About 1 in every 15 adults over the age of 40 smells “phantom odors” that aren’t really there, according to a new study. The implications for seniors’ caregivers can be significant.

Researchers with the National Institute of Health came to that conclusion by delving into the data of more than 7,400 participants in a national nutrition survey. They noted that patients who perceive these phantom odors often can have a “miserable quality of life” and struggle to maintain their weight.

Participants in the 2011-2014 National Health and Nutrition Examination Survey, from which the findings were derived, were asked the question “Do you sometimes smell an unpleasant, bad or burning order when nothing is there?” And those with the NIH’s National Institute on Deafness and Other Communication Disorders correlate the results with each respondent’s age, sex, educational level, race, etc.

While the ability to detect odors typically deteriorates with age, researchers found that phantom odor perception seems to improve, particularly for those ages 40 to 60. Other risk factors for developing phantom odors might include head injury, dry mouth, poor overall health, and lower socioeconomic status. While the root causes of the phenomenon aren’t known, a good step to unlocking those secrets is clearly describing the phenomenon, according to the study, which was published in the JAMA Otolaryngol-Head and Neck Surgery.

“Problems with the sense of smell are often overlooked, despite their importance. They can have a big impact on appetite, food preferences, and the ability to smell danger signals such as fire, gas leaks, and spoiled food,” said Judith A. Cooper, Ph.D., acting director of the NIDCD, in press release