Sensation and Perception Specifically the Interaction Between Taste and Smell

Taste and Smell

Age Related Changes in Perception of Flavor and Aroma

It has been posited that the perception of flavor and aroma are derived from the senses of chemical irritation, taste and smell (Rawson, 2003).

Together, these senses constitute what has been termed chemosensation, although these sensory systems are purportedly considerably variant in their physiology and anatomy. Nevertheless, they do have the ability to regenerate, and their noted susceptibility to aging and age associated diseases has been noted (Rawson, 2003). It has been reported that nearly one third of all older individuals report dissatisfaction with their sense of smell and taste, and the actual occurrence of sensory loss amongst the elderly is maintained to be even higher (Pelchat, 2001). Furthermore, it has been asserted that age related sensory loss affects both personal safety and quality of life (Rawson, 2003). Moreover, the impact of the loss on the elderly's physical well being and emotional well being should not be underestimated. If older persons are complaining about chemosensory function, it should be taken seriously both for the significance and prevalence to the older individual and as a possible indicator of neurological disorder (Rawson, 2003).

Article Overview

Researchers posit that there are several features of the human sensory system related to smell, taste, and chemical irritation that make them especially susceptible to age and associated disease changes that may lead to deficits in functionality. These features reportedly include long-term exposure to harsh environmental externalities, replacement of receptor cells for taste and smell over the course of the life span, dependence on the ability of stimuli to penetrate through and dissolve in watery protective layers, and dependency on multiple types of receptors which are necessary to perceive the entirety of the sensory spectrum (Rawson, 2003).

Loss within the sensory system has been attributed to changes in structural anatomy such as loss of olfactory receptor cells or taste buds, changes or variance in the levels of particular receptor proteins or ion channels, or environmental changes surrounding the receptor cell such as changes in the composition of mucus in the nasal passages or reduction in salivation. An example provider by researcher Nancy Rawson in her (2003) article "Age Related Changes in Perception of Flavor and Aroma," is the use of dentures as they have the ability to contribute to changes in taste perception because of the physical barrier to some of the membranes where receptors reside, reduced salivation and the exposure of the receptors to compounds that the dental adhesive tends to release. Chronic diseases are also posited as impactful on sensory functionality, particularly cancer and diabetes, or even therapeutic interventions such as radiation, surgery and certain medications.

In many instances, what causes chemosensory loss is undetermined and is often untreatable until the cause is determined and more is known regarding the age related factors that lead to such phenomenon. Researchers have also posited that deficits in sensory perception may be indicative of neurological disorders such as Alzheimer's disease and/or Parkinson's disease. Individuals with Alzheimer's are considered less able to identify odors that are gender and age matched healthy individuals (Morgan, Nordin, & Murphy, 1995). Distortions in smell and taste and/or diminished sensitivity have also been associated with particular endocrinological disorders to include hypothyroidism (McConnell et al., 1975).

The researcher describes chemical irritation as the chemosensory mechanism by which individuals detect sensations such as the tingle of carbonation, the heat associated with hot peppers or the cooling effects attributed to menthol (Rawson, 2003). Dehydration, disease or medications have the ability to reduce or increase the stimuli to the nerve endings that have been altered, particularly with aging. These perceptions have the ability to interfere or interact with food flavors and cause unfamiliar qualities that prove difficult for older individuals to describe (Stevens & Cain, 1989). Moreover, it is not uncommon for older individuals to report that 'things don't taste right', and these complaints have been generally attributable to changes in odor perception (Rawson, 2003).

Rawson (2003) posits a significant number of medications that have the ability to elicit chemosensory side effects which has the ability to lead to poor pharmacological compliance or altered selection of nutritional status and foods. Metabolites or the medications themselves can be secreted into the nasal mucus or into the saliva and directly impact receptor cells. This is often evidenced by the unpleasant taste frequently associated with antibiotics (Chodosh et al., 1998). In instances when medication known to alter the senses must be taken for extended periods of time, however, an adjustment in dosage may serve to remediate the problem.

Analysis and Conclusion

Rawson, in the aforementioned article provided scholarly and empirical information regarding the impact on the perceptions of flavor and aroma and the senses of taste, smell and chemical irritation as it relates to older age. The peer reviewed article provided both physiological, pharmacological social consequences of changes the elderly can experience as a result of changes and/or deficits in the sensory system. Empirical studies were provided as a foundation by which the research was posited upon, issues of well being, taste aversion, and food/drink altering were addressed. Chemosensory loss was explored in significant detail and issues of infections, and medication were discussed.