Objective: To assess the cognitive phenotype of glucocerebrosidase (GBA) mutation carriers with early-onset Parkinson disease (PD). Methods:We administered a neuropsychological battery and the University of Pennsylvania Smell Identification Test (UPSIT) to participants in the CORE-PD study who were tested for mutations in PARKIN, LRRK2, and GBA. Participants included 33 GBA mutation carriers and 60 noncarriers of any genetic mutation. Primary analyses were performed on 26 GBA heterozygous mutation carriers without additional mutations and 39 age-and PD duration-matched noncarriers. Five cognitive domains, psychomotor speed, attention, memory, visuospatial function, and executive function, were created from transformed z scores of individual neuropsychological tests. Clinical diagnoses (normal, mild cognitive impairment [MCI], dementia) were assigned blind to genotype based on neuropsychological performance and functional impairment as assessed by the Clinical Dementia Rating (CDR) score. The association between GBA mutation status and neuropsychological performance, CDR, and clinical diagnoses was assessed.

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Objective-To determine the motor phenotype of LRRK2 G2019S mutation carriers Background-LRRK2 mutation carriers were previously reported to manifest the tremor-dominant (TD) motor phenotype, which has been associated with slower motor progression and less cognitive impairment compared to the postural instability gait difficulty (PIGD) phenotype. Design-Cross sectional observational study Setting-13 movement disorders centersParticipants-925 Early Onset Parkinson Disease (EOPD) cases defined as age at onset (AAO) !50.Main Outcome Measures-LRRK2 mutation status and PD motor phenotype: TD or PIGD Methods-Demographic information, family history of PD (FHPD), and the Unified Parkinson Disease Rating Scale (UPDRS) were collected on all participants. DNA samples were genotyped for LRRK2 mutations (G2019S, I2020T, R1441C and Y1699C). Logistic regression was used to examine associations of G2019S mutation status with motor phenotype adjusting for disease duration, Ashkenazi Jewish (AJ) ancestry, levodopa dose, and FHPD.Results-34 cases (3.7%) (14 previously reported) were G2019S carriers. No other mutations were found. Carriers were more likely to be AJ (55.9% vs. 11.9% p<0.001), but did not significantly differ in any other demographic or disease characteristics. Carriers had a lower tremor score (p=0.026) and were more likely to have a PIGD phenotype (92.3% vs. 58.9% p=0.003). The association of the G2019S mutation with PIGD phenotype remained after controlling for disease duration and AJ (OR= 17.7, p< 0.001). Conclusion-EOPD G2019SLRRK2 carriers are more likely to manifest the PIGD phenotype, which may have implications for disease course.

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While little is known about risk factors for cognitive impairment in early onset Parkinson disease (EOPD), postmortem studies have shown an association between dementia with Lewy bodies (DLB) and glucocerebrosidase (GBA) mutation. We compared Mini-Mental State Examination (MMSE) performance and self-reported cognitive impairment in 699 EOPD participants genotyped for mutations in parkin (PRKN), leucine-rich repeat kinase-2 (LRRK2), and GBA. Logistic regression was used to assess the association between reported cognitive impairment and MMSE score, as well as between GBA group membership and self-reported impairment and MMSE. GBA carriers reported more impairment, but MMSE performance did not differ among genetic groups. Detailed neuropsychological testing is required to explore the association between cognitive impairment and GBA mutations.

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Background Ashkenazi Jewish (AJ) LRRK2 carriers are more likely to manifest the postural instability gait difficulty (PIGD) motor phenotype than non-carriers but perform similarly to non-carriers on cognitive screening tests. Objective To compare the cognitive profiles of AJ with Parkinson’s disease (PD) with and without LRRK2 G2019S mutations using a comprehensive neuropsychological battery. Methods We administered a neuropsychological battery to PD participants in the Michael J. Fox Foundation AJ consortium. Participants (n=236) from Beth Israel Medical Center, NY, Columbia University Medical Center, NY and Tel Aviv Medical Center, Israel included 116 LRRK2 G2019S carriers and 120 non-carriers. Glucocerbrosidase mutation carriers were excluded. We compared performance on each neuropsychological test between carriers and non-carriers. Participants in New York (n=112) were evaluated with the entire battery. Tel Aviv participants (n=124) were evaluated on attention, executive function and psychomotor speed tasks. The association between G2019S mutation status (predictor) and each neuropsychological test (outcome) was assessed using linear regression models adjusted for PIGD motor phenotype, site, sex, age, disease duration, education, Unified Parkinson’s Disease Rating Scale (UPDRS) Part III, levodopa equivalent dose, and Geriatric Depression Score (GDS). Results Carriers had longer disease duration (p<0.001) and were more likely to manifest the PIGD phenotype (p=0.024). In adjusted regression models, carriers performed better than non-carriers in Stroop Word Reading (p<0.001), Stroop Interference (p=0.011) and Category Fluency (p=0.026). Conclusion In AJ-PD, G2019S mutation status is associated with better attention (Stroop Word Reading), executive function (Stroop Interference) and language (Category Fluency) after adjustment for PIGD motor phenotype.