title: Cognitive impairment in early-stage non-demented Parkinson's disease patients.
abstract: OBJECTIVE
  In Parkinson's disease (PD), Parkinson's disease dementia (PDD) and Parkinson's disease-mild cognitive impairment (PD-MCI) are common. PD-MCI is a risk factor for developing PDD. Knowledge of cognition in early-stages PD is essential in understanding and predicting the dementia process.
  
  
  METHODS
  We describe the cognitive profile in early-stage PD patients with no prior clinical suspicion of cognitive impairment, depression or psychiatric disturbances, and investigate possible features distinguishing patients with cognitive deficits, defining a PD-MCI risk-profile. Single Photon Emission Computerized Tomography (SPECT) DaT-scan and neurological examination confirmed the diagnosis. Mini-mental state examination-, Addenbrooke's Cognitive Examination, Unified Parkinson's Disease Rating Scale scoring, Hoehn &Yahr/Activity of Daily Living staging and a neuropsychological test battery were applied. Mild cognitive impairment patients were identified according to modified criteria by Troster necessarily omitting subjective cognitive complaints. 80 patients, mean age 61.0 years (SD 6.6), mean duration of disease 3.4 years (SD 1.2) were included. 76 patients were neuropsychologically tested.
  
  
  RESULTS
  26 (34%) patients fulfilled modified PD-MCI criteria, 18 (69%) of these showed episodic memory deficits, 14 (54%) executive dysfunction, 13 (50%) language/praxis deficits, 12 (46%) visuospatial/constructional deficits and 9 (35%) attention/working memory deficits. Cognitive impairment was associated with higher Unified Parkinson's Disease Rating scale (UPDRS)-, bradykinesia- and rigidity scores and more symmetric distribution of symptoms, but not tremor scores. Patients with cognitive impairment were less educated. Other demographic and clinical variables were comparable.
  
  
  CONCLUSIONS
  34% of early-stage PD patients without prior clinical suspicion of cognitive impairment exhibit cognitive impairment, which is associated to disease severity, especially bradykinesia, rigidity, axial symptoms and less asymmetry of motor symptoms, even at early disease stages and when cognitive symptoms are mild.
authors.affiliation: Department of Neurology, Bispebjerg University Hospital, Copenhagen, Denmark; Department of Clinical Physiology and Nuclear Medicine, Bispebjerg University Hospital, Copenhagen, Denmark.
authors.forename: H C V
authors.initials: HC
authors.lastname: Pfeiffer
authors.forename: A
authors.initials: A
authors.lastname: Løkkegaard
authors.forename: M
authors.initials: M
authors.lastname: Zoetmulder
authors.forename: L
authors.initials: L
authors.lastname: Friberg
authors.forename: L
authors.initials: L
authors.lastname: Werdelin
mesh_terms: D003072:Cognition Disorders / Q000453:epidemiology / Q000209:etiology*; D060825:Cognitive Dysfunction / Q000453:epidemiology / Q000209:etiology; D005260:Female; D006801:Humans; D018476:Hypokinesia / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008875:Middle Aged; D009127:Muscle Rigidity / Q000453:epidemiology / Q000209:etiology; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000453:epidemiology / Q000523:psychology*; D012720:Severity of Illness Index
keywords: Parkinson's Disease; early-stage; mild cognitive impairment