A third of COVID-19 survivors suffer from long-term brain or psychiatric disorders, scientists reported Tuesday.

Researchers studied more than 236,000 patients, mostly in the U.S., finding that 34% of survivors were diagnosed with a neurological or psychological condition within six months of infection. Researchers call it the largest study to date on the connection between coronavirus and brain health.

Researchers looked at 14 neurological and mental health disorders in total. According to the observational study, published Tuesday in the journal Lancet Psychiatry, anxiety was the most common diagnosis, affecting 17% of survivors.

The neurological effects were more severe among patients who had been hospitalized — but remained common even in less severe cases. Mood disorders were the second-most common diagnosis, at 14%, followed by substance misuse disorders at 7% and insomnia at 5%.

Neurological diagnoses, like stroke and dementia, were rarer, but not uncommon. Among patients admitted to intensive care with severe COVID-19, 7% had a stroke within six months, and nearly 2% were diagnosed with dementia.

For 13% of patients, it was their first recorded neurological or psychiatric diagnosis.

"These are real-world data from a large number of patients. They confirm the high rates of psychiatric diagnoses after COVID-19 and show that serious disorders affecting the nervous system (such as stroke and dementia) occur too," lead author Paul Harrison said in a statement Wednesday. "While the latter are much rarer, they are significant, especially in those who had severe COVID-19."

Researchers compared the electronic health records of COVID-19 patients to those who experienced other respiratory infections during the same time period. Taking into account underlying health characteristics, they found that those with coronavirus had a 44% higher chance of neurological or psychiatric diagnoses compared to patients recovering from influenza, and a 16% greater risk than those with other respiratory tract infections.

Previous research by the same scientists last year found that 20% of coronavirus survivors were diagnosed with a psychiatric disorder within just three months.

"Our results indicate that brain diseases and psychiatric disorders are more common after COVID-19 than after flu or other respiratory infections, even when patients are matched for other risk factors," said co-author Max Taquet. "We now need to see what happens beyond six months. The study cannot reveal the mechanisms involved, but does point to the need for urgent research to identify these, with a view to preventing or treating them."

Researchers are concerned that long-term brain or psychiatric disorders could put even further strain on a health care system already pushed to its limits.

"Although the individual risks for most disorders are small, the effect across the whole population may be substantial for health and social care systems due to the scale of the pandemic and that many of these conditions are chronic," Harrison said. "As a result, health care systems need to be resourced to deal with the anticipated need, both within primary and secondary care services."

Researchers noted several setbacks to the study, including that patients with medical records of their symptoms are likely those to have been more severely affected by COVID-19. Additionally, the severity of the brain disorders in these patients is not known.

Because the study was observational, researchers could only note associations, not causality. However, experts not involved in the study remain concerned by the findings.

"This is a very important paper. It confirms beyond any reasonable doubt that COVID-19 affects both brain and mind in equal measure," Simon Wessely, chair of psychiatry at King's College London, told Reuters.

"The impact COVID-19 is having on individuals' mental health can be severe," said Lea Milligan, chief executive of the MQ Mental Health research charity. "This is contributing to the already rising levels of mental illness and requires further, urgent research."

Source