A comparison of clinical and pathological features of young‐ and old‐onset Parkinson's disease

We compared 46 patients having onset of Parkinson's disease before age 45 years with 52 having onset after age 70. Young-onset cases more often presented with muscular stiffness (43%) and old-onset with difficulty walking (33%). One-third of young-onset cases had off-period dystonia, mostly affecting the legs, but no dystonia was recorded in old-onset cases. Presentation with rest tremor occurred in 41% of young-onset and 63% of old-onset. There were no differences in the number of affected relatives, endocrine disease, personality characteristics, dementia, or dyskinesia. A pathological study of 12 young-onset and 22 old-onset cases showed 24% greater nigral cell loss in the young, but no differences in the basic Lewy body pathology. Median disease duration in young cases was 5 years longer in the clinical study and 12 years longer in the pathological study. These studies show that the Parkinson's disease process is similar in young- and old-onset cases.