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Parkinson's disease is generally characterized as a movement disorder. Over the last years, however, there has been an increasing awareness that many people with PD may also suffer so-called "non-motor features," including problems with mental functioning, depression, falling asleep or staying awake, and autonomic functions (for example bladder and bowel problems). Furthermore, when patients are treated over the long term with dopaminergic drugs (e.g. levodopa) they may start to experience motor or psychiatric side effects. Although all these different features are aspects of PD, not all PD patients will have the same problems. There are differences between patients concerning the age at onset of their symptoms, the rate of disease progression, and the combination of symptoms and side-effects, suggesting the existence of subgroups. These clinical differences between patients may in turn result in different consequences on the level of disability, quality of life and required care.

Fundamental to our understanding of how one patient may differ from another is the availability of good quality measures that cover the broad spectrum of motor and nonmotor features of PD. The SCales for Outcomes in PD (SCOPA) program ( was begun in 1999 to develop rating scales that measure motor and nonmotor features of PD as well as disability and global outcomes of health. In 2003, the SCOPA-PROPARK cohort study started, in which 420 patients are evaluated annually with the SCOPA scales.

The current project aims to identify groups of patients (subtypes) that share characteristics with respect to their motor and nonmotor features and their progression. Knowledge about how the expression of PD varies between patients may help our understanding of the mechanisms that underlie the development of the disease.

Final Outcome

Using cluster analysis on patients enrolled in the SCOPA-PROPARK Cohort, Dr. van Hilten's team identified three main patient clusters:

1. Mild symptoms on all variables (benign): Young age of onset; short treatment duration; stable progression.

2. Benign with motor fluctuations: Highest treatment with dopamine agonist drugs; longest disease duration; youngest age of onset.

3. Postural Instability and Gait Disorder (PIGD): Significant axial symptoms (such as speech, neck rigidity, rising from a chair, posture, gait, and postural stability); depression; malignant course. 
Results of this project were published in the Journal of Neurology, Neurosurgery & Psychiatry.


  • Jacobus Johannes van Hilten, MD, PhD

    Leiden Netherlands

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