title: Abnormal MoCA and normal range MMSE scores in Parkinson disease without dementia: cognitive and neurochemical correlates.
abstract: BACKGROUND
  The Montreal Cognitive Assessment (MoCA) is increasingly being used as a cognitive screening test in Parkinson disease (PD). The MoCA's popularity likely reflects its ability to detect executive dysfunction, a relative deficiency of the Mini-Mental State Examination (MMSE).
  
  
  OBJECTIVE
  To compare neurochemical and neuropsychological functions in non-demented PD patients with mild cognitive impairment (PD-MCI) and without, as defined by MoCA (PD-MCI = MoCA<26).
  
  
  METHODS
  Non-demented PD subjects underwent combined MoCA and MMSE, detailed cognitive testing and [¹¹C]methyl-4-piperidinyl propionate acetylcholinesterase and [¹¹C]dihydrotetrabenazine monoaminergic PET imaging.
  
  
  RESULTS
  Eighteen subjects met MoCA PD-MCI criteria but had MMSE scores in the normal range, compared to 29 subjects with normal MoCA and MMSE scores. The MoCA-defined PD-MCI group had reduced performance in global cognition (t = 2.91, P = 0.0056), most significantly in executive function (t = 3.18, P = 0.002), as well as significant reduction in dorsal caudate nucleus dopaminergic innervation (t = 2.72, P = 0.009) compared to the PD without MCI group. Both MoCA and MMSE had poor diagnostic accuracy for PD-MCI (65.3%) when using the Level 2 Movement Disorder Society Task Force definition.
  
  
  CONCLUSIONS
  PD subjects with normal range MMSE but abnormal MoCA scores had evidence of caudate nucleus dopaminergic denervation and mild cognitive changes, predominantly in executive function. The MoCA may be able to preferentially detect executive dysfunction compared to the MMSE, but the MoCA has limited diagnostic accuracy for PD-MCI, and should not be used alone to make this diagnosis.
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Kelvin L
authors.initials: KL
authors.lastname: Chou
authors.affiliation: Wayne State University School of Medicine, Detroit, MI, USA.
authors.forename: Adrienne
authors.initials: A
authors.lastname: Lenhart
authors.affiliation: Department of Radiology, Division of Nuclear Medicine, University of Michigan, Ann Arbor, MI, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Koeppe
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA; Department of Radiology, Division of Nuclear Medicine, University of Michigan, Ann Arbor, MI, USA; Neurology Service and GRECC, VAAAHS, Ann Arbor, MI, USA. Electronic address: klchou@med.umich.edu.
authors.forename: Nicolaas I
authors.initials: NI
authors.lastname: Bohnen
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D003072:Cognition Disorders / Q000209:etiology*; D005260:Female; D006146:Guanidines / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000150:complications / Q000175:diagnosis / Q000378:metabolism; D049268:Positron-Emission Tomography; D013747:Tetrabenazine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism
chemical_list: C520643:4-hydroxyphenethylguanidine; D006146:Guanidines; C493452:SLC18A2 protein, human; D050493:Vesicular Monoamine Transport Proteins; C032811:dihydrotetrabenazine; D000110:Acetylcholinesterase; D013747:Tetrabenazine
keywords: Assessment of cognitive disorders/dementia; MCI (mild cognitive impairment); PD (Parkinson disease); PET (positron emission tomography)
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