COVID-19, Cognitive Impairment and Dementia

COVID-19 (coronavirus disease) is an infectious disease caused by the SARS-CoV-2 virus. Neuropsychiatric symptoms can occur in people during the acute COVID-19 illness, and can persist or develop afterwards, as part of “long COVID”.

COVID-19 causes brain dysfunction through various mechanisms. SARS-CoV-2 infection can cause neuroinflammation, cytokine storm, microglial activation, and endothelial dysfunction, which lead to neurotoxicity, altered neurotransmission, hypoxic ischemic injury, microstrokes, and neuronal damage. Long COVID has also been associated with reduced serotonin levels, a neurotransmitter important for mood and memory.

Neuropsychiatric symptoms of COVID-19 may include fatigue, sleep disturbances, depression, anxiety, and cognitive dysfunction, with changes in memory, attention and concentration, executive function, language, and slowness in thinking.  Headaches, muscle aches, loss of sense of smell and/or taste are also common neurologic symptoms due to COVID-19.

Among people who had mild to moderate COVID-19 with persistent symptoms of depression and cognitive changes after their illness, a neuroimaging study found they had abnormal microglial activation in certain areas of the brain, and these changes were also associated with slower motor speed.

People with SARS-CoV-2 infection have been found to have a higher risk of developing a new diagnosis of Alzheimer’s disease within a year from their infection, especially women and people older than 85. SARS-CoV-2 infection can also increase the risk of stroke, which can result in vascular dementia.

Although cognitive impairment and dementia are associated with COVID-19, a person should not assume that their symptoms have been caused by COVID-19 alone. A comprehensive evaluation remains important in uncovering all the conditions that could be contributing to a person’s symptoms, especially since some may be treatable.

References and Resources

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