The article "When disease resists diagnosis" (Science, Volume 391, Number 6792, Page 1329, March 2026) discusses the challenges in diagnosing diseases that resist pinpointing. A study from Finland's University of Turku and Turku University Hospital showed that up to one in six Parkinson's disease diagnoses change after ten years of follow-up.[1] Most of the changes in diagnoses occurred within two years of the original diagnosis.[1] When dementia with Lewy bodies is separated as a separate category, the revision rate rises to 17.7%.[1] The study followed over 1,600 patients diagnosed by neurologists between 2006 and 2020.[1] Common revised diagnoses included vascular parkinsonism, progressive supranuclear palsy, multisystem atrophy, and clinically undetermined parkinsonism.[1] Despite the use of dopamine transporter (DAT) imaging, diagnostic difficulties remain, with postmortem pathologies confirming the original diagnosis in 64% of cases in 3% of deceased patients.[1]