Genome-wide association study identifies candidate genes for Parkinson's disease in an Ashkenazi Jewish population.

BACKGROUND: To date, nine Parkinson disease (PD) genome-wide association studies in North American, European and Asian populations have been published. The majority of studies have confirmed the association of the previously identified genetic risk factors, SNCA and MAPT, and two studies have identified three new PD susceptibility loci/genes (PARK16, BST1 and HLA-DRB5). In a recent meta-analysis of datasets from five of the published PD GWAS an additional 6 novel candidate genes (SYT11, ACMSD, STK39, MCCC1/LAMP3, GAK and CCDC62/HIP1R) were identified. Collectively the associations identified in these GWAS account for only a small proportion of the estimated total heritability of PD suggesting that an 'unknown' component of the genetic architecture of PD remains to be identified. METHODS: We applied a GWAS approach to a relatively homogeneous Ashkenazi Jewish (AJ) population from New York to search for both 'rare' and 'common' genetic variants that confer risk of PD by examining any SNPs with allele frequencies exceeding 2%. We have focused on a genetic isolate, the AJ population, as a discovery dataset since this cohort has a higher sharing of genetic background and historically experienced a significant bottleneck. We also conducted a replication study using two publicly available datasets from dbGaP. The joint analysis dataset had a combined sample size of 2,050 cases and 1,836 controls. RESULTS: We identified the top 57 SNPs showing the strongest evidence of association in the AJ dataset (p < 9.9 × 10(-5)). Six SNPs located within gene regions had positive signals in at least one other independent dbGaP dataset: LOC100505836 (Chr3p24), LOC153328/SLC25A48 (Chr5q31.1), UNC13B (9p13.3), SLCO3A1(15q26.1), WNT3(17q21.3) and NSF (17q21.3). We also replicated published associations for the gene regions SNCA (Chr4q21; rs3775442, p = 0.037), PARK16 (Chr1q32.1; rs823114 (NUCKS1), p = 6.12 × 10(-4)), BST1 (Chr4p15; rs12502586, p = 0.027), STK39 (Chr2q24.3; rs3754775, p = 0.005), and LAMP3 (Chr3; rs12493050, p = 0.005) in addition to the two most common PD susceptibility genes in the AJ population LRRK2 (Chr12q12; rs34637584, p = 1.56 × 10(-4)) and GBA (Chr1q21; rs2990245, p = 0.015). CONCLUSIONS: We have demonstrated the utility of the AJ dataset in PD candidate gene and SNP discovery both by replication in dbGaP datasets with a larger sample size and by replicating association of previously identified PD susceptibility genes. Our GWAS study has identified candidate gene regions for PD that are implicated in neuronal signalling and the dopamine pathway.

Neuropsychological Profile of Parkin Mutation Carriers with and without Parkinson Disease: The CORE-PD Study.

The cognitive profile of early onset Parkinson's disease (EOPD) has not been clearly defined. Mutations in the parkin gene are the most common genetic risk factor for EOPD and may offer information about the neuropsychological pattern of performance in both symptomatic and asymptomatic mutation carriers. EOPD probands and their first-degree relatives who did not have Parkinson's disease (PD) were genotyped for mutations in the parkin gene and administered a comprehensive neuropsychological battery. Performance was compared between EOPD probands with (N = 43) and without (N = 52) parkin mutations. The same neuropsychological battery was administered to 217 first-degree relatives to assess neuropsychological function in individuals who carry parkin mutations but do not have PD. No significant differences in neuropsychological test performance were found between parkin carrier and noncarrier probands. Performance also did not differ between EOPD noncarriers and carrier subgroups (i.e., heterozygotes, compound heterozygotes/homozygotes). Similarly, no differences were found among unaffected family members across genotypes. Mean neuropsychological test performance was within normal range in all probands and relatives. Carriers of parkin mutations, whether or not they have PD, do not perform differently on neuropsychological measures as compared to noncarriers. The cognitive functioning of parkin carriers over time warrants further study.

Total knee arthroplasty and Parkinson disease: enhancing outcomes and avoiding complications.

Total knee arthroplasty (TKA) is typically an extremely successful method of restoring pain-free function and providing good long-term outcomes for patients with end-stage knee disease. However, outcomes are less predictable in persons with Parkinson disease. The limited literature available and our experience lead us to conclude that complication rates in the perioperative and postoperative periods with TKA are comparatively high in persons with Parkinson disease. In addition, a good functional outcome is less certain than in the general population. For persons with Parkinson disease who require TKA, we propose an integrative, collaborative approach to avoid complications and optimize outcomes.

Case-control study of the parkin gene in early-onset Parkinson disease.

BACKGROUND: Mutations in parkin are estimated to account for as much as 50% of familial Parkinson disease (PD) and 18% of sporadic PD. Single heterozygous mutations in parkin in both familial and sporadic cases may also increase susceptibility to PD. To our knowledge, all previous studies have been restricted to PD cases; this is the first study to systematically screen the parkin coding regions and exon deletions and duplications in controls. OBJECTIVE: To determine the frequency and spectrum of parkin variants in early-onset PD cases (aged < or =50 years) and controls participating in a familial aggregation study. PATIENTS AND METHODS: We sequenced the parkin gene in 101 cases and 105 controls. All cases and controls were also screened for exon deletions and duplications by semiquantitative multiplex polymerase chain reaction. RESULTS: Thirteen (12.9% [95% confidence interval, 7%-21%]) of the 101 cases had a previously described parkin mutation: 1 was homozygous, 11 were heterozygous, and 1 was a compound heterozygote. The mutations Arg42Pro (exon 2) and Arg275Trp (exon 7) were recurrent. The previously reported synonymous substitution Leu261Leu (c.884A>G) was identified in 4 (3.9%) of 101 cases and 2 (2%) of 105 controls (P = .44). Excluding the synonymous substitution Leu261Leu (heterozygotes), 10 (9.9% [95% confidence interval, 4.6%-17.5%]) carried mutations. CONCLUSIONS: The frequency of mutations among cases that were not selected based on family history of PD is similar to what has previously been reported in sporadic PD. The similar frequency of Leu261Leu in cases and controls suggests it is a normal variant rather than a disease-associated mutation. We confirmed that heterozygous parkin mutations may increase susceptibility for early-onset PD.

Visual search deficits in Parkinson's disease are attenuated by bottom-up target salience and top-down information.

Patients with Parkinson's disease (PD), a degenerative disorder primarily affecting the nigrostriatal dopamine system, exhibit deficits in selecting task-relevant stimuli in the presence of irrelevant stimuli, such as in visual search tasks. However, results from previous studies suggest that these deficits may vary as a function of whether selection must rely primarily on the "bottom-up" salience of the target relative to background stimuli, or whether "top-down" information about the identity of the target is available to bias selection. In the present study, moderate-to-severe medicated PD patients and age-matched controls were tested on six visual search tasks that systematically varied the relationship between bottom-up target salience (feature search, noisy feature search, conjunction search) and top-down target knowledge (Target Known versus Target Unknown). Comparison of slope and intercepts of the RT x set size function provided information about the efficiency of search and non-search (e.g., decision, response) components, respectively. Patients exhibited higher intercepts than controls as bottom-up target salience decreased, however these deficits were disproportionately larger under Target Unknown compared to Target Known conditions. Slope differences between PD and controls were limited to the Target Unknown Conjunction condition, where patients exhibited a shallower slope in the target absent condition, indicating that they terminated search earlier. These results suggest that under conditions of high background noise, medicated PD patients were primarily impaired in decision and/or response processes downstream from the target search itself, and that the deficit was attenuated when top-down information was available to guide selection of the target signal.

Maintenance of response readiness in patients with Parkinson's disease: evidence from a simple reaction time task.

The authors explored the effect of Parkinson's disease (PD) on the generation and maintenance of response readiness in a simple reaction time task. They compared performance of idiopathic PD patients without dementia, age-matched controls, and younger controls over short (1-, 3-, and 6-s) and long (12- and 18-s) foreperiod intervals. After each trial, the authors probed memory for visual information that also had to be maintained during the trial interval. Patients and controls did not differ overall in their ability to maintain readiness over long delays. However, within the PD group only, errors in maintaining visual information were correlated with difficulty in maintaining readiness, suggesting that systems impaired in PD may facilitate the maintenance of processing in both motor and cognitive domains.

The Saitohin 'Q7R' polymorphism and tau haplotype in multi-ethnic Alzheimer disease and Parkinson's disease cohorts.

In a multi-ethnic cohort we analyzed the Saitohin (STH) gene 'Q7R' polymorphism in 200 late-onset Alzheimer's disease cases (LOAD), 60 Parkinson's disease cases with dementia (PDD), 84 Parkinson's disease cases without dementia and 458 controls. We found no significant differences in genotype or allele frequencies when LOAD or PD cases were compared to controls. Ethnic differences in STH genotype frequencies for cases and controls were observed and these were statistically significant (cases n=344, P<0.03; controls n=458, P<0.001). We also observed a trend in non-Hispanic white PDD cases with the STH 'QQ' (Tau H1/H1) genotype increased (76%) compared to PD cases without dementia (61.7%) and controls (56.6%); however, this difference was not statistically significant (PDD vs. controls OR 2.1; 95% CI: 0.8-5.8, P=0.2).

The Mortal Stage of late life.

A Mortal Stage of later life may be considered as a subdivision of Erik Erikson's eighth stage of life which he called Mature Age, characterized by issues of integrity versus disgust, despair. Mortality poses the optimal task of Realization (in many positive coping and existential senses) versus Denial (or other non-recognition or emotional paralysis) or Fear (or apprehension or even terror). Premorbid awareness of illness may contribute to or challenge Realization. Literary examples also suggest a reviewing of one's life and works, possible regressions from genitality to anal preoccupations, little social withdrawal, and a compassionate interest in the next generation. In dying the self is not given up, but rather the alternate universe of further interpersonal relations had one lived on.

Cognitive and motor function in long-duration PARKIN-associated Parkinson disease.

IMPORTANCE: Data on the long-term cognitive outcomes of patients with PARKIN-associated Parkinson disease (PD) are unknown but may be useful when counseling these patients. OBJECTIVE: Among patients with early-onset PD of long duration, we assessed cognitive and motor performances, comparing homozygotes and compound heterozygotes who carry 2 PARKIN mutations with noncarriers. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 44 participants at 17 different movement disorder centers who were in the Consortium on Risk for Early-Onset PD study with a duration of PD greater than the median duration (>14 years): 4 homozygotes and 17 compound heterozygotes (hereafter referred to as carriers) and 23 noncarriers. MAIN OUTCOMES AND MEASURES: Unified Parkinson Disease Rating Scale Part III (UPDRS-III) and Clinical Dementia Rating scores and neuropsychological performance. Linear regression models were applied to assess the association between PARKIN mutation status and cognitive domain scores and UPDRS-III scores. Models were adjusted for age, education, disease duration, language, and levodopa equivalent daily dose. RESULTS: Carriers had an earlier age at onset of PD (P < .001) and were younger (P = .004) at time of examination than noncarriers. They performed better than noncarriers on the Mini-Mental State Examination (P = .010) and were more likely to receive lower scores on the Clinical Dementia Rating (P = .003). In multivariate analyses, carriers performed better than noncarriers on the UPDRS-III (P = .02) and on tests of attention (P = .03), memory (P = .03), and visuospatial (P = .02) cognitive domains. CONCLUSIONS AND RELEVANCE: In cross-sectional analyses, carriers demonstrated better cognitive and motor performance than did noncarriers with long disease duration, suggesting slower disease progression. A longitudinal follow-up study is required to confirm these findings.

Clinical and pathological characteristics of LRRK2 G2019S patients with PD.

The objective of this study is to describe the neuropathologic findings in three LRRK2 G2019S carriers with Parkinson's disease (PD). We cross-referenced a list of 956 PD individuals that had been previously genotyped in clinical studies at Columbia University, with 282 subjects with a parkinsonian syndrome who came to autopsy in our brain bank since 1991. We found three autopsies of G2019S mutation carriers. Pathological analyses of the samples were blind to the genetic findings. We retrospectively reviewed the clinical records of the three patients. All three had a clinical and pathological diagnosis of PD. Cognitive impairment was a late feature in two out of three patients. Cortical involvement varied significantly: one had diffuse Lewy body (LB) pathology, tau inclusions, and amyloid pathology consistent with advanced Alzheimer's disease; one had diffuse cortical LB; and one had only brainstem predominant LB pathology. Cognitive impairment may be a long-term complication in G2019S mutation carriers. However, the extent of cortical involvement is variable. Larger longitudinal follow-up of LRRK2 G2019S mutation carriers is required to assess for risk factors for cortical involvement and dementia.

Predictors of parkin mutations in early-onset Parkinson disease: the consortium on risk for early-onset Parkinson disease study.

BACKGROUND: Mutations in the parkin gene are the most common genetic cause of early-onset Parkinson disease (PD). Results from a multicenter study of patients with PD systematically sampled by age at onset have not been reported to date. OBJECTIVE: To determine risk factors associated with carrying parkin mutations. DESIGN: Cross-sectional observational study. SETTING: Thirteen movement disorders centers. PARTICIPANTS: A total of 956 patients with early-onset PD, defined as age at onset younger than 51 years. MAIN OUTCOME MEASURES: Presence of heterozygous, homozygous, or compound heterozygous parkin mutations. RESULTS: Using a previously validated interview, 14.7% of patients reported a family history of PD in a first-degree relative. Sixty-four patients (6.7%) had parkin mutations (3.9% heterozygous, 0.6% homozygous, and 2.2% compound heterozygous). Copy number variation was present in 52.3% of mutation carriers (31.6% of heterozygous, 83.3% of homozygous, and 81.0% of compound heterozygous). Deletions in exons 3 and 4 and 255delA were common among Hispanics (specifically Puerto Ricans). Younger age at onset (<40 years) (odds ratio [OR], 5.0; 95% confidence interval [CI], 2.8-8.8; P = .001), Hispanic race/ethnicity (OR compared with white non-Hispanic race/ethnicity, 2.7; 95% CI, 1.3-5.7; P = .009), and family history of PD in a first-degree relative (OR compared with noncarriers, 2.8; 95% CI, 1.5-5.3; P = .002) were associated with carrying any parkin mutation (heterozygous, homozygous, or compound heterozygous). Hispanic race/ethnicity was associated with carrying a heterozygous mutation (OR compared with white non-Hispanic race/ethnicity, 2.8; 95% CI, 1.1-7.2; P = .03) after adjustment for covariates. CONCLUSIONS: Age at onset, Hispanic race/ethnicity, and family history of PD are associated with carrying any parkin mutation (heterozygous, homozygous, or compound heterozygous) and heterozygous mutations alone. The increased odds of carrying a parkin mutation among Hispanics warrants further study.

Self-report of cognitive impairment and mini-mental state examination performance in PRKN, LRRK2, and GBA carriers with early onset Parkinson's disease.

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.

Association of glucocerebrosidase mutations with dementia with lewy bodies.

BACKGROUND: Mutations in the glucocerebrosidase (GBA) gene are associated with Lewy body (LB) disorders. OBJECTIVE: To determine the relationship of GBA mutations and APOE4 genotype to LB and Alzheimer disease (AD) pathological findings. DESIGN: Case-control study. SETTING: Academic research. PARTICIPANTS: The 187 subjects included patients with primary neuropathological diagnoses of LB disorders with or without AD changes (95 cases), randomly selected patients with AD (without significant LB pathological findings; 60 cases), and controls with neither LB nor AD pathological findings (32 cases). MAIN OUTCOME MEASURES: GBA mutation status, APOE4 genotype, LB pathological findings (assessed according to the third report of the Dementia With Lewy Body Consortium), and Alzheimer plaque and tangle pathological findings (rated by criteria of Braak and Braak, the Consortium to Establish a Registry for Alzheimer Disease, and the National Institute on Aging-Reagan Institute). RESULTS: GBA mutations were found in 18% (34 of 187) of all subjects, including 28% (27 of 95) of those with primary LB pathological findings compared with 10% (6 of 60) of those with AD pathological findings and 3% (1 of 32) of those without AD or LB pathological findings (P=.001). GBA mutation status was significantly associated with the presence of cortical LBs (odds ratio, 6.48; 95% confidence interval, 2.45-17.16; P<.001), after adjusting for sex, age at death, and presence of APOE4. GBA mutation carriers were significantly less likely to meet AD pathological diagnostic (National Institute on Aging-Reagan Institute intermediate or high likelihood) criteria (odds ratio, 0.35; 95% confidence interval, 0.15-0.79; P=.01) after adjustment for sex, age at death, and APOE4. CONCLUSION: GBA mutations may be associated with pathologically "purer" LB disorders, characterized by more extensive (cortical) LB, and less severe AD pathological findings and may be a useful marker for LB disorders.

Motor phenotype of LRRK2 G2019S carriers in early-onset Parkinson disease.

OBJECTIVE: To determine the motor phenotype of LRRK2 G2019S mutation carriers. LRRK2 mutation carriers were previously reported to manifest the tremor dominant motor phenotype, which has been associated with slower motor progression and less cognitive impairment compared with the postural instability and gait difficulty (PIGD) phenotype. DESIGN: Cross-sectional observational study. SETTING: Thirteen movement disorders centers. PARTICIPANTS: Nine hundred twenty-five early-onset Parkinson disease cases defined as age at onset younger than 51 years. MAIN OUTCOME MEASURES: LRRK2 mutation status and Parkinson disease motor phenotype: tremor dominant or PIGD. Demographic information, family history of Parkinson disease, and the Unified Parkinson's Disease Rating Scale score 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 ancestry, levodopa dose, and family history of Parkinson disease. RESULTS: Thirty-four cases (3.7%) (14 previously reported) were G2019S carriers. No other mutations were found. Carriers were more likely to be Ashkenazi Jewish (55.9% vs 11.9%; P < .001) but did not significantly differ in any other demographic or disease characteristics. Carriers had a lower tremor score (P = .03) and were more likely to have a PIGD phenotype (92.3% vs 58.9%; P = .003). The association of the G2019S mutation with PIGD phenotype remained after controlling for disease duration and Ashkenazi Jewish ancestry (odds ratio, 17.7; P < .001). CONCLUSION: Early-onset Parkinson disease G2019S LRRK2 carriers are more likely to manifest the PIGD phenotype, which may have implications for disease course.

Risk of Parkinson disease in carriers of parkin mutations: estimation using the kin-cohort method.

OBJECTIVE: To estimate the risk of Parkinson disease (PD) in individuals with mutations in the Parkin gene. DESIGN: We assessed point mutations and exon deletions and duplications in the Parkin gene in 247 probands with PD (age at onset < or =50 years) and 104 control probands enrolled in the Genetic Epidemiology of Parkinson's Disease (GEPD) study. For each first-degree relative, a consensus diagnosis of PD was established. The probability that each relative carried a mutation was estimated from the proband's Parkin carrier status using Mendelian principles and from the relationship of the relative to the proband. SETTING: Tertiary care movement disorders center. Patients Cases, controls, and their first-degree relatives were enrolled in the GEPD study. MAIN OUTCOME MEASURES: Estimated age-specific penetrance in first-degree relatives. RESULTS: Parkin mutations were identified in 25 probands with PD (10.1%), 18 (72.0%) of whom were heterozygotes. One Parkin homozygote was reported in 2 siblings with PD. The cumulative incidence of PD to age 65 years in carrier relatives (age-specific penetrance) was estimated to be 7.0% (95% confidence interval, 0.4%-71.9%), compared with 1.7% (95% confidence interval, 0.8%-3.4%) in noncarrier relatives of the cases (P = .59) and 1.1% (95% confidence interval, 0.3%-3.4%) in relatives of the controls (compared with noncarrier relatives, P = .52). CONCLUSIONS: The cumulative risk of PD to age 65 years in a noncarrier relative of a case with an age at onset of 50 years or younger is not significantly greater than the general population risk among controls. Age-specific penetrance among Parkin carriers, in particular heterozygotes, deserves further study.

Construction and validation of a Parkinson's disease mutation genotyping array for the Parkin gene.

Parkin mutations account for the majority of familial and sporadic early onset Parkinson's disease (EOPD) cases with a known genetic association. More than 100 mutations have been described in the Parkin gene that includes homozygous, compound heterozygous, and single heterozygous mutations. We have designed a Parkin mutation genotyping array (gene chip) that includes published Parkin sequence variants and allows their simultaneous detection. The chip was validated by screening 85 PD cases and 47 controls previously tested for Parkin mutations. Similar genotyping microarrays have been developed for other genetically heterogeneous diseases including age-related macular degeneration. Here, we show the utility of a genotyping array for Parkinson's disease by analysis of 60 subjects from the Genetic Epidemiology of Parkinson Disease (GEPD) study that includes 15 early-onset PD case probands and 45 relatives.

Disparities in the recording of Parkinson's disease on death certificates.

Although little is known regarding potential socioeconomic or racial bias in the recording of Parkinson's disease (PD) on death certificates, studies of incidence, prevalence, and the etiology of PD frequently rely on this type of data. A national population-based survey was linked to death certificate data to investigate the concordance of PD reported on death certificates for persons reporting PD during life. Logistic regression was used to identify independent factors associated with differential reporting of PD at death. Among decedents with PD reported during life, 54.8% had PD recorded on the death certificate. Nearly 70% of persons in higher income categories had PD recorded at death compared to 35.4% for those earning $10,000 or less. Age and gender adjusted odds of having PD recorded at death was 2.3 (1.1-3.9), for those with an annual income of $35,000 or more. Income differences remain significant in multivariable models after controlling for age, gender, race, census region, family size, rural residence, and number of chronic medical conditions. In conclusion, this study found socioeconomic bias in the reporting of PD at death. This bias is large enough to confound death certificate-based investigations of incidence, prevalence, and risk factors that differ across socioeconomic strata.

Pilot association study of the beta-glucocerebrosidase N370S allele and Parkinson's disease in subjects of Jewish ethnicity.

Mutations in the beta-glucocerebrosidase gene cause Gaucher's disease, one of the most common lysosomal lipid storage diseases in the Ashkenazi Jewish population. The occurrence of parkinsonism in patients with Type 1 Gaucher's disease has been noted previously. In this pilot study, we evaluated a possible association between Parkinson's disease (PD) and the beta-glucocerebrosidase gene N370S allele (nt.1226 A>G) in 160 Parkinson's disease patients and 92 controls of Jewish ethnicity. We observed a higher frequency of the N370S genotype in PD cases (NS and SS, 10.7%) compared to controls (NS and SS 4.3%); however, the difference was not statistically significant (chi(2) = 3.4, P = 0.2). A total of 17 PD cases carry the N370S allele, including 2 homozygotes and 15 heterozygotes. The N370S allele (nt.1226 A>G) may be associated with PD in patients of Jewish ethnicity and should be examined in a larger study.

Diagnosing Parkinson's disease using videotaped neurological examinations: validity and factors that contribute to incorrect diagnoses.

Field work is commonly required in movement disorders research. Sending neurologists into the field can be logistically challenging and costly. Alternatively, neurological examinations may be videotaped and reviewed later. There is little knowledge of the validity of the videotaped neurological examination in the diagnosis of Parkinson's disease (PD). We examined the validity of the videotaped Unified Parkinson's Disease Rating Scale (UPDRS) motor examination in the diagnosis of PD, and sought to determine which factors are associated with incorrect diagnoses. PD patients and controls were enrolled in a familial aggregation study between August of 1998 and June of 2000, and as part of that study each was examined by a physician who performed an in-person UPDRS motor examination. Each also underwent a second, videotaped UPDRS motor examination. Based on the review of this videotape, a neurologist, who was blinded to the previous clinical diagnosis, assigned a diagnosis of PD or normal. A total of 211 of 231 PD patients (sensitivity = 91.3%), and 170 of 172 controls (specificity = 98.8%) were correctly identified based on the videotape. True positives had a higher mean rest tremor score (1.7 vs. 0.3; P < 0.001), action tremor score (0.9 vs. 0.3; P < 0.001), bradykinesia score (11.2 vs. 7.4; P = 0.02), and disease of longer mean duration (8.9 vs. 5.8 years; P = 0.001) than false negatives. False negatives did not differ from true positives in terms of age, total dose of levodopa, Hoehn and Yahr score, or rigidity, gait and posture, or facial masking scores (each assessed during the in-person examination). The videotaped UPDRS motor examination is a useful means of diagnosing PD and provides an alternative approach for the diagnosis of PD in field studies. A limitation is that patients with milder PD of shorter duration may not be recognized as PD.

Combined effect of age and severity on the risk of dementia in Parkinson's disease.

Age and severity of extrapyramidal signs have been consistently associated with incident dementia in Parkinson's disease. We evaluated the separate and combined effects of age and severity of extrapyramidal signs on the risk of incident dementia in Parkinson's disease in the setting of a population-based prospective cohort study. Age and the total Unified Parkinson's Disease Rating Scale motor score at baseline evaluation were dichotomized at the median. Four groups of Parkinson's disease patients were defined: younger age/low severity (reference), younger age/high severity, older age/low severity, and older age/high severity. Risk ratios for incident dementia were calculated with Cox proportional hazards models controlling for gender, education, ethnicity, and duration of Parkinson's disease. Of 180 patients, 52 (28.9%) became demented during a mean follow-up period of 3.6 +/- 2.2 years. The median age at baseline of the Parkinson's disease patients was 71.8 years (range, 38.5-95.9 years), and the median total Unified Parkinson's Disease Rating Scale motor score was 24 (range, 2-65). The group with older age/high severity had a significantly increased risk of incident dementia (relative risk, 9.7; 95% confidence interval, 3.9-24.4) compared with the group with younger age/low severity (reference), whereas the groups with older age/low severity (relative risk, 1.6; 95% confidence interval, 0.5-4.8) and younger age/high severity (relative risk, 1.2; 95% confidence interval, 0.5-3.2) did not. These findings suggest that the increased risk of incident dementia in Parkinson's disease associated with age and severity of extrapyramidal signs is related primarily to their combined effect rather than separate effects.