Journals of Gerontology Series A: Biological Sciences and Medical Sciences, Vol 54, Issue 8 M404-M409, Copyright © 1999 by The Gerontological Society of America
Does old age or Parkinson's disease cause bradyphrenia?
JG Phillips, T Schiffter, ME Nicholls, JL Bradshaw, R Iansek and LL Saling
Department of Psychology, Monash University, Clayton, Vic, Australia. psy193g@alpha1.cc.monash.edu.au
BACKGROUND: Age-related declines in intellectual functioning have been
linked to slower processing of information. However, any slowness with
advancing age could simply reflect slower movement rather than impaired
cognition. To assess any age-related decline in cognitive speed, we used an
accuracy-based task that does not require a speeded motor response and that
measures the time required to acquire information (inspection time). To
identify possible biological mechanisms of cognitive slowing, this task was
also applied to patients with Parkinson's disease, a basal ganglia disorder
that reportedly causes bradyphrenia (slower thought processes). METHODS: In
one experiment, 16 young (mean age 22.4 years) and 16 older adults (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
second experiment compared 16 patients diagnosed with idiopathic
Parkinson's disease and 16 age-matched controls upon the same task.
RESULTS: Older adults demonstrated significant cognitive slowing compared
to younger adults. Medicated nondemented Parkinsonian patients were not
impaired on this task compared to age-matched controls. CONCLUSIONS:
Clinical and empirical impressions of bradyphrenia in Parkinson's disease
may instead reflect advancing age or slower movement, because the effects
of age may be greater in some cases than the effects of basal ganglia
disease once motor dysfunction has been allowed for.
