ATN cerebrospinal fluid biomarkers in dementia with Lewy bodies: Initial results from the United States Dementia with Lewy Bodies Consortium.

INTRODUCTION: The National Institute on Aging - Alzheimer's Association (NIA-AA) ATN research framework proposes to use biomarkers for amyloid (A), tau (T), and neurodegeneration (N) to stage individuals with AD pathological features and track changes longitudinally. The overall aim was to utilize this framework to characterize pre-mortem ATN status longitudinally in a clinically diagnosed cohort of dementia with Lewy bodies (DLB) and to correlate it with the post mortem diagnosis. METHODS: The cohort was subtyped by cerebrospinal fluid (CSF) ATN category. A subcohort had longitudinal data, and a subgroup was neuropathologically evaluated. RESULTS: We observed a significant difference in Aß42/40 after 12 months in the A+T- group. Post mortem neuropathologic analyses indicated that most of the p-Tau 181 positive (T+) cases also had a high Braak stage. DISCUSSION: This suggests that DLB patients who are A+ but T- may need to be monitored to determine whether they remain A+ or ever progress to T positivity. HIGHLIGHTS: Some A+T- DLB subjects transition from A+ to negative after 12-months. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Monitoring of the A+T- sub-type of DLB may be necessary.

Parkinson Disease and Subthalamic Nucleus Deep Brain Stimulation: Cognitive Effects in GBA Mutation Carriers.

OBJECTIVE: This study was undertaken to compare the rate of change in cognition between glucocerebrosidase (GBA) mutation carriers and noncarriers with and without subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson disease. METHODS: Clinical and genetic data from 12 datasets were examined. Global cognition was assessed using the Mattis Dementia Rating Scale (MDRS). Subjects were examined for mutations in GBA and categorized as GBA carriers with or without DBS (GBA+DBS+, GBA+DBS-), and noncarriers with or without DBS (GBA-DBS+, GBA-DBS-). GBA mutation carriers were subcategorized according to mutation severity (risk variant, mild, severe). Linear mixed modeling was used to compare rate of change in MDRS scores over time among the groups according to GBA and DBS status and then according to GBA severity and DBS status. RESULTS: Data were available for 366 subjects (58 GBA+DBS+, 82 GBA+DBS-, 98 GBA-DBS+, and 128 GBA-DBS- subjects), who were longitudinally followed (range = 36-60 months after surgery). Using the MDRS, GBA+DBS+ subjects declined on average 2.02 points/yr more than GBA-DBS- subjects (95% confidence interval [CI] = -2.35 to -1.69), 1.71 points/yr more than GBA+DBS- subjects (95% CI = -2.14 to -1.28), and 1.49 points/yr more than GBA-DBS+ subjects (95% CI = -1.80 to -1.18). INTERPRETATION: Although not randomized, this composite analysis suggests that the combined effects of GBA mutations and STN-DBS negatively impact cognition. We advise that DBS candidates be screened for GBA mutations as part of the presurgical decision-making process. We advise that GBA mutation carriers be counseled regarding potential risks associated with STN-DBS so that alternative options may be considered. ANN NEUROL 2022;91:424-435.

Plasma Glucosylsphingosine in GBA1 Mutation Carriers with and without Parkinson's Disease.

BACKGROUND: Biallelic mutations in the GBA1 gene encoding glucocerebrosidase cause Gaucher's disease, whereas heterozygous carriers are at risk for Parkinson's disease (PD). Glucosylsphingosine is a clinically meaningful biomarker of Gaucher's disease but could not be assayed previously in heterozygous GBA1 carriers. OBJECTIVE: The aim of this study was to assess plasma glucosylsphingosine levels in GBA1 N370S carriers with and without PD. METHODS: Glucosylsphingosine, glucosylceramide, and four other lipids were quantified in plasma from N370S heterozygotes with (n = 20) or without (n = 20) PD, healthy controls (n = 20), idiopathic PD (n = 20), and four N370S homozygotes (positive controls; Gaucher's/PD) using quantitative ultra-performance liquid chromatography tandem mass spectrometry. RESULTS: Plasma glucosylsphingosine was significantly higher in N370S heterozygotes compared with noncarriers, independent of disease status. As expected, Gaucher's/PD cases showed increases in both glucocerebrosidase substrates, glucosylsphingosine and glucosylceramide. CONCLUSIONS: Plasma glucosylsphingosine accumulation in N370S heterozygotes shown in this study opens up its future assessment as a clinically meaningful biomarker of GBA1-PD. © 2021 International Parkinson and Movement Disorder Society.

The choice not to undergo genetic testing for Huntington disease: Results from the PHAROS study.

Rates of genetic testing in Huntington disease (HD) are lower than was predicted before direct DNA testing became available. Clinicians often do not have in-depth conversations with people at risk who chose not to test. We queried 733 research subjects who chose not to learn their HD gene status when enrolling in the Prospective Huntington At-Risk Observational Study, carried out between 1999 and 2008. Lack of an effective cure or treatment (66% of subjects) and inability to undo knowledge (66%) were the major reasons cited for choosing not to undergo HD DNA testing. Most subjects were not concerned about the length or burden of the testing process (61% and 59%, respectively). Subjects were optimistic that a treatment to improve symptoms or postpone onset would be developed within the next 10 years (56% and 53%, respectively), but they had less certainty about the prospects to prevent HD onset (36%). This is the first large, systematic study of why people at risk for HD choose not to undergo genetic testing. Attitudes about how people at risk for HD approach this life-altering choice should be reassessed as new treatments develop, and as clinical trials now require genetic testing at entry.

SMPD1 mutations, activity, and α-synuclein accumulation in Parkinson's disease.

BACKGROUND: SMPD1 (acid-sphingomyelinase) variants have been associated with Parkinson's disease in recent studies. The objective of this study was to further investigate the role of SMPD1 mutations in PD. METHODS: SMPD1 was sequenced in 3 cohorts (Israel Ashkenazi Jewish cohort, Montreal/Montpellier, and New York), including 1592 PD patients and 975 controls. Additional data were available for 10,709 Ashkenazi Jewish controls. Acid-sphingomyelinase activity was measured by a mass spectrometry-based assay in the New York cohort. α-Synuclein levels were measured in vitro following CRISPR/Cas9-mediated knockout and siRNA knockdown of SMPD1 in HeLa and BE(2)-M17 cells. Lysosomal localization of acid-sphingomyelinase with different mutations was studied, and in silico analysis of their effect on acid-sphingomyelinase structure was performed. RESULTS: SMPD1 mutations were associated with PD in the Ashkenazi Jewish cohort, as 1.4% of PD patients carried the p.L302P or p.fsP330 mutation, compared with 0.37% in 10,709 Ashkenazi Jewish controls (OR, 3.7; 95%CI, 1.6-8.2; P = 0.0025). In the Montreal/Montpellier cohort, the p.A487V variant was nominally associated with PD (1.5% versus 0.14%; P = 0.0065, not significant after correction for multiple comparisons). Among PD patients, reduced acid-sphingomyelinase activity was associated with a 3.5- to 5.8-year earlier onset of PD in the lowest quartile versus the highest quartile of acid-sphingomyelinase activity (P = 0.01-0.001). We further demonstrated that SMPD1 knockout and knockdown resulted in increased α-synuclein levels in HeLa and BE(2)-M17 dopaminergic cells and that the p.L302P and p.fsP330 mutations impair the traffic of acid-sphingomyelinase to the lysosome. CONCLUSIONS: Our results support an association between SMPD1 variants, acid-sphingomyelinase activity, and PD. Furthermore, they suggest that reduced acid-sphingomyelinase activity may lead to α-synuclein accumulation. © 2019 International Parkinson and Movement Disorder Society.

Arm swing as a potential new prodromal marker of Parkinson's disease.

BACKGROUND: Reduced arm swing is a well-known clinical feature of Parkinson's disease (PD), often observed early in the course of the disease. We hypothesized that subtle changes in arm swing and axial rotation may also be detectable in the prodromal phase. OBJECTIVE: The purpose of this study was to evaluate the relationship between the LRRK2-G2019S mutation, arm swing, and axial rotation in healthy nonmanifesting carriers and noncarriers of the G2019S mutation and in patients with PD. METHODS: A total of 380 participants (186 healthy nonmanifesting controls and 194 PD patients) from 6 clinical sites underwent gait analysis while wearing synchronized 3-axis body-fixed sensors on the lower back and bilateral wrists. Participants walked for 1 minute under the following 2 conditions: (1) usual walking and (2) dual-task walking. Arm swing amplitudes, asymmetry, variability, and smoothness were calculated for both arms along with measures of axial rotation. RESULTS: A total of 122 nonmanifesting participants and 67 PD patients were carriers of the G2019S mutation. Nonmanifesting mutation carriers walked with greater arm swing asymmetry and variability and lower axial rotation smoothness under the dual task condition when compared with noncarriers (P < .04). In the nonmanifesting mutation carriers, arm swing asymmetry was associated with gait variability under dual task (P = .003). PD carriers showed greater asymmetry and variability of movement than PD noncarriers, even after controlling for disease severity (P < .009). CONCLUSIONS: The G2019S mutation is associated with increased asymmetry and variability among nonmanifesting participants and patients with PD. Prospective studies should determine if arm swing asymmetry and axial rotation smoothness may be used as motor markers of prodromal PD. © 2016 International Parkinson and Movement Disorder Society.

The relationship between obsessive-compulsive symptoms and PARKIN genotype: The CORE-PD study.

BACKGROUND: Few studies have systematically investigated the association between PARKIN genotype and psychiatric co-morbidities of Parkison's disease (PD). PARKIN-associated PD is characterized by severe nigral dopaminergic neuronal loss, a finding that may have implications for behaviors rooted in dopaminergic circuits such as obsessive-compulsive symptoms (OCS). METHODS: The Schedule of Compulsions and Obsessions Patient Inventory (SCOPI) was administered to 104 patients with early-onset PD and 257 asymptomatic first-degree relatives. Carriers of one and two PARKIN mutations were compared with noncarriers. RESULTS: Among patients, carriers scored lower than noncarriers in adjusted models (one-mutation: 13.9 point difference, P = 0.03; two-mutation: 24.1, P = 0.001), where lower scores indicate less OCS. Among asymptomatic relatives, a trend toward the opposite was seen: mutation carriers scored higher than noncarriers (one mutation, P = 0.05; two mutations, P = 0.13). CONCLUSIONS: First, a significant association was found between PARKIN mutation status and obsessive-compulsive symptom level in both PD and asymptomatic patients, suggesting that OCS might represent an early non-motor dopamine-dependent feature. Second, irrespective of disease status, heterozygotes were significantly different from noncarriers, suggesting that PARKIN heterozygosity may contribute to phenotype. © 2014 International Parkinson and Movement Disorder Society.

Variability in interval production is due to timing-dependent deficits in Huntington's disease.

In Huntington's disease (HD), increased variability is seen in performance of motor tasks that require implicit control of timing. We examined whether timing variability was also evident in an explicit interval-timing task. Sixty subjects (21 controls, 19 manifest HD, and 20 pre-manifest HD) performed a single-interval production task with three target intervals (1.1 s, 2.2 s, 3.3 s). We analyzed accuracy (proportional error) and precision (standard deviation) across groups and intervals. No differences were seen in accuracy across groups or intervals. Precision was significantly lower in manifest (P = 0.0001) and pre-manifest HD (P = 0.04) compared with controls. This was particularly true for pre-manifest subjects close to diagnosis (based on probability of diagnosis in 5 years). Precision was correlated with proximity to diagnosis (r2 = 0.3, P < 0.01). To examine the source of reduced precision, we conducted linear regression of standard deviation with interval duration. Slope of the regression was significantly higher in manifest HD (P = 0.02) and in pre-manifest HD close to diagnosis (P = 0.04) compared with controls and pre-manifest participants far from diagnosis. Timing precision is impaired before clinical diagnosis in Huntington's disease. Slope analysis suggests that timing variability (decreased precision) was attributable to deficits in timing-dependent processes. Our results provide additional support for the proposal that the basal ganglia are implicated in central timekeeping functions. Because the single interval production task was sensitive to deficits in pre-manifest HD, temporal precision may be a useful outcome measure in future clinical trials.

Parkinson's disease with Lewy bodies associated with a heterozygous PARKIN dosage mutation.

BACKGROUND: PARKIN-related disease remains incompletely understood. First, the pathogenicity of heterozygous PARKIN mutations is unclear, although some evidence supports causality. Second, unlike sporadic Parkinson's disease (PD), Lewy bodies are present only in a minority of cases. Only one other heterozygote PARKIN carrier with autopsy findings has been described. Our case adds to the broadening pathological and clinical phenotype of PARKIN-related disease. METHODS: Clinical chart, genetic analysis, and pathological findings of a patient with familial PD are reviewed. RESULTS: A 44-year-old man developed slowly progressive tremor-predominant PD with excellent response to levodopa. Genetic analysis revealed a heterozygous PARKIN exon 3-4 deletion, also present in 2 family members with early-onset PD. Postmortem examination showed severe neuronal loss in the substantia nigra and nucleus coeruleus with the presence of diffuse Lewy bodies. CONCLUSIONS: The deletion is unlikely an incidental finding considering family history, age at onset, and the presence of clinical and pathological features not typical of sporadic PD.

Knowledge of and interest in genetic results among Parkinson disease patients and caregivers.

The purpose of the study is to investigate Parkinson disease (PD) patients' and caregivers' knowledge of and interest in genetic testing. Gaucher disease (GD) results from recessive mutations in glucocerebrosidase (GBA). Both heterozygote GBA carriers and GD patients are at greater risk for PD. Studies regarding knowledge of and interest in genetic testing have been limited and have not offered genetic results to participants. In this study, 353 PD patients and 180 caregivers were recruited to a PD genetic study. The association between GD, GBA mutations and PD was described to participants who reported their familiarity with genetic terms, answered questions on genetic concepts, and indicated their interest in knowing if they may have GD (two GBA mutations) and other genetic information that could impact their health. Ninety-three-percent of participants were interested in receiving GBA results; however, only 51.6 % of PD participants and 55.6 % of caregivers knew that "scientists have identified genes associated with a higher risk of developing PD." PD patients may benefit from education and genetic counseling on the implications of genetic testing.

Association of CSF α-Synuclein Seeding Amplification Assay Results With Clinical Features of Possible and Probable Dementia With Lewy Bodies.

BACKGROUND AND OBJECTIVES: The clinical diagnosis of dementia with Lewy bodies (DLB) depends on identifying significant cognitive decline accompanied by core features of parkinsonism, visual hallucinations, cognitive fluctuations, and REM sleep behavior disorder (RBD). Hyposmia is one of the several supportive features. α-Synuclein seeding amplification assays (αSyn-SAAs) may enhance diagnostic accuracy by detecting pathologic αSyn seeds in CSF. In this study, we examine how different clinical features associate with CSF αSyn-SAA positivity in a large group of clinically diagnosed participants with DLB. METHODS: Cross-sectional and longitudinal CSF samples from the multicentered observational cohort study of the DLB Consortium and similar studies within the Parkinson's Disease Biomarker Program, contributed by academic medical centers in the United States, underwent αSyn-SAA testing. Participants included those clinically diagnosed with DLB and 2 control cohorts. Associations between core DLB features and olfaction with αSyn-SAA positivity were evaluated using logistic regression. RESULTS: CSF samples from 191 participants diagnosed with DLB (mean age 69.9 ± 6.8, 15% female), 50 age-matched and sex-matched clinical control participants, and 49 younger analytical control participants were analyzed. Seventy-two percent (137/191) of participants with DLB had positive αSyn-SAAs vs 4% of the control groups. Among participants with DLB, those who were αSyn-SAA-positive had lower Montreal Cognitive Assessment scores (18.8 ± 5.7 vs 21.2 ± 5.2, p = 0.01), had worse parkinsonism on the Movement Disorders Society Unified Parkinson's Disease Rating Scale part III (33.8 ± 15.1 vs 25.6 ± 16.4, p = 0.001), were more likely to report RBD (114/133 [86%] vs 33/53 [62%], p < 0.0001), and had worse hyposmia on the University of Pennsylvania Smell Identification Test (UPSIT) (94/105 [90%] below 15th percentile vs 14/44 [32%], p < 0.0001). UPSIT percentile had the highest area under the curve (0.87, 95% CI 0.81-0.94) in predicting αSyn-SAA positivity and participants scoring at or below the 15th percentile of age and sex normative values had 18.3 times higher odds (95% CI 7.52-44.6) of having a positive αSyn-SAA test. Among 82 participants with longitudinal CSF samples, 81 (99%) had the same αSyn-SAA result for initial and follow-up specimens. DISCUSSION: A substantial proportion of clinically diagnosed participants with DLB had negative αSyn-SAA results. Hyposmia was the strongest clinical predictor of αSyn-SAA positivity. Hyposmia and αSyn-SAA may have utility in improving the diagnostic assessment of individuals with potential DLB. CLASSIFICATION OF EVIDENCE: This study provided Class III evidence that CSF αSyn-SAA distinguishes patients with clinically diagnosed DLB from normal controls.

Parkinson disease phenotype in Ashkenazi Jews with and without LRRK2 G2019S mutations.

The phenotype of Parkinson's disease (PD) in patients with and without leucine-rich repeat kinase 2 (LRRK2) G2019S mutations reportedly is similar; however, large, uniformly evaluated series are lacking. The objective of this study was to characterize the clinical phenotype of Ashkenazi Jewish (AJ) PD carriers of the LRRK2 G2019S mutation. We studied 553 AJ PD patients, including 65 patients who were previously reported, from three sites (two in New York and one in Tel-Aviv). Glucocerebrosidase (GBA) mutation carriers were excluded. Evaluations included the Montreal Cognitive Assessment (MoCA), the Unified Parkinson's Disease Rating Scale (UPDRS), the Geriatric Depression Scale (GDS) and the Non-Motor Symptoms (NMS) questionnaire. Regression models were constructed to test the association between clinical and demographic features and LRRK2 status (outcome) in 488 newly recruited participants. LRRK2 G2019S carriers (n = 97) and non-carriers (n = 391) were similar in age and age at onset of PD. Carriers had longer disease duration (8.6 years vs. 6.1 years; P < 0.001), were more likely to be women (51.5% vs. 37.9%; P = 0.015), and more often reported first symptoms in the lower extremities (40.0% vs. 19.2%; P < 0.001). In logistic models that were adjusted for age, disease duration, sex, education, and site, carriers were more likely to have lower extremity onset (P < 0.001), postural instability and gait difficulty (PIGD) (P = 0.043), and a persistent levodopa response for >5 years (P = 0.042). Performance on the UPDRS, MoCA, GDS, and NMS did not differ by mutation status. PD in AJ LRRK2 G2019S mutation carriers is similar to idiopathic PD but is characterized by more frequent lower extremity involvement at onset and PIGD without the associated cognitive impairment.

Cerebral pathological and compensatory mechanisms in the premotor phase of leucine-rich repeat kinase 2 parkinsonism.

Compensatory cerebral mechanisms can delay motor symptom onset in Parkinson's disease. We aim to characterize these compensatory mechanisms and early disease-related changes by quantifying movement-related cerebral function in subjects at significantly increased risk of developing Parkinson's disease, namely carriers of a leucine-rich repeat kinase 2-G2019S mutation associated with dominantly inherited parkinsonism. Functional magnetic resonance imaging was used to examine cerebral activity evoked during internal selection of motor representations, a core motor deficit in clinically overt Parkinson's disease. Thirty-nine healthy first-degree relatives of Ashkenazi Jewish patients with Parkinson's disease, who carry the leucine-rich repeat kinase 2-G2019S mutation, participated in this study. Twenty-one carriers of the leucine-rich repeat kinase 2-G2019S mutation and 18 non-carriers of this mutation were engaged in a motor imagery task (laterality judgements of left or right hands) known to be sensitive to motor control parameters. Behavioural performance of both groups was matched. Mutation carriers and non-carriers were equally sensitive to the extent and biomechanical constraints of the imagined movements in relation to the current posture of the participants' hands. Cerebral activity differed between groups, such that leucine-rich repeat kinase 2-G2019S carriers had reduced imagery-related activity in the right caudate nucleus and increased activity in the right dorsal premotor cortex. More severe striatal impairment was associated with stronger effective connectivity between the right dorsal premotor cortex and the right extrastriate body area. These findings suggest that altered movement-related activity in the caudate nuclei of leucine-rich repeat kinase 2-G2019S carriers might remain behaviourally latent by virtue of cortical compensatory mechanisms involving long-range connectivity between the dorsal premotor cortex and posterior sensory regions. These functional cerebral changes open the possibility to use a prospective study to test their relevance as early markers of Parkinson's disease.

Lack of association between cancer history and PARKIN genotype: a family based study in PARKIN/Parkinson's families.

A number of publications have attributed a tumor suppressive (TS) function to PARKIN, a gene associated with recessive familial early onset Parkinson's disease (EOPD). Discoveries of PARKIN deletions and point mutations in tumors, functional studies, and data from mouse models have been presented to support the hypothesis. We have asked whether PARKIN mutations are associated with history of cancer in humans. We interviewed 431 participants who were screened for PARKIN mutations, including 149 EOPD cases and their family members, who were unaware of mutation status. We found no significant difference in self-reported history of cancer among carriers of one or two PARKIN mutations and noncarriers, odds ratio 0.75 (95% confidence interval 0.27-1.83). In particular, no increase in cancer history was seen among homozygous and compound heterozygous mutation carriers compared to noncarriers. Therefore, we hypothesize that published studies attributing TS capability to PARKIN merit further exploration and we present a reevaluation of these data with respect to patterns of mutation frequencies in normal and cancer cells. We conclude that although Parkin may exert a suppressive effect in mice, further studies are required prior to assigning a TS function to PARKIN in humans.

The association between Mediterranean diet adherence and Parkinson's disease.

BACKGROUND: Recent studies have demonstrated an association between a Mediterranean-type diet and Alzheimer's risk. We assessed the association between Mediterranean-type diet adherence and Parkinson's disease (PD) status. METHODS: Two hundred and fifty-seven PD participants and 198 controls completed the Willett semiquantitative questionnaire that quantifies diet during the past year. Scores were calculated using a 9-point scale; higher scores indicated greater adherence to the Mediterranean-type diet. Logistic regression models were used to assess the association between PD status and Mediterranean-type diet, adjusting for caloric intake, age, sex, education, and ethnicity. Adjusted linear regression models were used to examine the association between Mediterranean-type diet adherence and PD age at onset. RESULTS: Higher Mediterranean-type diet adherence was associated with reduced odds for PD after adjustment for all covariates (OR, 0.86; 95% CI, 0.77-0.97; P = .010). Lower Mediterranean-type diet score was associated with earlier PD age at onset (ß = 1.09; P = .006). CONCLUSIONS: PD patients adhere less than controls to a Mediterranean-type diet. Dietary behavior may be associated with age at onset.