Covid patients face increased risk of dementia and psychosis after 2 years, study finds
The risk of neurological and psychiatric conditions such as dementia, psychosis and seizures is higher two years after a Covid infection than it would be with comparable respiratory infections, research suggests.
The study from the University of Oxford and the National Institute for Health and Care Research (NIHR), published in the Lancet medical journal, analysed neurological and psychiatric diagnoses in over 1.25 million people following a Covid infection.
It compared these diagnoses to those recovering from other respiratory illnesses.
Since the early stages of the pandemic, Covid has been known to be associated with an increased risk of many long-term neurological and psychiatric consequences.
However, until now, there has been no large-scale data examining the risks of these diagnoses over a longer time period.
The good news from the study is that anxiety and depression were found to subside within two months after Covid infection.
After the initial increase, the risks for a depression or anxiety diagnosis dropped to below that of the control group, meaning that after two years, there was no difference in the overall incidence of depression and anxiety between the Covid group and the other respiratory infections group.
The bad news, however, confirms what was already believed by researchers, with diagnoses of brain disorders such as dementia and seizures more prevalent in adults who have had Covid, even after two years.
The same applies to psychotic disorders and "brain fog," a type of cognitive decline which includes reduced concentration and memory in sufferers.
Adults aged 18-64 who had Covid up to two years previously had a higher risk of brain fog and muscle disease.
Adults aged 65 and over had a higher occurrence of brain fog, dementia and psychotic disorder.
The likelihood of most neurological and psychiatric diagnoses after Covid was lower in children than in adults, and they were not at greater risk of anxiety or depression than children who had other respiratory infections.
However, like adults, children were more likely to be diagnosed with some conditions – including seizures and psychotic disorders – over the two years following Covid.
Professor Paul Harrison, from the department of psychiatry at the University of Oxford, said it is "good news" that the excess of depression and anxiety diagnoses after Covid is short-lived, but that it is "worrying" that some other disorders, such as dementia and seizures, continue to be more likely to be diagnosed.
The picture remains the same for all those infected with Covid – regardless of the severity of the strain – with an increased risk of psychotic disorder, cognitive deficit, dementia, and epilepsy or seizures persisting throughout.
The fact that outcomes were similar during the delta and omicron waves indicates that the burden on the healthcare system might continue even with variants that are less severe in other respects.
NIHR Academic Clinical Fellow Dr Max Taquet, who led the analyses, said: "The findings shed new light on the longer-term mental and brain health consequences for people following Covid infection.
"The results have implications for patients and health services and highlight the need for more research to understand why this happens after Covid, and what can be done to prevent these disorders from occurring, or treat them when they do."
