A recent UK study suggests that blood clots in the brain or lungs may explain some of the common symptoms experienced by people with "long Covid", including brain fog and fatigue. The study, which included 1,837 people admitted to hospital due to Covid, found that two blood proteins, fibrinogen and D-dimer, were associated with cognitive problems. It is estimated that 16% of these patients experience difficulties with thinking, concentrating, or remembering for at least six months.
However, it is important to note that these findings are only relevant to patients who were admitted to hospital and further research is needed to propose or test potential treatments. The study tracked cognitive problems at six and 12 months using tests and questionnaires, which may not be sensitive enough to capture all symptoms.
The research team, comprised of scientists from the universities of Oxford and Leicester, emphasize that there may be many different causes of long Covid. Professor Paul Harrison from the University of Oxford, one of the study authors, described these findings as a "key step" in understanding post-Covid brain fog.
According to Professor Chris Brightling, a respiratory medicine expert at the University of Leicester, the development of long Covid is influenced by a combination of factors, including a person's pre-existing health, the severity of the acute infection, and what happens afterwards.
The study highlights the experiences of individuals who are still struggling with cognitive problems after recovering from Covid. Dr Simon Retford, a university lecturer from Lancashire who spent two weeks in a coma due to Covid, continues to experience difficulties with concentration, short-term memory loss, and losing his train of thought. He compares his mental functioning to a slow computer and acknowledges that he may never fully recover. However, he remains optimistic and grateful for his survival.
The study, called the Post-hospitalisation Covid-19 study (PHosp-Covid), published in Nature Medicine, found that higher levels of fibrinogen and D-dimer were associated with brain fog. Fibrinogen may directly affect the brain and its blood vessels, while D-dimer often indicates blood clots in the lungs. Individuals with high D-dimer levels also reported extreme tiredness, shortness of breath, and difficulties with employment. A similar study in the US yielded similar results.
Overall, this research contributes to the understanding of long Covid and its potential causes. However, further investigation is necessary to develop effective treatments and address the diverse range of symptoms experienced by individuals with long Covid.