Sydney multicenter study of Parkinson's disease: Non‐<scp>L</scp>‐dopa–responsive problems dominate at 15 years

Abstract

One-third of the 149 people recruited 15 to 18 years ago in the Sydney Multicenter Study of Parkinson's disease have survived. The original study compared low-dose levodopa with low-dose bromocriptine. We now report the problems experienced by people who survive 15 years from diagnosis. The standardized mortality ratio is significantly elevated at 1.86 and is not significantly different between treatment arms. Falls occur in 81% of patients, and 23% sustained fractures. Cognitive decline is present in 84%, and 48% fulfill the criteria for dementia. Hallucinations and depression are experienced by 50%. Choking has occurred in 50%, symptomatic postural hypotension in 35%, and urinary incontinence in 41%. No patient is still employed, and 40% of patients live in aged care facilities. Although approximately 95% have experienced L-dopa-induced dyskinesia/dystonia and end of dose failure of medication, in the majority, these symptoms are not disabling. Dyskinesia and dystonia were delayed by early use of bromocriptine, but end-of-dose failure appeared at a similar time once L-dopa was added. The rate of disease progression is similar in both arms of the study. We conclude that the most disabling long-term problems of Parkinson's disease relate to the emergence of symptoms that are not improved by L-dopa. Neuroprotective interventions in Parkinson's disease should be judged by their ability to improve non-L-dopa-responsive aspects of the disease, rather than just by their capacity to delay the introduction of L-dopa or reduce its associated side effects.