CDC last month added "mood disorders, including depression, and schizophrenia spectrum disorders" to its list of medical conditions associated with a higher risk of severe Covid-19—a decision based largely on multiple studies that suggested a link between mental health disorders and a higher chance of infection as well as more severe outcomes, Rhitu Chatterjee reports for NPR's "Shots."

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Studies suggest a link between mental health disorders and more severe Covid-19 outcomes

For one study, published last year in JAMA Network Open, researchers analyzed data from five facilities within the Yale New Haven Health System to compare outcomes between individuals with mental health disorders who had been hospitalized as a result of Covid-19 and patients who were hospitalized with Covid-19 but did not have a history of mental health disorders. 

"What we found was we had a higher level of mortality for those [who] had a prior psychiatric history," said psychiatrist Luming Li, CMO at the Harris Center for Mental Health and IDD.

In fact, researchers found that patients with a history of mental illness were 50% more likely to die from Covid-19 compared with patients with no history of mental illness.

In another study, published last year in the Official Journal of the World Psychiatric Association (WPA), researchers analyzed a nationwide database of EHRs to compare the rates of hospitalization and death among Covid-19 patients with a mental health disorder, Covid-19 patients with no mental health disorder, and those with a mental health disorder but no Covid-19 diagnosis.

According to study author Nora Volkow, director of the National Institute on Drug Abuse, "If an individual had a history of a mental disorder, they were more likely to get infected," and  "if they got infected, then they were more likely to have negative outcomes, such as hospitalization and death."

Why does this link exist?

According to Volkow, there are several reasons this link between mental health illness and Covid-19 infection and severe outcomes could exist. For instance, she pointed out that mental illnesses can often alter people's behaviors, potentially making them less likely to engage in behaviors such as social distancing or masking that would help protect them from infection. 

In addition, according to Volkow, individuals with mental illness typically have poorer health overall and often have chronic health issues, such as diabetes, cardiovascular problems, and kidney disease. "It is this very high prevalence of comorbid medical conditions that's likely to actually be putting them at greater risk for negative outcomes [from Covid-19]," Volkow said.

Further, experts acknowledge that people with mental illness tend to live shorter lives and often die from health conditions other than their mental health diagnosis, Chatterjee writes.  "They suffer prematurely from chronic illnesses, medical neglect," Ashwin Vasan, president and CEO of Fountain House, a mental health nonprofit, said.

According to Vasan, individuals diagnosed with mental illnesses tend to be among the most isolated people in society—which can take a significant toll on their bodies—ultimately putting them at a higher risk of chronic illnesses. "There have been study after study showing that it leads to inflammation, immunologic stress, neurodegenerative decline, immunologic impairment, endocrinological impairment," said Vasan. In fact, he equated it to smoking 15 cigarettes a day.

In addition, many medications intended to treat mental illnesses—specifically antipsychotics—often increase risk of chronic health problems, according to Volkow. "This has been one of the main challenges that we have with the use of antipsychotics overall, which help control certain symptoms in schizophrenia but are negatively associated with a much higher risk of diabetes and hypertension and metabolic diseases," Volkow said.

For these reasons and more, several experts told Chatterjee they were happy CDC added mental illnesses to its list of high-risk conditions, although some said this was a step that should have been taken much earlier—especially since 40% of the 13 million people with serious mental illness in the United States have no access to care at all.

That said, Li noted that individuals with serious mental illnesses may not even be aware of the new CDC recommendations—or the elevated risk people with mental illness face. "It's going to be a very important first step to make sure that they have their vaccines to start out with and then, second, to be able to get the boosters," Li said. (Chatterjee, "Shots," NPR, 11/22)