Adverse sensory and cognitive side effects from prescription medications can lead to noncompliance and thus jeopardize the health and well-being of older individuals. However, the prevalence of these effects in the population, their severity, their time course, their specificity, their reversibility, and their underlying causes/mechanisms has not been quantified in prospective studies. This hypothesis-driven study will investigate the role of anticholinergic activity as a mechanism for sensory and cognitive side-effects of medications. Over 250 drugs (including 47.5 percent of the 131 most frequently prescribed medications as measured by IMS America's National Prescription Audit) have been reported clinically to impair the senses of taste and/or smell. Most of these drugs are also associated clinically with impaired vision, audition, somesthesis and/or cognition. Of the drugs that cause taste, smell and other sensory/cognitive distortions, a significant proportion has anticholinergic activity (e.g. reduced salivary secretion/dry mouth, dilated pupils/blurred vision, altered cognitive function including memory loss and contusion), and these adverse drug reactions are reported more frequently in older individuals. This prospective study will determine the effects of medications taken systemically on the chemical senses as well as vision, audition, somesthesis, and cognition. Three hypotheses will be tested: a) Medications that exhibit anticholinergic activity (group 1) will impair all the senses (taste, smell, vision, audition, somesthesis) and cognition. For these drugs, the magnitude of loss will be related to the level of anticholinergic activity as measured by total salivary flow. The degree of sensory impairment will also be correlated with the degree of cognitive dysfunction. The magnitude of loss is expected to increase with the number of anticholinergic drugs taken. b) Medications that are reported clinically to cause taste and smell impairments but have no anticholinergic side-effects (group 2) are predicted to impair taste and smell as measured psychophysically but will not impair cognitive function. They may or may not alter the senses of vision and audition. c) Changes in taste and smell sensitivity will be found for medications in groups I and 2 both over time and in comparison to a control group not on medications. These studies will provide evidence-based data for physicians and patients on relative risks, magnitude, progression, and potential reversibility of drug-induced sensory and cognitive side-effects of medications in elderly people.
