Does old age or Parkinson's disease cause bradyphrenia?

Background. Age-related declines in intellectual functioning have been link ed to slower processing of information. However, any slowness with advancin g age could simply reflect slower movement rather than impaired cognition. To assess any age-related decline in cognitive speed, we used an accuracy-b ased task that does not require a speeded motor response and that measures the time required to acquire information (inspection time). To identify pos sible biological mechanisms of cognitive slowing, this task was also applie d to patients with Parkinson's disease, a basal ganglia disorder that repor tedly causes bradyphrenia (slower thought processes). Methods. In one experiment, 16 young (mean age 22.4 years) and 16 older adu lts (mean age 71.6 years) matched for intelligence and education completed an inspection time task The task required judgments as to order of onset of two lights. where the interval between onsets ranged from 20-250 msec. A s econd experiment compared 16 patients diagnosed with idiopathic Parkinson's disease and 16 age-marched controls upon the same task. Results. Older adults demonstrated significant cognitive slowing compared t o younger adults. Medicated nondemented Parkinsonian patients were not impa ired on this task compared to age-marched controls. Conclusions, Clinical and empirical impressions of bradyphrenia in Parkinso n's disease may instead reflect advancing age or slower movement, because t he effects of age may be greater in some cases than the effects of basal ga nglia disease once motor dysfunction has been allowed for.