COVID-19 is linked to an increased risk of developing brain fog and dementia after an infection, according to a recent medical study.
More than 596 million COVID-19 cases have been recorded globally — including nearly 10 million in Australia — and many of the long-term impacts are yet to be seen.
However, the recent study helps shed light on the risk of neurological disorders after an infection.
Here's what we know about brain fog and how COVID-19 affects your brain.
Is brain fog a symptom of long COVID?
Yes, some people develop neurological symptoms after being infected.
While brain fog isn't a medical term, it's generally used for certain symptoms that can affect your ability to think.
Respiratory Physician Anthony Byrne says brain fog is one of the most common symptoms he's seen—and he works in Australia's first long COVID clinic, at St Vincent's Hospital in Sydney.
"It's a serious problem. Many patients come to see us because they are unable to perform their usual activities including work and study due to their post-COVID neurological effects," he says.
"But there is a spectrum — some are mild and their change in cognition is barely noticeable whilst others are unable to work at all."
Australia's Health Department also notes one of the most common neurological symptoms is, "difficulty concentrating … what's often called brain fog, where people just are unable to think clearly".
How does COVID-19 affect the brain?
Two years after having COVID-19, diagnoses of brain fog, dementia and epilepsy are more common than after other respiratory infections, according to the recent study by the University of Oxford.
But anxiety and depression are no more likely in adults or children two years on, the research published in the Lancet Psychiatry found.
Experts say more research is needed to understand how and why this happens after a COVID-19 infection, and what can be done to prevent or treat these disorders from occurring when they do.
The study looked at the risks of 14 different disorders in 1.28 million patients over a two-year period from patients in the US and several countries, including Australia.
Dr Byrne says the study is consistent with what he's seeing among his patients in Sydney.
"The good news is that the study shows children are not as severely affected on the whole and tend to recovery over a finite time," he says.
In June, researchers at La Trobe University found "toxic clumps of protein", or amyloid assemblies, appearing in the brain after a COVID-19 infection appeared to be similar to those found in Alzheimer's disease and dementia.
They said this may have been responsible for some of the neurological symptoms of long-COVID, or what many call "brain fog".
Authors of the study, published in Nature Communications, cautioned that the implications of the changes were unclear and did not necessarily suggest lasting damage.
Do variants carry greater risk?
Yes, researchers found more neurological and psychiatric disorders were seen during the Delta variant wave than with the prior Alpha variant.
The Omicron wave was linked with similar neurological and psychiatric risks as Delta.
Although, the University of Oxford study notes it has several limitations.
It's not known how severe, or how long-lasting, the disorders are. Nor is it clear when they began, since problems may be present for some time before a diagnosis is made. As well, unrecorded cases of COVID-19 and unrecorded vaccinations introduce some uncertainty to the results.
What should you do if you may be experiencing COVID-19 brain fog?
Visit your doctor and let them know all of the ongoing symptoms you're experiencing, lecturer in neurology at Harvard Medical School Andrew Budson says.
"This includes your brain fog and other neurological symptoms, such as weakness, numbness, tingling, loss of smell or taste, and also problems such as shortness of breath, palpitations, and abnormal urine or stool."
As for brain fog, what might help?
To help clear brain fog as best possible, Dr Budson recommends the following to boost thinking and memory:
- Get some exercise. You may need to start slow, perhaps just two to three minutes a few times a day. While there is no established "dose" of exercise to improve brain health, 30 minutes a day, five days a week is generally recommended.
- Eat Mediterranean-style meals. A healthy diet including olive oil, fruits and vegetables, nuts and beans, and whole grains has been proven to improve thinking, memory and brain health.
- Avoid alcohol and drugs. Give your brain the best chance to heal by avoiding substances that can adversely affect it.
- Sleep well. Sleep is a time when the brain and body can clear out toxins and work toward healing. Give your body the sleep it needs.
- Participate in social activities. We are social animals. Not only do social activities benefit our moods, but they help our thinking and memory as well.
- Pursue other beneficial activities, including engaging in novel and cognitively stimulating activities, listening to music, practising mindfulness and keeping a positive mental attitude.
It should be noted that this is general advice. As yet, Dr Byrne says there are no specific proven, medically prescribed therapies to treat "brain fog". So keep in mind:
- Pace yourself and give yourself time to recover. Everybody's journey is different. Don't be too hard on yourself if you are not meeting your expectations for recovery.
- See your GP and consider specialist referral if there are "red flag" symptoms that could be new-onset dementia or epilepsy.
