A new study that measures age-related damage to all five senses has found that 94 percent of older adults in the United States have at least one sensory deficit, 38 percent have two, and 28 percent have three, four, or five.
“We know that sensory impairment is common and is often a harbinger of serious health problems, such as cognitive decline or falls, as well as more subtle ones like burns, caused by loss of touch sensitivity, food poisoning that goes undetected because of loss of smell and taste, and smoke inhalation, from loss of smell,” said study author Jayant Pinto, M.D., an associate professor of surgery at the University of Chicago.
“Our findings here give us a better appreciation of the prevalence of multi-sensory loss, a first step toward learning more about what causes the senses to decline.”
The study, published in the Journal of the American Geriatrics Society, also found that deficits in multiple senses were strongly associated with age, gender, and race.
For instance, older participants in the study had more sensory deficits, with large differences in hearing, vision and smell. Men scored worse on hearing, smell, and taste, but better than women for corrected vision, the study found. African-Americans scored lower on all senses, except hearing. Hispanics had lower scores on vision, touch, and smell, but scored higher on taste.
Some of these deficits were mild, but many were serious, the researcher noted.
Nearly two-thirds (64 percent) of those in the study — which included 3,005 people between the ages of 57 and 85 — suffered from a significant deficit in at least one sense; while 22 percent had major deficits in two or more senses, according to the researchers.
The most prevalent sensory deficit, affecting 74 percent of participants in the study, was a decrease in the sense of taste. According to the study’s findings, 26 percent had a sense of taste rated only as fair, and 48 percent were rated poor.
Decreased sense of touch was also common. While 30 percent had a normal sense of touch, 38 percent were rated as fair, and 32 percent as poor.
According to the researchers, they found evidence of a common process underlying impairment of the five senses. They said they suspect this could involve nerve degeneration, environmental insults, or underlying genetic susceptibility that contributes to sensory loss associated with aging.
The sensory impairment study was part of the National Social Life, Health and Aging Project (NSHAP), the first in-home study of social relationships and health in older adults. In the first wave of NSHAP, conducted in 2005-06, professional survey teams from the independent research organization NORC at the University of Chicago used validated tests to measure each subject’s ability to see, feel, smell, taste, and hear.
The vision study allowed participants to wear their glasses or contact lenses and measured their ability to see under typical home lighting conditions. Subjects with vision rated as 20/40 or better were ranked as good. Those between 20/40 and 20/63 were fair; those below 20/63 were considered poor.
Touch measured their ability to distinguish between two points on the index finger of their dominant hand. Those who could feel two separate contact points four millimeters apart were considered good, eight mm apart was fair, 12 mm (about half an inch) or more was poor.
Smell was assessed using a validated taste that presents five different smells, one at a time. Those who correctly identified at least four of the five were rated good. Those who identified two or three were considered fair, and those who identified one or none were rated poor.
Taste testing relied on four paper strips — sour, bitter, sweet, and salty — applied to the tongue. Those who correctly described all four were rated as good. Those who got one or two right were rated fair, and those who got all four wrong were rated as poor.
Interviewers then rated the subjects’ ability to hear on a five-point scale based on how they responded during their conversation and categorized them as good, fair or poor. Subjects were allowed to wear their hearing aids if they chose to.
The interviewers also assessed participants’ age, physical and mental health, social and financial resources, education, and alcohol or substance abuse through structured interviews, testing, and questionnaires.
Sensory loss related to age is an understudied issue, but it’s an important one, according to the researchers.
The gradual decline of input from the senses “constrains how the elderly cope with social, physical and cognitive stresses,” Pinto said. “It is a major part of why older people report decreased quality of life.”
“We need to understand the biology behind the links between age and sensory loss and design better ways to prevent its decline,” he said. “People caring for older adults, including family members, caregivers, and physicians, should pay close attention to impairments in vision, hearing, and smell.”
There are interventions “that could make a big difference,” he added, listing eyeglasses, hearing aids and smell training.
“Even simple things like increasing spices in foods could help those with taste loss or providing tactile clues for people with loss of touch could improve function,” he said.