder (CUD). A time-dependent escalation of cue reactivity (incubation) occurs during extended, forced abstinence from cocaine self-administration in rats. The investigational serotonin (5-HT) 5-HT2A receptor (5-HT2AR) antagonist/inverse agonist M100907 suppresses impulsive action, or the inability to withhold premature responses, and cocaine-seeking behaviors. The present preclinical study was designed to establish the potential for repurposing the Food and Drug Administration-approved selective 5-HT2AR antagonist/inverse agonist pimavanserin as a therapeutic agent to forestall relapse vulnerability in CUD. In male Sprague-Dawley rats, pimavanserin suppressed impulsive action (premature responses) measured in the 1-choice serial reaction time (1-CSRT) task, similarly to M100907. We also used the 1-CSRT task to establish baseline levels of impulsive action before cocaine self-administration and evaluation of cue reactivity (lever presses reinforced by the discrete cue complex previously paired with cocaine delivery). We observed an incubation of cocaine cue reactivity between day 1 and day 30 of forced abstinence from cocaine self-administration. Baseline levels of impulsive action predicted incubated levels of cocaine cue reactivity in late abstinence. We also found that baseline impulsive action predicted the effectiveness of pimavanserin to suppress incubated cue reactivity in late abstinence from cocaine self-administration at doses that were ineffective in early abstinence. These data suggest that integration of clinical measures of impulsive action may inform refined, personalized pharmacotherapeutic intervention for the treatment of relapse vulnerability in CUD.

Turkish version of Parkinson Fatigue Scale: Validity and reliability study of binary scoring method

OBJECTIVES

The aim of the present study was to translate and cross-culturally adapt the Parkinson Fatigue Scale (PFS) into Turkish and to evaluate its reliability and validity.

PATIENTS AND METHODS

Between September 2015 and May 2016, a total of 138 patients (84 males, 54 females; mean age 62.8±9.3 years; range, 42 to 83 years) with Parkinson's disease (PD) were included in this study. The Turkish version of the PFS was analyzed for data quality, scaling assumptions, acceptability, reliability, and validity. We used the binary scoring method of the Parkinson Fatigue Scale.

RESULTS

The data quality for the Turkish version of the PFS was excellent. The scaling assumption was acceptable. The scale provided an acceptable internal consistency (Cronbach's alpha was 0.955 for a test and 0.941 for a retest, and corrected item-to-total correlations were ranged from 0.478 to 0.849. The test-retest reliability (correlation coefficients were ranged from 0.650 to 0.875) was adequate. Although the total binary score of the PFS was not associated with demographic and clinical data, it was significantly correlated with some of the clinical rating scale scores, including the Unified Parkinson's Disease Rating Scale, Schwab & England Activities of Daily Living Scale, Hospital Anxiety and Depression Scale, Epworth Sleepiness Scale, Pittsburg Sleep Quality Index, 36-item Short Form Health Survey, 39-item Parkinson's Disease Questionnaire, and Fatigue Severity Scale.

CONCLUSION

The Turkish version of the PFS is an acceptable, valid, and reliable tool for the assessment of fatigue in PD patients.

Treatment of Nonmotor Symptoms in Parkinson's Disease

Nonmotor symptoms (NMS) are integral to Parkinson's disease (PD) and the management can often be challenging. In spite of the growing evidence that NMS have a key impact on the quality of life of patients and caregivers, most clinical trials still focus on motor symptoms as primary outcomes. As a consequence strong evidence-based treatment recommendations for NMS occurring in PD are spare. In this chapter, the current data addressing the treatment of major NMS such as sleep, cognitive and autonomic dysfunction, and depression and anxiety are described.

A Personalized Approach to Parkinson's Disease Patients Based on Founder Mutation Analysis

While the phenotype of Parkinson disease (PD) is heterogeneous, treatment approaches are mostly uniform. Personalized medicine aims to treat diseases with targeted therapies based on cumulative variables, including genotype. We believe that sufficient evidence has accumulated to warrant the initiation of personalized medicine in PD based on subjects genotype and provide examples for our reasoning from observations of GBA and LRRK2 mutations carriers. While PD patients who carry the G2019S mutation in the LRRK2 gene seem to develop relatively mild disease with more frequent postural instability gait disturbance phenotype, carriers of mutations in the GBA gene tend to have an early onset, rapidly deteriorating disease, with more pronounced cognitive and autonomic impairments. These characteristics have significant implications for treatment and outcome and should be addressed from an early stage in the attempt to improve the patient's quality of life.

Rasagiline for sleep disorders in patients with Parkinson's disease: a prospective observational study

INTRODUCTION

Rasagiline is a selective, irreversible monoamine oxidase B inhibitor that ameliorates the symptoms of Parkinson's disease (PD) by inhibiting striatal dopamine metabolism. There is also evidence that monoamine oxidase B inhibitors increase melatonin levels in the pineal gland and may have a beneficial effect on sleep disorders, which are a common feature in patients with PD.

METHODS

This single-center, prospective, observational, 12-week study compared the effect of combination therapy with levodopa 200-300 mg/d + rasagiline 1 mg/d (n=19) with levodopa 200-300 mg/d alone (n=19) in the treatment of sleep disorders in patients with idiopathic PD.

RESULTS

After 12 weeks' treatment, mean sleep latency was significantly (P<0.001) lower and the improvement in sleep latency from baseline was significantly (P=0.001) greater in patients receiving levodopa + rasagiline than in patients receiving levodopa alone. Similarly, at the end of the study, the mean total sleep time was significantly (P=0.002) longer and the improvement from baseline in mean total sleep time was significantly (P=0.026) greater in patients receiving levodopa + rasagiline than levodopa alone. There were no significant differences between treatment groups for the mean number of awakenings reported at week 12 nor the change from baseline to week 12 in mean number of awakenings.

CONCLUSION

Adding rasagiline to levodopa improved sleep outcomes and may be an appropriate option for patients with PD experiencing sleep disorders.

Patterns of Neuropsychological Profile and Cortical Thinning in Parkinson's Disease with Punding

BACKGROUND

Punding, one of dopamine replacement treatment related complications, refers to aimless and stereotyped behaviors. To identify possible neural correlates of punding behavior in patients with Parkinson's disease (PD), we investigated the patterns of cognitive profiles and cortical thinning.

METHODS

Of the 186 subjects with PD screened during the study period, we prospectively enrolled 10 PD patients with punding and 43 without punding on the basis of a structured interview. We performed comprehensive neuropsychological tests and voxel-based and regions-of-interest (ROIs)-based cortical thickness analysis between PD patients with and without punding.

RESULTS

The prevalence of punding in patients with PD was 5.4%. Punding behaviors were closely related to previous occupations or hobbies and showed a temporal relationship to changes of levodopa-equivalent dose (LED). Significant predisposing factors were a long duration of PD and intake of medications of PD, high total daily LED, dyskinesia, and impulse control disorder. Punding severity was correlated with LED (p = 0.029). The neurocognitive assessment revealed that PD patients with punding showed more severe cognitive deficits in the color Stroop task than did those without punding (p = 0.022). Voxel-based analysis showed that PD-punders had significant cortical thinning in the dorsolateral prefrontal area relative to controls. Additionally, ROI-based analysis revealed that cortical thinning in PD-punders relative to PD-nonpunders was localized in the prefrontal cortices, extending into orbitofrontal area.

CONCLUSIONS

We demonstrated that PD patients with punding performed poorly on cognitive tasks in frontal executive functions and showed severe cortical thinning in the dorsolateral prefrontal and orbitofrontal areas. These findings suggest that prefrontal modulation may be an essential component in the development of punding behavior in patients with PD.

Multidisciplinary intensive rehabilitation treatment improves sleep quality in Parkinson's disease

BACKGROUND

Sleep disturbances are among the most common non-motor symptoms of Parkinson's disease (PD), greatly interfering with daily activities and diminishing life quality. Pharmacological treatments have not been satisfactory because of side effects and interactions with anti-parkinsonian drugs. While studies have shown that regular exercise improves sleep quality in normal aging, there is no definitive evidence in PD.

METHODS

In a retrospective study, we determined whether an intense physical and multidisciplinary exercise program improves sleep quality in a large group of patients with PD. We analyzed the scores of PD Sleep Scale (PDSS), which was administered twice, 28 days apart, to two groups of patients with PD of comparable age, gender, disease duration and pharmacological treatment. The control group (49 patients) did not receive rehabilitation, The treated group (89 patients) underwent a 28-day multidisciplinary intensive rehabilitation program (three one-hour daily sessions comprising cardiovascular warm-up, relaxation, muscle-stretching, balance and gait training, occupational therapy to improve daily living activities).

RESULTS

At enrolment, control and treated groups had similar UPDRS and PDSS scores. At re-test, 28 days later, UPDRS and total PDSS scores improved in the treated (p < 0.0001) but not in the control group. In particular, the treated group showed significant improvement in PDSS scores for sleep quality, motor symptoms and daytime somnolence. The control group did not show improvement for any item.

CONCLUSIONS

These results suggest that multidisciplinary intensive rehabilitation treatment may have a positive impact on many aspects of sleep in PD.

Comparison of sleep and other non-motor symptoms between SWEDDs patients and de novo Parkinson's disease patients

BACKGROUND

SWEDDs (Scans Without Evidence of Dopaminergic Deficits) was defined from a series of pharmaceutical trials on Parkinson's disease (PD). Non-motor features including sleep-related problems are common even in early-stage PD patients; however, little is known about the burden of the non-motor symptoms in SWEDDs patients.

METHODS

The Non-motor Symptoms Assessment Scale (NMSS), revised version of the Parkinson's Disease Sleep Scale (PDSS-2), Epworth Sleepiness Scale (ESS), and EuroQol 5-Dimension (EQ-5D) were applied to evaluate 17 SWEDDs patients and 28 de novo PD patients. The presence of clinically probable rapid eye movement sleep behavior disorder (cpRBD) was assessed using the International Classification of Sleep Disorders-Revised (ICSD-R) criteria.

RESULTS

The total NMSS score for the SWEDDs group was significantly lower than for the de novo PD group (p = 0.032). The most distinct difference was in taste or smell change (p < 0.000). Prevalence of cpRBD was higher in de novo PD patients than in SWEDDs patients (p = 0.030), though no significant differences in the PDSS-2 total score (p = 0.496) or the ESS score (p = 0.517) were found. The SWEDDs patients did not significantly differ from the de novo PD patients with regard to quality of life, as measured by the EQ-5D index score (p = 0.177).

CONCLUSIONS

The patients with SWEDDs have less non-motor problems than newly diagnosed untreated PD patients. Given the difficulty distinguishing between SWEDDs and early PD, identifying some of non-motor symptoms, such as RBD or olfactory impairment, could aid clinicians in their work.

Why psychosis is frequently associated with Parkinson's disease?

Psychosis is a common non-motor symptom of Parkinson's disease whose pathogenesis remains poorly understood. Parkinson's disease in conjunction with psychosis has been shown to induce injury to extracorticospinal tracts as well as within some cortical areas. In this study, Parkinson's disease patients with psychosis who did not receive antipsychotic treatment and those without psychosis underwent diffusion tensor imaging. Results revealed that in Parkinson's disease patients with psychosis, damage to the left frontal lobe, bilateral occipital lobe, left cingulated gyrus, and left hippocampal white-matter fibers were greater than damage to the substantia nigra or the globus pallidus. Damage to white-matter fibers in the right frontal lobe and right cingulate gyrus were also more severe than in the globus pallidus, but not the substantia nigra. Damage to frontal lobe and cingulate gyrus white-matter fibers was more apparent than that to occipital or hippocampal fiber damage. Compared with Parkinson's disease patients without psychosis, those with psychosis had significantly lower fractional anisotropy ratios of left frontal lobe, bilateral occipital lobe, left cingu-lated gyrus, and left hippocampus to ipsilateral substantia nigra or globus pallidus, indicating more severe damage to white-matter fibers. These results suggest that psychosis associated with Par-kinson's disease is probably associated with an imbalance in the ratio of white-matter fibers be-tween brain regions associated with psychiatric symptoms (frontal lobe, occipital lobe, cingulate gyrus, and hippocampus) and those associated with the motor symptoms of Parkinson's disease (the substantia nigra and globus pallidus). The relatively greater damage to white-matter fibers in psychiatric symptom-related brain regions than in extracorticospinal tracts might explain why chosis often occurs in Parkinson's disease patients.

The default mode network is disrupted in Parkinson's disease with visual hallucinations

BACKGROUND

Visual hallucinations (VH) are one of the most striking nonmotor symptoms in Parkinson's disease (PD), and predict dementia and mortality. Aberrant default mode network (DMN) is associated with other psychoses. Here, we tested the hypothesis that DMN dysfunction contributes to VH in PD.

METHODS

Resting state functional data was acquired from individuals with PD with VH (PDVH) and without VH (PDnonVH), matched for levodopa drug equivalent dose, and a healthy control group (HC). Independent component analysis was used to investigate group differences in functional connectivity within the DMN. In addition, we investigated whether the functional changes associated with hallucinations were accompanied by differences in cortical thickness.

RESULTS

There were no group differences in cortical thickness but functional coactivation within components of the DMN was significantly lower in both PDVH and PDnonVH groups compared to HC. Functional coactivation within the DMN was found to be greater in PDVH group relative to PDnonVH group.

CONCLUSION

Our study demonstrates, for the first time that, within a functionally abnormal DMN in PD, relatively higher "connectivity" is associated with VH. We postulate that aberrant connectivity in a large scale network affects sensory information processing and perception, and contributes to "positive" symptom generation in PD.

Dopaminergic role in regulating neurophysiological markers of sleep homeostasis in humans

While dopamine affects fundamental brain processes such as movement control, emotional responses, addiction, and pain, the roles for this neurotransmitter in regulating wakefulness and sleep are incompletely understood. Genetically modified animal models with reduced dopamine clearance exhibit hypersensitivity to caffeine, reduced-responsiveness to modafinil, and increased homeostatic response to prolonged wakefulness when compared with wild-type animals. Here we studied sleep-wake regulation in humans and combined pharmacogenetic and neurophysiologic methods to analyze the effects of the 3'-UTR variable-number-tandem-repeat polymorphism of the gene (DAT1, SLC6A3) encoding dopamine transporter (DAT). Previous research demonstrated that healthy homozygous 10-repeat (10R/10R) allele carriers of this genetic variant have reduced striatal DAT protein expression when compared with 9-repeat (9R) allele carriers. Objective and subjective estimates of caffeine sensitivity were higher in 10R allele homozygotes than in carriers of the 9R allele. Moreover, caffeine and modafinil affected wakefulness-induced changes in functional bands (delta, sigma, beta) of rhythmic brain activity in wakefulness and sleep in a DAT1 genotype-dependent manner. Finally, the sleep deprivation-induced increase in well established neurophysiologic markers of sleep homeostasis, including slow-wave sleep, electroencephalographic slow-wave activity (0.5-4.5 Hz), and number of low-frequency (0.5-2.0 Hz) oscillations in non-rapid-eye-movement sleep, was significantly larger in the 10R/10R genotype than in the 9R allele carriers of DAT1. Together, the data suggest that the dopamine transporter contributes to homeostatic sleep-wake regulation in humans.

Serotonin at the nexus of impulsivity and cue reactivity in cocaine addiction

Cocaine abuse and addiction remain great challenges on the public health agendas in the U.S. and the world. Increasingly sophisticated perspectives on addiction to cocaine and other drugs of abuse have evolved with concerted research efforts over the last 30 years. Relapse remains a particularly powerful clinical problem as, even upon termination of drug use and initiation of abstinence, the recidivism rates can be very high. The cycling course of cocaine intake, abstinence and relapse is tied to a multitude of behavioral and cognitive processes including impulsivity (a predisposition toward rapid unplanned reactions to stimuli without regard to the negative consequences), and cocaine cue reactivity (responsivity to cocaine-associated stimuli) cited as two key phenotypes that contribute to relapse vulnerability even years into recovery. Preclinical studies suggest that serotonin (5-hydroxytryptamine; 5-HT) neurotransmission in key neural circuits may contribute to these interlocked phenotypes well as the altered neurobiological states evoked by cocaine that precipitate relapse events. As such, 5-HT is an important target in the quest to understand the neurobiology of relapse-predictive phenotypes, to successfully treat this complex disorder and improve diagnostic and prognostic capabilities. This review emphasizes the role of 5-HT and its receptor proteins in key addiction phenotypes and the implications of current findings to the future of therapeutics in addiction. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Nonmotor symptoms in drug-induced parkinsonism and drug-naïve Parkinson disease

BACKGROUND

The clinical manifestations of drug-induced parkinsonism (DIP) and Parkinson disease (PD) are nearly indistinguishable, making it difficult to differentiate DIP from PD, especially in the early stages. We compared non-motor symptoms between patients with DIP and those with drug-naïve PD in the early stages using the Non Motor Symptoms Scale (NMSS).

METHODS

We prospectively enrolled 28 patients with DIP, 35 patients with drug-naïve PD, and 32 controls with no history of neurological diseases or related medical problems. We investigated demographic characteristics, medical and drug history, parkinsonian motor symptoms, and non-motor symptoms. We used the NMSS to evaluate non-motor symptoms in all patients.

RESULTS

The total NMSS scores were higher in patients with PD than those with DIP, as were the scores for certain domains, including the cardiovascular, sleep/fatigue, urinary, sexual, and miscellaneous domains. When controlling for age and gender, the correlation analysis revealed that scores for urinary symptoms (urgency, frequency and nocturia), sleep disturbances (daytime sleep, restless legs), concentration, taste or smell were significantly associated with PD.

CONCLUSIONS

Our data suggest that non-motor symptoms, particularly urinary symptoms, excessive daytime sleepiness, restless leg syndrome, attention deficit and hyposmia may be helpful to differentiate between DIP and PD in the early stages.

Substance of abuse and movement disorders: complex interactions and comorbidities

The relationship between movement disorders and substance abuse, which we previously reviewed, is updated. We examine these relationships bidirectionally with focus on drugs of abuse that are known to cause movement disorders, as well as primary movement disorders that are associated with use and abuse of alcohol and dopaminergic medications. First, we review the movement disorders that may develop from the acute use or withdrawal of frequent drugs of abuse, including alcohol, cocaine, heroin, amphetamine and methcathinone. We then comment on the interaction between alcoholism and alcohol-responsive movement disorders, such as essential tremor and myoclonus-dystonia. Lastly, we discuss the potential for abuse of antiparkinsonian dopaminergic agents in patients with Parkinson's disease (PD).

A short scale for evaluation of neuropsychiatric disorders in Parkinson's disease: first psychometric approach

The neuropsychiatric symptoms and behavioral disorders affecting Parkinson's disease (PD) patients are common and disabling. A PD-specific interview-based 12-item scale, the Scale for Evaluation of Neuropsychiatric Disorders in Parkinson's Disease (SEND-PD), has been developed to assess the severity of neuropsychiatric manifestations. The present study is aimed at testing some basic psychometric attributes of this scale. A total of 633 consecutive patients and their caregivers were included in this cross-sectional, multicenter, observational study. In addition to the tested scale, the following assessments were applied: Hoehn and Yahr staging, Scales for Outcomes in Parkinson's Disease Motor and Psychiatric complications, MiniMental State Examination, Clinical Impression of Severity Index, and the Zarit Caregiver Burden Inventory. Patients in all stages of disease were included and 18.38 % were demented. The SEND-PD was responded by patients (86.16 %), caregivers (13.15 %), or both (0.69 %). Three factors (accounting for 66.63 % of the variance) were identified and considered as subscales: Psychotic symptoms, Mood/Apathy, and Impulse control disorders. The subscales showed satisfactory scaling assumptions (multitrait-item success rate 100 %) and internal consistency (alpha indices >0.70). The convergent validity with other measures of psychiatric symptoms and the discriminant validity to distinguish between categories of patients' age, duration and severity of disease, and dopaminergic treatment were satisfactory. The precision of the scale dimensions was acceptable. The SEND-PD performed as an acceptable, consistent, valid, and precise scale for evaluation of neuropsychiatric symptoms in Parkinson's disease.