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

May 2014

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.

Daniela Berg, Co-ChairRon Postuma, Co-ChairThe 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.

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?

From the outset, the committee identified several critical issues that are challenging our conceptualization of PD.  These include:

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.

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Recent Comments

Redefinition for the future
jorge luis orozco

Redefinition clinical subtypes premotor with a specific marker would have a future interest in the research and application of treatments that change the course of the disease. It will be better to have patients grouped for when that time comes.

Redefining PD- Beyond tremors and Lewy bodies!
Pooja Mailankody

Requirement of a tissue diagnosis would seriously limit the research potential as only a few select centers in this world have the facilities for the same. Research to compare the clinical, electrophysiological, and therapeutic aspects of ‘non-Lewy body PD’ with that of ‘Lewy body PD’ could have therapeutic implications. The concept of ‘DLB subtype’ is better than having DLB as a separate diagnostic entity. The criteria to diagnose dementia in the presence of PD should be clearly delineated. Conventional tests for assessment of higher mental functions may not reflect the true mental status as bradykinesia of both thought and action is an invariable accompaniment of PD. The division of PD into subtypes is helpful for both prognostication and appropriate decision making with regard to surgical intervention. In addition to RBD, anosmia and autonomic dysfunction (Olanow, 2012), I would also include family history and functional imaging in the diagnostic criteria for prodromal PD.

Relevant in face of the new discoveries
Alexandre Aluizio Costa Machado

The importance of probable diagnosis, in clinical practice and clinical research. So, I believe that some points should be considered:

1) I think that clinical relative is more difficult to define and should be avoided like dementia and clinical instability.

2) The presence of hiposmia, REM disturb, obstipation, depression, must be considered as second line manifestations to do the diagnosis.

3) Typical rest tremor associated with other typical symptoms like akinesia and/or bradykinesia must be the first line to do a probable diagnosis; the typical tremor in general is more relevant to the bradykinesia.

I hope to have contributed to this complex task.

Alexandre A. C. Machado, MD, PhD

Movement disordes group of neurology division in Sao Paulo Medical University

Sao Paulo - Brazil

Is it too premature?
Srinivasa Rangasetty

Pathology and molecular genetics are the arbiter for the diagnosis.Till such time a robust 'non-invasive' bio marker ,either advanced imaging or biochemical marker,is available to identify alpha synuclein or otherwise are we wasting in reclassifict

Response to Dr. Hettich
Daniela and Ron

Transcranial ultrasound may help differentiate PD from other parkinsonisms. However, we defined strict criteria for inclusion of a diagnostic test (3 studies 80% specificity); so far, ultrasound does not qualify (this may change in the future).

Daniela Berg

Yes, you are absolutely right: Side predominance is a major hallmark and diagnostic feature in PD. We will make sure, that this is considered more explicitly in the MDS clinical criteria for PD.

About Transcranial echography in Parkinson criteria
Héctor Farías Hettich

Good morning.

H.Farías,fellow of movement dissorder,Chile.

We consider very important include de Echography in the new guide (hight + predictive value)

There is any chance to have a preview of the new criteria? , only for academic purposes.


Unilateral onset and persisting asymmetry as supportive criteria
Njide Okubadejo

Thanks for the excellent presentation. Considering the importance accorded unilateral onset and persisting asymmetry as a supportive feature for PD in the UKPDS BB criteria, is this feature incorporated in the proposed criteria?