Use of antidepressants and the risk of Parkinson's disease: a prospective study

Depression and the risk of Parkinson's disease: A Mendelian randomization study

This study aimed to investigate the potential causal relationship between depression and Parkinson's disease (PD) using Mendelian randomization (MR). Summary statistics for depression and PD were obtained from 2 large-scale genome-wide association studies (GWAS) involving individuals of European ancestry. Independent genetic loci associated with depression and PD were identified as instrumental variables. The inverse variance weighting (IVW) approach was used as the primary method for causal inference, while MR-Egger and weighted median methods served as supplementary analyses to verify the robustness of the results. Heterogeneity tests, multiple validity checks, and leave-one-out sensitivity analyses were conducted to assess the reliability of the findings. The IVW analysis yielded an odds ratio of 1.44 (95% confidence interval: 1.001-2.077, P = .048), suggesting a potential causal relationship between depression and PD. No evidence of heterogeneity or horizontal pleiotropy was found, and sensitivity analyses confirmed the reliability of the results. This study applied 2-sample MR analysis to genetic data, revealing a causal link between depression and the development of PD. These findings highlight the importance of early screening and intervention for individuals with depression to reduce the risk of developing PD.

Prodromal Parkinson's disease and subsequent risk of Parkinson's disease and mortality

Association of prodromal Parkinson's disease (PD) with risk of PD and risk of mortality in individuals with PD warrant investigation through large-scale prospective study. We included 501,475 participants without PD at baseline. Eight prodromal features were measured. Incident PD cases were identified via hospital admission, death register, and self-report. Cox regression models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs). Multivariable-adjusted HRs3+vs.0 prodromal PD features and 95%CIs were 3.12 (2.58-3.78) for men and 2.71 (2.11-3.47) for women. Prodromal PD predicted only PD onset occurred during the first 6 years of follow-up (HR3+vs.0 prodromal features = 10.5; 95% CI: 8.60-12.9), but not after 6 years (HR = 1.00; 95%CI: 0.76-1.32). The presence of prodromal PD conferred a higher risk of mortality among participants with PD. Having prodromal PD were associated with higher probability of developing PD in short-term and higher risk of mortality among individuals with PD.

The effect of serotonin reuptake and serotonin-noradrenaline reuptake inhibitors on motor symptoms in Parkinson's disease: A PPMI-based matched-subject study

Background: Depression often co-occurs with Parkinson's disease (PD) and is effectively treated with selective serotonin reuptake inhibitors (SSRI) and serotonin and noradrenaline reuptake inhibitors (SNRI), but their effect on motor symptoms has not yet been conclusively demonstrated. Objective: To assess the impact of the SSRI/SNRI on the motor symptoms of PD. Methods: We used data from the Parkinson's Progression Markers Initiative database, in a matched subject design with a target group (N = 47) which had been taking SSRI/SNRI medication and a control group (N = 90) which had not. Matching criteria included Movement Disorders Society Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS-III) total score and its subscales' scores, and levodopa equivalent daily dose (LEDD) at the time of the first examination (initial LEDD). For the target group, we compared the MDS-UPDRS-III score before and after taking the SSRI/SNRI medication, while for the control group we compared two equally spaced examinations. Results: In the target group, we found a greater worsening of motor scores, which was associated with lower values of initial LEDD. In addition, apathy was an independent predictor of motor worsening. Conclusions: SSRI/SNRI-use seems to be characterized by a steeper worsening of motor symptoms, which can be predicted by a lower initial LEDD. Further research should continue to investigate the effect of SSRI/SNRI-use on motor symptoms in PD.

Revisiting serotonin's role in spatial memory: A call for sensitive analytical approaches

The serotonergic system is involved in various psychiatric and neurological conditions, with serotonergic drugs often used in treatment. These conditions frequently affect spatial memory, which can serve as a model of declarative memory due to well-known cellular components and advanced methods that track neural activity and behavior with high temporal resolution. However, most findings on serotonin's effects on spatial learning and memory come from studies lacking refined analytical techniques and modern approaches needed to uncover the underlying neuronal mechanisms. This In Focus review critically investigates available studies to identify areas for further exploration. It finds that well-established behavioral models could yield more insights with modern tracking and data analysis approaches, while the cellular aspects of spatial memory remain underexplored. The review highlights the complex role of serotonin in spatial memory, which holds the potential for better understanding and treating memory-related disorders.

Study on the mechanism of gut microbiota in the pathogenetic interaction between depression and Parkinson 's disease

Depression and Parkinson's disease share pathogenetic characteristics, meaning that they can impact each other and exacerbate their respective progression. From a pathogenetic perspective, depression can develop into Parkinson's disease and is a precursor symptom of Parkinson's disease; Parkinson's disease is also often accompanied by depression. From a pharmacological perspective, the use of antidepressants increases the risk of developing Parkinson's disease, and therapeutic medications for Parkinson's disease can exacerbate symptoms of depression. Therefore, identifying how Parkinson's disease and depression impact each other in their development is key to formulating preventive measures and targeted treatment. One commonality in the pathogenesis of depression and Parkinson's disease are alterations in the gut microbiota, with mechanisms interacting in neural, immune inflammatory, and neuroendocrine pathways. This paper reviews the role of gut microbiota in the pathogenesis of depression and Parkinson's disease; conducts a study of the relationship between both conditions and medication; and suggests that dysregulated gut microbiota may be a key factor in explaining the relationship between Parkinson's disease and depression. Finally, on the basis of these findings, this article hopes to provide suggestions that new ideas for the prevention and treatment of depression and Parkinson's disease.

Metabolic profiling reveals circulating biomarkers associated with incident and prevalent Parkinson's disease

The metabolic profile predating the onset of Parkinson's disease (PD) remains unclear. We aim to investigate the metabolites associated with incident and prevalent PD and their predictive values in the UK Biobank participants with metabolomics and genetic data at the baseline. A panel of 249 metabolites was quantified using a nuclear magnetic resonance analytical platform. PD was ascertained by self-reported history, hospital admission records and death registers. Cox proportional hazard models and logistic regression models were used to investigate the associations between metabolites and incident and prevalent PD, respectively. Area under receiver operating characteristics curves (AUC) were used to estimate the predictive values of models for future PD. Among 109,790 participants without PD at the baseline, 639 (0.58%) individuals developed PD after one year from the baseline during a median follow-up period of 12.2 years. Sixty-eight metabolites were associated with incident PD at nominal significance (P < 0.05), spanning lipids, lipid constituent of lipoprotein subclasses and ratios of lipid constituents. After multiple testing corrections (P < 9 × 10-4), polyunsaturated fatty acids (PUFA) and omega-6 fatty acids remained significantly associated with incident PD, and PUFA was shared by incident and prevalent PD. Additionally, 14 metabolites were exclusively associated with prevalent PD, including amino acids, fatty acids, several lipoprotein subclasses and ratios of lipids. Adding these metabolites to the conventional risk factors yielded a comparable predictive performance to the risk-factor-based model (AUC = 0.766 vs AUC = 0.768, P = 0.145). Our findings suggested metabolic profiles provided additional knowledge to understand different pathways related to PD before and after its onset.

Depressive Symptoms and the Subsequent Risk of Parkinson's Disease: A Nationwide Cohort Study

OBJECTIVE

Only a few studies have focused on depressive symptoms and Parkinson's disease (PD) risk. As a time lag exists from the onset of depressive symptoms to the diagnosis of depression, elucidating the association between depressive symptoms and PD development might be helpful for the early prediction of PD. We investigate the association between depressive symptoms and subsequent PD risk using nationwide population-based cohort database.

DESIGN AND SETTING

Cohort study using the Korean National Health Insurance Service data between 2007 and 2017, with longitudinal follow-up until 2019.

PARTICIPANTS

A total of 98,296 elderly people responded to a self-reported questionnaire from the National Health Screening Program on depressive symptoms.

MEASUREMENTS

The association between depressive symptoms such as 1) decreased activity or motivation, 2) worthlessness, and 3) hopelessness and PD risk was analyzed.

RESULTS

During median 5.06-year follow-up, 839 PD cases occurred: 230 in individuals with depressive symptoms and 609 in those without symptoms. Results showed an increased risk of PD development in those with depressive symptoms (HR = 1.47, 95% CI, 1.26-1.71), with dose-response association between the number of depressive symptoms and PD risk. Even in those already diagnosed with depression, combined depressive symptoms were linked to a higher risk compared to those without symptoms (with symptoms, HR = 2.71, 95% CI, 2.00-3.68; without symptoms, HR = 1.84, 95% CI, 1.43-2.36).

CONCLUSION

Individuals with depressive symptoms were at an increased risk of developing PD, and there was a dose-response association between the number of depressive symptoms and PD risk.

Investigating the potential effects of α-synuclein aggregation on susceptibility to chronic stress in a mouse Parkinson's disease model

BACKGROUND

Parkinson's disease (PD) is a motor disorder characterized by the degeneration of dopaminergic neurons, putatively due to the accumulation of α-synuclein (α-syn) in Lewy bodies (LBs) in Substantia Nigra. PD is also associated with the formation of LBs in brain areas responsible for emotional and cognitive regulation such as the amygdala and prefrontal cortex, and concurrent depression prevalence in PD patients. The exact link between dopaminergic cell loss, α-syn aggregation, depression, and stress, a major depression risk factor, is unclear. Therefore, we aimed to explore the interplay between sensitivity to chronic stress and α-syn aggregation.

METHODS

Bilateral injections of α-syn preformed fibrils (PFFs) into the striatum of C57Bl/6 J mice were used to induce α-syn aggregation. Three months after injections, animals were exposed to chronic social defeat stress.

RESULTS

α-syn aggregation did not affect stress susceptibility but independently caused increased locomotor activity in the open field test, reduced anxiety in the light-dark box test, and increased active time in the tail suspension test. Ex vivo analysis revealed modest dopaminergic neuron loss in the substantia nigra and reduced dopaminergic innervation in the dorsal striatum in PFFs injected groups. α-Syn aggregates were prominent in the amygdala, prefrontal cortex, and substantia nigra, with minimal α-syn aggregation in the raphe nuclei and locus coeruleus.

CONCLUSIONS

Progressive bilateral α-syn aggregation might lead to compensatory activity increase and alterations in emotionally regulated behavior, without affecting stress susceptibility. Understanding how α-syn aggregation and degeneration in specific brain structures contribute to depression and anxiety in PD patients requires further investigation.

Prevalence and causative drugs of drug-induced Parkinsonism in pediatric patients

Although several studies provided evidence on the epidemiology of drug-induced Parkinsonism (DIP) and its causative drugs, it is still limited in pediatrics. This study aimed to investigate the prevalence and risk of DIP in pediatrics. We used the Health Insurance Review and Assessment Service-Pediatric Patients Sample in Korea between 2010 and 2017 to estimate the annual prevalence of DIP and causative drug use using a cross-sectional design. The risk of DIP associated with causative drugs was evaluated using a case-crossover design. Adjusted odds ratios (aOR) with 95% confidence intervals (CI) were calculated using a conditional logistic regression. A total of 2925 pediatric patients had diagnosed with DIP from 2010 to 2017. Most patients were aged between 12 and19 years old, and 99.8% had any diagnosis of mental health disorder (MHD). During the study period, the prevalence of DIP increased by 10.0-fold from 2010 to 2017. All causative drugs showed a corresponding increase in their use, with atypical antipsychotics being the most prominent (increase ratio, 2.07). For both in the prevalence of DIP and atypical antipsychotic use, the increment was much bigger in patients with non-psychotic MHD than that in patients with psychotic MHD. In the case-crossover study, antipsychotics showed the largest aOR with DIP. Risperidone among antipsychotics showed the highest risk for DIP (aOR = 7.09, 95% CI = 3.83-13.09), followed by aripiprazole (aOR = 5.03, 95% CI = 2.88-8.80). This study suggests that the increase in DIP prevalence in pediatric patients might be because of the increased use of atypical antipsychotics.

Screening and Targeting Risk Factors for Prodromal Synucleinopathy: Taking Steps toward a Prescriptive Multi-modal Framework

As the prevalence of Parkinson's disease (PD) grows, so too does the population at-risk of developing PD, those in the so-called prodromal period. This period can span from those experiencing subtle motor deficits yet not meeting full diagnostic criteria or those with physiologic markers of disease alone. Several disease-modifying therapies have failed to show a neuroprotective effect. A common criticism is that neurodegeneration, even in the early motor stages, has advanced too far for neuro-restoration-based interventions to be effective. Therefore, identifying this early population is essential. Once identified, these patients could then potentially benefit from sweeping lifestyle modifications to alter their disease trajectory. Herein, we review the literature on risk factors for, and prodromal symptoms of, PD with an emphasis on ones which may be modifiable in the earliest possible stages. We propose a process for identifying this population and speculate on some strategies which may modulate disease trajectory. Ultimately, this proposal warrants prospective studies.

Use of antipsychotics and long-term risk of parkinsonism

INTRODUCTION

Few epidemiological studies have assessed the risk of parkinsonisms after prolonged use of neuroleptics. We aimed to examine the long-term risk of degenerative parkinsonisms (DP) associated with previous use of neuroleptics.

METHODS

All residents in Piedmont, Northern-west Italy, older than 39 years (2,526,319 subjects), were retrospectively followed up from 2013 to 2017. Exposure to neuroleptics was assessed through the regional archive of drug prescriptions. The development of DP was assessed using the regional archives of both drug prescriptions and hospital admissions. We excluded prevalent DP cases at baseline as well as those occurred in the first 18 months (short-term risk). The risk of DP associated with previous use of neuroleptics was examined through Cox regression, using a matched cohort design.

RESULTS

The risk of DP was compared between 63,356 exposed and 316,779 unexposed subjects. A more than threefold higher risk of DP was observed among subjects exposed to antipsychotics, compared to those unexposed (HR = 3.27, 95% CI 3.00-3.57), and was higher for exposure to atypical than typical antipsychotics. The risk decreased after 2 years from therapy cessation but remained significantly elevated (HR = 2.38, 95% CI 1.76-3.21).

CONCLUSIONS

These results indicate a high risk of developing DP long time from the start of use and from the cessation for both typical and atypical neuroleptics, suggesting the need of monitoring treated patients even after long-term use and cessation.

Low-frequency and rare coding variants of NUS1 contribute to susceptibility and phenotype of Parkinson's disease

NUS1 has been recently identified as a candidate gene for Parkinson's disease (PD). Few studies have examined the association of NUS1 variants with PD susceptibility and phenotypes. In the first cohort, whole-exome sequencing was performed to identify variants in NUS1 exon-coding and exon-intron regions in 1542 cases and 1625 controls. 13 variants were totally detected, of which 10 rare variants and 3 low-frequency variants. Burden analysis showed that rare NUS1 variants significantly enriched in PD (p=0.016). We also performed a meta-analysis based on previous and our studies to correlate NUS1 mutations with PD susceptibility. Integrating our previous cohort (3210 cases and 2807 controls) and the first cohort identified the significant association of rs539668656 with PD risk (odds ratio (OR) = 2.82, p = 0.016). The genotype-phenotype association analysis showed that patients carrying rare variants, or rs539668656 were significantly associated with earlier onset age, depression, emotional impairment and severe disease condition. Our results support the role of NUS1 rare variants and rs539668656 towards PD susceptibility and phenotype.

Association between depression and risk of Parkinson's disease in South Korean adults

BACKGROUND

Depression is considered a predictive factor for cognitive impairments. At the same time, Parkinson's disease (PD) is a growing public health problem. The aim of this study is to examine the association between depression and PD risk among South Korean adults.

METHODS

Data from 21,766 participants aged over 40, derived from the National Health Insurance Service National Sample Cohort (2002-2013), were included. Propensity score matching (1:1) was used to match participants with and without depression (case: 10,875, control: 10,875). The dependent variable was PD risk. A Cox proportional hazards regression model was built to analyze the associations between variables.

RESULTS

People with depression had a higher risk of PD than those without depression (hazard ratio (HR) = 1.61, 95% confidence interval (CI) = 1.26-2.06). Among individuals with disabilities, those with depression had a higher risk of PD (HR = 2.31, 95% CI = 1.08-4.94). According to the Charlson Comorbidity Index (CCI) score, those with depression had a higher risk of PD than their counterparts (CCI score ≥ 5: HR = 1.63, 95% CI = 1.21-2.20).

LIMITATIONS

The limitations include the inability to 1) explore factors such as smoking and drinking status, which could be related to PD risk and 2) identify undiagnosed PD that already existed at the time of diagnosis of depression.

CONCLUSIONS

The results suggest that having depression places individuals at a higher risk of PD. Interventions to alleviate the risk of PD should focus on adequate depression management.

Trend of recognizing depression symptoms and antidepressants use in newly diagnosed Parkinson's disease: Population-based study

OBJECTIVES

Although depression symptoms are common among patients with Parkinson's disease (PD), the medical literature still reports underrecognition of depression in patients with PD. Our main objective is to examine the trend of depression recognition during the first year of PD diagnosis using large population data.

METHODS

We conducted a population-based study of residents in Wales, using the Secure Anonymized Information Linkage (SAIL) Databank. We included newly diagnosed patients with PD aged 40 years or older with a first PD diagnosis between 2000 and 2015. Depression and antidepressants related data were extracted from SAIL. A series of multilevel logistic regressions were run to determine the factors affecting depression recognition. The results were presented using odds ratios (ORs) with 95% confidence intervals (CI).

RESULTS

The study included 6596 patients with PD. About 38% of patients had a recorded code of antidepressants, depression diagnosis, or both within the first year of PD diagnosis. There was a significant association of depression diagnosis, antidepressant use, or both with the year of PD diagnosis (OR 0.972, 95% CI 0.962-0.983). We also found that patients who used monoamine oxidase inhibitors (MAO-B inhibitors) were associated with a lower depression diagnosis, use antidepressants, or both, compared to those who did not use MAO-B inhibitors (OR 0.769, 95% CI 0.627-0.943).

CONCLUSION

There is a slight decrease in depression recognition in PD patients between 2000 and 2015, which could be due to an increase in depression recognition during the prodromal phase of PD.

Antidepressant-Like Properties of Intrastriatal Botulinum Neurotoxin-A Injection in a Unilateral 6-OHDA Rat Model of Parkinson's Disease

Parkinson’s patients often suffer from depression and anxiety, for which there are no optimal treatments. Hemiparkinsonian (hemi-PD) rats were used to test whether intrastriatal Botulinum neurotoxin-A (BoNT-A) application could also have antidepressant-like properties in addition to the known improvement of motor performance. To quantify depression- and anxiety-like behavior, the forced swim test, tail suspension test, open field test, and elevated plus maze test were applied to hemi-PD rats injected with BoNT-A or vehicle. Furthermore, we correlated the results in the forced swim test, open field test, and elevated plus maze test with the rotational behavior induced by apomorphine and amphetamine. Hemi-PD rats did not show significant anxiety-like behavior as compared with Sham 6-OHDA- + Sham BoNT-A-injected as well as with non-injected rats. However, hemi-PD rats demonstrated increased depression-like behaviors compared with Sham- or non-injected rats; this was seen by increased struggling frequency and increased immobility frequency. Hemi-PD rats intrastriatally injected with BoNT-A exhibited reduced depression-like behavior compared with the respective vehicle-receiving hemi-PD animals. The significant effects of intrastriatally applied BoNT-A seen in the forced swim test are reminiscent of those found after various antidepressant drug therapies. Our data correspond with the efficacy of BoNT-A treatment of glabellar frown lines in treating patients with major depression and suggest that also intrastriatal injected BoNT-A may have some antidepressant-like effect on hemi-PD.

Association between Anemia and Risk of Parkinson Disease

METHODS

We systematically searched articles on electronic databases such as PubMed, Embase, Scopus, and Google Scholar between January 1, 2000 and July 30, 2020. Articles were independently evaluated by two authors. We included observational studies (case-control and cohort) and calculated the risk ratios (RRs) for associated with anemia and PD. Heterogeneity among the studies was assessed using the Q and I 2 statistic. We utilized the random-effect model to calculate the overall RR with 95% CI.

RESULTS

A total of 342 articles were identified in the initial searches, and 7 full-text articles were evaluated for eligibility. Three articles were further excluded for prespecified reasons including insufficient data and duplications, and 4 articles were included in our systematic review and meta-analysis. A random effect model meta-analysis of all 4 studies showed no increased risk of PD in patients with anemia (N = 4, RRadjusted = 1.17 (95% CI: 0.94-1.45, p = 0.15). However, heterogeneity among the studies was significant (I 2 = 92.60, p = <0.0001). The pooled relative risk of PD in female patients with anemia was higher (N = 3, RRadjusted = 1.14 (95% CI: 0.83-1.57, p = 0.40) as compared to male patients with anemia (N = 3, RRadjusted = 1.09 (95% CI: 0.83-1.42, p = 0.51).

CONCLUSION

This is the first meta-analysis that shows that anemia is associated with higher risk of PD when compared with patients without anemia. However, more studies are warranted to evaluate the risk of PD among patients with anemia.

Treatment response and age of onset as risk indicators for parkinson disease in patients with major depressive disorder: A nationwide longitudinal study

BACKGROUND

Individuals with major depressive disorder (MDD) have a higher risk of developing Parkinson disease (PD). This study investigated whether response to treatment with antidepressants for MDD can determine patients at risk of developing PD later in life.

METHODS

We enrolled 3303 patients with newly-diagnosed MDD and 13,212 controls between 2002 and 2004 using Taiwan's Nationwide Health Insurance Research Database. We stratified patients with MDD according to the number of antidepressant regimens prescribed to them and the age at MDD onset and followed all participants until the end of 2013. During follow-up, we evaluated patients for the possibility of developing PD.

RESULTS

Patients with MDD had a greater likelihood of developing PD than controls. Patients with difficult-to-treat (DTT) MDD had a higher risk of developing PD than the other MDD subgroups (hazard ratio [HR] = 3.44, 95% confidence interval [95% CI]: = 1.99-5.95). When stratified by age (<50, 50-65, >65 years), DTT patients with middle-age or late-onset MDD exhibited elevated risks of developing PD (50-65 years: HR: 7.03, 95% CI: 2.95-16.76; >65 years: HR: 2.89, 95% CI: 1.26-6.65).

DISCUSSION

Patients with MDD and an onset age of >50 years who responded poorly to antidepressant treatment have an associated higher risk of subsequently developing PD. Therefore, when treating patients with MDD, clinicians should provide intensive antidepressant treatment and evaluations for PD so that risk-prevention measures can be implemented upon MDD diagnosis.

Premotor Parkinson's disease: Overview of clinical symptoms and current diagnostic methods

Parkinson's disease (PD) is characterized by typical motor symptoms. However, recent studies show several non-motor features that may precede the development of the motor symptoms of PD. The best known premotor symptoms include hyposmia, REM sleep behavior disorder (RBD), constipation, and depression; other symptoms are excessive daytime somnolence, orthostatic hypotension and symptomatic hypotension, erectile or urinary dysfunction, musculoskeletal symptoms, pain, and global cognitive deficit. In this review, we summarize currently available diagnostic methods for these symptoms. We also briefly summarize neuroimaging, polyneuropathy, peripheral markers, and cerebrospinal fluid biomarkers that may be used in the early diagnosis of PD.

The effect of monoamine oxidase-B inhibitors on the alleviation of depressive symptoms in Parkinson's disease: meta-analysis of randomized controlled trials

BACKGROUND

Depression is a major nonmotor symptom of Parkinson's disease (PD). However, few treatments exist for PD depression. Monoamine oxidase-B inhibitors (MAOB-Is) provide symptomatic relief for the motor symptoms of PD and exert antidepressive effects. The present meta-analysis of randomized controlled trials (RCTs) investigated the effects of MAOB-Is on depressive symptoms in patients with PD.

METHODS

Articles on PD-management-related RCTs using one of three MAOB-Is approved by the US Food and Drug Administration, that is, selegiline, rasagiline, and safinamide, were identified. The primary outcomes were the benefits of MAOB-Is for depressive symptoms. Subgroup analysis included the effects of MAOB-Is on patients in the early versus middle-to-late stages of PD and the effect of short-term versus long-term treatment.

RESULTS

Overall, six studies were included, four of which were conducted on patients with early stage PD. Overall, MAOB-Is significantly reduced the severity of depressive symptoms [standardized mean difference (SMD): -0.14, 95% confidence interval (CI): -0.21 to -0.06, p < 0.001]. Subgroup analysis indicated that the positive effect of MAOB-Is was significant in patients with early stage PD (SMD: -0.20, 95% CI: -0.31 to -0.09, p < 0.001), but not in those with middle-to-late-stage PD (SMD: -0.07, 95% CI: -0.17 to 0.03, p = 0.18). The antidepressive effect was significant for short-term treatment, that is, 90-120 days (SMD: -0.23, 95% CI: -0.35 to -0.10, p < 0.001), but not long-term treatment, that is, 24 weeks to 18 months (SMD: -0.08, 95% CI: -0.18 to 0.01, p = 0.09).

CONCLUSION

In addition to the treatment of PD motor symptoms, MAOB-Is may help reduce the severity of depressive symptoms in PD, especially in patients with early stage PD. Considering the tolerability and simultaneous benefits of MAOB-Is, further RCTs are warranted to confirm their therapeutic effects in moderate-to-severe PD depression.

Acupuncture Treatment Reduces Incidence of Parkinson's Disease in Patients With Depression: A Population-Based Retrospective Cohort Study in Taiwan

Depression is a risk factor for subsequent Parkinson's disease (PD). Some patients with depression undergo acupuncture treatment because of other diseases in Taiwan. Therefore, the present study used data from Taiwan's National Health Insurance Research Database (NHIRD) to investigate the incidence of PD in patients having depression with and without acupuncture treatment. We conducted a retrospective study of a matched cohort of 48,981 patients with newly diagnosed depression between 2000 and 2012 who were selected from the NHIRD. The 1:1 propensity score method was utilized to match an equal number of patients (N = 9,189) in the acupuncture and non-acupuncture cohorts. We employed Cox proportional hazard models to evaluate the risk of PD. The cumulative incidence of PD in both cohorts was estimated using the Kaplan–Meier method, and the difference was examined through a log-rank test. Patients with depression who received acupuncture treatment demonstrated a lower risk of PD [adjusted hazard ratio (aHR) = 0.39, 95% confidence interval = 0.31–0.49] than those who did not undergo acupuncture treatment, after adjusting for age, sex, insurance amount, geographic region, urbanization levels, comorbidities, and drugs. The cumulative incidence of PD was significantly lower in the acupuncture cohort than in the non-acupuncture cohort (log-rank test, p < 0.001). The database did not indicate the severity of depression and acupoints. The results suggest that acupuncture treatment significantly reduced the development of PD in patients with depression; however, a future study should be conducted to provide more objective evidence.

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

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

Depression Comorbid With Stroke, Traumatic Brain Injury, Parkinson's Disease, and Multiple Sclerosis: Diagnosis and Treatment

Depression is common among patients with neurologic disorders, and it has long been considered more difficult to treat than depression in the general population. In this review, the authors consider challenges in the diagnosis and treatment of depression among patients with stroke, traumatic brain injury, Parkinson's disease, and multiple sclerosis. For each disorder, the authors discuss the epidemiology and time course of depression as well as review the physiologic and psychological etiologies of depression. In addition, for each disorder, they review screening tools and diagnostic considerations, including differential diagnosis; discuss etiological factors, both neurobiological and psychological; and assess evidence for various depression treatments, including pharmacologic, psychosocial, and neuromodulatory therapies. The evidence suggests that depression is common among patients with neurologic disorders and that it is crucial for general psychiatrists to provide treatment for this population.

Depression and Anxiety in Parkinson Disease

Depression and anxiety are common neuropsychiatric manifestations of Parkinson disease. However, they are often under-recognized because the somatic symptoms of depression often overlap with the motor symptoms of Parkinson disease and there is low self-reporting. Clinicians need to be vigilant about early detection and treatment of anxiety and depression in the patient with Parkinson disease. The development of new therapeutic strategies, including diet, exercise, and counseling along with antidepressants provide a holistic approach to management.

The Neuropsychiatry of Parkinson Disease: A Perfect Storm

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

Sleep and risk of parkinsonism and Parkinson's disease: a population-based study

Sleep disturbances may signal presence of prodromal parkinsonism, including Parkinson's disease. Whether general sleep quality or duration in otherwise healthy subjects is related to the risk of parkinsonism remains unclear. We hypothesized that both worse self-reported sleep quality and duration, as well as a longitudinal deterioration in these measures, are associated with the risk of parkinsonism, including Parkinson's disease. In the prospective population-based Rotterdam Study, we assessed sleep quality and duration with the Pittsburgh Sleep Quality Index in 7726 subjects (mean age 65 years, 57% female) between 2002 and 2008, and again in 5450 subjects between 2009 and 2014. Participants were followed until 2015 for a diagnosis of parkinsonism and Parkinson's disease. Outcomes were assessed using multiple modalities: interviews, physical examination, and continuous monitoring of pharmacy records and medical records of general practitioners. We used Cox regression to associate sleep, and changes in sleep over time, with incident parkinsonism and Parkinson's disease, adjusting for age, sex, education and smoking status. Over 64 855 person-years in 13 years of follow-up (mean: 8.4 years), 75 participants developed parkinsonism, of whom 47 developed Parkinson's disease. We showed that within the first 2 years of follow-up, worse sleep quality {hazard ratio (HR) 2.38 per standard deviation increase [95% confidence interval (CI 0.91-6.23)]} and shorter sleep duration [HR 0.61 per standard deviation increase (95% CI 0.31-1.21)] related to a higher risk of parkinsonism. Associations of worse sleep quality [HR 3.86 (95% CI 1.19-12.47)] and shorter sleep duration [HR 0.48 (95% CI 0.23-0.99)] with Parkinson's disease were more pronounced, and statistically significant, compared to parkinsonism. This increased risk disappeared with longer follow-up duration. Worsening of sleep quality [HR 1.76 per standard deviation increase (95% CI 1.12-2.78)], as well as shortening of sleep duration [HR 1.72 per standard deviation decrease (95% CI 1.08-2.72)], were related to Parkinson's disease risk in the subsequent 6 years. Therefore, we argue that in the general population, deterioration of sleep quality and duration are markers of the prodromal phase of parkinsonism, including Parkinson's disease.

Early and Accurate Identification of Parkinson Disease Among US Veterans

Early and accurate identification and management of veterans at risk for Parkinson disease is an important priority area for the US Department of Veterans Affairs because of the substantial impact on quality of life and disability-adjusted life years.

Evidence of Repurposing Drugs and Identifying Contraindications from Real World Study in Parkinson's Disease

There is great unmet need in discovering novel treatment for Parkinson's disease (PD) and identifying the new agents potentially causing drug-induced parkinsonism. New indications and contraindications of drugs are typically approved following rigorous randomized controlled trial (RCT) evaluation. However, RCTs have their inherent limitations, since they are usually conducted in ideal conditions, with high cost and limited follow-up periods. In the past decade, large cohort studies with long follow-up outcome data was derived from a PD database in a real-world setting. Studies based on real world data (RWD) can help to augment and extrapolate data obtained in RCTs and provide information about the safety and effectiveness of a medication in heterogeneous, large populations. In the present review, we focus on the published real world studies designed to develop new treatment strategies for repurposing drugs and identifying contraindications for PD. We also outline the challenges and limitations in these studies. Subsequently we introduce PaWei app platform, which hopefully can facilitate PD management and address real-world problems associated with PD. Better understanding of RWD collection and analysis is needed if RWD is to achieve its full potential.

Non-motor features of Parkinson's disease in a nested case-control study of US men

BACKGROUND

Several non-motor features may individually contribute to identify prodromal Parkinson's disease (PD), but little is known on how they interact.

METHODS

We conducted a case-control study nested within the Health Professionals Follow-up Study in a large cohort of men age 40-75 at recruitment in 1986. Cases (n=120) had confirmed PD, were<85 in January 2012, returned a 2012 questionnaire with questions on probable rapid eye movement sleep behaviour disorder (RBD) and constipation sent to all cohort participants and completed in 2014 the Brief Smell Identification Test and a questionnaire assessing parkinsonism and other non-motor PD features (including depressive symptoms, excessive daytime sleepiness, impaired colour vision and body pain). Controls (n=6479) met the same criteria as cases, except for the PD diagnosis.

RESULTS

Concurrent constipation, probable RBD and hyposmia were present in 29.3% of cases and 1.1% of controls, yielding an age-adjusted OR of 160(95%CI 72.8to353) for three features versus none. The odds of PD increased exponentially with additional non-motor features (OR for 6-7 features versus none: 1325; 95%CI333to5279). Among men without PD, the number of non-motor features was associated with odds of parkinsonism (OR for 6-7 features versus none: 89; 95%CI21.2to375). We estimated that in a population with a prodromal PD prevalence of 2%, concurrent constipation, probable RBD and hyposmia would have a maximum sensitivity of 29% and a positive predictive value (PPV) of 35%. The PPV could increase up to 70% by including additional features, but with sharply decreased sensitivity.

CONCLUSIONS

Concurrent constipation, probable RBD and hyposmia are strongly associated with PD. Because these features often precede motor symptoms and their co-occurrence could provide an efficient method for early PD identification.

Association between depression and the subsequent risk of Parkinson's disease: A meta-analysis

BACKGROUND

Observational studies, including recent large cohort studies, have reported an association between depression and the risk of Parkinson's disease (PD); however, conclusions were inconsistent. Clarifying this relation might improve the understanding of risk factors for and the disease mechanisms in PD. Therefore, we performed a meta-analysis to examine whether depression is associated with an increased risk of PD.

METHODS

A literature search in the PubMed, EMBASE, Scopus, PsycINFO and Web of Science databases was undertaken through March 2018, looking for observational studies evaluating the association between depression and the risk of PD. Pooled relative risk (RR) estimates and 95% confidence intervals (CIs) were calculated using a random-effects model. Subgroup analyses and sensitivity analyses were also performed.

RESULTS

A random-effects meta-analysis of 5 cohort studies and 6 case-control studies demonstrated a significant positive association between depression and a subsequent risk of PD (RR, 2.20; 95% CI, 1.87-2.58), and it was consistent across subgroups. Furthermore, sensitivity analysis confirmed the stability of the results; visual examination of funnel plots and Begg's and Egger's tests showed no evidence of publication bias.

CONCLUSIONS

Our meta-analysis demonstrated that persons with depression exhibited an increased risk of a subsequent PD diagnosis. The pathophysiological and psychological mechanisms underlying this association are still unclear and warrant further research.

Advances in markers of prodromal Parkinson disease

Efforts to develop neuroprotective therapy for Parkinson disease (PD) are focusing on the early stages of disease, which offer the best opportunity to intervene. Early PD can be divided into preclinical, prodromal and clinical stages; in this Review, we focus on the prodromal stage and markers that can be used to identify prodromal PD. We consider the necessary properties of a marker, before providing an overview of the proven and potential markers of prodromal PD, including clinical nonmotor markers, clinical motor markers, neuroimaging markers and tissue biomarkers. Markers for which the ability to predict conversion to PD is supported by the strongest evidence include olfactory loss, REM sleep behaviour disorder and constipation. Markers with the highest diagnostic strength include REM sleep behaviour disorder, dopaminergic imaging and subtle motor parkinsonism. The lead time - the period between the appearance of a marker and conversion to PD - is highly variable between markers, ranging from 5 years for impaired motor performance to >20 years for autonomic symptoms. The cost of screening for these markers also varies dramatically: some require just questionnaires, whereas others require sophisticated scanning techniques. Finally, we summarize how prodromal and risk markers can be combined to estimate the probability that an individual has prodromal PD, with a focus on the International Parkinson Disease and Movement Disorders Society (MDS) Prodromal Parkinson Criteria.

Clinical Significance of REM Sleep Behavior Disorders and Other Non-motor Symptoms of Parkinsonism

Rapid eye movement sleep behavior disorder (RBD) is one of the most common non-motor symptoms of parkinsonism, and it may serve as a prodromal marker of neurodegenerative disease. The mechanism underlying RBD is unclear. Several prospective studies have reported that specific non-motor symptoms predict a conversion risk of developing a neurodegenerative disease, including olfactory dysfunction, abnormal color vision, autonomic dysfunction, excessive daytime sleepiness, depression, and cognitive impairment. Parkinson's disease (PD) with RBD exhibits clinical heterogeneity with respect to motor and non-motor symptoms compared with PD without RBD. In this review, we describe the main clinical and pathogenic features of RBD, focusing on its association with other non-motor symptoms of parkinsonism.

[Anxiety and depressive disorders in Parkinson's disease]

This review presents the most recent data of worldwide research on anxiety and depressive disorders in patients with Parkinson's disease. Their characteristics and epidemiology, pathogenetic and clinical features, methods of diagnosis and treatment are presented. Depression occurs in 40-50% of patients with PD, anxiety in 17-43% of patients. Pramipexole, a dopamine agonist, is only one drug recommended for depression treatment. Nortriptyline and desipramine, belonging to the group of tricyclic antidepressants (TCAs), are considered to be possibly effective. There are no clear recommendations for treatment of anxiety. In general, methods of therapy of anxiety and depressive disorders in PD are not well understood which determines the conduct of large-scale studies in the future.

REM sleep without atonia in middle-aged and older psychiatric patients and Lewy body disease: a case series

OBJECTIVE

Rapid eye movement (REM) sleep behavior disorder (RBD) is commonly associated with Lewy body disease, narcolepsy, or depression. In contrast, the relationship between REM sleep without atonia (RWA), which is a hallmark of RBD on polysomnography, and clinical characteristics remains unclear. The purpose of this study is to investigate the clinical features of psychiatric patients exhibiting RWA and its relevance to Lewy body disease.

METHODS

Of 55 consecutive patients who underwent polysomnography at the psychiatric ward, 25 patients with sleep apnea syndrome were excluded, and 12 patients exhibiting RWA were identified. The clinical profiles were compared between the groups with and without RWA.

RESULTS

The mean age and the frequency of neurocognitive disorders were significantly higher in 12 patients with RWA than in 18 without. Only five of the 12 patients exhibiting RWA had episodes of dream-enactment behavior, and fulfilled the clinical criteria for RBD. Two young patients were diagnosed with narcolepsy, while the other middle-aged and older patients fulfilled the clinical criteria for Parkinson's disease (n = 1), dementia with Lewy bodies (n = 4), idiopathic RBD (n = 2), and major depressive disorder (MDD) (n = 3). The patients with MDD exhibited constipation and/or olfactory dysfunction. Moreover, neuroimaging examinations in the patients with MDD revealed isolated occipital hypoperfusion in three patients and mild dopamine transporter deficit in one patient.

CONCLUSIONS

Rapid eye movement sleep without atonia itself may be associated with specific clinical profiles, even when dream-enactment behavior is absent. Continued follow-up of the patients with MDD exhibiting RWA is warranted to determine if they represent the prodromal Parkinson's disease/dementia with Lewy bodies. Copyright © 2016 John Wiley & Sons, Ltd.

Melatoninergic System in Parkinson's Disease: From Neuroprotection to the Management of Motor and Nonmotor Symptoms

Melatonin is synthesized by several tissues besides the pineal gland, and beyond its regulatory effects in light-dark cycle, melatonin is a hormone with neuroprotective, anti-inflammatory, and antioxidant properties. Melatonin acts as a free-radical scavenger, reducing reactive species and improving mitochondrial homeostasis. Melatonin also regulates the expression of neurotrophins that are involved in the survival of dopaminergic neurons and reduces α-synuclein aggregation, thus protecting the dopaminergic system against damage. The unbalance of pineal melatonin synthesis can predispose the organism to inflammatory and neurodegenerative diseases such as Parkinson's disease (PD). The aim of this review is to summarize the knowledge about the potential role of the melatoninergic system in the pathogenesis and treatment of PD. The literature reviewed here indicates that PD is associated with impaired brain expression of melatonin and its receptors MT₁ and MT₂. Exogenous melatonin treatment presented an outstanding neuroprotective effect in animal models of PD induced by different toxins, such as 6-hydroxydopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), rotenone, paraquat, and maneb. Despite the neuroprotective effects and the improvement of motor impairments, melatonin also presents the potential to improve nonmotor symptoms commonly experienced by PD patients such as sleep and anxiety disorders, depression, and memory dysfunction.

MDS research criteria for prodromal Parkinson's disease

This article describes research criteria and probability methodology for the diagnosis of prodromal PD. Prodromal disease refers to the stage wherein early symptoms or signs of PD neurodegeneration are present, but classic clinical diagnosis based on fully evolved motor parkinsonism is not yet possible. Given the lack of clear neuroprotective/disease-modifying therapy for prodromal PD, these criteria were developed for research purposes only. The criteria are based upon the likelihood of prodromal disease being present with probable prodromal PD defined as ≥80% certainty. Certainty estimates rely upon calculation of an individual's risk of having prodromal PD, using a Bayesian naïve classifier. In this methodology, a previous probability of prodromal disease is delineated based upon age. Then, the probability of prodromal PD is calculated by adding diagnostic information, expressed as likelihood ratios. This diagnostic information combines estimates of background risk (from environmental risk factors and genetic findings) and results of diagnostic marker testing. In order to be included, diagnostic markers had to have prospective evidence documenting ability to predict clinical PD. They include motor and nonmotor clinical symptoms, clinical signs, and ancillary diagnostic tests. These criteria represent a first step in the formal delineation of early stages of PD and will require constant updating as more information becomes available.

Tricyclic Antidepressants Amitriptyline and Desipramine Induced Neurotoxicity Associated with Parkinson's Disease

Recent studies report that a history of antidepressant use is strongly correlated with the occurrence of Parkinson's disease (PD). However, it remains unclear whether antidepressant use can be a causative factor for PD. In the present study, we examined whether tricyclic antidepressants amitriptyline and desipramine can induce dopaminergic cell damage, both in vitro and in vivo. We found that amitriptyline and desipramine induced mitochondria-mediated neurotoxicity and oxidative stress in SH-SY5Y cells. When injected into mice on a subchronic schedule, amitriptyline induced movement deficits in the pole test, which is known to detect nigrostriatal dysfunction. In addition, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was reduced in amitriptyline-injected mice. Our results suggest that amitriptyline and desipramine may induce PD-associated neurotoxicity.

Depression and subsequent risk of Parkinson disease: A nationwide cohort study

OBJECTIVE

To investigate the long-term risk of Parkinson disease (PD) after depression and evaluate potential confounding by shared susceptibility to the 2 diagnoses.

METHODS

The nationwide study cohort included 140,688 cases of depression, matched 1:3 using a nested case-control design to evaluate temporal aspects of study parameters (total, n = 562,631). Potential familial coaggregation of the 2 diagnoses was investigated in a subcohort of 540,811 sibling pairs. Associations were investigated using multivariable adjusted statistical models.

RESULTS

During a median follow-up period of 6.8 (range, 0-26.0) years, 3,260 individuals in the cohort were diagnosed with PD. The multivariable adjusted odds ratio (OR) for PD was 3.2 (95% confidence interval [CI], 2.5-4.1) within the first year of depression, decreasing to 1.5 (95% CI, 1.1-2.0) after 15 to 25 years. Among participants with depression, recurrent hospitalization was an independent risk factor for PD (OR, 1.4; 95% CI, 1.1-1.9 for ≥5 vs 1 hospitalization). In family analyses, siblings' depression was not significantly associated with PD risk in index persons (OR, 1.1; 95% CI, 0.9-1.4).

CONCLUSIONS

The time-dependent effect, dose-response pattern for recurrent depression, and lack of evidence for coaggregation among siblings all indicate a direct association between depression and subsequent PD. Given that the association was significant for a follow-up period of more than 2 decades, depression may be a very early prodromal symptom of PD, or a causal risk factor.

Premotor and nonmotor features of Parkinson's disease

PURPOSE OF REVIEW

This review highlights recent advances in premotor and nonmotor features in Parkinson's disease, focusing on these issues in the context of prodromal and early-stage Parkinson's disease.

RECENT FINDINGS

Although Parkinson's disease patients experience a wide range of nonmotor symptoms throughout the disease course, studies demonstrate that nonmotor features are not solely a late manifestation. Indeed, disturbances of smell, sleep, mood, and gastrointestinal function may herald Parkinson's disease or related synucleinopathies and precede these neurodegenerative conditions by 5 or more years. In addition, other nonmotor symptoms such as cognitive impairment are now recognized in incident or de-novo Parkinson's disease cohorts. Many of these nonmotor features reflect disturbances in nondopaminergic systems and early involvement of peripheral and central nervous systems, including olfactory, enteric, and brainstem neurons as in Braak's proposed pathological staging of Parkinson's disease. Current research focuses on identifying potential biomarkers that may detect persons at risk for Parkinson's disease and permit early intervention with neuroprotective or disease-modifying therapeutics.

SUMMARY

Recent studies provide new insights into the frequency, pathophysiology, and importance of nonmotor features in Parkinson's disease as well as the recognition that these nonmotor symptoms occur in premotor, early, and later phases of Parkinson's disease.

Prediction of Parkinson's disease subsequent to severe depression: a ten-year follow-up study

Major depressive disorder (MDD) has been associated with an increased risk of subsequent Parkinson's disease (PD) in case-control and cohort studies. However, depression alone is unlikely to be a useful marker of prodromal PD due to its low specificity. In this longitudinal observational study, we assessed whether the presence of other potential markers of prodromal PD predicts the subsequent development of PD in MDD patients. Of 57 patients with severe MDD but no diagnosis of PD who underwent a structured interview, olfactory and motor investigation and transcranial sonography at baseline, 46 (36 women; mean age 54.9 ± 11.7 years) could be followed for up to 11 (median, 10) years. Three patients (2 women; age 64, 65 and 70 years) developed definite PD after 1, 7, and 9 years, respectively. The combined finding of mild asymmetric motor slowing, idiopathic hyposmia, and substantia nigra hyperechogenicity predicted subsequent PD in all patients who could be followed for longer than 1 year. Out of the whole study cohort, only the subjects with subsequent PD presented with the triad of asymmetric motor slowing, idiopathic hyposmia, and substantia nigra hyperechogenicity in combination with at least two out of four reportable risk factors (family history of PD, current non-smoker, non-coffee drinker, constipation) at baseline investigation. Post-hoc analysis revealed that additional rating of eye and eye-lid motor abnormalities might further improve the prediction of PD in larger cohorts. Findings of this pilot-study suggest that MDD patients at risk of subsequent PD can be identified using an inexpensive non-invasive diagnostic battery.

Targeting impulsivity in Parkinson's disease using atomoxetine

Noradrenergic dysfunction may play a significant role in cognition in Parkinson's disease due to the early degeneration of the locus coeruleus. Converging evidence from patient and animal studies points to the role of noradrenaline in dopaminergically insensitive aspects of the parkinsonian dysexecutive syndrome, yet the direct effects of noradrenergic enhancement have not to date been addressed. Our aim was to directly investigate these, focusing on impulsivity during response inhibition and decision making. To this end, we administered 40 mg atomoxetine, a selective noradrenaline re-uptake inhibitor to 25 patients with Parkinson's disease (12 female /13 male; 64.4 ± 6.9 years old) in a double blind, randomized, placebo controlled design. Patients completed an extensive battery of neuropsychological tests addressing response inhibition, decision-making, attention, planning and verbal short term memory. Atomoxetine improved stopping accuracy on the Stop Signal Task [F(1,19) = 4.51, P = 0.047] and reduced reflection impulsivity [F(1,9) = 7.86, P = 0.02] and risk taking [F(1,9) = 9.2, P = 0.01] in the context of gambling. The drug also conferred effects on performance as a function of its measured blood plasma concentration: it reduced reflection impulsivity during information sampling [adjusted R(2) = 0.23, F(1,16) = 5.83, P = 0.03] and improved problem solving on the One Touch Stockings of Cambridge [adjusted R(2) = 0.29, F(1,17) = 8.34, P = 0.01]. It also enhanced target sensitivity during sustained attention [F(1,9) = 5.33, P = 0.046]. The results of this exploratory study represent the basis of specific predictions in future investigations on the effects of atomoxetine in Parkinson's disease and support the hypothesis that targeting noradrenergic dysfunction may represent a new parallel avenue of therapy in some of the cognitive and behavioural deficits seen in the disorder.

Antidepressants and REM sleep behavior disorder: isolated side effect or neurodegenerative signal?

OBJECTIVES

Antidepressants, among the most commonly prescribed medications, trigger symptoms of REM sleep behavior disorder (RBD) in up to 6% of users. Idiopathic RBD is a very strong prodromal marker of Parkinson disease and other synuclein-mediated neurodegenerative syndromes. It is therefore critically important to understand whether antidepressant-associated RBD is an independent pharmacologic syndrome or a sign of possible prodromal neurodegeneration.

DESIGN

Prospective cohort study.

SETTING

Tertiary sleep disorders center.

PARTICIPANTS

100 patients with idiopathic RBD, all with diagnosis confirmed on polysomnography, stratified to baseline antidepressant use, with 45 matched controls.

MEASUREMENTS/RESULTS

Of 100 patients, 27 were taking antidepressants. Compared to matched controls, RBD patients taking antidepressants demonstrated significant abnormalities of 12/14 neurodegenerative markers tested, including olfaction (P = 0.007), color vision (P = 0.004), Unified Parkinson Disease Rating Scale II and III (P < 0.001 and 0.007), timed up-and-go (P = 0.003), alternate tap test (P = 0.002), Purdue Pegboard (P = 0.007), systolic blood pressure drop (P = 0.029), erectile dysfunction (P = 0.002), constipation (P = 0.003), depression indices (P < 0.001), and prevalence of mild cognitive impairment (13% vs. 60%, P < 0.001). All these abnormalities were indistinguishable in severity from RBD patients not taking antidepressants. However, on prospective follow-up, RBD patients taking antidepressants had a lower risk of developing neurodegenerative disease than those without antidepressant use (5-year risk = 22% vs. 59%, RR = 0.22, 95%CI = 0.06, 0.74).

CONCLUSIONS

Although patients with antidepressant-associated RBD have a lower risk of neurodegeneration than patients with "purely-idiopathic" RBD, markers of prodromal neurodegeneration are still clearly present. Development of RBD with antidepressants can be an early signal of an underlying neurodegenerative disease.

Psychosocial risk factors, pre-motor symptoms and first-time hospitalization with Parkinson's disease: a prospective cohort study

BACKGROUND AND PURPOSE

Experimental studies support a link between stress and development of parkinsonian symptoms, but prospective population studies are lacking. The aim of the current study is to determine the effects of several psychosocial factors on the risk of Parkinson's disease (PD), as well as to identify potential pre-motor symptoms for PD in a large prospective cohort study.

METHODS

In 1991-1993, a total of 9955 women and men free of PD from the Copenhagen City Heart Study were asked about major life events, economic hardship, social network, impaired sleep and vital exhaustion. The participants were followed for first-time hospitalization with PD in nationwide registers until 2011.

RESULTS

Vital exhaustion was associated with a higher risk of PD hospitalization in an exposure-dependent manner (P(trend) = 0.001), with high vs. low vital exhaustion being associated with a hazard ratio of 2.50 [95% confidence interval (CI): 1.28-4.89]. A slightly higher risk of PD hospitalization (hazard ratio = 1.49; 95% CI: 0.87-2.56) was suggested in participants with impaired sleep at baseline. No more than weak associations were observed for economic hardship, major life events or inadequate social network in the current study.

CONCLUSIONS

Overall, the hypothesis that psychosocial risk factors affect the risk of PD is not supported. The results, however, suggest that vital exhaustion may be a pre-motor marker of the neurodegenerative process eventually leading to motor symptoms and clinical PD. Vital exhaustion may be useful for screening aimed at early detection and when considering disease-modifying therapies in people at high risk of clinical PD.

Attenuated neural response to gamble outcomes in drug-naive patients with Parkinson's disease

Parkinson's disease results from the degeneration of dopaminergic neurons in the substantia nigra, manifesting as a spectrum of motor, cognitive and affective deficits. Parkinson's disease also affects reward processing, but disease-related deficits in reinforcement learning are thought to emerge at a slower pace than motor symptoms as the degeneration progresses from dorsal to ventral striatum. Dysfunctions in reward processing are difficult to study in Parkinson's disease as most patients have been treated with dopaminergic drugs, which sensitize reward responses in the ventral striatum, commonly resulting in impulse control disorders. To circumvent this treatment confound, we assayed the neural basis of reward processing in a group of newly diagnosed patients with Parkinson's disease that had never been treated with dopaminergic drugs. Thirteen drug-naive patients with Parkinson's disease and 12 healthy age-matched control subjects underwent whole-brain functional magnetic resonance imaging while they performed a simple two-choice gambling task resulting in stochastic and parametrically variable monetary gains and losses. In patients with Parkinson's disease, the neural response to reward outcome (as reflected by the blood oxygen level-dependent signal) was attenuated in a large group of mesolimbic and mesocortical regions, comprising the ventral putamen, ventral tegmental area, thalamus and hippocampus. Although these regions showed a linear response to reward outcome in healthy individuals, this response was either markedly reduced or undetectable in drug-naive patients with Parkinson's disease. The results show that the core regions of the meso-cortico-limbic dopaminergic system, including the ventral tegmental area, ventral striatum, and medial orbitofrontal cortex, are already significantly compromised in the early stages of the disease and that these deficits cannot be attributed to the contaminating effect of dopaminergic treatment.