title: Cognitive function in 1736 participants in NINDS Exploratory Trials in PD Long-term Study-1.
abstract: Clinical cohort studies suggest that mild cognitive impairment (MCI) is common in early Parkinson's disease (PD). The objectives of this paper were to describe cognitive function in a large clinical trial of early treated PD patients at baseline and over time using two brief cognitive screening tests.
  
  
  
  In total 1741 participants were enrolled in the NINDS Exploratory Trials in Parkinson's disease (NET-PD) Long-term Study-1 (LS-1). The Symbol Digit Modalities Test (SDMT) was collected annually. The SCales for Outcomes in PArkinson's disease-COGnition (SCOPA-COG) was collected at baseline and at year 5. The trial was stopped early based on a planned interim analysis after half the cohort completed 5 years of follow-up. The median length of follow-up was 4 years (range 3-6 years). Predictors of cognitive change were examined using cross sectional (baseline) and longitudinal multivariable linear regression.
  
  
  
  The mean (SD) change from baseline to 5 years was -1.9 (5.1) for the SCOPA-COG and -2.1 (11.1) for the SDMT. Age and baseline UPDRS motor scores were associated with a more rapid decline in SDMT scores and 5 year SCOPA-COG scores. Male gender was associated with more rapid decline in SDMT. Self-reported income was a novel predictor of baseline cognitive function, even adjusted for educational status, although not significantly associated with change over time.
  
  
  
  This large prospective cohort study demonstrated mild cognitive decline in early treated Parkinson's disease. The study identified income level as a novel predictor of cognitive function.
authors.affiliation: Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA. Electronic address: awills@partners.org.
authors.forename: Anne-Marie A
authors.initials: AA
authors.lastname: Wills
authors.affiliation: Medical University of South Carolina, Division of Biostatistics & Epidemiology, Charleston, SC, USA.
authors.forename: Jordan J
authors.initials: JJ
authors.lastname: Elm
authors.affiliation: The Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Ye
authors.affiliation: University of Michigan, Departments of Neurology and Neurosurgery, Ann Arbor, MI, USA.
authors.forename: Kelvin L
authors.initials: KL
authors.lastname: Chou
authors.affiliation: Struthers Parkinson's Center, Golden Valley, MN, USA.
authors.forename: Sotirios A
authors.initials: SA
authors.lastname: Parashos
authors.affiliation: University of South Florida, Department of Neurology, USF Health Byrd Parkinson's Disease and Movement Disorders Center, Tampa, FL, USA; University of South Florida, Department of Molecular Pharmacology and Physiology, USF Health Byrd Parkinson's Disease and Movement Disorders Center, Tampa, FL, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Hauser
authors.affiliation: State University of New York, Downstate Medical Center, Departments of Neurology and Ophthalmology, Brooklyn, NY, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Bodis-Wollner
authors.affiliation: Department of Neurology, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Vanessa K
authors.initials: VK
authors.lastname: Hinson
authors.affiliation: Department of Neurology, University of California, San Francisco, CA, USA.
authors.forename: Chadwick W
authors.initials: CW
authors.lastname: Christine
authors.affiliation: Dept. of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Schneider
mesh_terms: D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D055825:National Institute of Neurological Disorders and Stroke (U.S.) / Q000706:statistics & numerical data; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications* / Q000453:epidemiology; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology
keywords: Cognitive impairment; MCI; Parkinson's disease; SCOPA-COG; SDMT