Researchers have long suspected that COVID-19 takes a toll on the brain. Now a large study has confirmed that 1 in 3 people with the disease develop a neurological or psychiatric disorder within six months after infection. They most commonly develop an anxiety or mood disorder such as depression, although some are diagnosed with conditions such as stroke and dementia.
The most common psychological disorders after COVID-19 were anxiety disorders, which 17 percent of all patients developed. Mood disorders such as depression and bipolar disorder came in second, showing up in 14 percent. The next most common were substance misuse disorders at 7 percent and insomnia at 5 percent, according to the study, which was based on electronic health records of more than 236,000 COVID-19 patients in the US.
Neurological disorders were less common. About 2 percent of all COVID-19 patients who saw a doctor had a stroke, 0.7 percent were diagnosed with dementia, and 0.6 percent had a brain hemorrhage.
“It does highlight that there is something unique going on with COVID,” Allison Navis, a professor of neuro-infectious diseases at the Icahn School of Medicine at Mount Sinai, told STAT. “But the more severe things like strokes are still fairly uncommon.”
The risk of developing a brain disorder is higher for people with severe COVID-19. Of patients who needed treatment in the ICU, about 46 percent were diagnosed with a brain disorder.
The researchers also compared diagnoses after COVID-19 to those after the flu and other respiratory viruses. They found that COVID-19 is 44 percent more likely to lead to a brain disorder than the flu and 16 percent more likely than other respiratory illnesses. The only two conditions they analyzed that weren’t higher after COVID-19 were Parkinson’s disease and a rare nerve disorder called Guillain-Barre syndrome.
How COVID-19 has such a unique impact on the brain is unclear. One theory is that the stress of having COVID-19 could lead to psychiatric disorders. Other stressors like loss of income and total isolation could also play a role. The virus may also be able to work on the brain directly. It can likely enter the brain through the olfactory bulb, which is responsible for taste and smell, according to STAT. Inflammation from COVID-19 can also damage blood vessels in the brain, which could lead to neurological effects.
In a commentary that was published alongside the study, mental health experts Jonathan Rogers and Anthony David of University College London wrote, “Sadly, many of the disorders identified in this study tend to be chronic or recurrent, so we can anticipate that the impact of Covid-19 could be with us for many years.”