Gender Differences in Age-Related Striatal Dopamine Depletion in Parkinson's Disease

Dysphagia Pattern in Early to Moderate Parkinson's Disease Caused by Abnormal Pharyngeal Kinematic Function

Airway invasion is common in patients with Parkinson's disease (PD) and can cause serious complications. However, a PD-related dysphagic pattern has not been clearly elucidated. In this study, 53 patients with early to moderate PD were enrolled to undergo a videofluoroscopic study of swallowing evaluation (VFSS) and a battery of neuropsychological assessments. A set of VFSS variables (three visuoperceptual, nine temporal, and six spatial) were measured. The main effects of bolus viscosity and volume on airway invasion were calculated. Statistical analyses were performed to determine key kinematic factors of airway invasion for swallowing each bolus type. Airway invasion frequency was significantly higher for liquid boluses (liquid vs. pudding P < 0.001; liquid vs. honey P = 0.006). Laryngeal vestibule closure reaction time (LVCrt) was the key kinematic factor of airway invasion for 3 ml liquid swallow (P = 0.040), anterior displacement of hyoid bone was the key kinematic factor for both 5 ml and 10 ml liquid swallows (P = 0.010, 0.034, respectively). Male sex and advanced Hoehn and Yahr stage were significantly related to reduced anterior displacement of hyoid bone. These results reveal the dysphagic pattern related to PD, demonstrating that prolonged LVCrt and reduced anterior displacement of hyoid bone are two crucial kinematic factors contributing to airway invasion during the liquid swallow. In addition, hyoid bone dysfunction was correlated with disease severity and male sex. Our findings warrant further investigation of the pathophysiological mechanism of dysphagia in PD and would guide clinical intervention.

Temporal trends in Parkinson's disease among older adults in the United States from 1999 to 2020: Retrospective analysis from CDC WONDER database

This retrospective study assessed the mortality trends related to Parkinson's Disease (PD) between 1999 and 2020. We assessed individuals aged 65 years and older and a total of 831,793 deaths were identified. Of these total number of deaths, place of death was accessible for 830,176 cases. Majority of the deaths occurred in nursing homes of long-term care facilities (367,633), followed by at home (212,886), medical facilities (165,450), other locations (44,506), and hospice (39,701). Analysis of age-adjusted mortality rates (AAMR) revealed an overall rise from 1999 to 2020, 88.9 to 119.6 per 100,000 population. AAMR showed an initial decline between 1999 and 2013, followed by a slight increase between 2013 and 2018 and then a significant rise from 2018 to 2020. Gender-based analysis showed a constantly higher AAMR for older men compared to older women. Variations in AAMR based on race and ethnicity revealed that Non-Hispanic White population had the highest AAMRs. Geographic disparities among states showed that Nebraska, Vermont, Minnesota, Utah, and Idaho had a significantly higher AAMR than Hawaii, Florida, Nevada. New York, and District of Columbia. Midwest region had a consistently higher AAMR followed by West, South, and Northeast. Additionally, nonmetropolitan areas had a higher AAMR than metropolitan areas. These findings offer valuable insights into mortality patterns related to PD among the elderly, highlighting the significance of incorporating demographic and geographic variables into public health planning and interventions.

Age and gender effects on striatal dopamine transporter density and cerebral perfusion in individuals with non-degenerative parkinsonism: a dual-phase 18F-FP-CIT PET study

BACKGROUND

Dual-phase fluorine-18 labeled N-3-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) nortropane (18F-FP-CIT) positron emission tomography (PET) scans could be used to support disorders like Parkinson's disease (PD). Dopamine transporter (DAT) binding and cerebral perfusion are associated with ageing and gender. We investigated the effects of age and gender on non-degenerative parkinsonism, using automated quantification in striatum: specific binding ratios (SBRs) for DAT binding in delayed phase PET (dCIT) and standardized-uptake-value ratios (SUVRs) for cerebral perfusion in early phase PET (eCIT). We also examined the correlations between SBR and SUVR.

METHODS

This retrospective study analyzed subjects with dual-phase 18F-FP-CIT PET scans. The eCIT images were acquired immediately post-injection, and dCIT images were taken 120 min later. With Brightonix software, automated quantification of SBRs for dCIT and SUVRs for eCIT were acquired from visually normal scans. The effects of aging and gender were assessed by regressing SBRs and SUVRs on age for both genders. The correlations between SUVRs and SBRs were evaluated.

RESULTS

We studied 79 subjects (34 males and 45 females). An age-related reduction in SBRs was observed in the dorsal striatum, ventral striatum, caudate nucleus, and putamen for both genders. SUVRs were found to negatively correlate with age in the dorsal striatum, ventral striatum, caudate nucleus, and putamen for males and in the dorsal striatum and caudate nucleus for females. Positive correlations between SBRs and SUVRs in the dorsal striatum, ventral striatum, caudate nucleus, and putamen for male and in the dorsal striatum, caudate nucleus, and putamen for females.

CONCLUSIONS

Using quantified values from dual-phase 18F-FP-CIT PET with a single injection, we demonstrate a negative impact of age on SBRs (DAT binding) in the striatum for both genders and SUVRs (cerebral perfusion) in the dorsal striatum and caudate nucleus for both genders and in the ventral striatum and putamen for males. Additionally, we found positive associations between SBR and SUVR values in the dorsal striatum, caudate nucleus, and putamen for both genders and in the ventral striatum for males.

Impact of frailty and sex-related differences on postural control and gait in older adults with Parkinson's Disease

BACKGROUND

Parkinson's Disease (PD), a neurodegenerative condition, affects normal aging and leads to reduced motor abilities. In addition, frailty syndrome can increase vulnerability and risks of undesirable effects such as disease progression, falls, disability, and premature death among individuals with PD.

AIMS

To assess the impact of frailty on balance and gait parameters in older with PD and to determine if sex mediates these measures.

METHODS

Twenty-seven (27) participants (n = 18 men; n = 10 frail) performed 4 balance tasks on a force platform (eyes opened/closed in bipodal/semi-tandem position) while linear center of pressure (COP) parameters were calculated. Participants also performed two different speed walks on a gait analysis system to assess gait parameters.

RESULTS

Significant differences between the frail and non-frail group were observed on postural control (mainly for area of COP p = 0.013/d = 0.47/70 %; sway velocity p = 0.048/d = 0.41/23 %) where frail reported poor balance. No significant sex differences were reported for postural control. Gait analysis was comparable between frail and non-frail, while significant differences between men and women were observed for step length (p = 0.002, d = 0.71), step width (p = 0.001, d = 0.75) and base of support (p = 0.012, d = 0.64) variables.

CONCLUSION

Frail Parkinson's individuals present poorer postural control than non-frail individuals, but comparable gait parameters. Men and women are comparable on postural control but show different gait parameters. These results may have implications in clinical decision-making in rehabilitation for frailty in older adults, men and women with Parkinson's disease when balance and gait are of concern.

Cut-Off Value of Voluntary Peak Cough Flow in Patients with Parkinson's Disease and Its Association with Severe Dysphagia: A Retrospective Pilot Study

Background and Objectives. Swallowing and coughing reflexes are both closely associated with airway protection. Peak cough flow (PCF) is associated with dysphagia in several neurogenic diseases. In this study, we aimed to analyze the relationship between PCF and aspiration in Parkinson's disease (PD) and determine the cut-off value of PCF. Materials and Methods. We retrospectively analyzed the records of patients with PD who underwent a videofluoroscopic swallowing study and checked for PCF. A total of 219 patients were divided into an aspiration group (n = 125) and a non-aspiration group (n = 94). Results. Significantly lower PCF values were observed in the aspiration group compared to the non-aspiration group (132.63 ± 83.62 vs. 181.38 ± 103.92 L/min, p < 0.001). Receiver operating characteristic curve analysis revealed that a PCF cut-off value of 153 L/min (area under the receiver operating characteristic curve, 0.648; sensitivity, 73.06%; specificity, 51.06%) was associated with aspiration in PD. Additionally, a univariate analysis showed that the male sex, lower body mass indexes, higher Hoehn and Yahr scales, and PCF values of ≤153 L/min indicated an increased risk of aspiration. Conclusions. Through a multivariate analysis, we demonstrated that a PCF value ≤153 L/min was associated with an increased risk of aspiration (odds ratio 3.648; 1.797-7.407), highlighting that a low PCF is a risk factor for aspiration in patients with PD.

Worldwide trends in mortality related to Parkinson's disease in the period of 1994–2019: Analysis of vital registration data from the WHO Mortality Database

Background

Mortality due to Parkinson's disease (PD) and its long-term trends worldwide in recent decades remain unknown. No previous studies have simultaneously studied age- and sex-specific mortality trends at a population level worldwide. Insights gained from this study can help identify high-risk populations and inform healthcare service requirements for managing Parkinson's disease globally.

Objectives

The aim of the study was to examine trends in mortality from Parkinson's disease by age-group and sex across countries all over the world. In this study, we used worldwide registry data to examine the temporal trends in PD mortality across most counties of the world from 1994 to 2019 using joinpoint regression.

Results

In data from vital registration systems, huge variations in the patterns of deaths due to Parkinson's disease were observed both over time and between countries. Between 1994 and 2019, there was a significant increase in mortality rates globally in both men and women. In more detail, the mortality rate (per 100,000) in 1994 was 1.76 and reached 5.67 in 2019. Greater increases in mortality were seen in men than in women; and in older than in younger people.

Conclusions

There has been a striking rising trend in Parkinson's disease mortality globally. Persistent age and sex disparities are found in Parkinson's disease mortality trends. Our findings may have important implications for future research, healthcare planning, and provision.

Temporalis Muscle Thickness as an Indicator of Sarcopenia Is Associated With Long-term Motor Outcomes in Parkinson's Disease

BACKGROUND

To investigate the relationship between temporalis muscle thickness (TMT) at baseline as a surrogate marker for sarcopenia and long-term motor outcomes in patients with Parkinson's disease (PD).

METHODS

We enrolled 249 patients with drug-naïve early-stage PD (119 males and 130 females, follow-up > 3 years). Baseline TMT of each patient was measured on the axial plane of T1-weighted images. The association between baseline TMT and long-term motor outcomes in PD was assessed using Cox regression models for levodopa-induced dyskinesia, wearing-off, and freezing of gait and a linear mixed model for the longitudinal increases in levodopa-equivalent dose per body weight over time. Statistical analyses were performed separately for sex if an interaction effect between TMT and sex was assumed.

RESULTS

TMT differed substantially between the sexes, and male PD patients had higher TMT (6.69 ± 1.39 mm) than female PD patients (5.64 ± 1.34 mm, p < .001). Cox regression models demonstrated that baseline TMT was not associated with the risk of developing levodopa-induced dyskinesia, wearing-off, or freezing of gait during the follow-up period. The linear mixed model was applied separately for sex and demonstrated that higher TMT at baseline was associated with slower increases in levodopa-equivalent dose per body weight in male PD patients, but not in female PD patients.

CONCLUSIONS

This study demonstrated that baseline TMT could be an indicator of the longitudinal requirement for dopaminergic medications in male patients with PD, suggesting that sarcopenia may have a detrimental effect on disease progression in PD in a sex-specific manner.

Dopamine Transporter Imaging, Current Status of a Potential Biomarker: A Comprehensive Review

A major goal of current clinical research in Parkinson's disease (PD) is the validation and standardization of biomarkers enabling early diagnosis, predicting outcomes, understanding PD pathophysiology, and demonstrating target engagement in clinical trials. Molecular imaging with specific dopamine-related tracers offers a practical indirect imaging biomarker of PD, serving as a powerful tool to assess the status of presynaptic nigrostriatal terminals. In this review we provide an update on the dopamine transporter (DAT) imaging in PD and translate recent findings to potentially valuable clinical practice applications. The role of DAT imaging as diagnostic, preclinical and predictive biomarker is discussed, especially in view of recent evidence questioning the incontrovertible correlation between striatal DAT binding and nigral cell or axon counts.

Parkinson's disease in women: Mechanisms underlying sex differences

Parkinson's disease is a neurodegenerative disease which is associated with different motor, cognitive and mood-related problems. Though it has been established that Parkinson's disease is less prevalent in women in comparison to men, the differences tend to diminish with the advancing age. Different genetic, hormonal, neuroendocrinal and molecular players contribute towards the differences in the Parkinson's disease pathogenesis. Furthermore, data available with respect to the therapeutic management of Parkinson's disease in females is limited; women often tend to suffer more from the side effects of the currently available drugs. The present review highlights the sex-specific differences which play a role in the manifestation of these symptoms and side effects of the currently available therapeutic strategies. We have also discussed the current and upcoming therapeutic strategies which are in the clinical trials such as adenosine 2A (A2A) receptor antagonists, estrogen replacement therapy, α-synuclein targeting vaccines and antibodies, Botulinum toxin A, Fas-associated factor-1 (FAF-1) inhibitors, thiazolidinediones, 5-HT1_A receptor agonists, dopamine D1/D5 receptor agonists, Glucagon-like peptide 1 (GLP-1) analogues and certain plant based principles for the treatment of Parkinson's disease in women.

Emerging Concepts of Motor Reserve in Parkinson's Disease

The concept of cognitive reserve (CR) in Alzheimer's disease (AD) explains the differences between individuals in their susceptibility to AD-related pathologies. An enhanced CR may lead to less cognitive deficits despite severe pathological lesions. Parkinson's disease (PD) is also a common neurodegenerative disease and is mainly characterized by motor dysfunction related to striatal dopaminergic depletion. The degree of motor deficits in PD is closely correlated to the degree of dopamine depletion; however, significant individual variations still exist. Therefore, we hypothesized that the presence of motor reserve (MR) in PD explains the individual differences in motor deficits despite similar levels of striatal dopamine depletion. Since 2015, we have performed a series of studies investigating MR in de novo patients with PD using the data of initial clinical presentation and dopamine transporter PET scan. In this review, we summarized the results of these published studies. In particular, some premorbid experiences (i.e., physical activity and education) and modifiable factors (i.e., body mass index and white matter hyperintensity on brain image studies) could modulate an individual's capacity to tolerate PD pathology, which can be maintained throughout disease progression.

Predictors of Pharyngeal Dysphagia in Patients with Parkinson's Disease

BACKGROUND

Diagnosis of pharyngeal dysphagia in patients with Parkinson's disease is often difficult as reliable screening methods are lacking so far and clinical examination fails to adequately assess the pharyngeal phase of swallowing.

OBJECTIVE

To identify clinical predictors indicating the presence of pharyngeal dysphagia in patients at risk.

METHODS

We examined pharyngeal dysphagia in a large cohort of patients with Parkinson's disease (n = 200) divided in three clinical subtypes (tremor-dominant (TD), mainly bradykinetic (BK) and early postural instability and gait difficulty PIGD)) by using flexible endoscopic evaluation of swallowing. ANOVA-multivariance analysis and following t-tests as well as binary logistic regression analysis were performed to detect group differences and to identify clinical predictors for dysphagia.

RESULTS

Statistically significant differences were found in the dysphagic group: age, male gender, disease duration, stage of the disease, Levodopa equivalent dose and higher scores on the Unified Parkinson's disease rating scale III and II, item 7. The PIGD subtype was affected more frequently than the TD and BK subtype. In a logistic regression model higher age (>63.5 years p < 0.05) and Levodopa equivalent dose (>475 mg, p < 0.01) were identified to be independent predictors for the presence of pharyngeal dysphagia.

CONCLUSION

Particularly patients with an age > 63.5 years and a daily Levodopa equivalent dose >475 mg show an increased risk for pharyngeal dysphagia. These findings may partly be influenced by presbyphagia but are likely to represent disease progression. The PIGD subtype seems to be a risk factor due to more pronounced dyscoordination of oropharyngeal muscle movements.

Joint Multi-modal Parcellation of the Human Striatum: Functions and Clinical Relevance

The human striatum is essential for both low- and high-level functions and has been implicated in the pathophysiology of various prevalent disorders, including Parkinson's disease (PD) and schizophrenia (SCZ). It is known to consist of structurally and functionally divergent subdivisions. However, previous parcellations are based on a single neuroimaging modality, leaving the extent of the multi-modal organization of the striatum unknown. Here, we investigated the organization of the striatum across three modalities-resting-state functional connectivity, probabilistic diffusion tractography, and structural covariance-to provide a holistic convergent view of its structure and function. We found convergent clusters in the dorsal, dorsolateral, rostral, ventral, and caudal striatum. Functional characterization revealed the anterior striatum to be mainly associated with cognitive and emotional functions, while the caudal striatum was related to action execution. Interestingly, significant structural atrophy in the rostral and ventral striatum was common to both PD and SCZ, but atrophy in the dorsolateral striatum was specifically attributable to PD. Our study revealed a cross-modal convergent organization of the striatum, representing a fundamental topographical model that can be useful for investigating structural and functional variability in aging and in clinical conditions.

Sex-specific association of urate and levodopa-induced dyskinesia in Parkinson's disease

BACKGROUND AND PURPOSE

As a major antioxidant, uric acid (UA) is known to be associated with the clinical progression of Parkinson's disease (PD). This study investigated whether baseline UA levels are associated with the risk for levodopa-induced dyskinesia (LID) in PD in a sex-dependent manner.

METHODS

In all, 152 patients with de novo PD (78 males and 74 females) who were followed up for >2 years were enrolled. The effect of baseline serum UA levels on LID-free survival was assessed by Cox regression, separately for sex, whilst being adjusted for potential confounding factors. The optimal UA level cut-off value to determine the high-risk group for LID was set using Contal and O'Quigley's method.

RESULTS

Levodopa-induced dyskinesia developed in 23 (29.5%) male patients and 30 (40.5%) female patients. Cox regression showed a significant interaction between UA level and sex. Higher UA levels were associated with a higher risk for LID in male PD patients (hazard ratio 1.380; 95% confidence interval 1.038-1.835; P = 0.027), although this relationship was not observed in female PD patients. The optimal UA level cut-off for LID in male PD was 7.2 mg/dl, and the high UA group had a 5.7-fold higher risk of developing LID than the low UA group.

CONCLUSIONS

Contrary to a presumptive beneficial role of UA, the present study demonstrated that higher UA levels are associated with increased risk of LID occurrence in male patients with PD, suggesting a sex-dependent role of UA in LID.

Does the Side Onset of Parkinson's Disease Influence the Time to Develop Levodopa-Induced Dyskinesia?

BACKGROUND

Aberrant plasticity is closely linked to the development of levodopa-induced dyskinesia (LID) in Parkinson's disease (PD).

OBJECTIVE

This study investigated whether dominant-side patients with PD exhibit a shorter time to LID development, based on the hypothesis that the dominant hemisphere may have greater plasticity than non-dominant-side patients.

METHODS

We analyzed data from 387 right-handed patients with PD who exhibited asymmetric motor deficits and received PD medications for ≥2 years (191 dominant-side and 196 non-dominant-side patients). The influence of side onset on time for LID development was assessed by Kaplan-Meier estimates and time-dependent Cox regression models based on the 5-year time point, after adjusting for age at PD onset, dopamine transporter activity in the posterior putamen, and daily levodopa dose.

RESULTS

LID developed in 46 (23.4%) patients with non-dominant-side PD and in 35 (18.1%) patients with dominant-side PD. The Kaplan-Meier analyses revealed that non-dominant-side patients developed LID earlier than dominant-side patients (p = 0.027). The time-dependent Cox regression models showed that the risk of LID within 5 years of treatment was significantly higher in non-dominant-side than in dominant-side patients (hazard ratio 1.954; p = 0.034), whereas the risk after 5 years was similar between groups (p = 0.528).

CONCLUSIONS

The present study demonstrated that LID developed earlier in non-dominant-side than in dominant-side patients with PD. These results suggested a greater potential of synaptic plasticity in the dominant hemisphere that may exert a protective role for the development of LID compared to the non-dominant hemisphere.

The sex-specific interaction of the microbiome in neurodegenerative diseases

Several neurologic diseases exhibit different prevalence and severity in males and females, highlighting the importance of understanding the influence of biologic sex and gender. Beyond host-intrinsic differences in neurologic development and homeostasis, evidence is now emerging that the microbiota is an important environmental factor that may account for differences between men and women in neurologic disease. The gut microbiota is composed of trillions of bacteria, archaea, viruses, and fungi, that can confer benefits to the host or promote disease. There is bidirectional communication between the intestinal microbiota and the brain that is mediated via immunologic, endocrine, and neural signaling pathways. While there is substantial interindividual variation within the microbiota, differences between males and females can be detected. In animal models, sex-specific microbiota differences can affect susceptibility to chronic diseases. In this review, we discuss the ways in which neurologic diseases may be regulated by the microbiota in a sex-specific manner.

Beneficial effect of estrogen on nigrostriatal dopaminergic neurons in drug-naïve postmenopausal Parkinson's disease

This study aimed to investigate the potential beneficial effects of estrogen on nigrostriatal dopaminergic neuron degeneration in postmenopausal drug-naïve Parkinson's disease (PD). Based on the ratio of lifetime estrogen exposure length to the total length of the estrogen exposure and deprivation period, postmenopausal women with drug-naïve PD were divided into low (n = 31) and high (n = 31) estrogen exposure ratio groups. We performed a comparative analysis of the striatal dopamine transporter (DAT) availability between the two groups. Additionally, we evaluated the longitudinal change in the levodopa equivalent dose per month using a linear mixed model. The motor symptoms were more severe in the low estrogen exposure ratio group than in the high estrogen exposure ratio group (P = 0.016). PD patients in the two groups had significantly lower DAT availability on all striatal sub-regions except for ventral striatum than did age- and sex-matched normal controls. When comparing the two groups, PD patients in the low estrogen exposure ratio group exhibited significantly lower DAT availability in the posterior putamen (P = 0.024) and in the ventral putamen (P = 0.036) than those in the high estrogen exposure ratio group. The estimated monthly levodopa equivalent dose changes were 10.9 in the low estrogen exposure ratio group and 7.1 in the high estrogen exposure ratio group with a significant interaction between the two groups (P = 0.001). These in vivo data provide indirect evidence showing that estrogen may elicit a beneficial effect on nigrostriatal dopamine neurons in PD.

Predictive clinical factors for penetration and aspiration in Parkinson's disease

BACKGROUND

Do the current swallow-specific subquestions of neurological diagnostic tools reflect the objective swallowing function in Parkinson's disease (PD) patients or are clinical factors superior to predict critical aspiration?

METHODS

In a cross-sectional, observational study a total of 119 Parkinson outpatients were examined clinically and by flexible-endoscopic evaluation of swallowing (FEES). Self-reported dysphagia by subquestions of the MDS-UPDRS and NMS questionnaire and history of subjective aspiration signs were collected.

KEY RESULTS

Nearly, all PD patients showed deglutition abnormalities in FEES (113/119) while only 12%-27% of them reported swallowing problems in the swallow-specific subquestions of neurological standard diagnostic tools (MDS-UPDRS and NMS-Quest), and the answers were heterogeneous and poorly reproducible. With a sensitivity of up to a maximum of 50%, self-reported dysphagia is therefore no reliable tool for identifying dysphagia in PD. While most clinical parameters were linked to dysphagia to some extent, logistic regression analysis revealed high age (Odds Ratio (OR) 1.1 in years, 95% CI 1.03-1.18, P < 0.01), gender (OR 0.3 for females, 95% CI 0.08-0.97, P = 0.04), and affirmed subjective aspiration signs (OR 8.6, 95% CI 3.05-26.52, P < 0.001) as the most significant predictors for critical dysphagia.

CONCLUSIONS AND INFERENCES

Self-perception of swallowing is no reliable tool for identifying dysphagia and questionnaires are insufficient for detecting previous aspiration. Consequent and specific asking for previous subjective aspiration signs is the single most important measure for identifying PD patients at risk for critical aspiration.

Lack of consistent sex differences in D-amphetamine-induced dopamine release measured with [18F]fallypride PET

RATIONALE

Sex differences in the dopaminergic response to psychostimulants could have implications for drug abuse risk and other psychopathology involving the dopamine system, but human data are limited and mixed.

OBJECTIVES

Here, we sought to investigate sex differences in dopamine release after oral D-amphetamine administration.

METHODS

We used [¹⁸F]fallypride positron emission tomography (PET) to measure the change in dopamine D2/3 receptor availability (%ΔBP_ND, an index of dopamine release) between placebo and D-amphetamine sessions in two independent datasets containing a total of 39 females (on either hormonal birth control n = 18, postmenopausal n = 10, or studied in the first 10 days of their menstrual cycle n = 11) and 37 males.

RESULTS

Using both a priori anatomical regions of interest based on previous findings and voxelwise analyses, we failed to consistently detect broad sex differences in D-amphetamine-induced dopamine release. Nevertheless, there was limited evidence for greater right ventral striatal dopamine release in young adult males relative to similarly aged females, but this was not consistently observed across samples. Plasma estradiol did not correlate with dopamine release and this measure did not differ in females on and off hormonal birth control.

CONCLUSIONS

While our finding in young adults from one dataset of greater %ΔBP_ND in males is partially consistent with a previously published study on sex differences in D-amphetamine-induced dopamine release, our data do not support the presence of consistent widespread sex differences in this measure of dopamine release.

The analysis of relationship between selected sociodemografic factors and disorders of speech organs in Parkinson`s patients

Background

Evaluation of speech disorders in PD taking into account sociodemographic conditions is not frequent. This paper aims to establish correlations between articulation disorders in PD patients and factors such as the patients’ sex, age, education and residence.

Methods

The study included 92 patients with idiopathic PD diagnosed by means of multiple neurological examinations, biochemical tests, MRI and CT scanning carried out in accordance with the United Kingdom Parkinson’s Disease Society Brain Bank (UKPDSBB) criteria. A speech and language test involved the assessment of the mobility of the speech organs as well as the reflexes inside the oral cavity. Frenchay Dysarthria Assessment was applied for an objective evaluation of dysarthria.

Results

The study revealed the existence of significant relationship between the functionality of articulators in PD patients and their education and residence. Big city dwellers demonstrated lower incidence of disorders within speech organs, particularly those affecting mobility of the soft palate while eating. Disorders of moderate intensity were more frequently found in subjects living in villages. Subjects with a university education displayed better position of the lips at rest and better performance of both lips and the mandible while speaking.

Conclusions

Abnormal functioning of the articulatory organs was observed more frequently in PD patients residing in rural areas than in those inhabiting urban areas. As for education, our cohort university graduates displayed a better position of the lips at rest and better performance of the lips and jaw during speaking than those with secondary and vocational education.

Development of a clinically feasible [11C]PE2I PET method for differential diagnosis of parkinsonism using reduced scan duration and automated reference region extraction

[¹¹C]PE2I is a highly selective dopamine transporter PET ligand. Parametric images based on dynamic [¹¹C]PE2I scans, showing dopamine transporter availability (BP_ND) and relative cerebral blood flow (R₁), can be used in differential diagnosis of parkinsonism. This work aimed to investigate a shortened scan duration and automated generation of parametric images which are two prerequisites for routine clinical application. Twelve subjects with parkinsonism and seventeen healthy controls underwent 80 min dynamic [¹¹C]PE2I PET scans. BP_ND and R₁ images were generated using cerebellum reference region defined on a co-registered MRI, as well as a supervised cluster analysis (SVCA)-based reference. Initial 20, 30 and 40 min of the scans were extracted and images of standardized uptake value ratio (SUVR) and R₁ were computed using MRI- and SVCA-based reference. Correlation was high between striatal 80 min MRI-based BP_ND and 40 min SVCA-based SUVR-1 (R²=0.95). High correlation was also found between R₁ values in striatal and limbic regions (R²≥0.91) whereas correlation was moderate for cortical regions (R²=0.71). The results indicate that dynamic [¹¹C]PE2I scans can be restricted to 40 min and that SVCA can be used for automatic extraction of a reference region. These outcomes will support routine applications of [¹¹C]PE2I PET in clinical settings.

Gender differences in Parkinson's disease: A clinical perspective

Available data indicate that there are gender differences in many features of Parkinson's disease (PD). Precise identification of the gender differences is important to tailor treatment, predict outcomes, and meet other individual and social needs in women and men with PD. The aim of this study was to review the available clinical data on gender differences in PD. Original articles and meta-analyses published between 1990 and 2016 systematically exploring gender differences in PD were reviewed. There is slight male preponderance in incidence and prevalence of PD. PD starts earlier in men. Women tend to be more prone to develop tremor-dominant PD but are less rigid than men. Motor improvement after deep brain stimulation is equal in both sexes, but women tend to show better improvement in activities of daily living. Furthermore, women with PD show better results on tests for general cognitive abilities, outperform men in verbal cognitive tasks, show more pain symptoms, and score higher on depression scales. It seems, however, that the differences in cognition, mood, and pain perception are not disease specific as similar gender differences can be found in healthy subjects and in other neurological conditions. Despite PD being the most frequently studied movement disorder, studies investigating gender differences in PD are still scarce with most of the studies being cross-sectional. Good-quality, prospective, longitudinal studies analyzing gender differences in PD and comparing them to matched healthy controls are needed in order to properly address the issues of gender differences in PD.

Trait impulsiveness is related to smaller post-commissural putamen volumes in males but not females

Impulsivity is considered a vulnerability trait for addiction. Recently, we found trait non-planning impulsiveness measured with the Karolinska Scales of Personality was negatively correlated with dopamine D_2/3 receptor availability in the ventral striatum of healthy humans. While also observed in rodents, human studies have failed to find this association with other measures of trait impulsivity. We explored whether another rodent finding, reduced ventral striatum volume with greater impulsivity, could also be observed in humans using this scale. Non-planning impulsiveness was measured in 52 healthy subjects (21 female; mean age: 33.06 ± 9.69) using the Karolinska Scales of Personality. Striatal subregion volumes, including the globus pallidus, were acquired using the Multiple Automatically Generated Templates (MAGeT-Brain) algorithm. Although failing to support our a priori hypothesis, there was a significant sex interaction in the post-commissural putamen with impulsiveness. Exploratory analyses revealed impulsiveness was negatively correlated with post-commissural putamen volumes in males, but positively correlated in females. We replicated this finding in males in an increased sample (including all 52 previous subjects) who provided impulsiveness measured by the Temperament and Character Inventory (n = 73; 32 female; mean age: 33.48 ± 9.75). These correlations by sex were statistically different from one another, the main finding with the Kasolinksa Scales of Personality surviving correction for multiple comparisons. While impulsivity may be related to reduced ventral striatal D_2/3 receptors across sexes, males but not females may show significant reductions in post-commissural putamen volume. These findings have important implications for understanding biological markers underlying sex differences in drug addiction vulnerability.

The relationship between subcortical brain volume and striatal dopamine D2/3 receptor availability in healthy humans assessed with [11 C]-raclopride and [11 C]-(+)-PHNO PET

BACKGROUND

Abnormalities in dopamine (DA) and brain morphology are observed in several neuropsychiatric disorders. However, it is not fully understood how these abnormalities may relate to one another. For such in vivo findings to be used as biomarkers for neuropsychiatric disease, it must be understood how variability in DA relates to brain structure under healthy conditions. We explored how the availability of striatal DA D_2/3 receptors (D_2/3 R) is related to the volume of subcortical brain structures in a sample of healthy humans. Differences in D_2/3 R availability measured with an antagonist radiotracer ([¹¹ C]-raclopride) versus an agonist radiotracer ([¹¹ C]-(+)-PHNO) were examined.

METHODS

Data from 62 subjects scanned with [¹¹ C]-raclopride (mean age = 38.98 ± 14.45; 23 female) and 68 subjects scanned with [¹¹ C]-(+)-PHNO (mean age = 38.54 ± 14.59; 25 female) were used. Subcortical volumes were extracted from T1-weighted images using the Multiple Automatically Generated Templates (MAGeT-Brain) algorithm. Partial correlations were used controlling for age, gender, and total brain volume.

RESULTS

For [¹¹ C]-(+)-PHNO, ventral caudate volumes were positively correlated with BP_ND in the dorsal caudate and globus pallidus (GP). Ventral striatum (VS) volumes were positively correlated with BP_ND in the VS. With [¹¹ C]-raclopride, BP_ND in the VS was negatively correlated with subiculum volume of the hippocampus. Moreover, BP_ND in the GP was negatively correlated with the volume of the lateral posterior nucleus of the thalamus.

CONCLUSION

Findings are purely exploratory and presented corrected and uncorrected for multiple comparisons. We hope they will help inform the interpretation of future PET studies where concurrent changes in D_2/3 R and brain morphology are observed. Hum Brain Mapp 38:5519-5534, 2017. © 2017 Wiley Periodicals, Inc.

Single nucleotide polymorphisms in the toll-like receptor 2 (TLR2) gene are associated with sporadic Parkinson's disease in the North-eastern Han Chinese population

Growing evidences suggested that inflammatory process played a critical role in the pathogenesis of Parkinson's disease (PD). Given that TLR2 has been implicated in the perpetuation of inflammatory responses in the central nervous system (CNS), we investigated the association between two genetic variants (rs3804099 and rs3804100) of TLR2 and sporadic PD in Han Chinese population. 395 Han Chinese sporadic PD patients and 413 healthy age and gender-matched controls were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The sporadic PD patients showed a higher T allele frequency than the healthy-matched control (p=0.019). Furthermore rs3804099 dominate model TT versus (vs.) TC+CC increase the risk of sporadic PD (OR=1.376, 95%CI=1.043-1.814, p=024). From the subgroup analysis, the variant allele T of rs3804099 was higher in sporadic PD cases (73.1%) than in controls (67.4%) in the late-onset cohort. Meanwhile rs3804099 revealed significant association in dominant model: Subjects with TT genotypes vs. those with TC+CC genotype showed evident significant in late-onset cohort (LOPD OR=1.417, 95%CI=1.051-1.911, p=022). In contrast, allele frequencies at rs3804100 were similar between patients and controls. Taken together, this study reveals that polymorphism of TLR2 locus is associated with risk of sporadic PD in the North-eastern part of Han Chinese population. Further studies are required to evaluate the association.

Potential therapeutic effects of odorants through their ectopic receptors in pigmented cells

Several olfactory receptors (ORs) have been characterized outside the olfactory neuroepithelium in neuronal and non-neuronal tissues, where they were implicated in the recognition of diverse chemical signals. ORs have been found to regulate melanogenesis in skin melanocytes, and OR expression has been found in the human brain nigrostriatal dopaminergic neurons, where production of melanin occurs as neuromelanin and can change with age; OR expression is downregulated in Parkinson's disease. Therefore, we propose several odorants as new functional ligands to ORs expressed in non-olfactory pigmented cells as dopaminergic neurons and melanocytes, where, by acting on cAMP-induced melanin production, they could help to counteract melanogenic and neurodegenerative dysfunctions, including melanoma and Parkinson's disease.

Patterns of age related changes for phosphodiesterase type-10A in comparison with dopamine D2/3 receptors and sub-cortical volumes in the human basal ganglia: A PET study with 18F-MNI-659 and 11C-raclopride with correction for partial volume effect

Phosphodiesterase 10A enzyme (PDE10A) is an important striatal target that has been shown to be affected in patients with neurodegenerative disorders, particularly Huntington´s disease (HD). PDE10A is expressed on striatal neurones in basal ganglia where other known molecular targets are enriched such as dopamine D_2/3 receptors (D_2/3 R). The aim of this study was to examine the availability of PDE10A enzyme in relation with age and gender and to compare those changes with those related to D_2/3 R and volumes in different regions of the basal ganglia. As a secondary objective we examined the relative distribution of D_2/3 R and PDE10A enzyme in the striatum and globus pallidus. Forty control subjects (20F/20M; age: 44±11y, age range 27-69) from an ongoing positron emission tomography (PET) study in HD gene expansion carriers were included. Subjects were examined with PET using the high-resolution research tomograph (HRRT) and with 3T magnetic resonance imaging (MRI). The PDE10A radioligand ¹⁸F-MNI-659 and D_2/3 R radioligand ¹¹C-raclopride were used. The outcome measure was the binding potential (BP_ND) estimated with the two-tissue compartment model (¹⁸F-MNI-659) and the simplified reference tissue model (¹¹C-raclopride) using the cerebellum as reference region. The PET data were corrected for partial volume effects. In the striatum, PDE10A availability showed a significant age-related decline that was larger compared to the age-related decline of D_2/3 R availability and to the age-related decline of volumes measured with MRI. In the globus pallidus, a less pronounced decline of PDE10A availability was observed, whereas D_2/3 R availability and volumes seemed to be rather stable with aging. The distribution of the PDE10A enzyme was different from the distribution of D_2/3 R, with higher availability in the globus pallidus. These results indicate that aging is associated with a considerable physiological reduction of the availability of PDE10A enzyme in the striatum. Moreover as result of the analysis, in the striatum for both the molecular targets, we observed a gender effect with higher BP_ND the female group.

Dose-Response Analysis of the Effect of Carbidopa-Levodopa Extended-Release Capsules (IPX066) in Levodopa-Naive Patients With Parkinson Disease

Parkinson disease is an age-related disorder of the central nervous system principally due to loss of dopamine-producing cells in the midbrain. Levodopa, in combination with carbidopa, is widely regarded as an effective treatment for the symptoms of Parkinson disease. A dose-response relationship is established for carbidopa-levodopa extended-release capsules (IPX066) in levodopa-naive Parkinson disease patients using a disease progression model. Unified Parkinson Disease Rating Scale (UPDRS) part II plus part III scores from 171 North American patients treated with placebo or IPX066 for approximately 30 weeks from a double-blind, parallel-group, dose-ranging study were used to develop the pharmacodynamic model. The model comprised 3 components: a linear function describing disease progression, a component describing placebo (or nonlevodopa) effects, and a component to describe the effect of levodopa. Natural disease progression in early Parkinson disease as measured by UPDRS was 11.6 units/year and faster in patients with more severe disease (Hoehn-Yahr stage 3). Maximum placebo/nonlevodopa response was 23.0% of baseline UPDRS. Maximum levodopa effect from IPX066 was 76.7% of baseline UPDRS, and the ED50 was 450 mg levodopa. Equilibration half-life for the effect compartment was 62.8 days. Increasing age increased and being female decreased equilibration half-life. The quantitative model allowed description of the entire time course of response to clinical trial intervention.