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

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

However, new research suggests that there may be long-term neurological consequences for those who survive COVID infections, including more than seven million Americans and another 27 million people worldwide. Particularly troubling is the mounting evidence that many survivors can experience mild – but very real – brain damage that causes ubiquitous but subtle cognitive, behavioral, and psychological problems.

How COVID damages the brain

COVID can damage the brain directly through encephalitis, which can have devastating or subtle consequences. In a UK study of 12 patients with encephalitis, one made a full recovery, 10 recovered partially and one died. This study also found that a number of patients with COVID had strokes. Indeed, COVID infection is a risk factor for stroke. A group of Canadian doctors found that people over the age of 70 were at a particularly high risk of stroke related to COVID infection, but even young people are seven times more likely to have a stroke with this coronavirus than a typical flu virus.

Autopsy data from COVID patients in Finland suggests that another leading cause of brain damage is oxygen starvation. Of particular concern is that some of the autopsied patients showed no signs of brain injury in the course of their COVID infection – but all of them had brain damage. One patient experienced loss of taste and two patients had "minimal breathlessness", but none of these patients were believed to have had brain damage during their lifetime.

Important cognitive effects of COVID

In ICU survivors due to acute respiratory failure or shock for any reason, one-third of people have such a degree of cognitive impairment that performance on neuropsychological tests is comparable to that of moderate traumatic brain injury. In everyday life, such cognitive effects on memory, attention, and executive function can lead to difficulties in drug use, financial management, understanding written materials, and even talking to friends and family. Commonly observed long-term psychological effects of intensive care are anxiety, depression, and post-traumatic stress disorder (PTSD). The effects of COVID stays in the ICU are expected to be similar – a prediction that has already been confirmed by the studies in the UK, Canada and Finland discussed 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 patients with severe illness requiring intensive care units are more likely to experience brain damage and the effects are usually evident. But what if COVID disease isn't that severe? Can there still be brain damage?

A Chinese group of doctors and researchers studied various aspects of cognitive function in 29 people believed to have fully recovered from COVID infection. They noted a persistent impairment of sustained attention – the ability to handle important information for as long as it is relevant.

Long-term cognitive effects of COVID infection

Why should sustained alertness be permanently impaired in people believed to have fully recovered from COVID? The Chinese group believed this could be related to the underlying inflammatory processes. However, it's just as likely that patients with COVID have suffered silent strokes or a lack of oxygen that damaged their brains. As explained above, strokes due to COVID are common, especially among those over 70. We know that silent strokes are common and a risk factor for both major strokes and dementia. Silent strokes usually 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 if broken it will compromise continued attention.

The final result

An inevitable conclusion emerges from these studies: COVID infection often leads to brain damage – especially in those over 70. While the damage to the brain is sometimes obvious and leads to serious cognitive impairment, more often the damage is minor, leading to difficulty with sustained attention.

Although many people who have recovered from COVID can easily return to their daily lives – even if they have some deficits in attention – there are a number of people who may have difficulties now or later. A recent article by a group of German and American doctors concluded that the combination of direct effects of the virus, systemic inflammation, stroke, and damage to body organs (such as the lungs and liver) could put even COVID survivors at high risk of Alzheimer's disease in the future. Individuals whose professions include medical care, legal advice, financial planning, or leadership – including political leaders – may need to be carefully assessed using formal neuropsychological testing, including sustained alertness measures, to ensure that their cognition has not been compromised.