A recent study by Oxford University showed that 1 in 5 COVID-19 survivors is likely to develop a mental illness within 90 days of catching the virus.

Among these illnesses include anxiety, post-traumatic stress disorder, depression, insomnia, and dementia.

“People have been worried that COVID-19 survivors will be at greater risk of mental health problems, and our findings … show this to be likely,” Oxford Professor of psychiatry Paul Harrison said, according to Reuters.

The study looked at the medical records of 69 million Americans, more than 60,000 of which contracted COVID-19. They also found a correlation between preexisting mental illness and an increased chance of contracting the virus. People with mental illnesses were 65% more likely to contract COVID-19. The study showed that patients with attention deficit hyperactivity disorder (ADHD), bipolar disorder, depression, and schizophrenia were the most likely to test positive.

Michael Bloomfield, a consultant psychiatrist at University College London, attributes this to “a combination of the psychological stressors associated with this particular pandemic and the physical effects of the illness.”

Simon Wessely, a professor of psychiatry at King’s College London, further elaborated, saying “COVID-19 affects the central nervous system, and so might directly increase subsequent disorders. But this research confirms that is not the whole story, and that this risk is increased by previous ill health.”