The Parkinsonian Motor Spectrum in Nonagenarians: A Population‐Based Study

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BACKGROUND: Population-based data on mild parkinsonian signs (MPS) and parkinsonism in nonagenarians are scarce. OBJECTIVES: To estimate the prevalence of MPS, definite parkinsonism, and broader parkinsonian motor phenotypes; assess MPS after excluding idiopathic Parkinson disease and definite parkinsonism; and examine associations with sex and dementia in a cohort of nonagenarians. METHODS: This cross-sectional analysis included 144 participants from the Neurological Disorders in Central Spain (NEDICES) cohort aged ≥90 years on May 1, 1999; 97 were examined, and 47 had reliable indirect information. Unified Parkinson's Disease Rating Scale (UPDRS) motor data were evaluable in 96 of the examined participants. MPS were classified using established UPDRS-based operational criteria. Definite parkinsonism was defined primarily by a bradykinesia score ≥2 plus rigidity ≥1 or rest tremor ≥1; participants with an established Parkinson's disease diagnosis receiving antiparkinsonian treatment were also retained as definite cases when supported by prior clinical documentation. Bradykinesia ≥2 plus postural instability ≥2 in the absence of rest tremor and rigidity defined an instability-defined phenotype. Wilson's 95% confidence intervals (CIs) and two-sided Fisher's exact tests were used. RESULTS: MPS were present in 90/96 participants (93.8%; 95% CI, 87.0-97.1%). Prevalence remained 93.4% (85/91; 95% CI, 86.4-96.9%) after excluding idiopathic Parkinson's disease and 92.6% (75/81; 95% CI, 84.8-96.6%) after excluding all 15 examined definite cases. Definite parkinsonism affected 16/144 participants (11.1%; 95% CI, 7.0-17.3%), including 5 with idiopathic Parkinson's disease (3.5%; 95% CI, 1.5-7.9%). Among the 96 UPDRS-evaluable participants, 15 had definite parkinsonism, 7 additional participants had instability-defined parkinsonism, and inclusion of uncertain phenotypes expanded the broader parkinsonian motor spectrum to 63/96 (65.6%; 95% CI, 55.7%-74.4%). Dementia was more frequent with definite parkinsonism (13/16 vs 28/128; P < .001). Definite parkinsonism did not differ by sex; rest tremor was more frequent in men (P = .006). CONCLUSIONS: Parkinsonian motor features were frequent and phenotypically diverse among nonagenarians with evaluable UPDRS motor assessments. Definite parkinsonism represented only part of the broad parkinsonian motor spectrum, and idiopathic Parkinson's disease comprised only a small proportion of definite cases. These findings should not be interpreted either as synonymous with Parkinson's disease or as merely reflecting normal aging.