Cognitive Phenotypes in Parkinson's Disease
Condition: Parkinson Disease
MeSH terms: Parkinson Disease
Study type: Observational

Summary: 
      -  a data driven approach has identified different cognitive phenotypes in Parkinson's
           disease (PD)

        -  this heterogeneity possibly reflects the diversity of the neuronal damage caused by the
           disease

        -  we hypothesize that the different clinical presentations are associated to specific
           anatomical and functional correlates
    

Detailed description: 
      Cognitive impairments are frequent in PD, even in non-demented patients. However, there is a
      substantial heterogeneity in the clinical presentation of cognitive deficits in PD 2 and also
      in their progression. This heterogeneity possibly reflects the diversity of the neuronal
      damage caused by the disease and recent studies suggest that these different clinical
      influence the risk of developing dementia.

      Most studies on cognitive phenotypes in PD have used predefined categories, such as demented
      vs. non-demented, or PD-mild cognitive impairment vs. cognitively intact patients. However,
      such an approach may miss less obvious or unexpected presentations. To this end, in a first
      part of this study, we have used a data-driven approach (cluster analysis) to identify
      different cognitive phenotypes in PD. With such an approach where phenotypical profiles arise
      from the data without a priori assumptions, five cognitive presentations were identified: i°)
      cognitively intact patients (19.39%), ii°) patients with slight mental slowing and mild
      executive dysfunction (41.29%), iii°) patients with slightly impaired overall cognitive
      efficiency and deficits in all cognitive domains except recognition memory (12.93%), iv°)
      patients with severe mental slowing, impaired overall cognitive efficiency, and severe
      cognitive impairment in all domains, including memory (23.88%), and v°) patients with very
      severe impairment in all cognitive domains (2.51%). From these results, it could be
      hypothesized that cognitive deterioration in PD progresses along a continuum, with the
      exception of the fourth group that also exhibits memory deficits. This group may be
      characterized by a different underlying pathology, or comorbidity with Alzheimer's disease.
      The role of vascular factors has also to be considered.

      The objectives of the current project are:

        1. to validate the identified cognitive profiles prospectively in a new population using
           confirmatory cluster analysis.

        2. to identify specific anatomical correlates for the identified cognitive profiles by
           magnetic resonance-imaging (MRI) scanning

        3. to identify specific functional correlates of the identified cognitive profiles by
           high-density EEG (hd-EEG)
    

Intervention name(s): data
Intervention type(s): Behavioral
Intervention description(s): comparisons of clinical characteristics
comparisons of cognitive profiles
comparisons of grey matter density patterns
comparisons of EEG rhythms features
Observational model: Case-Only
Time perspective: Prospective
Sampling method: Non-Probability Sample
Study population: 
        Patients with Parkinson's disease, according to international criteria, irrespective of
        their disease stage or their current antiparkinsonian medication