Task Force Paper: Definition of Parkinson's disease
By Dr. Daniela Berg, Chair and Dr. Ron Postuma, Co-Chair
Task Force on Definition of Parkinson's disease
Since PD was originally described, our understanding of the disease has evolved tremendously. As our knowledge changes, so does our conceptualization (and our definition) of disease. In recognition of the major developments in the field the MDS created a task force to update the definition of PD. This task force is chaired by Daniela Berg and Ron Postuma.
The task force has been meeting for the last 18 months, and has produced an introductory statement. This introductory statement is a means to introduce the work of the task force to the broader MDS community, and most critically, to provide opportunity for members to provide their input before a formal definition statement/diagnostic criteria is published. This website is your means to do so.
From the outset, the committee identified several critical issues that are challenging our conceptualization of PD. These include:
1) Conflict in diagnosis between clinical, genetic, and pathologic tiers. For example, patients with parkin mutations meet clinical PD criteria, but without synuclein deposition, do not meet pathologic PD criteria. Who arbitrates the final diagnosis?
2) Tensions in our distinction between Dementia with Lewy Bodies and Parkinson Disease with Dementia - Is the distinction valid?
3) The often extreme variability in severity and manifestations in PD - Do we need to define subtypes?
4) The recent recognition that in many (or most) cases, PD may not start in the motor areas - Do we need to diagnose disease earlier?
The paper outlines the discussion of these issues. No final prescriptions are provided, but some specific points are proposed. The task force proposes retaining pathology as the ultimate arbiter of diagnosis, but suggests adding a subcategory of clinicogenetic PD for the non-Lewy body mutations. We suggest that dementia be no longer considered an exclusion criteria for PD, even if it is an early feature. We outline previously-proposed subtype classifications of PD, including tremor-predominance, age, and other non-motor aspects; whether they are robust enough to warrant delineation remains unclear. We propose a skeleton of a new diagnostic criteria for prodromal PD, to allow diagnosis before the motor syndrome is fully manifest. Finally, we outline the need for new clinical diagnostic criteria for PD, and discuss the basic concepts that must underlie development of the criteria.
We solicit your comment on these issues as we outlined them. Some specific points to comment on:
Is pathology the best final arbiter of diagnosis?
Is a separate clinicogenetic category for non-Lewy body PD a good idea?
Are diagnoses of DLB and PD mutually exclusive? Do you agree with removing dementia from this list of exclusion criteria for PD? If so, what do you think of the terminology (e.g. DLB subtype)?
Is it important to formally delineate disease subtypes? Are the potential subgroups of PD sufficiently compelling to be incorporated into a formal subtype definition?
For early stages of PD, does a staging system of preclinical/prodromal/classic stages work? Do you agree with the approach? If you were creating prodromal PD criteria, what factors would you consider important to include?
Do you agree with the overall concepts of diagnostic criteria for PD? If you were creating diagnostic criteria, what factors would you consider important to include?
Your feedback is very much encouraged and appreciated. Please leave your comments below.