Findings reveal significant diagnostic instability in Parkinson's disease, with 13.3% of diagnoses revised over a 10-year period.

Researchers emphasize the urgent need for improved diagnostic processes, better training for neurologists, increased postmortem examinations, and the development of cost-effective biomarkers.

A retrospective study conducted from 2006 to 2020 analyzed patient records at Turku University Hospital and three regional hospitals in Finland, focusing on the long-term diagnostic stability and accuracy of Parkinson's disease.

The study followed over 1,600 patients initially diagnosed with Parkinson's disease, highlighting the challenges in distinguishing it from similar disorders, particularly dementia with Lewy bodies.

Despite the frequent use of dopamine transporter imaging, postmortem examinations confirming diagnoses were conducted in only 3% of deceased patients, reflecting a decline in such practices.

Of the postmortem examinations conducted, 64% confirmed initial Parkinson's disease diagnoses, indicating a need for more thorough diagnostic confirmation.

When considering dementia with Lewy bodies as a separate category, the revision rate increases to 17.7%, underscoring the complexities involved in accurate diagnosis.

Most diagnostic changes occurred within the first two years of diagnosis, illustrating the uncertainty clinicians face, according to Professor Valtteri Kaasinen.

The study questions the effectiveness of the 'one-year rule' used to differentiate Parkinson's disease from dementia with Lewy bodies, suggesting it may not be relevant due to symptom overlap.

Kaasanen calls for urgent improvements in diagnostic processes, including enhanced clinical training and increased postmortem diagnostic confirmation.

Common misdiagnoses included vascular parkinsonism, progressive supranuclear palsy, multiple system atrophy, and clinically undetermined parkinsonism.

Increasing autopsy rates could enhance understanding of diagnostic accuracy, particularly in unclear cases, while cost-effective biomarkers could improve diagnostic precision in non-specialized settings.