Molecular triggers of symptoms of parosmia and insights into the underlying mechanism (preprint)

The molecular stimuli that trigger a parosmic response have been identified. Parosmia is a debilitating condition in which familiar smells become distorted and unpleasant, frequently leading to clinical depression. Often a result of post infectious smell loss, incidences are increasing as COVID-19 cases escalate worldwide. Until now, there was little understanding of its pathophysiology, and the prevailing hypothesis for the underlying mechanism is a mis-wiring of olfactory sensory neurons. However, with novel application of flavour chemistry techniques as a relatively rapid screening tool for assessment of both quantitative and qualitative olfactory loss, we identified 15 different molecular triggers in coffee. This provides evidence for peripheral causation, but places constraints on the mis-wiring theory. Furthermore, it provides the basis for development of a practical diagnostic tool and treatment strategies.

An analysis of patients’ perspectives on qualitative olfactory dysfunction using social media (preprint)

SUMMARY Background The impact of qualitative olfactory disorders is underestimated. Parosmia is the triggered perception of distorted odours whereas phantosmia is the perception of odours in the absence of a trigger. Both can arise from post-infectious anosmia and have increased substantially since the outbreak of COVID-19. Methodology/Principal Thematic analysis of a social media support group for parosmia and phantosmia was used to articulate the perspectives and concerns of those affected by these debilitating olfactory disorders. Results A novel symptom (olfactory perseveration) was identified where a triggered, identifiable, and usually unpleasant olfactory percept persisted in the absence of an ongoing stimulus. Fluctuations in intensity and duration of perseveration, parosmia and phantosmia were observed. Coffee, meat, onion, and toothpaste were identified as common triggers of these disorders, but people struggled to describe the distortions, using words associated with disgust and revulsion. Common strategies to avoid triggers may result in a diet lacking in both nutrition and reward. The emotional aspect of living with qualitative olfactory dysfunction was evident and highlighted the detrimental impact on mental health. Conclusions The data acquired can inform rehabilitation strategies and drive our ongoing research into understanding the molecular triggers associated with parosmia, and research into patient benefit.