Vitor Tumas

• PhD
• Propfessor at University of São Paulo

What is known and objective: Cannabidiol (CBD) is the main non-psychotropic component of the Cannabis sativa plant. REM sleep behaviour disorder (RBD) is a parasomnia characterized by the loss of muscle atonia during REM sleep associated with nightmares and active behaviour during dreaming. We have described the effects of CBD in RBD symptoms in p...

The present review paper describes results indicating the influence of nitric oxide (NO) on motor control. Our last studies showed that systemic injections of low doses of inhibitors of NO synthase (NOS), the enzyme responsible for NO formation, induce anxiolytic effects in the elevated plus maze whereas higher doses decrease maze exploration. Also...

Chronic l-DOPA pharmacotherapy in Parkinson's disease is often accompanied by the development of abnormal and excessive movements known as l-DOPA-induced dyskinesia. Rats with 6-hydroxydopamine lesion of dopaminergic neurons chronically treated with l-DOPA develop a rodent analog of this dyskinesia characterized by severe axial, limb, locomotor and...

The management of psychosis in Parkinson's disease (PD) has been considered a great challenge for clinicians and there is a need for new pharmacological intervention. Previously an antipsychotic and neuroprotective effect of Cannabidiol (CBD) has been suggested. Therefore, the aim of the present study was to directly evaluate for the first time, th...

The treatment of Parkinson's disease (PD) is a challenge, especially because it is considered highly individualized. The Brazilian Academy of Neurology (ABN) has identified the need to disseminate knowledge about its management, adapting the best evidence to the Brazilian population. The present article aims to report the recommendations for the tr...

Background Spatial orientation involves egocentric and allocentric strategies that switch in the brain. Disturbances in switching may indicate Neurocognitive Disorders, which contribute to early detection of Alzheimer’s Disease. The “Ego‐Allo‐Switching Task” (EAST) needs to be adapted for cross‐cultural use in Brazil. Method 61 participants were d...

Background: The Montreal Cognitive Assessment (MoCA) is widely used to evaluate global cognitive function in older Brazilian adults. However, concerns persist regarding its applicability in non-homogeneous socio-demographic groups. This study scrutinizes the Brazilian version of the MoCA, focusing on its measurement properties in a diverse cohort o...

Background The MDS‐UPDRS has been available in English since 2008, showing satisfactory clinimetric results and being proposed as the new official benchmark scale for Parkinson's disease (PD), being cited as a core instrument for PD in the National Institutes of Neurological Disorders and Stroke Common Data Elements program. For this reason, the MD...

Latin Americans are underrepresented in genetic studies, increasing disparities in personalized genomic medicine. Despite available genetic data from thousands of Latin Americans, accessing and navigating the bureaucratic hurdles for consent or access remains challenging. To address this, we introduce the Genetics of Latin American Diversity (GLAD)...

Higher serum cortisol levels appear to be associated with stress that can overlap or manifest anxiety, fatigue, depression, and sleep dysfunction. These are common and intrusive non-motor symptoms of Parkinson’s disease (PD). Thus, stress has been proposed to mediate Parkinson’s disease development, and cortisol has been suggested as a biomarker fo...

The global impact of the Coronavirus Disease (COVID-19) pandemic has extended beyond physical health, leading to widespread mental health issues. Beyond respiratory symptoms, there is a growing concern about long-term cognitive effects, particularly in individuals who experienced mild cases of the infection. We aimed to investigate the neuropsychol...

Background Parkinson's disease (PD) is the second most common neurodegenerative disease following Alzheimer's disease. Nearly 30 causative genes have been identified for PD and related disorders. However, most of these genes were identified in European‐derived families, and little is known about their role in Latin American populations. Objectives...

Objective To compare the dopamine transporter (DAT) density with other risk factors for L-DOPA-induced dyskinesia (LID) in patients with Parkinson’s disease (PD), with and without LID. Materials and Methods We evaluated 67 subjects: 44 patients with idiopathic PD of varying degrees of severity (PD group), and 23 healthy age-matched volunteers (con...

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by extracellular accumulation of amyloid-β (Aβ) peptides in the brain. This study demonstrates the direct association of the disposable pipette extraction (DPX) with tandem mass spectrometry (MS/MS) for the analysis of Aβ peptides in cerebrospinal fluid (CSF) samples. Different...

After more than 200 years since its initial description, the clinical diagnosis of Parkinson's disease (PD) remains an often-challenging endeavor, with broad implications that are fundamental for clinical management. Despite major developments in understanding it's pathogenesis, pathological landmarks, non-motor features and potential paraclinical...

Although over 90 independent risk variants have been identified for Parkinson’s disease using genome-wide association studies, most studies have been performed in just one population at a time. Here we performed a large-scale multi-ancestry meta-analysis of Parkinson’s disease with 49,049 cases, 18,785 proxy cases and 2,458,063 controls including i...

Background Hereditary or familial spastic paraplegias (SPG) comprise a group of genetically and phenotypically heterogeneous diseases characterized by progressive degeneration of the corticospinal tracts. The complicated forms evolve with other various neurological signs and symptoms, including movement disorders and ataxia. Objective To summarize...

Objective There are scarce data comparing Parkinson’s disease (PD) and Progressive Supranuclear Palsy (PSP) in social cognition (SC). We aimed to compare patients with PSP and PD in SC. Methods We included three groups: PD (n = 18), PSP (n = 20) and controls (n = 23). Participants underwent neuropsychological exams, including the mini-version of t...

Parkinson’s disease (PD) is a common neurodegenerative disease associated with cognitive impairment. The Montreal Cognitive Assessment (MoCA) has been used as a recommended global cognition scale for patients with PD, but there are some concerns about its application, partially due to the floor and ceiling effects. Objectives: To explore the floor...

The Monogenic Network of the Global Parkinson's Genetics Program (GP2) aims to create an efficient infrastructure to accelerate the identification of novel genetic causes of Parkinson's disease (PD) and to improve our understanding of already identified genetic causes, such as reduced penetrance and variable clinical expressivity of known disease-c...

The Global Parkinson’s Genetics Program (GP2) will genotype over 150,000 participants from around the world, and integrate genetic and clinical data for use in large-scale analyses to dramatically expand our understanding of the genetic architecture of PD. This report details the workflow for cohort integration into the complex arm of GP2, and toge...

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by an extracellular accumulation of amyloid beta peptides in the brain. The concentration of the amyloid beta peptides in cerebrospinal fluid (CSF) have been evaluated as potential biomarkers of AD for early diagnostic. In this work, an in‐tube solid‐phase microextraction (in‐tu...

Background: Sex differences in Parkinson's disease (PD) risk are well-known. However, the role of sex chromosomes in the development and progression of PD is still unclear. Objective: The objective of this study was to perform the first X-chromosome-wide association study for PD risk in a Latin American cohort. Methods: We used data from three...

Spinocerebellar ataxias (SCAs) have a worldwide average prevalence of 2.7 cases per 100,000 individuals, with significant geographic variability. This study aimed to develop resource-limited strategies to detect and characterize the frequency and genetic-clinical profile of SCAs in an unexplored population from Alagoas State, a low Human Developmen...

Background Handicap is a patient‐centered measure of health status that encompasses the impact of social and physical environment on daily living, having been assessed in advanced and late‐stage Parkinson's Disease (PD). Objective To characterize the handicap of a broader sample of patients. Methods A cross‐sectional study of 405 PD patients duri...

Background NUFFACE was created to identify the locus of name‐face failure common in healthy aging and dementia. Psychometric studies are necessary for the development of the Brazilian version. Therefore, we intend to verify the evidence of predictive (or diagnostic) validity of this instrument. Methods a total 24 participants were included in this...

Background: Levodopa-induced dyskinesia (LID) is a common motor complication of levodopa therapy in patients with Parkinson`s disease (PD). Doxycycline is a widely used and inexpensive tetracycline with anti-inflammatory properties. Objective: Evaluate the efficacy and safety of doxycycline in patients with PD and LID. Methods: This was an open-lab...

Sex differences in Parkinson Disease (PD) risk are well-known. However, it is still unclear the role of sex chromosomes in the development and progression of PD. We performed the first X-chromosome Wide Association Study (XWAS) for PD risk in Latin American individuals. We used data from three admixed cohorts: (i) Latin American Research consortium...

Background: As gene-targeted therapies are increasingly being developed for Parkinson's disease (PD), identifying and characterizing carriers of specific genetic pathogenic variants is imperative. Only a small fraction of the estimated number of subjects with monogenic PD worldwide are currently represented in the literature and availability of cl...

Background and aims Molecular imaging of the dopamine transporters (DAT) provides valuable information about neurodegenerative diseases, such as Parkinson’s. This study assessed the accuracy and precision of DAT-SPECT quantification methods. Methods Twenty-three DAT-SPECT images of a striatal phantom were acquired. The specific (caudate and putame...

Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) represent the second most common type of degenerative dementia in patients aged 65 years and older, leading to progressive cognitive dysfunction and impaired quality of life. This study aims to provide a consensus based on a systematic Brazilian literature review and a comprehen...

Parkinson’s disease dementia (PDD) and dementia with Lewy bodies (DLB) represent the second most common type of degenerative dementia in patients aged 65 years and older, leading to progressive cognitive dysfunction and impaired quality of life. This study aims to provide a consensus based on a systematic Brazilian literature review and a comprehen...

Mentalizing and emotion recognition are impaired in behavioral variant frontotemporal dementia (bvFTD). It is not clear whether these abilities are also disturbed in other conditions with prominent frontal lobe involvement, such as progressive supranuclear palsy (PSP). Our aim was to investigate social cognition (facial emotion recognition, recogni...

Background: Cannabidiol (CBD) is one of the main nonpsychoactive components of Cannabis sativa and may represent an alternative treatment for Restless Legs Syndrome/Willis-Ekbom Disease (RLS/WED) in patients with Parkinson's disease (PD) and REM (Rapid Eye Movement) sleep behavior disorder (RBD). Objective: Our purpose was a post hoc exploratory a...

Purpose: The aim of this study was to evaluate different quantitative indexes of striatum dopamine transporter density in healthy subjects and patients with PD. Patients and methods: Sixty-seven patients, 23 healthy (8 male; 59 ± 11 years old) and 44 age-matched patients (29 male; 59 ± 7 years old), with various degrees of severity of idiopathic...

Background and Aims: Molecular imaging of the dopamine transporters (DAT) provides usefull information about neurodegenerative diseases, such as Parkinson’s. This study assessed the accuracy and precision of DAT-SPECT quantification methods. Methods: Twenty-three DAT-SPECT images of a striatal phantom. The specific chambers (caudate and putamen) an...

Background Large-scale Parkinson's disease (PD) genome-wide association studies (GWAS) have, until recently, only been conducted on subjects with European-ancestry. Consequently, polygenic risk scores (PRS) constructed using PD GWAS data are likely to be less predictive when applied to non-European cohorts. Methods Using GWAS data from the largest...

Background: Episodic memory impairment may occur in progressive supranuclear palsy (PSP). However, it remains uncertain whether this is due to executive dysfunction or to the involvement of brain areas responsible for memory. Objectives: To investigate the specific brain regions underlying episodic memory impairment in PSP. Methods: Twenty-one...

Background Levodopa-induced dyskinesia (LID) is a common motor complication of levodopa therapy in patients with Parkinson’s disease (PD). Doxycycline is a widely used and inexpensive tetracycline with anti-inflammatory properties. Objective Evaluate the efficacy and safety of doxycycline in patients with PD and LID. Methods This was an open-labe...

Huntington’s disease (HD) is an inherited neurodegenerative disease characterized by motor, cognitive and behavioral deficits. Some evidence suggests that the endocannabinoid system participates in the pathophysiology of HD. We conducted a cross-sectional study comparing plasma levels of anandamide and 2-arachidonoylglycerol in manifest HD gene-exp...

Levodopa-induced dyskinesia (LID) is a common complication of Parkinson’s disease (PD) therapy. Nitric oxide in the central nervous system may have a role in its pathophysiology. The present work investigates plasma and CSF levels of nitric oxide metabolites nitrite and nitrate in patients with PD, LID, and healthy control. We measured plasma and C...

The existence of few biomarkers and the lack of a better understanding of the pathophysiology of levodopa-induced dyskinesia (LID) in Parkinson's disease (PD) require new approaches, as the metabolomic analysis, for discoveries. We aimed to identify a metabolic profile associated with LID in patients with PD in an original cohort, and to confirm th...

Background: Large-scale Parkinson's disease (PD) genome-wide association studies (GWAS) and meta-analyses have, until recently, only been conducted on subjects with European-ancestry. Consequently, polygenic risk scores (PRS) constructed using PD GWAS data are likely to be less predictive when applied to non-European cohorts. Methods: Using GWAS da...

Background Dentatorubral-pallidoluysian atrophy (DRPLA) is a rare autosomal dominant spinocerebellar ataxia due to pathological expansion of CAG trinucleotide repeats in the ATN1 gene. Most cases were described in patients from Japanese ancestry who presented with adult-onset progressive cerebellar ataxia associated with cognitive decline, choreoat...

In adulthood, the ability to digest lactose, the main sugar present in milk of mammals, is a phenotype (lactase persistence) observed in historically herder populations, mainly Northern Europeans, Eastern Africans, and Middle Eastern nomads. As the –13910∗T allele in the MCM6 gene is the most well-characterized allele responsible for the lactase pe...

Background: Increasing numbers of mutations causing monogenic forms of Parkinson's disease (PD) have been described, mostly among patients in Europe and North America. Since genetic architecture varies between different populations, studying the specific genetic profile of Brazilian patients is essential for improving genetic counseling and for se...

Objective: This work was undertaken in order to identify Parkinson's disease (PD) risk variants in a Latino cohort, to describe the overlap in the genetic architecture of PD in Latinos compared to European-ancestry subjects, and to increase the diversity in PD genome-wide association (GWAS) data. Methods: We genotyped and imputed 1497 PD cases a...

Background: REM sleep behaviour disorder (RBD) is a common non-motor feature of Parkinson's disease (PD). Cannabidiol (CBD) is one of the main non-psychoactive components of Cannabis sativa and may represent an alternative route for treating RBD. Objective: This study assessed the efficacy and safety of CBD for RBD in PD. Methods: We conducted...

Essential tremor (ET) is a common clinical syndrome characterized by action tremors affecting both upper limbs that can compromise manual tasks' execution and impair functional and social performance. The primary pharmacological treatment is symptomatic, but effective medicines are somewhat limited. There is a clear need to find new effective thera...

Background: Restless legs syndrome or Willis-Ekbom disease is a disorder characterized by unpleasant sensations associated with the need to mobilize the lower limbs. In Parkinson disease patients, restless legs syndrome is associated with worse quality of life and excessive sleepiness. Regarding other factors, results of different studies are contr...

Background: Apathy is a multidimensional syndrome that impairs motivation and mechanisms of behavioural regulation. As apathy is almost ubiquitous in neurodegenerative disorders, understanding the neural basis is required to expand knowledge and ameliorate our instruments. Objective: Verify the feasibility, safety, and adherence of a remote physica...

Background: Parkinson's disease is the second most common neurodegenerative disorder and affects people from all ethnic backgrounds, yet little is known about the genetics of Parkinson's disease in non-European populations. In addition, the overall identification of copy number variants at a genome-wide level has been understudied in Parkinson's p...

Background: Huntington's disease (HD) is a progressive disorder characterized by motor, cognitive and psychiatric features. Cerebellar ataxia is classically considered as uncommon in HD clinical spectrum. Objective: To determine the prevalence of cerebellar ataxia in patients with HD, both in the early and in the late stages of HD. Methods: Seventy...

To date, over 90 Parkinson’s disease (PD) risk variants have been reported from genome-wide association studies (GWAS). However, these GWAS efforts have been limited to individuals of European and East Asian ancestry. We performed the first GWAS of Latino PD patients from South America, comparing 807 cases against 690 controls followed by associati...

Introduction: A diagnosis of rapid eye movement sleep behavior disorder (RBD) currently requires confirmation with polysomnography (PSG). However, PSG may not be sufficiently available. In these situations, a clinical diagnostic measure might be useful. Objective: To validate the Brazilian Portuguese version of RBD screening questionnaire (RBDSQ)...

Levodopa-induced dyskinesias (LID) in Parkinson’s disease (PD) are frequent complications, and the endocannabinoid system has a role on its pathophysiology. To test the hypothesis that the functioning of the endocannabinoid system would be altered in PD and in LID by measuring plasma and CSF levels of α-N-arachidonoylethanolamine (AEA) and 2-arachi...

Hereditary spastic paraplegias (HSP) are a group of genetically and phenotypically heterogeneous disorders resulting from progressive degeneration of the corticospinal tract.¹ They may have autosomal dominant, autosomal recessive, x‐linked or mitochondrial inheritance and the main clinical features derive from lower limb spasticity. There are now m...

Background Levodopa-induced dyskinesias (LID) in Parkinson’s disease (PD) are frequent complications, and the endocannabinoid system has a role on its pathophysiology. Objective To test the hypothesis that the functioning of the endocannabinoid system would be altered in PD and in LID by measuring plasma and CSF levels of α-N-arachidonoylethanolam...

Introduction Levodopa-induced dyskinesias (LID) in Parkinson’s disease (PD) are frequent complications, and nitric oxide has a role on its pathophysiology. The present work aims to investigate CSF levels of nitric oxide metabolites nitrite and nitrate (NOx) in patients with PD and LID. Methods We measured CSF NOx levels in patients with PD with an...

Objective: We evaluated differences between direct and indirect functional assessment methods to evaluate functional abilities in PD patients. Methods: We evaluated 32 patients with PD and suspected mild dementia using direct and indirect assessment methods. Results: There was a significant difference between the scores of direct and indirect met...

Background: Parkinson's disease is the second most common neurodegenerative disorder and affects people from all ethnic backgrounds, yet little is known about the genetics of Parkinson's disease in non-European populations. In addition, the overall identification of copy number variants at a genome-wide level has been understudied in Parkinson's di...

Background: There are currently no methods to predict the development of levodopa-induced dyskinesia (LID), a frequent complication of Parkinson's disease (PD) treatment. Clinical predictors and single nucleotide polymorphisms (SNP) have been associated to LID in PD. Objective: To investigate the association of clinical and genetic variables with...

Little is known about the genetic basis of amyotrophic lateral sclerosis (ALS) outside Europe and US. In this study, we investigated whether intermediate CAG expansions at ATXN1 were associated to ALS in the Brazilian population. To accomplish that, representative samples from 411 unrelated patients and 436 neurologically normal controls from 6 cen...

Purpose The aim of this study was to evaluate the effect of ordered subsets maximization expectation (OSEM) and filtered backprojection (FBP) reconstruction algorithms for the qualitative interpretation of DAT-SPECT. Methods Data were acquired using an anthropomorphic striatal phantom and a gamma camera (SPECT/CT). Images were reconstructed using...

Background Cannabidiol (CBD) is one of the main components of Cannabis sativa and has anxiolytic properties, but no study has been conducted to evaluate the effects of CBD on anxiety signs and symptoms in patients with Parkinson’s disease (PD). This study aimed to evaluate the impacts of acute CBD administration at a dose of 300 mg on anxiety measu...

In elderly individuals, low educational level may represent a risk factor for the development of dementia and a proxy of cognitive reserve. Objective: This study examined the cognitive and neuroanatomic correlates of high versus low educational levels in cognitively healthy community-dwelling older adults in Brazil. Methods: Fifty-three older a...

Objective: To determine the factors associated with OSA in PD patients com DP. Methods: A cross-sectional study was performed with 88 consecutive patients with PD from the outpatient clinic. Participants underwent clinical interviews with neurologists and a psychiatrist, assessment using standardized scales (Epworth Sleepiness Scale, Parkinson's D...

Background: Insomnia complaints are frequent in Parkinson disease (PD), affecting up to 55% of patients. Factors related to insomnia in PD are multifactorial and may be associated with the degenerative process of the disease, comorbidities related to aging, and medication use. The aim of this study is to determine the factors associated with the p...

Background Idiopathic focal dystonia is a motor syndrome associated with dysfunction of basal ganglia circuits. Observations have suggested that many other non-motor symptoms may also be part of the clinical picture. The aim was to assess the prevalence and correlation of non-motor symptoms in patients with common idiopathic focal or segmental dyst...

Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor symptoms such as bradykinesia, rest tremor, postural disturbances, and rigidity. PD is also characterized by non-motor symptoms such as sleep disturbances, cognitive deficits, and psychiatric disorders such as psychosis, depression, and anxiety. The pharmacologi...

Dystonia is a relatively common movement disorder but some of its epidemiological and clinical aspects have not been well characterized in Brazilian patients. Also, a new clinical classification for the disorder has been proposed and its impact on clinical practice is unclear. We aimed to describe the clinical and demographic characteristics of a B...

SUMMARY The Parkinson's disease is a neurodegenerative condition in which the most common motor symptoms result from the nigrostriatal path cells death and the resulting dopaminergic depletion on striatum. Dopaminergic agonists are drugs acting directly on dopamine receptors and its therapeutic use is associated to a lower frequency of motor fluctu...

Aim Sleep disorders can be associated with an increased risk for cognitive decline in patients with Parkinson’s disease (PD). The aim of this study was to examine the association between cognitive status and presence of sleep symptoms and sleep disorders in PD patients. Methods We evaluated excessive sleepiness, other sleep symptoms and performed...

The objectives of this study were to describe the characteristics of RBD in a group of PD patients and verify the accuracy of the clinical interview in this group, determine the causes of failure of the interview, as well as to verify the clinical and polysomnographic differences between the groups of PD patients with and without RBD. So, a cross-s...

Rapid eye movement (REM) sleep behavior disorder (RBD) is a parasomnia characterized by the presence of a complex of signals resulting from the loss of REM sleep atony and manifested by vigorous and sometimes violent motor jerks and nocturnal vocalizations associated with dream enactment. RBD might be a clinical predictor of severity for Parkinson'...

The nitric oxide (NO) system has been proven to be a valuable modulator of L‐DOPA‐induced dyskinesia in parkinsonian rodents. NO activates the enzyme soluble guanylyl cyclase and elicits the synthesis of the second messenger cGMP. Although we have previously described the anti‐dyskinetic potential of NO synthase inhibitors on L‐DOPA‐induced dyskine...

Endocannabinoids (ECs) are endogenous lipid-based retrograde neurotransmitters that bind to cannabinoid receptors [cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2)]. Many ECs have been characterized; anandamide (AEA) and 2-arachidonoyl glycerol (2-AG) are still considered the primary ECs signaling mediators. Dysregulation of ECs has be...

Diseases with a choreic phenotype can be due to a variety of genetic etiologies. As testing for Huntington's disease (HD) becomes more available in previously resource-limited regions, it is becoming apparent that there are patients in these areas with other rare genetic conditions which cause an HD-like phenotype. Documentation of the presence of...

[This corrects the article DOI: 10.1038/s41531-017-0020-6.].

Objectives: To determine the frequency of major sleep disorders in patients with Parkinson's disease (PD), diagnosed according to the third international classification of sleep disorders, and assess the relationship of those disorders with the quality of life. Methods: A cross-sectional study was performed involving 88 consecutive patients with...

Background Among non-motor symptoms of Parkinson’s disease (PD), anxiety occurs in up to 67% of patients. Clinically, PD patients report worsening of tremors in anxiogenic situations. Objective The aim of this study was to evaluate the association between motor symptoms and anxiety in PD patients and compare their performances with those of health...