Study explores ‘brain fog’ following COVID-19

Many individuals infected with the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) have experienced persistent health issues.

A recent survey conducted in the United Kingdom revealed that approximately one in every five experiences prolonged coronavirus disease 2019 (COVID-19) symptoms five weeks post-infection. Also, one in seven people reported persistent symptoms even after twelve weeks.

Further, one in ten people was found to remain sick even one year after the COVID-19 infection. This group of individuals is said to be suffering from "long COVID."

People suffering from long COVID experience a reduction in their ability to carry out certain everyday activities or return to work many weeks after the initial COVID-19 diagnosis.

Long COVID symptoms

Scientists have defined long COVID as a condition of post-acute COVID-19 syndrome, where symptoms persist between 4 and 12 weeks post-infection. It also includes chronic COVID-19 disease, where symptoms are retained beyond 12 weeks.

Individuals who suffer from long COVID often complain of wide-ranging fluctuating symptoms, such as fatigue, chest pain, breathlessness, autonomic nervous system disruption and cognitive dysfunction.

Even though the underlying pathophysiology behind the above-stated long COVID symptoms remains unclear, scientists have explained the probable reasons that result in these conditions. They stated that persistent viremia, deconditioning, relapse or reinfection, inflammatory immune reactions, and several psychological factors are potential contributors to long COVID.

Previous studies reported that almost a quarter of a million COVID-19 recovered patients, both hospitalized and non-hospitalized, had succumbed to certain neurological and psychiatric conditions. However, severely infected patients are most prone to these conditions.

Approximately 25% of patients experienced disturbing moods, such as anxiety. Some patients also report experiencing serious problems like psychosis.

Several other neurocognitive symptoms experienced by this group include cerebrovascular events, insomnia, dementia, encephalitis, and disorders of peripheral nerves, nerve roots, or plexus.

Additionally, previous surveys associated with non-hospitalized long COVID patients reported short-term memory, attention disorders and a general befuddled state of mind, which has been called "brain fog."

Brain fog and COVID-19

Even though adolescents and children are considered at low risk of COVID-19 infection, recent research highlighted that brain fog was also found in this group.

Scientists have identified various possible pathophysiologies for brain fog, such as direct neuroinvasion, neuronal injury or toxicity, glial activation, viral persistence and chronic inflammation, microvascular injury, Lewy body production, and activation of autoimmune mechanisms.

Previous studies related to bioimaging had revealed a differential loss of grey matter, in COVID-19 patients, in several key regions of the brain. As a result, individuals suffering from such cognitive impairments face immense difficulties in their daily activities, such as making decisions, communicating, and maintaining social relationships.

A new study

A new study published on the medRxiv* preprint server has focussed on three main areas, i.e., a) neurocognitive symptoms experienced by adults with long COVID, b) impact of long COVID symptoms on these individuals, and c) how do these individuals handle the situation? Further, the researchers of this study also aimed to reveal the mechanism behind psycho-cognitive processes and the pathological effects behind long COVID.

This study contained a total of 50 participants, among which 23 were recruited from a previous qualitative study associated with lived experience of long COVID patients, and 27 participants were recruited from online support groups with persistent neurological problems following COVID-19 infection.

In this study, 84% of the participants were female and 60% belonged to White British ethnicity. All the participants were invited to describe their cognitive symptoms, and researchers followed them up via email, 4-6 months later.

The authors of this study audiotaped, transcribed, anonymized the data, and coded using the qualitative data analysis computer software, NVIVO. These data were analyzed by an interdisciplinary team, whose expertise extends across clinical neuroscience, general practice, and the sociology of chronic illness. The interpretation was subsequently evaluated by three people who experienced brain fog.

The qualitative analysis revealed mixed views on the description of the term "brain fog." However, researchers obtained detailed descriptions of the experiences of the participants related to neurocognitive impairments, i.e., disorders associated with attention, memory, and language and executive functions. They reported on the fluctuations in the symptoms. Some of the participants revealed that they recovered from all these symptoms over time.

Researchers established the interaction between cognitive and physical symptoms, along with the psychosocial impact on professional and personal activities. The participants used several strategies to mitigate the effects of brain fog, e.g., communication strategies; however, these strategies had only minimal success.

These qualitative findings add to the research about the epidemiology and pathophysiology underlying symptoms caused by COVID-19. These patients should be provided with the following services: an ongoing therapeutic relationship with a clinician who engages with the illness within its personal, social, and occupational context, as well as access to specialist services that are comprehensive, interdisciplinary, and easily navigable.

Limitations of the study

One of the limitations of this study is that the samples were entirely UK-based. Further, researchers could not include samples from different demographics, minority ethnic groups, and the diversity in occupational classes was also not well captured. Lastly, the participants mainly were infected during the first wave of the COVID-19 pandemic, and long COVID has changed substantially since then.

The researchers conclude, "In dealing with COVID-19, it is crucial that health policy begins to shift from acute disaster response to managing a chronic crisis. This study has brought neuroscientists and qualitative researchers to align the subjective illness experience as directly described by patients with the objective disease models that underpin therapeutic options for ongoing 'brain fog' experienced by long COVID patients. The profoundly disabling, persistent impacts in some people revealed here adds weight to arguments that we need to prevent COVID -19 to reduce the long-term burden of this disease on patients, the health service, and the wider economy. Moreover, it is crucial to mitigate the impact for those already affected through a better understanding of the pathophysiological mechanisms of this neurotrophic virus and further exploration of the best approaches to support cognitive, psychological, and occupational restoration."

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Written by

Dr. Priyom Bose

Priyom holds a Ph.D. in Plant Biology and Biotechnology from the University of Madras, India. She is an active researcher and an experienced science writer. Priyom has also co-authored several original research articles that have been published in reputed peer-reviewed journals. She is also an avid reader and an amateur photographer.