Brain Fog and Long Covid

Dr Steve Allder, Consultant Neurologist at Re:Cognition Health:


It is unknown who is most affected by cognitive complaints induced by Covid-19 and how long they persist; however, patient experiences and published summaries of long Covid have described “brain fog” to be a common and debilitating symptom. It is thought that up to three quarters of people suffering with Long Covid effects experience problems with their memory, attention and other cognitive functions.


People with Long Covid exhibit involvement and impairment in the structure and function of multiple organs. Numerous symptoms of Long Covid have been reported and attributed to various organs including the heart, spleen, liver, blood vessels, gastrointestinal tract, kidney, pancreas, lung and brain.


Studies have explored cognitive function and deficits in patients with Covid-19 and suggest that the virus can cause septic encephalopathy, non-immunological effects such as hypotension, hypoxia, and vascular thrombosis, and immunological effects such as adaptive autoimmunity, microglial activation, and a maladaptive cytokine profile. Additionally, patients admitted to hospital with Covid-19 have presented with a range of complaints including encephalopathy, cognitive impairment, cerebrovascular events/disease, seizures, hypoxic brain injuries, corticospinal tract signs, dysexecutive syndrome, an altered mental status, and psychiatric conditions. These findings reveal that neurological symptoms associated with Covid-19 are common, diverse, and could pose substantial problems for rehabilitation and ongoing care following recovery from Covid-19.


There are many ways patients with Covid can develop brain fog. In patients who have a severe acute respiratory syndrome, or need long-term ventilator support, both of these conditions are known to have detrimental effects on long term cognition. A retrospective study of 1040 ICU treated patients, conducted before the pandemic, found that 71% had delirium which lasted around four months following discharge. A further study found that, at 3 months post-discharge, 40% of ICU treated patients had cognition scores like those of patients with moderate traumatic brain injury, while 26% had scores similar to patients with mild Alzheimer’s disease. Delirium was also widely reported, with a longer duration of delirium associated with worse cognition.


Other patients develop brain fog is association with other new neurological conditions such as stroke and headache. The ONS estimating the 5week prevalence of headache at 10.1% of all Covid-19 survivors. Exaggerated levels of systemic inflammation, observed in some patients as a “cytokine storm,” in addition to activation glial cells, poses a substantial risk to the brain and increases the likelihood of neurological manifestations including encephalitis and stroke. Hypercoagulability and cardio-embolisms, formed because of virus related cardiac injury, are manifestations that could result in increased incidences of stroke following Covid-19 infection. Covid-19 has also been associated with an increased risk of developing neurological conditions including Guillain-Barré syndrome, and neurodegenerative conditions such as Alzheimer’s disease.


Other patients will have brain fog secondary to psychiatric and psychological complications of COVID. People who have had Covid-19 can exhibit long term psychiatric symptoms including post-traumatic stress disorder (PTSD), depression, anxiety, and obsessive-compulsive symptom.


All of us will have been affected by quarantine, isolation, and social distancing, which are potentially  damaging effects to our mental health and cognition. The longer a person is confined to quarantine, the poorer the outcomes for their mental health and cognition, while periods of isolation and the inability to work can cause anxiety, loneliness, and financial concerns, and living through a global health crisis can lead to avoidance behaviors and behavioral changes. The mental health of the older population is greatly affected by social distancing and similar measures.


By assessing the associations between loneliness, physical activity, and mental health both before and during the pandemic, one study found that negative changes of these factors were not solely owing to longitudinal situations before 2020, therefore the pandemic exerted extra unfavorable effects on loneliness, physical activity, and mental health. People living in care homes, including people with dementia, are vulnerable to Covid-19 and to other impacts of the pandemic. Those with dementia in care homes have been observed to become more depressed, anxious, agitated, and lonely. Protracted social isolation has resulted in exacerbation of neuropsychiatric and behavioral disturbances, including apathy, anxiety, agitation, boredom, and confusion in dementia patients living in care homes, to a greater degree than for care home residents without dementia.


Sleeplessness is also commonly reported following recovery from Covid-19, with many studies finding poor sleep quality and sleep disturbances to be frequent following recovery from acute illness. Furthermore, a retrospective study of medical records of Covid-19 patients treated in Seoul, South Korea, found that after prescriptions to treat fever, cough, and rhinorrhea, medications for sleep problems were the next most prescribed treatments. Knowledge of the Covid-19 death toll also has a negative impact on quality of sleep, stress, anxiety, and other negative emotions, and sleep problems have been shown to be associated with Covid-19 related loneliness. This leads us to question whether post-Covid-19 sleep disturbances are a result of Covid-19 infection, the negative effects of the pandemic, or a combination of both.


Evidence specific to Covid-19 is lacking, therefore cognitive impairment should be managed with support, including setting tailored, achievable goals and implementing validated screening tools. Managing cognitive impairment will require a holistic approach, however, patients should be advised that most people gradually recover from cognitive impairment following severe illness. The holistic approach to treatment should extend to the services offered, with professionals including occupational and speech and language therapists addressing cognitive changes.


If you or any of your loved ones are experiencing debilitating effects of Long Covid or if the symptoms are negatively impacting your quality of life, it’s important to consult with a medical professional to optimise treatment and recovery.



For further information on Re:Cognition Health’s Long Covid Clinic visit:



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