Thread by @ZdenekVrozina

Another piece of the puzzle. Post-COVID changes are not just an isolated problem affecting a few unlucky individuals. They appear to have consequences at the population level🧵

A striking headline from Austria - 4 in 10 people report smell or taste problems.
That figure comes from a new cross-sectional survey of 2340 adults in Austria, Germany, and Switzerland looking at self-reported smell and taste disorders after the COVID era.

The key point is that this was not mainly about complete smell loss.
The most commonly reported problems were olfactory intolerance, phantosmia, and parosmia - in other words, abnormal, distorted, or intrusive smell experiences.

That matters because these symptoms are not trivial.
In the study, phantosmia and parosmia were the strongest independent predictors of reduced quality of life. Around 41% of those with smell and taste disorders also reported decreased life satisfaction.

And for many people, these problems did not simply fade away.
Depending on the symptom, roughly half or more reported that things had stayed the same or even worsened since onset.

This is where the discussion gets more important.
Smell is not just the nose. Smell signals travel through neural pathways into brain regions involved in perception, memory, and emotion.

So when smell remains disturbed long after infection, that points to ongoing dysfunction in a neuro-sensory system, not just an annoying leftover symptom.

Yes, this study does not by itself prove structural brain damage.
But it fits very well into the broader picture, because longitudinal MRI studies after COVID have already described changes in regions linked to smell processing - including the orbitofrontal cortex and the parahippocampal gyrus.

So persistent smell and taste disorders after COVID are consistent with ongoing dysfunction of the olfactory pathways and fit with studies that have already described brain changes after COVID.

Smell is probably only the part we can see more clearly. People notice it quickly, it is relatively easy to measure, and it is harder to dismiss than many other lingering effects.

In other words. Smell dysfunction is the visible tip of a much bigger post-COVID burden.

Rehman at al., Self-Reported Smell and Taste Disorders in the General Population: A Cross-Sectional Survey in Austria, Germany and Switzerland. researchgate.net/publication/40…