The hidden long-term cognitive effects of COVID-19 – Harvard Health Blog

The COVID pandemic has now claimed as many American lives as World War I, the Vietnam War and the Korean War combined. Most of these deaths are due to the well-known pulmonary complications of the coronavirus. However, it is increasingly recognized that the virus also attacks the nervous system. Doctors at a large Chicago medical center found that more than 40% of patients with COVID had neurological manifestations early on, and more than 30% of these had impaired cognition. Sometimes the neurological manifestations can be devastating and even lead to death.

However, new research now suggests there could be long-term neurological consequences in those who survive COVID infections, including more than seven million Americans and 27 million people worldwide. Particularly disturbing is the growing evidence that there may be mild – but very real – brain damage that occurs in many survivors, causing pervasive yet subtle cognitive, behavioral and psychological problems.

How COVID damages the brain

COVID can cause brain damage directly from encephalitis, which can have devastating or subtle consequences. In a UK study of 12 patients with encephalitis, one recovered fully, 10 recovered partially and one died. This study also found that a number of patients with COVID have suffered strokes. In fact, COVID infection is a risk factor for stroke. A group of Canadian doctors have found that people over the age of 70 are particularly at risk of stroke from COVID infection, but even young individuals are seven times more likely to have a stroke of this coronavirus compared to a typical influenza virus.

Autopsy data from COVID patients in Finland suggests that another major cause of brain damage is lack of oxygen. Of particular concern is the fact that several of the autopsied patients showed no signs of brain damage during their COVID infection – but all had brain damage. In one patient, there was loss of taste, and in two, “minimal respiratory distress”, but neither patient appeared to have suffered brain damage during their lifetime.

Main cognitive effects of COVID

Among survivors of an intensive care unit (ICU) stay with acute respiratory failure or shock from any cause, one-third of people have a degree of cognitive impairment so profound that Performance on neuropsychological tests is comparable to those with moderate head trauma. In everyday life, these cognitive effects on memory, attention, and executive function can lead to difficulties in managing medications, managing finances, understanding written documents, and even maintaining conversations with friends and family. . Commonly observed long-term psychological effects of intensive care stays include anxiety, depression, and post-traumatic stress disorder (PTSD). The effects of COVID stays in intensive care are expected to be similar – a prediction that has already been confirmed by studies in Britain, Canada and Finland reviewed above.

Subtle cognitive effects of COVID

It is clear that COVID can cause brain damage through direct infection (encephalitis), stroke, and lack of oxygen. It is also clear that when patients suffer from a serious illness requiring a stay in intensive care, brain damage is very likely to occur and its effects are usually evident. But what if the COVID disease isn’t that bad? Can brain damage still occur?

A Chinese group of doctors and researchers examined several aspects of cognitive function in 29 people who were thought to have fully recovered from COVID infection. They found a persistent impairment in sustained attention – the ability to attend to important information as long as it is relevant.

Long-term cognitive effects of COVID infection

Why would sustained attention be constantly diminished in people who are believed to have fully recovered from COVID? The Chinese group thought it could be linked to underlying inflammatory processes. But it’s just as likely that patients with COVID suffered silent strokes or lack of oxygen that damaged their brains. As discussed above, strokes from COVID are common, especially among those over 70. We know that silent strokes occur frequently and are a risk factor for both major strokes and dementia. Silent strokes typically affect the brain’s white matter – the wiring between brain cells that allows different parts of the brain to communicate with each other. This wiring is essential for attention, and when damaged, sustained attention is impaired.

The bottom line

There is one inevitable conclusion from these studies: COVID infection frequently leads to brain damage – especially in those over 70. While sometimes the brain damage is obvious and leads to major cognitive impairment, more frequently the lesions are benign, causing difficulty in sustained attention. .

While many people who have recovered from COVID can resume their daily lives without difficulty – even if they have attention deficits – there are a number of people who may experience difficulty now or in the future. A recently published article by a group of German and American doctors concluded that the combination of the direct effects of the virus, systemic inflammation, stroke, and damage to bodily organs (like the lungs and liver) could even make COVID survivors at high risk of Alzheimer’s disease. In the future. People whose professions involve medical care, legal advice, financial planning, or leadership – including political leaders – may need to be carefully assessed with formal neuropsychological tests, including sustained attention measures, for s ‘ensure that their cognition has not been compromised.

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Jothi Venkat

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