Will Covid Make My Brain Shrink?

For people who have had Covid and may still be living with Long Covid, a news article that ran on Monday, 7 March in the BBC, “Scans reveal how Covid may change the brain” could be perceived as alarming.  Of course, the thought of a shrinking brain is unnerving.  That this shrinkage is observed in parts of the brain linked to sense of smell and memory might be even more frightening to Covid survivors who have experienced and/or are still experiencing anosmia (loss of sense of smell) and brain fog.  However, a key message highlighted by one of the scientists in the study is that “the brain is really plastic”.  But what does that actually mean?

The Brain Can Recover

Researchers often talk about the ‘plasticity’ of our brain.  When they say this, they mean the brain’s incredible ability to make new connections and change in response to our environment.  One Stanford University neuroscientist put it this way: “I use the term ’livewired’ to represent that [one has] billions of neurons reconfiguring their circuitry every second. The connections between them are changing their strength and unplugging and re-plugging in elsewhere.”

As a result of this plasticity, we are capable of learning new things and in many cases, can overcome physical adversities such as stroke or brain injury.  I was able to see this first-hand when my mother, at the age of 56, suffered a stroke.  She was paralysed on her right side and unable to speak.  Within a year, with physical and speech therapy, she was able to speak, write and walk without aid.  Her plastic brain found a way around the injury to re-learn these functions.

In people with sleep apnoea, there is also observed brain alteration.  Sleep apnoea is a serious sleep disorder in which breathing repeatedly stops and starts.  One study found that participants with severe, untreated sleep apnoea, showed signs of brain damage, accompanied by impairments to cognition, mood and daytime alertness when compared to control subjects.  Twelve months of CPAP therapy (Continuous Positive Airway Pressure – a machine that blows air through a mask, designed to hold the airways open during sleep) led to an almost complete reversal of the damage and also produced significant improvements in nearly all cognitive tests, mood, alertness and quality of life.  In other words, the changes to the brains of patients with sleep apnoea were reversible with appropriate treatment.

Use It or Lose It

Just because scientists noticed that brain matter is reduced in Covid patients compared to non-Covid ones, does not necessarily mean that this shrinkage is due to the Covid infection directly causing damage to the brain.  Our brains often engage in pruning mechanisms.  This happens most frequently in the developing teenage brain[1] and is the time of life when the phrase “use it or lose it” is most appropriate. At this time of life, if a behaviour is repeated frequently, the neuronal connections are strengthened.  If a behaviour is not used at all, those connections get lost in the cut.

The researchers of the Covid brain study showed that the losses occurred in the areas linked to the sense of smell (olfactory area).  What they could not say is whether this decrease in size is due to the virus attacking this area tissue or whether the tissue shrank due to lack of use because patients had already lost their sense of smell.  Further clarification is certainly necessary in order to draw any conclusions as to cause and effect in this case.

Brain, Heal Thyself…or Maybe Get Some Help

So, should scientists discover that the changes in brain size they have observed in Covid have behavioural or physiological implications, all hope is not lost.  It may be that the brain heals itself and these functional deficits resolve in time.  Indeed, in one Oxford study, scientists observing cognitive difficulties (aka. brain fog) in a group who had mild Covid also noted that after six to nine months these people recovered from the deficits.

It may also be that something can be done to treat symptoms of Covid.  In support of this concept, the BBC article on Monday featured a woman who lost her sense of smell after having Covid and, with help from the charity AbScent, is retraining her brain to regain it.  So, people with anosmia or brain fog, there is hope for recovery.

As unnerving as this article may have been to people suffering the effects of Covid, acute or long, don’t stress; it is not definitive. Instead, it raises more questions about what happens in the brain in Covid survivors. Is this alteration in size physiologically significant?  Is it the cause of symptoms or the result of a loss of sensory input?  Is this a permanent change?  Will it recover on its own?  Is there some brain re-training required?

What it does is to inspire scientists to look further.  Research is geared up and new data is emerging frequently.  It may take a little time for these questions to be answered.  But the first stage in getting to the answers is asking the right questions.  And the scientists are doing just that. 

And, if any of this worries you, talk to your doctor.

[1] The Teenage Brain: A Neuroscientist's Survival Guide to Raising Adolescents and Young Adults, by Frances E. Jensen, M.D., HarperCollins Publishers (1 Jan. 2015)

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