The inability to taste is so intricately linked with smell that it is often difficult to tell whether the problem lies in tasting or smelling. An estimated two to four million people in the United States suffer from some sort of taste or smell disorder. The inability to taste or smell not only robs an individual of certain sensory pleasures, it can also be dangerous. Without smell or taste, for example, people cannot determine whether food is spoiled, making them vulnerable to food poisoning. Also, some psychiatrists believe that the lack of taste and smell can have a profoundly negative affect on a person's quality of life, leading to depression or other psychological problems.
There are a variety of causes for taste and smell disorders, from a biological breakdown to the effects of environmental toxins. In addition to cold or flu, common physical ailments that can assault the sense of taste and smell include allergies and various viral or bacterial infections that produce swollen mucous membranes. Fortunately, most of these problems are temporary and treatable. However, neurological disorders due to brain injury or diseases like Parkinson disease or Alzheimer disease can cause more permanent damage to the intricate neural network that processes the sense of taste and smell. Some drugs can also cause these disorders by inhibiting certain enzymes, affecting the body's metabolism, and interfering with the neural network and receptors needed to taste and smell. Exposure to environmental toxins like lead, mercury, insecticides, and solvents can also wreak havoc on the ability to smell and taste by causing damage to taste buds and sensory cells in the nose or brain.
See also Perception.
Ackerman, Diane. A Natural History of the Senses. New York: Vintage Books, 1991.
Moller, Aage R. Sensory Systems: Anatomy and Physiology. New York: Academic Press, 2002.
Lewis, Ricki. "When Smell and Taste Go Awry." FDA Consumer (November 1991): 29-33.
Tyler, Aubin. "Disorders That Rob You of Taste & Smell." Good Housekeeping (October 1992): 257-258.
Willoughby, John. "Taste? Bud to Bud, Tongues May Differ." New York Times (December 7, 1994): C1, C11.