Increased Survival in Contemporary Parkinson's Disease: A 47-Year Autopsy Study

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The main clinical features are bradykinesia, rigidity, and resting tremor. Other neurodegenerative disorders such as progressive supranuclear palsy and multiple system atrophy share some of these clinical manifestations. All those disorders are collectively known as parkinsonism or Parkinson syndrome (PS). Definite diagnosis of PD requires brain autopsy. There is no known cure for PD. Since its discovery in the 1960s, levodopa (LD) has remained the best and most widely used medication in PD. The impact of that is important to understanding the neuroepidemiology of PD. The incidence of PD rises with advancing age. In the last six decades, life expectancy in the general population has increased resulting in a larger pool of at-risk persons. Onset age of PD is the most reliable indicator of PD survival as older onset cases have shorter survival. We report on survival in autopsy-confirmed PD cases with onset age <70 years treated with LD and compare that with similar onset-age cases of PD before the discovery of LD.

The Saskatchewan Movement Disorders Program (SMDP) has operated uninterrupted since 1968. Long follow-up and autopsy studies are a special interest of the SMDP. All PS cases followed by the SMPD during 47 years (1968-2015) that came to autopsy were considered. Those with autopsy-confirmed PD and onset <70 years were included and were compared with pre-LD cases of similar age of onset.

Overall, 392 PS cases were seen in our clinic between 1968 and 2015 and had brain pathology studies. A total of 314 (80%) of those had PD. Overall, 128 (41%) of the PD cases had onset <70 years and were included in this study. Their median survival was 18 years.

Prior to widespread use of LD, nearly all PD cases had onset <70 years and mean survival was 9.4 years. Longer survival in our study is attributed primarily to modern treatment. Increased survival has resulted in a larger number of older, chronically treated, higher comorbidity, and complicated PD patients. These changes present new challenges. It requires a larger and increasingly diverse workforce for patient care and research.