Cognitive Impairment and Dementia in Parkinson Disease

Dopamine in the prefrontal cortex plays multiple roles in the executive function of patients with Parkinson's disease

Parkinson's disease can affect not only motor functions but also cognitive abilities, leading to cognitive impairment. One common issue in Parkinson's disease with cognitive dysfunction is the difficulty in executive functioning. Executive functions help us plan, organize, and control our actions based on our goals. The brain area responsible for executive functions is called the prefrontal cortex. It acts as the command center for the brain, especially when it comes to regulating executive functions. The role of the prefrontal cortex in cognitive processes is influenced by a chemical messenger called dopamine. However, little is known about how dopamine affects the cognitive functions of patients with Parkinson's disease. In this article, the authors review the latest research on this topic. They start by looking at how the dopaminergic system, is altered in Parkinson's disease with executive dysfunction. Then, they explore how these changes in dopamine impact the synaptic structure, electrical activity, and connection components of the prefrontal cortex. The authors also summarize the relationship between Parkinson's disease and dopamine-related cognitive issues. This information may offer valuable insights and directions for further research and improvement in the clinical treatment of cognitive impairment in Parkinson's disease.

Seizures due to pyridoxine deficiency in Parkinson's disease

Parkinson's disease (PD) is a complex neurodegenerative disorder characterized not only by its hallmark motor symptoms but also by a myriad of non-motor manifestations, including cognitive decline, autonomic manifestations, and gastrointestinal disturbances. Amidst these, a lesser-known but critical aspect is the increased risk of functional deficiency of pyridoxine (vitamin B6) in patients with PD, which is linked to an increased risk of seizures. This review investigates the intersection of PD, new-onset seizures, and pyridoxine deficiency, aiming to elucidate the significance of these associations and their contributions to the neurologic burden in PD. Case reports documenting the occurrence of seizures in patients with PD, particularly in the context of high-dose dopaminergic therapy and the subsequent revelation of pyridoxine deficiency were included. These cases, which often featured extensive workups revealing unremarkable findings aside from pyridoxine deficiency, underscore the multifaceted nature of PD and its treatment-related complications. The findings in these case reports suggest that dietary insufficiencies, gastrointestinal dysfunctions, and drug-nutrient interactions may eventually precipitate pyridoxine deficiency, which in turn may lead to seizures by disrupting GABAergic neurotransmission. This sheds the light on the need for increased clinical awareness and routine monitoring of pyridoxine levels in patients with PD, especially those undergoing significant therapeutic adjustments or exhibiting comorbidities that might interfere with their dietary intake such as gastrointestinal manifestations or depression. Such proactive measures could potentially mitigate the impact of this complication in patients with PD, ultimately enhancing patient care and quality of life.

Cognitive Reserve proxies can modulate motor and non-motor basal ganglia circuits in early Parkinson's Disease

Parkinson's Disease (PD) is hallmarked by dysfunctional circuitry between the basal ganglia and dorsolateral-prefrontal cortex. Recently progress has been made in understanding factors contributing to differential susceptibility to pathology mitigating disease-related cognitive decline. Cognitive reserve, the brain processing resources accumulated throughout life while engaged in mentally stimulating activities, can play an important protective role in cognitive performance. We tested the hypothesis that Cognitive Reserve proxies may exert an impact on the basal ganglia and dorsolateral-prefrontal atrophy in early PD. Forty-five early patients with PD and 20 age-gender-matched healthy controls (HC) completed the Cognitive Reserve Index questionnaire to quantify Cognitive Reserve proxies by three indexes (CRI-Education, CRI-Working Activity, CRI-Leisure Time) and a structural MRI examination (3T). Morphometrical indexes for basal ganglia (bilateral putamen, caudate, pallidum volume) and dorsolateral-prefrontal cortex (cortical thickness) were computed. Significant differences between HC and PD were tested by direct comparisons in demographics, cognitive level, and cognitive reserve proxies indexes. Then two multiple regression analyses were performed to identify predictors of the basal ganglia and dorsolateral-prefrontal cortex structural integrity. Regression analysis revealed that basal ganglia volume was significantly predicted by CRI-Education (pFDR = 0.029), sex (pFDR = 0.029), and Total Intracranial Volume (pFDR < 0.001). Instead, the dorsolateral-prefrontal thickness was predicted by CRI-Leisure Time (pFDR = 0.030) and age (pFDR = 0.010). Cognitive Reserve proxies, especially education and leisure-time activities, can play a protective role on the structural integrity of the basal ganglia and dorsolateral-prefrontal cortex, respectively, critical regions hallmarking brain status of early phases of PD.

3-Year test-retest reliability in Parkinson's disease and healthy older adults: The Parkinson's progression markers initiative study

Repeated neuropsychological assessments are often conducted in clinical and research settings to track cognitive changes over single or multiple intervals in patients with Parkinson's disease (PD). Yet few studies have documented test-retest reliability in PD. To address this gap, we used data from the Parkinson's Progression Markers Initiative (PPMI) to investigate the reliability of five well-known neuropsychological tests over a 3-year follow-up assessment in early-stage PD with either normal (PD-NC; N = 158) or abnormal (PD-AC; N = 39) cognitive screening, categorized based on recommended cutoffs for the Montreal Cognitive Assessment (MoCA), and healthy older adults (HOA; N = 102). All participants analyzed maintained the same cognitive status category across the assessment points. Intraclass correlation coefficients (ICCs) estimated reliability. The overall ICCs calculated across time points were as follows: Judgment of Line Orientation (PD-NC = .47, PD-AC = .50, HOA = .59); Letter-Number Sequencing (PD-NC = .64, PD-AC = .64, HOA = .65); Semantic Fluency (PD-NC = .69, PD-AC = .89, HOA = .77); Symbol Digit Modalities Test (PD-NC = .67, PD-AC = .83, HOA = .71). For the two primary components of the Hopkins Verbal Learning Test-Revised, we found the following ICCs: immediate recall (PD-NC = .46, PD-AC = .57, HOA = .58); delayed recall (PD-NC = .42, PD-AC = .57, HOA = .54). Findings from this study provide useful information for clinicians and researchers toward selecting suitable neuropsychological tests to monitor cognition at two or more time points among newly diagnosed individuals with PD and HOA.

Parkinson's Disease Dementia Patients: Expression of Glia Maturation Factor in the Brain

Parkinson's disease (PD) is the second most common progressive neurodegenerative disease characterized by the presence of dopaminergic neuronal loss and motor disorders. PD dementia (PDD) is a cognitive disorder that affects many PD patients. We have previously demonstrated the proinflammatory role of the glia maturation factor (GMF) in neuroinflammation and neurodegeneration in AD, PD, traumatic brain injury (TBI), and experimental autoimmune encephalomyelitis (EAE) in human brains and animal models. The purpose of this study was to investigate the expression of the GMF in the human PDD brain. We analyzed the expression pattern of the GMF protein in conjunction with amyloid plaques (APs) and neurofibrillary tangles (NFTs) in the substantia nigra (SN) and striatum of PDD brains using immunostaining. We detected a large number of GMF-positive glial fibrillary acidic protein (GFAP) reactive astrocytes, especially abundant in areas with degenerating dopaminergic neurons within the SN and striatum in PDD. Additionally, we observed excess levels of GMF in glial cells in the vicinity of APs, and NFTs in the SN and striatum of PDD and non-PDD patients. We found that the majority of GMF-positive immunoreactive glial cells were co-localized with GFAP-reactive astrocytes. Our findings suggest that the GMF may be involved in the pathogenesis of PDD.

Facial emotion expressivity in patients with Parkinson's and Alzheimer's disease

Parkinson's disease (PD) and Alzheimer's disease (AD) are neurodegenerative disorders with some overlapping clinical features. Hypomimia (reduced facial expressivity) is a prominent sign of PD and it is also present in AD. However, no study has experimentally assessed hypomimia in AD and compared facial expressivity between PD and AD patients. We compared facial emotion expressivity in patients with PD, AD, and healthy controls (HCs). Twenty-four PD patients, 24 AD patients and 24 HCs were videotaped during neutral facial expressions and while posing six facial emotions (anger, surprise, disgust, fear, happiness, and sadness). Fifteen raters were asked to evaluate the videos using MDS-UPDRS-III (item 3.2) and to identify the corresponding emotion from a seven-forced-choice response format. We measured the percentage of accuracy, the reaction time (RT), and the confidence level (CL) in the perceived accuracy of the raters' responses. We found the highest MDS-UPDRS 3.2 scores in PD, and higher in AD than HCs. When evaluating the posed expression captures, raters identified a lower percentage of correct answers in the PD and AD groups than HCs. There was no difference in raters' response accuracy between the PD and AD. No difference was observed in RT and CL data between groups. Hypomimia in patients correlated positively with the global MDS-UPDRS-III and negatively with Mini Mental State Examination scores. PD and AD patients have a similar pattern of reduced facial emotion expressivity compared to controls. These findings hold potential pathophysiological and clinical implications.

Chronic diseases and multimorbidity patterns, their recent onset, and risk of new-onset Parkinson's disease and related functional degeneration in older adults: a prospective cohort study

Background

Certain chronic diseases contribute to increased risks of Parkinson's disease (PD), but the association between time-varying multimorbidity patterns and new-onset PD remains underexplored.

Methods

Data were from the Survey of Health, Ageing and Retirement in Europe (SHARE) waves 5-8 conducted between January 2013 and March 2020. Eleven chronic diseases were included, with ≥2 denoting multimorbidity. Three multimorbidity patterns were further defined: somatic multimorbidity (SMM), neuropsychiatric multimorbidity (NPM), and cardiometabolic multimorbidity (CMM). PD-related function degeneration included functional limitations, mobility limitations, depressive symptoms, and cognitive decline. Time-dependent analyses, competing-risk analyses, and mixed-effect models were utilised.

Findings

In this prospective cohort study, 557 developed new-onset PD during follow-ups among 64,273 participants included at baseline, as defined by participants' self-reported physician diagnoses. Participants with (vs. without) multimorbidity, SMM, NPM, and CMM were at 1.40-2.70 times higher PD risk after considering the competing role of all-cause death, which remained significant in all sensitivity analyses and were more pronounced in lower-income participants (P for interaction <0.05). Similarly, they tended to develop functional degeneration faster than those without these multimorbidity patterns (P < 0.05). Participants with recent-onset (newly diagnosed in 2015) multimorbidity patterns were at 1.45-3.72 times higher risk of PD than those never diagnosed. Interestingly, they were at comparable or even higher (though P values for >0.05) PD risk compared to participants with multimorbidity patterns diagnosed in 2013 or before. Furthermore, recent-onset (vs. prior diagnosed) NPM exhibited faster functional deterioration and cognitive decline (P for difference <0.05).

Interpretation

Our findings suggest that promoting early prevention of multimorbidity, especially recent-onset multimorbidity and NPM, could prevent some subsequent cases of PD and related functional degeneration among older adults. However, further studies are needed to confirm this association.

Funding

The National Key Research and Development Program, Ministry of Science and Technology, China; Zhongnanshan Medical Foundation of Guangdong Province; Major Project of the National Social Science Fund of China; Fundamental Research Funds for the Central Universities.

Pathological Correlates of Cognitive Decline in Parkinson's Disease: From Molecules to Neural Networks

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the death of dopaminergic neurons in the substantia nigra and appearance of protein aggregates (Lewy bodies) consisting predominantly of α-synuclein in neurons. PD is currently recognized as a multisystem disorder characterized by severe motor impairments and various non-motor symptoms. Cognitive decline is one of the most common and worrisome non-motor symptoms. Moderate cognitive impairments (CI) are diagnosed already at the early stages of PD, usually transform into dementia. The main types of CI in PD include executive dysfunction, attention and memory decline, visuospatial impairments, and verbal deficits. According to the published data, the following mechanisms play an essential role demonstrates a crucial importance in the decline of the motor and cognitive functions in PD: (1) changes in the conformational structure of transsynaptic proteins and protein aggregation in presynapses; (2) synaptic transmission impairment; (3) neuroinflammation (pathological activation of the neuroglia); (4) mitochondrial dysfunction and oxidative stress; (5) metabolic disorders (hypometabolism of glucose, dysfunction of glycolipid metabolism; and (6) functional rearrangement of neuronal networks. These changes can lead to the death of dopaminergic cells in the substantia nigra and affect the functioning of other neurotransmitter systems, thus disturbing neuronal networks involved in the transmission of information related to the regulation of motor activity and cognitive functions. Identification of factors causing detrimental changes in PD and methods for their elimination will help in the development of new approaches to the therapy of PD. The goal of this review was to analyze pathological processes that take place in the brain and underlie the onset of cognitive disorders in PD, as well as to describe the impairments of cognitive functions in this disease.

Compliance with National and International Guidelines in the Treatment of Nonmotor Symptoms in Late-Stage Parkinson's Disease

Background

National as well as international Parkinson's disease (PD) treatment guidelines are available to guide clinicians. Previous research has shown that nonmotor symptoms (NMS) are pronounced in late-stage PD and has suggested that current treatment is insufficient and could be improved.

Objectives

The aim of this study was to investigate to which degree the national and international treatment guidelines are followed in the treatment of NMS in late-stage PD.

Methods

This Swedish cohort was part of the Care of Late-Stage Parkinsonism (CLaSP) study. Late-stage PD was defined as Hoehn and Yahr stages IV-V in "on" and/or ≤50% on the Schwab and England Activities of Daily Living (ADL) scale. NMS were assessed with the NMS scale (NMSS), cognition with the Mini-Mental State Examination (MMSE), and depressive symptoms with the Geriatric Depression Scale (GDS-30). Symptomatic individuals were defined as ≥ 6 on an item of the NMSS; for dementia, a cutoff of ≤18 on the MMSE; for depression, a cutoff of ≥10 on the GDS.

Results

All 107 participants exhibited NMS to various degrees and severities; the median NMSS score was 91. Among symptomatic individuals, for depressive symptoms, 37/63 (59%) were treated with antidepressants; for hallucinations and delusions, 9/18 (50%) and 5/13 (38%) were treated with antipsychotics; and for dementia, 9/27 (33%) were treated with rivastigmine and 1 (4%) was treated with donepezil. For orthostatic hypotension, 11/19 (58%) with lightheadedness and 7/8 (88%) with fainting were treated with antihypotensives; for sialorrhea, 2/42 (5%) were treated with botulinum toxin; and for constipation, 19/35 (54%) were treated with laxatives. For insomnia, 4/16 (25%) were treated with hypnotics, and for daytime sleepiness, 1/29 (3%) was treated with psychostimulants.

Conclusions

The present analyses suggest a need for clinicians to further screen for and treat NMS. Optimizing treatment of NMS according to the national and international treatment guidelines may improve symptomatology and enhance quality of life in late-stage PD.

Cognitive Impairment in Parkinson's Disease: An Updated Overview Focusing on Emerging Pharmaceutical Treatment Approaches

Cognitive impairment in patients with Parkinson's disease (PD) is one of the commonest and most disabling non-motor manifestations during the course of the disease. The clinical spectrum of PD-related cognitive impairment includes subjective cognitive decline (SCD), mild cognitive impairment (MCI) and PD dementia (PDD). As the disease progresses, cognitive decline creates a significant burden for the family members and/or caregivers of patients with PD, and has a great impact on quality of life. Current pharmacological treatments have demonstrated partial efficacy and failed to halt disease progression, and novel, effective, and safe therapeutic strategies are required. Accumulating preclinical and clinical evidence shows that several agents may provide beneficial effects on patients with PD and cognitive impairment, including ceftriaxone, ambroxol, intranasal insulin, nilotinib, atomoxetine, mevidalen, blarcamesine, prasinezumab, SYN120, ENT-01, NYX-458, GRF6021, fosgonimeton, INT-777, Neuropeptide S, silibinin, osmotin, cordycepin, huperzine A, fibroblast growth factor 21, Poloxamer 188, ginsenoside Rb1, thioredoxin-1, tangeretin, istradefylline and Eugenia uniflora. Potential underlying mechanisms include the inhibition of a-synuclein aggregation, the improvement of mitochondrial function, the regulation of synaptic plasticity, an impact on the gut-brain axis, the modulation of neuroinflammation and the upregulation of neurotrophic factors, as well as cholinergic, dopaminergic, serotoninergic and norepinephrine neurotransmission. In this updated overview, we aim to cover the clinical aspects of the spectrum of PD-related cognitive impairment and discuss recent evidence on emerging treatment approaches that are under investigation at a preclinical and clinical level. Finally, we aim to provide additional insights and propose new ideas for investigation that may be feasible and effective for the spectrum of PD-related cognitive impairment.

Clinical characteristics in early Parkinson's disease with excessive daytime sleepiness: A cross-sectional and longitudinal study

We aimed to explore excessive daytime sleepiness (EDS) and correlates of clinical characteristics by using cross-sectional and longitudinal analyses from the Parkinson's Progression Markers Initiative database. Four hundred twenty-three patients with Parkinson's disease (PD; EDS: non-EDS = 357:66) and 195 healthy controls (HCs; EDS: nEDS = 171:24) were enrolled in our study at baseline. Multiple linear and linear mixed-effects models were used to research the relationships between EDS/daytime sleepiness severity and clinical characteristics. Relationships between the change rates of clinical characteristics and daytime sleepiness severity were further investigated through multiple linear regression models. Mediating effect analysis was used to determine whether autonomic dysfunction was the mediator between cognition assessments and daytime sleepiness severity. Patients with PD with EDS and greater daytime sleepiness severity presented faster cognitive decline, high possibility for rapid eye movement sleep behavior disorder, autonomic dysfunction, depression, and anxiety from cross-sectional and longitudinal analyses. Furthermore, HC individuals with EDS showed a higher striatal binding ratio of the right putamen, right striatum, and mean striatum. Autonomic dysfunction may act as a mediator between PD and cognitive decline. In early PD, EDS and daytime sleepiness severity were related to several clinical variables, suggesting that EDS might play an essential role in regulating PD progression.

Monoterpenoid Epoxidiol Ameliorates the Pathological Phenotypes of the Rotenone-Induced Parkinson’s Disease Model by Alleviating Mitochondrial Dysfunction

Parkinson’s disease is the second most common neurodegenerative disease. Unfortunately, there is still no definitive disease-modifying therapy. In our work, the antiparkinsonian potential of trans-epoxide (1S,2S,3R,4S,6R)-1-methyl-4-(prop-1-en-2-yl)-7-oxabicyclo [4.1.0]heptan-2,3-diol (E-diol) was analyzed in a rotenone-induced neurotoxicity model using in vitro, in vivo and ex vivo approaches. It was conducted as part of the study of the mitoprotective properties of the compound. E-diol has been shown to have cytoprotective properties in the SH-SY5Y cell line exposed to rotenone, which is associated with its ability to prevent the loss of mitochondrial membrane potential and restore the oxygen consumption rate after inhibition of the complex I function. Under the conditions of rotenone modeling of Parkinson’s disease in vivo, treatment with E-diol led to the leveling of both motor and non-motor disorders. The post-mortem analysis of brain samples from these animals demonstrated the ability of E-diol to prevent the loss of dopaminergic neurons. Moreover, that substance restored functioning of the mitochondrial respiratory chain complexes and significantly reduced the production of reactive oxygen species, preventing oxidative damage. Thus, E-diol can be considered as a new potential agent for the treatment of Parkinson’s disease.

Copper Induces Cognitive Impairment in Mice via Modulation of Cuproptosis and CREB Signaling

It has been reported that disordered Cu metabolism is associated with several neurodegenerative diseases, including Alzheimer's disease (AD) and Parkinson's disease (PD). However, the underlying mechanism is still unclear. In this study, 4-week-old male mice were exposed to Cu by free-drinking water for three months. Then, the effects of Cu on cognitive functions in mice were tested by Morris water maze tests, and the potential mechanisms were investigated by the ELISA, immunochemistry, TUNEL, and Western blot tests. It was found that Cu exacerbates learning and memory impairment, and leads to Cu-overload in the brain and urine of mice. The results showed that Cu induces neuronal degeneration and oxidative damage, promotes the expression of apoptosis-related protein Bax, cuproptosis-related proteins FDX1 and DLAT and the proteotoxic stress marker HSP70, and decreases Fe-S cluster proteins. In addition, Cu affects the pre-synaptic and post-synaptic regulatory mechanisms through inhibiting the expression of PSD-95 and SYP. Cu also suppresses phosphorylation levels in CREB and decreases the expression of BDNF and TrkB in the mouse hippocampus. In conclusion, Cu might mediate cuproptosis, damage synaptic plasticity and inhibit the CREB/BDNF pathway to cause cognitive dysfunction in mice.

Treatment for cognitive and neuropsychiatric non-motor symptoms in Parkinson's disease: current evidence and future perspectives

INTRODUCTION

Non-motor symptoms (NMS) affect patients with Parkinson's disease (PD) from the prodromal to the advanced stages. NMS phenotypes greatly vary and have a huge impact on patients' and caregivers' quality of life (QoL). The management of cognitive and neuropsychiatric NMS remains an unmet need.

AREAS COVERED

The authors, herein, review the dopaminergic and non-dopaminergic pathogenesis, clinical features, assessment, and pharmacological and non-pharmacological treatments of cognitive and neuropsychiatric NMS in PD. They discuss the current evidence and report the findings of an overview of ongoing trials on pharmacological and selected non-pharmacological strategies.

EXPERT OPINION

The treatment of cognitive and neuropsychiatric NMS in PD is poorly explored, and therapeutic options are unsatisfactory. Pharmacological treatment of cognitive NMS is based on symptomatic active principles used in Alzheimer's disease. Dopamine agonists, selective serotonin, and serotonin-norepinephrine reuptake inhibitors have some evidence on PD-related depression. Clozapine, quetiapine, and pimavanserin may be considered for psychosis in PD. Evidence on the treatment of other neuropsychiatric NMS is limited or lacking. Addressing pathophysiological and clinical issues, which hamper solid evidence on the treatment of cognitive and neuropsychiatric NMS, may reduce the impact on QoL for PD patients and their caregivers.

Should patients with Parkinson’s disease only visit a neurologist’s office? - a narrative review of neuropsychiatric disorders among people with Parkinson’s disease

Introduction: Parkinson’s disease is a neurodegenerative disease that is often accompanied by disorders such as depression, psychotic disorders, cognitive disorders, anxiety disorders, sleep disorders, impulse control disorders. The aim of the study was to review the literature and present the characteristics of neuropsychiatric disorders occurring in people suffering from Parkinson’s disease, with the specification of the above-mentioned disorders.

Material and method: The literature available on the PubMed platform from 1986 to 2022 was reviewed using the following keywords: Parkinson’s disease, depression, anxiety disorders, psychotic disorders, sleep disorders, cognitive disorders, impulse control disorders. Original studies, reviews, meta-analyzes and internet sources were analyzed.

Results: The above-mentioned neuropsychiatric disorders appear with different frequency among people suffering from Parkinson’s disease and occur at different times of its duration or even precede its onset for many years. The non-motor symptoms in the form of depressed mood, energy loss or changes in the rhythm of the day may result in a delay of appropriate therapy and thus in complications. Neuropathological changes in the course of Parkinson’s disease as well as dopaminergic drugs used in its therapy influence the development of neuropsychiatric disorders.

Conclusions: In order to avoid misdiagnosis, practitioners should use, e.g. scales intended for patients with Parkinson’s disease. To prevent the consequences of the aforementioned disease entities, methods of early diagnosis, determination of risk factors and standardization of the treatment process must be determined. Consistent care for patients with Parkinson’s disease is significant, not only in the neurological field, but also in the psychiatric one.

Blunt dopamine transmission due to decreased GDNF in the PFC evokes cognitive impairment in Parkinson's disease

Studies have found that the absence of glial cell line-derived neurotrophic factor may be the primary risk factor for Parkinson's disease. However, there have not been any studies conducted on the potential relationship between glial cell line-derived neurotrophic factor and cognitive performance in Parkinson's disease. We first performed a retrospective case-control study at the Affiliated Hospital of Xuzhou Medical University between September 2018 and January 2020 and found that a decreased serum level of glial cell line-derived neurotrophic factor was a risk factor for cognitive disorders in patients with Parkinson's disease. We then established a mouse model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and analyzed the potential relationships among glial cell line-derived neurotrophic factor in the prefrontal cortex, dopamine transmission, and cognitive function. Our results showed that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex weakened dopamine release and transmission by upregulating the presynaptic membrane expression of the dopamine transporter, which led to the loss and primitivization of dendritic spines of pyramidal neurons and cognitive impairment. In addition, magnetic resonance imaging data showed that the long-term lack of glial cell line-derived neurotrophic factor reduced the connectivity between the prefrontal cortex and other brain regions, and exogenous glial cell line-derived neurotrophic factor significantly improved this connectivity. These findings suggested that decreased glial cell line-derived neurotrophic factor in the prefrontal cortex leads to neuroplastic degeneration at the level of synaptic connections and circuits, which results in cognitive impairment in patients with Parkinson's disease.

Liquid-Liquid Phase Separation Promotes Protein Aggregation and Its Implications in Ferroptosis in Parkinson’s Disease Dementia

The pathological features of PDD are represented by dopaminergic neuronal death and intracellular α-synuclein (α-syn) aggregation. The interaction of iron accumulation with α-syn and tau was further explored as an essential pathological mechanism of PDD. However, the links and mechanisms between these factors remain unclear. Studies have shown that the occurrence and development of neurodegenerative diseases such as PDD are closely related to the separation of abnormal phases. Substances such as proteins can form droplets through liquid-liquid phase separation (LLPS) under normal physiological conditions and even undergo further liquid-solid phase transitions to form solid aggregates under disease or regulatory disorders, leading to pathological phenomena. By analyzing the existing literature, we propose that LLPS is the crucial mechanism causing abnormal accumulation of α-syn, tau, and other proteins in PDD, and its interaction with iron metabolism disorder is the key factor driving ferroptosis in PDD. Therefore, we believe that LLPS can serve as one of the means to explain the pathological mechanism of PDD. Determining the significance of LLPS in neurodegenerative diseases such as PDD will stimulate interest in research into treatments based on interference with abnormal LLPS.

Frailty and cognitive impairment in Parkinson’s disease: a systematic review

BACKGROUND

Frailty can lead to increased vulnerability in older people and patients with Parkinson's disease (pwPD) and worsen their health conditions. These patients can also develop cognitive function impairment. The objective is to analyze whether there is a relationship between frailty and cognitive impairment in pwPD, and to find out which instruments to use for its evaluation.

METHODS

Publications were searched in PubMed, Medline, Web of Science, Cinalh, Cochrane Library, Embase, Phycinfo, and Scopus. The results were measured with the instruments that are used to assess frailty and cognitive impairment, and analyze their relationship.

RESULTS

Two hundred seventy-one articles were identified, of which 12 met the inclusion criteria. All studies assessed frailty and cognitive function in pwPD. Five studies analyzed the relationship between frailty and cognitive impairment. The most used instruments were the Fried scale followed by the Clinical Frailty Scale (CFS) for frailty. Cognitive impairment was mostly evaluated with the Mini-Mental State Examination and the Montreal Cognitive Assessment. The prevalence data ranged from 20.2 to 51.5% with the Fried scale and from 35.6 to 83.9% with the CFS. Cognitive impairment was present in 15 to 45.2% of the pwPD.

CONCLUSION

Analysis of the included studies shows a relationship between frailty and cognitive impairment in pwPD. There was significant variability in the application of the scales used, which influences the prevalence data. More observational and experimental studies are needed to provide more evidence on this association and to determine which is the optimal tool to identify frailty in pwPD using multidimensional scales.

Exclusion of older adults from clinical trials in cancer-related pain

Pain is one of the most common symptoms in cancer patients including older adults. The objective of this study was to evaluate the enrollment criteria that can limit the inclusion of older adults in clinical trials concerning cancer-related pain (CRP). The study included 356 trials registered with ClinicalTrials.gov. Our primary outcome measures were the proportion of trials that excluded patients based on upper age limits (80 years of age or less), strict organ-specific exclusion criteria, broad and imprecise criteria, and inadequate performance score. One hundred and twenty-six trials (35.4%) had upper age limits. Strict exclusion criteria were used in 95 (26.7%) trials. Broad and imprecise exclusion criteria were listed in 57 (16.2%) trials. Low performance score was used as an exclusion criterion in 4 trials (1.1%). Overall, in 241 trials (67.7%) there was either an upper age limit or at least one strict or broad and imprecise exclusion criterion, or a criterion involving the performance status. The odds of excluding older adults were significantly higher in certain neoplasm types, study objectives, intervention types, and center locations. In conclusion, considerable proportion of recent clinical trials concerning CRP either explicitly exclude older adults or create high risk of such exclusion which substantially limits the evidence base for the treatment of such patients in clinical practice. Sponsors and investigators should consider careful modification of the enrollment criteria to improve the inclusion of older individuals who make up the major proportion of cancer patients population.

Associations of cognitive dysfunction with motor and non-motor symptoms in patients with de novo Parkinson's disease

The risk factors of mild cognitive impairment (MCI) in patients with de novo Parkinson’s disease (PD) remain unclear. Therefore, the objective of this study was to compare motor and non-motor symptoms between de novo patients with PD with and without MCI. Moreover, detailed relationships between each cognitive deficit and other clinical characteristics in de novo patients with PD were investigated. Consecutive patients with de novo PD were retrospectively enrolled in this study. Motor symptoms were assessed using the Unified Parkinson’s Disease Rating Scale (UPDRS) part-III and the Hoehn and Yahr (HY) stage. Non-motor symptoms including depression, anxiety, fatigue, and autonomic dysfunction were measured using representative questionnaires. Motor symptoms, depression, and dysautonomia were associated with MCI in de novo patients with PD. Compared with the non-MCI group with PD, the MCI group with PD had higher scores of UPDRS-III, HY stage, depression, and dysautonomia, but not fatigue or anxiety. Both UPDRS-III and HY stage were significantly linked to all cognitive deficits except attention. Logistic regression analysis showed that depression was associated with memory, visuospatial, and executive impairment, and dysautonomia was related to visuospatial and executive impairment. The results of this study suggest that cognitive impairment in PD might have a different relationship pattern to the motor and some non-motor symptoms.

A New Instrument Combines Cognitive and Social Functioning Items for Detecting Mild Cognitive Impairment and Dementia in Parkinson’s Disease

Background

The commonly used screening tests for Parkinson’s disease (PD) are the Montreal Cognitive Assessment (MoCA) and Mini-Mental State Examination (MMSE), both of which only focus on cognitive function. A composite assessment that considers both cognitive and social dysfunction in PD would be helpful in detecting mild cognitive impairment (MCI) and PD dementia (PDD).

Objective

We aimed to simplify the commonly used tools and combine cognitive and social functioning tests to detect early MCI and PDD.

Materials and Methods

A total of 166 participants (84 PD patients and 82 healthy) were recruited who completed the MMSE, MoCA, PD social functioning scale (PDSFS), clock drawing test, activities of daily living, comprehensive neuropsychological assessment (e.g., executive, attention, language, memory, and visuospatial functions), and movement disorder society (MDS)-unified PD rating scale. According to the MDS diagnostic criteria, the patients were grouped into PD-nonMCI, PD-MCI, or PDD.

Results

To detect PD-MCI, the optimal cut-off scores for the simplified MoCA and the combined test were 9 and 35. The discrimination values measured by the area under the receiver operating characteristic curve (AUC) of the two tests were 0.767 (p < 0.001) and 0.790 (p < 0.001). When the simplified MoCA was 7 or the combined test 30, the patients would be classified as having PDD. The AUCs of the two tests were 0.846 (p < 0.001) and 0.794 (p = 0.003).

Conclusion

We suggest considering both cognitive and social functions when detecting PD-MCI and PDD.

Caring for patients with cognitive dysfunction, fluctuations and dementia caused by Parkinson's disease

Cognitive dysfunction is one of the most prevalent non-motor symptoms in patients with Parkinson's disease (PD). While it tends to worsen in the later stages of disease, it can occur at any time, with 15-20% of patients exhibiting cognitive deficits at diagnosis (Aarsland et al., 2010; Goldman and Sieg, 2020). The characteristic features of cognitive dysfunction include impairment in executive function, visuospatial abilities, and attention, which vary in severity from subtle impairment to overt dementia (Martinez-Horta and Kulisevsky, 2019). To complicate matters, cognitive dysfunction is prone to fluctuate in PD patients, impacting diagnosis and the ability to assess progression and decision-making capacity. The diagnosis of cognitive impairment or dementia has a huge impact on patient independence, quality of life, life expectancy and caregiver burden (Corallo et al., 2017; Lawson et al., 2016; Leroi et al., 2012). It is therefore essential that physicians caring for patients with PD provide education, screening and treatment for this aspect of the disease. In this chapter, we provide a practical guide for the assessment and management of various degrees of cognitive dysfunction in patients with PD by approaching the disease at different stages. We address risk factors for cognitive dysfunction, prevention strategies prior to making the diagnosis, available tools for screening. Lastly, we review aspects of care, management and considerations, including decision-making capacity, that occur after the patient has been diagnosed with cognitive dysfunction or dementia.

Cognition and serotonin in Parkinson's disease

Cognitive impairment affects up to 80% of patients with Parkinson's disease (PD) and is associated with poor quality of life. PD cognitive dysfunction includes poor working memory, impairments in executive function and difficulty in set-shifting. The pathophysiology underlying cognitive impairment in PD is still poorly understood, but there is evidence to support involvements of the cholinergic, dopaminergic, and noradrenergic systems. Only rivastigmine, an acetyl- and butyrylcholinesterase inhibitor, is efficacious for the treatment of PD dementia, which limits management of cognitive impairment in PD. Whereas the role of the serotonergic system in PD cognition is less understood, through its interactions with other neurotransmitters systems, namely, the cholinergic system, it may be implicated in cognitive processes. In this chapter, we provide an overview of the pharmacological, clinical and pathological evidence that implicates the serotonergic system in mediating cognition in PD.

Neuromodulation of cognition in Parkinson's disease

Neuromodulation is a widely used treatment for motor symptoms of Parkinson's disease (PD). It can be a highly effective treatment as a result of knowledge of circuit dysfunction associated with motor symptoms in PD. However, the mechanisms underlying cognitive symptoms of PD are less well-known, and the effects of neuromodulation on these symptoms are less consistent. Nonetheless, neuromodulation provides a unique opportunity to modulate motor and cognitive circuits while minimizing off-target side effects. We review the modalities of neuromodulation used in PD and the potential implications for cognitive symptoms. There have been some encouraging findings with both invasive and noninvasive modalities of neuromodulation, and there are promising advances being made in the field of therapeutic neuromodulation. Substantial work is needed to determine which modulation targets are most effective for the different types of cognitive deficits of PD.

The Impact of Parkinson's Disease on General and Specific Motor Aptitudes: A Study of Older Brazilian Adults

This study investigated motor aptitude in older adults with and without Parkinson's disease (PD) to further specify known motor-related changes of PD. We divided 671 older adults (23.5% male; M_age = 69.6, SD = 6.6 years) into a Parkinson's Disease Group (PDG) and a non-Parkinson's Disease Group (NPG) and assessed their general motor aptitude (GMA) and their specific motor aptitudes (in Coordinative, Proprioceptive, and Perceptive domains) using the Motor Scale for Older Adults. We used the chi-squared tests and logistic regression to identify and affirm an associations between PD and motor aptitude, we found that most adults without PD showed normal motor aptitude (GMA: 80.7%; Proprioceptive: 82.3%; Perceptive: 81.4%) except for the Coordinative skills, for which 56.4% of these participants had motor impairment. Most partipants with PD showed motor impairments (GMA: 94.7%; Coordinative: 97.4%; Proprioceptive: 97.4%), except in the Perceptive domain, for which 68.4% of participants with PD showed normal aptitude. There were significant associations between PD and GMA (OR = 127.6), Coordinative motor skills (OR = 48.0), and Proprioceptive skills (OR = 204.4), even after the model was adjusted for gender and age. Our use of the Motor Scale for Older Adults in contrasting groups of older Brazilian adults provides further specificity to the motor aptitude characteristics of older adults with PD.

Parkinson's Disease Dementia: Synergistic Effects of Alpha-Synuclein, Tau, Beta-Amyloid, and Iron

Parkinson’s disease dementia (PDD) is a common complication of Parkinson’s disease that seriously affects patients’ health and quality of life. At present, the process and pathological mechanisms of PDD remain controversial, which hinders the development of treatments. An increasing number of clinical studies have shown that alpha-synuclein (α-syn), tau, beta-amyloid (Aβ), and iron are closely associated with PDD severity. Thus, we inferred the vicious cycle that causes oxidative stress (OS), due to the synergistic effects of α-syn, tau, Aβ, and, iron, and which plays a pivotal role in the mechanism underlying PDD. First, iron-mediated reactive oxygen species (ROS) production can lead to neuronal protein accumulation (e.g., α-syn andAβ) and cytotoxicity. In addition, regulation of post-translational modification of α-syn by iron affects the aggregation or oligomer formation of α-syn. Iron promotes tau aggregation and neurofibrillary tangles (NFTs) formation. High levels of iron, α-syn, Aβ, tau, and NFTs can cause severe OS and neuroinflammation, which lead to cell death. Then, the increasing formation of α-syn, Aβ, and NFTs further increase iron levels, which promotes the spread of α-syn and Aβ in the central and peripheral nervous systems. Finally, iron-induced neurotoxicity promotes the activation of glycogen synthase kinase 3β (GSK3β) related pathways in the synaptic terminals, which in turn play an important role in the pathological synergistic effects of α-syn, tau and Aβ. Thus, as the central factor regulating this vicious cycle, GSK3β is a potential target for the prevention and treatment of PDD; this is worthy of future study.

A Longitudinal Randomized Controlled Trial Protocol to Evaluate the Effects of Wuqinxi on Dynamic Functional Connectivity in Parkinson's Disease Patients

Background: Parkinson’s disease (PD) is a neurodegenerative movement disease that includes non-motor symptoms such as cognitive impairment. Long-term mind-body exercise has been shown to improve cognitive ability in PD patients, but the methods of assessment and intervention were inconsistent across studies. Wuqinxi is a mind-body exercise that is easy to learn, has few physical and cognitive demands, and is recommended for PD patients. Dynamic functional connectivity (DFC) has been associated with cognitive alterations in PD patients, but no studies have yet explored the effects of Wuqinxi on this association. The current protocol is designed to measure the effects of long-term Wuqinxi intervention on cognition in PD patients, and explore the underlying neural mechanisms through DFC.

Methods: A long-term single-blind, randomized trial will be conducted. PD patients and age- and gender-matched HC will be recruited; PD patients will be randomly assigned to either Wuqinxi or balance groups, and HC will all receive health education. The Wuqinxi group will receive a 90-min session of Wuqinxi intervention three times a week for 24 weeks, while the balance group will receive balance exercise instruction on the same schedule. Primary outcomes will include assessment of cognitive domains and dynamic temporal characteristics of functional connectivity. Secondary outcomes will include severity of motor symptoms, mobility, balance, and emotional state. Assessments will be conducted at baseline, at the end of 24 weeks of intervention, and 12 weeks after interventions have ended.

Discussion: This study will provide evidence to the effects of Wuqinxi exercise on cognitive improvements in PD patients from the perspective of DFC, and will contribute to the understanding of neural mechanisms underlying cognitive enhancement through Wuqinxi practice.

Clinical Trial Registration:www.chictr.org.cn, identifier ChiCTR2000038517.

Effect of Acupuncture on Cognitive Function of Insomnia Patients Compared with Drugs: A Protocol for Meta-analysis and Systematic Review

Insomnia, one of the most common sleep disorders, is thought to have an adverse effect on cognitive function. At the same time, people with cognitive dysfunction are more prone to insomnia. At present, pharmacotherapy is the main treatment for insomnia, but there are some shortcomings such as poor long-term efficacy and potential dependence. There is some evidence that acupuncture has some advantages in alleviating insomnia and improving cognitive function. This study is aimed at investigating the effects of acupuncture and drugs on cognitive function in patients with insomnia and evaluating the efficacy and safety of these two interventions, providing strong evidence for clinical decision-making. The study will retrieve eight major databases: China National Knowledge Infrastructure, Wanfang Database, VIP Database for Chinese Technical Periodicals, SinoMed, PubMed, Web of Science, Embase, and Cochrane Library. Dissertations, conference papers, and ongoing experiments will also be retrieved for supplement. Literature screening and data extraction will be completed by two authors independently (JJ and X-QW). If there were any disagreements, they would be discussed or referred to a third person for adjudication (W-ZW). Authors will use Cochrane risk of bias tool to assess the included studies. The Review Manager Statistical (RevMan) software is used to conduct the statistical process of meta-analysis, and funnel plot is used to evaluate reporting biases. The Grading of Recommendations Assessment Development and Evaluation (GRADE) Profiler can be used to be aware of the quality of evidence.

Semantic fluency and processing speed are reduced in non-cognitively impaired participants with Parkinson's disease

Introduction: Parkinson's disease (PD) is associated with a range of cognitive deficits. Few studies have carefully examined the subtle impacts of PD on cognition among patients who do not meet formal criteria for MCI or dementia. The aim of the current study was thus to describe the impact of PD on cognition in those without cognitive impairment in a well-characterized cohort.Methods: Non-cognitively impaired participants (122 with PD, 122 age- and sex-matched healthy volunteers) underwent extensive cognitive testing. Linear regression analyses compared diagnostic group performance across cognitive measures. For cognitive tasks that were significantly different between groups, additional analyses examined group differences restricting the group inclusion to PD participants with mild motor symptoms or disease duration less than 10 years.Results: Processing speed and semantic verbal fluency were significantly lower in the PD group (B = -3.77, 95% CIs [-5.76 to -1.77], p < .001, and B = -2.02, 95% CIs [-3.12, -0.92], p < .001, respectively), even after excluding those with moderate to severe motor symptoms (B = -2.73, 95% CIs [-4.94 to -0.53], p = .015 and B = -2.11, 95% CIs [-3.32 to -0.91], p < .001, respectively) or longer disease duration (B = -3.89, 95% CIs [-6.14 to -1.63], p < .001 and B = -1.58, 95% CIs [-2.78 to -0.37], p = .010, respectively). Semantic verbal fluency remained significantly negatively associated with PD diagnosis after controlling for processing speed (B = -1.66, 95% CIs [-2.79 to -0.53], p = .004).Conclusions: Subtle decline in specific cognitive domains may be present among people diagnosed with PD but without evidence to support a formal cognitive diagnosis. These results suggest the importance of early awareness of the potential for diminishing aspects of cognition in PD even among those without mild cognitive impairment or dementia.

Association between sleep disorders and cognitive dysfunctions in non-demented patients with advanced Parkinson's disease

Background

Parkinson’s disease (PD) is increasingly recognized as a multidimensional disorder, characterized by several non-motor symptoms, including disturbances of sleep and cognition. Current studies on the relationship between sleep problems and neuropsychological functions, mainly conducted in early to moderate PD patients, outline mixed results. In this study, we analysed the relationship between subjectively reported sleep alterations and cognitive functions in a large cohort of 181 advanced PD patients.

Methods

All consecutive, non-demented, advanced PD patients candidates for device-aided therapy completed two self-administered sleep questionnaires—the Parkinson’s Disease Sleep Scale (PDSS-2) and the Epworth Sleepiness Scale (ESS)—and underwent a comprehensive battery of neuropsychological tests encompassing five cognitive domains (reasoning, memory, attention, frontal executive functions, and language).

Results

Patients showed mild to moderate sleep problems (PDSS-2 score: 23.4 ± 1.2) and mild daytime sleepiness (ESS 8.6 ± 5.1). A significant correlation was found between PDSS-2 total score and non-verbal reasoning, as well as attentive skills, executive functions, and language abilities. No correlations were found between sleep measures and memory tests scores. Patients with clinically relevant sleep disturbances performed worse on attention, executive functions, and language. No significant correlations were found between daytime sleepiness and any neuropsychological test.

Conclusions

In advanced PD patients, sleep disturbances selectively correlate with specific neuropsychological functions and not with short-term memory and consolidation. Even if confirmations by means of longitudinal studies are needed, our observations suggest the importance of considering treatment of sleep disturbances to minimize their potential impact on cognition.

Lewy Body Dementias: A Coin with Two Sides?

Lewy body dementias (LBDs) consist of dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), which are clinically similar syndromes that share neuropathological findings with widespread cortical Lewy body deposition, often with a variable degree of concomitant Alzheimer pathology. The objective of this article is to provide an overview of the neuropathological and clinical features, current diagnostic criteria, biomarkers, and management of LBD. Literature research was performed using the PubMed database, and the most pertinent articles were read and are discussed in this paper. The diagnostic criteria for DLB have recently been updated, with the addition of indicative and supportive biomarker information. The time interval of dementia onset relative to parkinsonism remains the major distinction between DLB and PDD, underpinning controversy about whether they are the same illness in a different spectrum of the disease or two separate neurodegenerative disorders. The treatment for LBD is only symptomatic, but the expected progression and prognosis differ between the two entities. Diagnosis in prodromal stages should be of the utmost importance, because implementing early treatment might change the course of the illness if disease-modifying therapies are developed in the future. Thus, the identification of novel biomarkers constitutes an area of active research, with a special focus on α-synuclein markers.

Lipid metabolic dysregulation is involved in Parkinson's disease dementia

Dementia is very common in the late stage of patient with Parkinson's disease (PD). We aim to explore its underlying pathogenesis and identify candidate biomarkers using untargeted metabolomics analysis. Consecutive PD patients and healthy controls were recruited. Clinical data were assessed and patients were categorized into Parkinson's disease without dementia (PDND) and Parkinson's disease dementia (PDD). Fast plasma samples were obtained and untargeted liquid chromatography-mass spectrometry-based metabolomics analysis was performed. Based on the identified differentially-expressed metabolites from the metabolomics analysis, multivariate linear regression analyses and receiver operating characteristic (ROC) curves were further employed. According to the clinical data, the mean ages of PDND and PDD patients were significantly higher than those of healthy controls. The incidence of hypercholesterolemia was decreased in PDD patients. PDD patients also had lower levels of triglyceride, low-density lipoprotein cholesterol, and apolipoprotein B. There were 24 and 57 differentially expressed metabolites in PDD patients when compared with the healthy controls and PDND patients from the metabolomics analysis. Eleven lipid metabolites were simultaneously decreased between these two groups, and can be further subcategorized into fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, and prenol lipids. The plasma levels of the eleven metabolites were positively correlated with MMSE score and can be candidate biomarkers for PDD patients with areas under the curve ranging from 0.724 to 0.806 based on the ROC curves. Plasma lipoproteins are significantly lower in PDD patients. A panel of eleven lipid metabolites were also decreased and can be candidate biomarkers for the diagnosis of PDD patients. Lipid metabolic dysregulation is involved in the pathogenesis of Parkinson's disease dementia.

Frameworks for Parkinson's Disease Rehabilitation Addressing When, What, and How

PURPOSE OF REVIEW

This review summarizes the evidence on rehabilitation for people with Parkinson's disease, including when to refer, what rehabilitation professionals should address, and how to deliver rehabilitation care.

RECENT FINDINGS

Clinical practice guidelines support physical therapy, occupational therapy, and speech-language pathology for Parkinson's disease. However, integrating guidelines into practice may be difficult. Implementation studies take into account patient and clinician perspectives. Synthesizing guidelines with implementation research can improve local delivery. There is moderate to strong evidence supporting physical therapy, occupational therapy, and speech-language pathology soon after diagnosis and in response to functional deficits. We propose a framework of three pathways for rehabilitation care: (1) consultative proactive rehabilitation soon after diagnosis for assessment, treatment of early deficits, and promotion meaningful activities; (2) restorative rehabilitation to promote functional improvements; and (3) skilled maintenance rehabilitation for long-term monitoring of exercise, meaningful activities, safety, contractures, skin integrity, positioning, swallowing, and communication.

Approach to Cognitive Impairment in Parkinson's Disease

Cognitive dysfunction is common in Parkinson's disease (PD) and predicts poor clinical outcomes. It is associated primarily with pathologic involvement of basal forebrain cholinergic and prefrontal dopaminergic systems. Impairments in executive functions, attention, and visuospatial abilities are its hallmark features with eventual involvement of memory and other domains. Subtle symptoms in the premotor and early phases of PD progress to mild cognitive impairment (MCI) which may be present at the time of diagnosis. Eventually, a large majority of PD patients develop dementia with advancing age and longer disease duration, which is usually accompanied by immobility, hallucinations/psychosis, and dysautonomia. Dopaminergic medications and deep brain stimulation help motor dysfunction, but may have potential cognitive side effects. Central acetylcholinesterase inhibitors, and possibly memantine, provide modest and temporary symptomatic relief for dementia, although there is no evidence-based treatment for MCI. There is no proven disease-modifying treatment for cognitive impairment in PD. The symptomatic and disease-modifying role of physical exercise, cognitive training, and neuromodulation on cognitive impairment in PD is under investigation. Multidisciplinary approaches to cognitive impairment with effective treatment of comorbidities, proper rehabilitation, and maintenance of good support systems in addition to pharmaceutical treatment may improve the quality of life of the patients and caregivers.

Overdosing on iron: Elevated iron and degenerative brain disorders

IMPACT STATEMENT

Brain degenerative disorders, which include some neurodevelopmental disorders and age-associated diseases, cause debilitating neurological deficits and are generally fatal. A large body of emerging evidence indicates that iron accumulation in neurons within specific regions of the brain plays an important role in the pathogenesis of many of these disorders. Iron homeostasis is a highly complex and incompletely understood process involving a large number of regulatory molecules. Our review provides a description of what is known about how iron is obtained by the body and brain and how defects in the homeostatic processes could contribute to the development of brain diseases, focusing on Alzheimer's disease and Parkinson's disease as well as four other disorders belonging to a class of inherited conditions referred to as neurodegeneration based on iron accumulation (NBIA) disorders. A description of potential therapeutic approaches being tested for each of these different disorders is provided.