Olfactory and cognitive functioning in patients with fibromyalgia

Fibromyalgia is a complex syndrome characterized by chronic musculoskeletal pain. Previous research has found impaired olfactory function and cognitive deficits in patients with fibromyalgia. In non-clinical population (middle-aged and elderly populations) an association has been found between olfactory function and cognitive impairment. Therefore, olfactory impairment identification could be considered as a reliable and early marker predicting the decline of cognitive function in mild cognitive impairment, Alzheimer's disease and Parkinson's disease. Nevertheless, the relationship between cognitive and olfactory functioning has not been studied in fibromyalgia patients. The aims of the study have been to analyze the cognitive and olfactory functioning and their association in a sample of women with fibromyalgia in comparison to women without a chronic pain disease. A transversal study was conducted with fibromyalgia patients (n = 146) and women without a chronic pain disease (n = 122). Data were collected using the WAIS-III (cognitive functioning) and the CCCRC test (olfactory functioning). Descriptive analysis, Student's t test and chi-square tests were conducted. There were significant differences in perceptive organization and processing speed, and in odour identification, odour threshold and total CCCRC score; the lower scores were for fibromyalgia patients. Among the fibromyalgia patients there were significant differences in the verbal scale, the manipulative scale, the total scale and processing speed between normosmic and hyposmic patients, the lowest scores were for hyposmic patients. Although previous literature has shown that self-reports by fibromyalgia patients inform about an enhanced olfactory acuity, the current study suggests that there are deficits in olfactory functioning in these patients. Also, the relationship between olfactory and cognitive functioning in fibromyalgia patients, due to the lack of previous studies, suggests a new line of research. Taken together, these results suggest that olfactory functioning could be included in a bio-psycho-social approach of fibromyalgia patients, because of the association with cognitive functioning.