As more and more people get vaccinated against COVID-19, we begin see a light at the end of the tunnel. However, long-term side effects of the disease remain to be reckoned with. “Brain fog”, a set of long-term cognitive and memory impairments that persist even after recovering from the acute effects of COVID-19, is one such side effect reported by numerous people, even after milder cases.

Recent studies have indicated that the SARS-CoV-2 virus can affect the central nervous system, including the brain. One of the ways in which it is thought to act within the brain is by selectively targeting the mitochondria of neurons, compromising these cells’ metabolic rates by, essentially, “hijacking” the mitochondrial genome. 

Impairing mitochondrial metabolism leads to chronic hypoxia, a state of low oxygen supply. Brains are especially vulnerable to hypoxia because they require a large and constant supply of oxygen. In hypoxic conditions, oxygen-hungry neurons — such as those involved in important cognitive functions — become dysfunctional. This starts a vicious cycle: low-oxygen environments also promote viral replication and survival. As a person's viral infection worsens, their oxygen levels drop more, causing further cognitive impairment and confusion.

Deeper investigation into the long-term side effects of COVID-19 will be imperative, even after societal life eventually returns to normal. But studies examining the mechanisms behind COVID-associated brain fog provide a path toward treatment, hopefully alleviating symptom for people experiencing it.