Smell distortions: Prevalence, longevity and impact of parosmia in a population-based, longitudinal study spanning 10 years

• Main Authors: Olofsson, Jonas, Ekesten, Fredrik, Nordin, Steven
• Format: Other/Unknown Material
• Language: unknown
• Published: Center for Open Science 2021
• Subjects: Northern Sweden
• Online Access: http://dx.doi.org/10.31234/osf.io/nx8z9

Parosmia, experiences of distorted smell sensations, is a common consequence of covid-19. The phenomenon is not well understood in terms of its impact and long-term outcomes. We examined parosmia in a population-based sample from the Betula study that was conducted in Umeå in northern Sweden (baseline data collected in 1998-2000). We used a baseline sample of 2168 individuals aged 35-90 years and with no cognitive impairment at baseline. We investigated the prevalence of parosmia and, using regression analyses, its relationship to other olfactory and cognitive variables and quality of life. Benefitting from the longitudinal study design, we also assessed the persistence of parosmia over 5 and 10 years prospectively. Parosmia was prevalent in 5% of the population (n=104) and was often co-occurring with phantosmia (“olfactory hallucinations”), but was not associated with lower self-rated overall quality of life or poor performance on olfactory or cognitive tests. For some individuals, parosmia was retained 5 years (17%) or even 10 years later (10%). Thus, parosmia is relative common in the population, and can be persistent for some individuals. This work provides rare insights into the expected impact of, and recovery from parosmia, with implications for those suffering from qualitative olfactory dysfunction following covid-19.