Profiling cognitive and neuropsychiatric heterogeneity in Parkinson's disease

A disorder of great heterogeneity - here is one groups attempt to cluster sub-types of PD according to cognitive and neuropsychiatric symptoms... these may well represent different disease sub-types too. The first and second cluster are recognisable, although caution should be taken over the second group given its small size. The third and fourth cluster are also recognisable. It would be interesting to see how sleep fits in to all this...

Parkinsonism Relat Disord. 2016 May 15. pii: S1353-8020(16)30166-3. doi: 10.1016/j.parkreldis.2016.05.014. [Epub ahead of print]

van Balkom TD, Vriend C, Berendse HW, Foncke EM, van der Werf YD, van den Heuvel OA, Klein M.

http://www.sciencedirect.com/science/article/pii/S1353802016301663

BACKGROUND:

Parkinson's disease (PD) is a highly heterogeneous disease, in which motor symptom subtypes are often-described. While it is recognized that motor, cognitive and affective neuropsychiatric symptoms negatively influence the patients' quality of life, it is currently unknown how these symptoms contribute to phenotypic subtypes. The objective of this study was to assess subtypes of motor, cognitive and affective symptoms in PD.

METHODS:

A hierarchical cluster analysis was conducted on clinical data of 226 PD patients screened at the VU University Medical Center using comprehensive assessment of cognitive, affective and motor symptoms. Subsequent linear discriminant analyses were conducted to investigate discriminating constructs between clusters.

RESULTS:

The cluster analysis yielded four clusters: (1) a young-age (59.9 years), mildly affected cluster (N = 86), (2) an old-age (72.3 years) cluster with severe motor and non-motor symptoms (N = 15), (3) a cluster (age 64.7 years) with mild motor symptoms, below-average executive functioning and affective symptoms (N = 46) and (4) a cluster (age 64.8 years) with severe motor symptoms, affective symptoms and below-average verbal memory (N = 79).

CONCLUSIONS:

Cluster 1 and 2 seem to represent opposite ends of the PD disease stages. Patients in clusters 3 and 4 had similar age, educational level and disease duration but different symptom profiles - we therefore suggest that these clusters represent different pathways of disease progression, presumably with distinct underlying pathology localization. Future research on the neuropathophysiological characteristics of these two clusters and monitoring of disease progression is required.