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Probing peripheral and central cholinergic system responses
C A Naranjo1, J Fourie, N Herrmann
1Psychopharmacology Research Program, Sunnybrook and Women's College Health Sciences Centre, Toronto, ON. claudio.naranjo@utoronto.ca
Journal of Psychiatry & Neuroscience : JPN
|October 7, 2000
Summary
Aging affects pupil response to pilocarpine, not tropicamide. Pilocarpine may help assess cholinergic function in older adults, unlike tropicamide.
Area of Science:
- Neuroscience
- Ophthalmology
- Pharmacology
Background:
- Cholinergic system function is crucial for cognitive processes.
- Iris drug responses are used to predict central cholinergic deficits.
- Age-related changes in cholinergic function require further investigation.
Purpose of the Study:
- To assess the impact of normal aging on pupillary responses to tropicamide and pilocarpine.
- To evaluate scopolamine's effect on cognitive function in the elderly.
- To determine the correlation between peripheral and central cholinergic functioning.
Main Methods:
- A randomized, double-blind, controlled trial involving healthy elderly and young volunteers.
- Pupil diameter was measured using infrared pupillometry after tropicamide and pilocarpine administration.
- Cognitive function was assessed using the Buschke Selective Reminding Test after scopolamine administration.
Main Results:
- No significant age-related difference was observed in the pupillary response to tropicamide.
- Elderly individuals showed a significantly greater pilocarpine-induced decrease in pupil size compared to younger individuals.
- Elderly participants exhibited greater scopolamine-induced impairment in word recall.
Conclusions:
- Pilocarpine reveals an age-related pupillary response, unlike tropicamide.
- Pilocarpine may serve as a valuable tool for assessing central cholinergic function variations in the elderly.
- Findings suggest potential differences in cholinergic system aging between central and peripheral pathways.