COVID-19, caused by the SARS-CoV-2 virus, can affect the nervous system. The impact ranges from mild, transient symptoms during the acute infection to more severe and sometimes long-lasting conditions. These effects can involve various parts of the nervous system, including the brain, spinal cord, and peripheral nerves. Understanding these manifestations is important for recognizing the illness’s full scope.
How COVID Impacts the Nervous System
SARS-CoV-2 can affect the nervous system through multiple pathways. While direct viral invasion of brain cells is a possibility, research suggests it may not be the primary mechanism for most neurological symptoms. The virus uses the ACE2 receptor to enter host cells, present on various cell types, including some in the brain and blood vessels.
The body’s immune response to infection is a key driver of neurological issues. An overactive immune reaction, often referred to as a “cytokine storm,” can lead to widespread inflammation. This systemic inflammation can damage brain tissue and nerve cells, contributing to neurological symptoms.
COVID-19 also affects the vascular system, increasing the risk of blood clots. These clots can lead to cerebrovascular events, such as strokes, by blocking blood supply to the brain. Damage to endothelial cells lining blood vessels can further impair blood flow and brain function. Additionally, severe respiratory complications from COVID-19 can result in reduced oxygen supply to the brain (hypoxia), which can damage brain cells and contribute to neurological problems.
Neurological Symptoms During Acute Infection
During acute COVID-19 infection, various neurological symptoms can emerge. Common early signs include loss of smell (anosmia) and taste (ageusia). These sensory changes are frequently reported and can occur even without other typical respiratory symptoms.
Many also experience generalized neurological symptoms. These include headaches, fatigue, and dizziness. Some patients may also develop confusion or delirium, particularly older adults or those with more severe illness.
Less common but serious acute neurological complications can also arise. These include stroke, linked to COVID-19’s blood clotting abnormalities. Seizures and encephalitis (brain inflammation) have also been reported in some patients. The peripheral nervous system can also be involved, leading to muscle pain. In rare instances, an autoimmune condition called Guillain-Barré syndrome (GBS), an autoimmune condition attacking peripheral nerves, has been observed after COVID-19.
Persistent Neurological Conditions After COVID-19
Long COVID, or post-acute sequelae of COVID-19 (PASC), encompasses neurological issues persisting weeks to months after initial infection. A common symptom is “brain fog.” This involves difficulties with concentration, memory problems, and impaired cognitive processing.
Chronic fatigue is another long-term neurological condition, characterized by persistent tiredness impacting daily life. Lingering headaches and recurrent dizziness are common. Many individuals report sleep disturbances, including insomnia or difficulty falling and staying asleep.
Sensory changes can also persist beyond the acute phase. This includes prolonged or returning loss of smell and taste, or distorted senses like parosmia and phantosmia. Autonomic nervous system dysfunction (dysautonomia) is increasingly recognized. Symptoms can include heart rate irregularities, blood pressure fluctuations, digestive issues, and orthostatic intolerance (symptoms worsening upon standing, similar to Postural Orthostatic Tachycardia Syndrome (POTS)).
Mood disorders like anxiety and depression can develop or worsen. Some individuals also experience neuropathic pain (lingering nerve pain or tingling sensations). These persistent neurological effects highlight COVID-19’s ongoing impact on the nervous system.