It is controversial whether age of disease onset
is related to cognitive decline in Parkinson's disease
(PD). We administered 7 cognitive measures assessing visuospatial
skills, memory, and executive functions to 222 patients
with idiopathic PD and 108 normal control participants.
Regression analyses demonstrated that older age of disease
onset consistently predicted cognitive decline above and
beyond normative aging and duration of illness. These findings
suggest that older age of disease onset is a critical determinant
of cognitive deterioration in PD. (JINS, 1998,
4, 285–290.)