COVID-19 is more than an infection in the lungs. Over the course of the pandemic, since it first broke in Wuhan, China in December 2019, scientists have found it can also affect the heart and the liver. Patients have also exhibited neurological problems, including ‘brain fog’, a loss of sense of smell and taste among others.

The infection can also lead to long-term loss of brain tissue, the latest study by the University of Oxford suggests, PTI reported. Data from the UK Biobank – which stores genetic data and medical records of over 40,000 participants, was used in the study, which is yet to be peer-reviewed. 

Researchers selected a total of 782 participants, out of which 394 were ‘cases’ had tested positive for the coronavirus between March 2020 and April 2021. The rest were ‘controls’, people who had not contracted the virus. 

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Researchers conducted brain scans on both cases and controls and compared them with their scan from before the pandemic. The study used 2,360 different brain measurements. 

The two
sets of analyses (exploratory and hypothesis-driven) identified four and eight
measurements, respectively, which were statistically significantly associated
with COVID. All traits that showed a reduction in brain tissue associated with
a COVID infection were in regions of the brain devoted to the sense of smell.

While even
small losses in the volume of certain brain regions might seem alarming, subtle
brain changes don’t necessarily imply disease, even in adulthood. The
researchers interpret their findings as a direct harmful effect of COVID caused
by the virus entering the brain via the nose. However, another explanation is
that changes in olfactory regions of the brain (the parts that process odour)
are a consequence of a loss of taste and smell, not the cause of it.

Most people
with COVID experience a temporary loss of smell, which is an arguably annoying,
but fairly benign symptom. Loss of smell is probably caused by infection of
non-neuronal cells involved in smell, rather than direct injury to brain cells.

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Also,
widespread structural changes in the brain following the loss of sense of smell
have been documented before SARS-CoV-2, the virus that causes COVID, infected
the first human. There is even a common inflammatory condition, called chronic
rhinosinusitis that causes changes in grey matter that are highly reminiscent
of that reported in the Oxford study.

Fortunately,
sense of smell is regained by most COVID patients after a few months, in which
case alteration of the brain would be expected to be temporary.

Those
results about COVID-induced brain changes add further concerns about the
severity and extent of long COVID. Long-lasting symptoms have a clear biological
basis. Similar post-infection symptoms have been described for other infectious
diseases, such as the flu. Full recovery from severe disease, whatever its
cause, often takes a long time. And some of the worst affected patients never
fully recover.

What is
less obvious is the extent to which mild or even symptomless COVID might be
associated with persistent symptoms. Most research suggests COVID causes
long-term symptoms, such as fatigue and depression, even in mild cases. Yet all
studies, however well designed, cannot control for the fact that people who
know they had COVID will be aware from the media coverage that they may be at
risk of long-term symptoms.

Such
placebo or nocebo effects can have a strong effect on people’s health and
wellbeing. For example, people enrolled in the control arm of the Pfizer
vaccine trial reported fatigue (33 per cent) and headache (34 per cent) despite
not having been injected with the vaccine.

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It is
challenging for the media to raise awareness about possibly concerning
scientific findings without engaging in unhelpful scaremongering. The public
has the right to be informed about potential risks to their health, yet an
excessive focus on long COVID, however well intended, can contribute to
amplifying the problem as a self-fulfilling prophecy.

Minimising
health risks can kill, often through poor lifestyle choices and delayed
diagnoses. Conversely, magnification of health risks can also kill. The
association of chronic stress and a higher risk of cardiovascular disease is
well documented. There is even a recognised medical condition called
broken-heart syndrome – a potentially deadly heart condition caused by
emotional stress.