A new study finds people who had COVID-19 may be at increased risk of developing opioid use disorders and mental health issues such as anxiety and depression.

Researchers compared medical records of almost 154,000 COVID patients in the Veterans Health Administration system with records of a similar group of veterans who did not have COVID. Only patients with no mental health diagnoses or treatment at least two years before the study were included.

COVID patients were 34% more likely to develop opioid use disorders and 20% more likely to develop non-opioid substance use disorders, including alcoholism, compared with people without COVID during the same period, The New York Times reports.

People with COVID were 39% more likely to be diagnosed with depression and 35% more likely to be diagnosed with anxiety in the months after their illness.

“The increased risk of opioid use is of particular concern, especially considering the high rates of opioid use disorders pre-pandemic,” the researchers wrote.