The PSG is the largest non-profit clinical trial site network in North America conducting PD research. It is composed of over 155 sites with more than 375 credentialed investigators.

It was formed in 1986, prompted by the recognition that clinical research in Parkinson disease (PD) required the participation of large numbers of research patients under the cooperative care of skilled and experienced research physicians, coordinators and allied professionals.

Breaking PSG News

Dear PSG family,

It is with great sadness that we share the news that Ira Shoulson, MD, the co-founder of the Parkinson Study Group (PSG), has passed away. Dr. Shoulson’s contributions to the field of movement disorders have left an indelible mark on clinical research, particularly in Parkinson’s Disease and Huntington Disease. Throughout his illustrious career, he served as an invaluable colleague and mentor, touching the lives of countless individuals within the medical community. He will be sorely missed.

Ira co-founded the Parkinson Study Group in 1985 with the launch of the DATATOP trial, for which he was the overall Principal Investigator.  Working closely with Stanley Fahn, MD, and a committed group of like-minded academic clinical investigators, the PSG prospered under Ira’s leadership.  Between the time of its founding, and 2006, when Ira completed his tenure as Chair, the PSG conducted over two dozen trials, comprising over 5,000 patients with PD.  These studies led to the approval of 5 new drugs by the Food and Drug Administration.  Currently, the PSG includes over 375 credentialed investigators and coordinators at more than 160 sites across North America.  His unique combination of vision, persistence and organizational genius made this all possible.

Ira also transformed the way clinical trials are conducted to test new therapeutics for Parkinson’s disease.  Those who remember his tenure know that randomization and masked treatment assignment are the bedrock of rigorous clinical investigations.  We also learned the importance of terms like “equipoise” and crucial role of timely and adequate drug supply to the efficient conduct of multi-center clinical trials from Ira.  More recently, he has reminded us of the importance of straightforward patient-centered outcome measures as the ultimate standard of truth by which therapeutics should be measured.  A long list of trainees and colleagues who learned by Ira’s side carry his guiding principles forward.

In the months prior to his passing, the PSG was working diligently on our symposium for this year’s upcoming annual meeting, honoring our founders, Dr. Ira Shoulson & Dr. Stanley Fahn. Ira was thrilled with the idea and gave his blessing, along with Stan. We are sending this note to honor his memory but the PSG will be highlighting his extensive contributions to the PD field at our  2024 PSG Annual Meeting in Nashville, TN, December 5-8.

Contributions in Ira’s honor can be made to the Making Patients Heard Research Foundation.


Andrew, Hubert, Joohi, Michael
PSG Executive Committee Co-Chairs and Chairs, Current and Elect

Latest news:

PSG Orchestra Study

A 18-month Study to Evaluate the Efficacy, Safety…

Read more here.


Glucocerebrosidase (GCase) is a lysosomal enzyme, encoded by GBA1…

Read more here.


Aerobic exercise is a vital treatment for people living with Parkinson’s disease…

Read more here.


People with Parkinson’s can receive genetic testing and genetic counseling…

Read more here.

Become a PSG member.

The Parkinson Study Group is continually interested in expanding our clinicaltrial sites as opportunities for new Parkinson’s Disease studies become available. Regardless of location (hospital, community-based, academic, or private practice), the PSG seeks trained Parkinson’s disease investigators who are committed to and experienced in clinical trials.

PSG Committees

The PSG is comprised of eight (8) core committees that help execute and oversee our mission as a non-profit clinical trial organization.

Working Groups

The PSG Working Groups enable collaborations among investigators with related interests in PD.

Credentialed Sites

The PSG is composed of over 155 sites with more than 375 credentialed investigators.

Upcoming Events and Deadlines


Join our newsletter list for frequent updates and news alerts!


Find the resources you need to support your work!


Words from PSG Visiting Mentorship Program Participants:

“I had the privilege of receiving mentorship from Dr. Carlie Tanner which was supported by the PSG Mentored Award in 2019. Having dedicated time to meet with Dr. Tanner, and the opportunity to bring Dr. Tanner together with the mentors I have locally at my institution, was an invaluable experience. Dr. Tanner provided me with advice and guidance on my research and career which I continue to benefit from to this day.”