Self-perception of olfactory dysfunction is associated with history of Traumatic Brain Injury: post-hoc analysis from the OLFACAT survey

BACKGROUND: Traumatic brain injury (TBI) is one of the main causes of smell loss. However, epidemiological studies evaluating the incidence in general population are scarce. The aim of this analysis is to investigate the prevalence of TBI-induced olfactory dysfunction (OD) in a general-based population study. METHODOLOGY: A cross-sectional population-based survey was distributed to general population (260,000 households) through the newspaper. The survey included four microencapsulated odorants (smell test) to assess smell loss and two self-administered questionnaires (odour description and epidemiology/health status). Participants were divided into two groups, with or without a history of TBI. RESULTS: From 10,783 returned surveys, 9,348 were analysed. The survey profile was a 43-year old woman with medium-high educational level, living in a city. The overall prevalence of TBI was 5% (N=464, 44.5±14.1 years old, 57% females). Recorded causes of TBI were traffic, domestic, or work accidents. Subjects with TBI reported a poorer subjective smell self-perception compared to non-TBI participants, and a decreases ability to identify mercaptan (odour added to gas used in cities). Although, using the smell test, both groups showed similar smell capacities. CONCLUSIONS: Subjects with TBI history report a higher frequency of self-perceived OD, and a decrease ability to smell the odour added to domestic gas. Having said that, the prevalence of OD, according to the smell test, was similar in both groups.