Why some people get long COVID

Key points:

• 10 – 20 percent of people experienced a variety of mid- and long-term effects after their initial infection

• Up to 100 different symptoms have been recorded as part of the long COVID disease profile

• 128 people were involved in the University of New South Wales study, which found that a prolonged activation of the kynurenine — metabolic — pathway was closely associated with mild cognitive deficits for 12 months after initial infection

Researchers from the UNSW School of Psychology and Faculty of Medicine & Health have found that the activation of a metabolic pathway, known as the ‘kynurenine pathway,’ is closely associated with mild cognitive deficits in the 12-month period following initial COVID-19 infection.

‘Long COVID’ is characterised by fatigue, concentration difficulties, short-term memory loss, shortness of breath and flu-like symptoms in the aftermath of COVID-19 infection, although most people were likely to recover from continued symptoms within three to four months.

UNSW Associate Professor Lucette Cysique explained that the new study, in addition to the earlier St Vincent’s COVID-19 ADAPT study, found that ‘brain fog’ is associated with a “dysregulation of the immune response.”

“I think when patients go to the doctor’s with brain fog, it may be dismissed as a psychological problem. Our study speaks to the contrary, that there is a real biological mechanism behind long COVID brain fog,” A/Prof Cysique said.

“These findings lay the foundation for the kynurenine pathway as a potential diagnostic and monitoring marker, as well as a possible therapeutic target.

“Long COVID is a multi-organ disease, so people are differently affected across several of their body functions. This is not surprising as the immune system is involved across all body functions,” A/Prof Cysique continued.

“However, we now know that besides fatigue, cognitive changes are the most common symptoms associated with long COVID.

“With a little introspection, we can all imagine how long-term flu-like physical and mental fatigue would impact everyday function […] we are talking of mostly working-age people. Hence, these types of deficits can affect work efficiency to some degree and probably contribute to the economic impact of the pandemic.”

A/Prof Cysique and her team discovered that at two months, when the kynurenine pathway was the most activated, 60 percent of those who showed mild cognitive deficits, such as in attention/concentration and speed processing, showed an abnormal activation of the kynurenine pathway.

Notably, no other blood evidence, sex or clinical factors such as pre-existing or COVID-associated mental health, disease severity or respiratory function and sense of smell — were associated with cognition.

In Australia, long COVID is not considered a permanent disability, so people with the condition can’t access disability supports.

However, support is usually available through the health system and keeping in touch with your GP while you recover from COVID-19 can ensure you are given any medicine or treatment that might help with management.

To learn more about how you can manage COVID-19 at home with disability, please refer to the Disability Support Guide for symptom management. Let us know what your experience with COVID or long COVID was like on the Talking Disability social media platforms: Facebook, Twitter/X and LinkedIn.