Clinical differences among mild cognitive impairment subtypes in Parkinson's disease§


  • Funding agencies: This study was supported by grants from the National Institutes of Health (K23NS060949; to J.G.G.) and from the Parkinson's Disease Foundation.

  • Relevant conflicts of interest/financial disclosures: Jennifer G. Goldman has received grant/research support from NIH K23NS060949 and the Parkinson's Disease Foundation.

  • §

    Full financial disclosures and author roles may be found in the online version of this article.


Mild cognitive impairment is increasingly recognized as a construct in Parkinson's disease (PD) and occurs in about 25% of nondemented PD patients. Although executive dysfunction is the most frequent type of cognitive deficit in PD, the cognitive phenotype of PD mild cognitive impairment (PD-MCI) is broad. PD-MCI subtypes are represented by amnestic and nonamnestic domain impairment as well as single- and multiple-domain impairment. However, it is unclear whether patients with different PD-MCI subtypes also differ in other clinical characteristics in addition to cognitive profile. We studied 128 PD-MCI subjects at our Movement Disorders center, comparing clinical, motor, and behavioral characteristics across the PD-MCI subtypes. We found varying proportions of impairment subtypes: nonamnestic single domain, 47.7%; amnestic multiple domain, 24.2%; amnestic single domain, 18.8%; and nonamnestic multiple domain, 9.5%. Attentional/executive functioning and visuospatial abilities were the most frequently impaired domains. PD-MCI subtypes differed in their motor features, with nonamnestic multiple-domain PD-MCI subjects showing particularly pronounced problems with postural instability and gait. Differences among PD-MCI subtypes in age, PD duration, medication use, mood or behavioral disturbances, and vascular disease were not significant. Thus, in addition to differing cognitive profiles, PD-MCI subtypes differed in motor phenotype and severity but not in mood, behavioral, or vascular comorbidities. Greater postural instability and gait disturbances in the nonamnestic multiple-domain subtype emphasize shared nondopaminergic neural substrates of gait and cognition in PD. Furthermore, increased burden of cognitive dysfunction, rather than type of cognitive deficit, may be associated with greater motor impairment in PD-MCI. © 2012 Movement Disorder Society