Flu Season, and the Links Between Mental Health and Infectious Diseases: Public Health Watch

It’s flu season in the United States—and, believe it or not, that means it may also be depression season.

Researchers in China have found a link between the seasonal virus and mental health, and the findings should be a reminder (or perhaps a wake-up call) for clinicians treating patients with flu specifically and infectious diseases in general.

According to figures from the Centers for Disease Control and Prevention (CDC), some 24 million Americans are diagnosed with the flu annually, and another 5 million or more cases are prevented thanks to the influenza vaccine. CDC estimates suggest that vaccine uptake ranges from 30% to 70%, depending on age group.

The good news is that, in addition to preventing troubling cases of the flu, which can be fatal depending on the age and health status of the individual patient, the vaccine may also be helping preserve mental health. In a study published in October 2017 in BMC Infectious Diseases, researchers in China found that at least 60% to 75% of patients with influenza also experience anxiety and/or depression. Their findings were based on interviews with 839 patients with confirmed influenza.

The authors of the BMC study did not share their thoughts on particular reasons for the relationship between the 2 conditions, but they noted that significant numbers of influenza patients also experience problems engaging in normal daily activities as well as pain and discomfort.

Of course, this study is hardly the first time an infectious disease has been linked with mental health-related complications. Recently, studies have suggested that pregnant women diagnosed with Zika virus infection experience higher rates of anxiety and/or depression—likely due at least in part to the potential impact of the mosquito-borne disease on the health of their newborn children—and studies of patients with infectious diseases that effectively morph into chronic conditions—namely hepatitis C and HIV, among others—have also identified links with certain mental health conditions.

In fact, on this latter point, a study published in September in the International Journal of Women’s Health, differentiated between “behaviorally infected” HIV-positive women (those who were diagnosed later in life as a result of engaging in high-risk behaviors) and those who were “perinatally” infected, and found higher levels of “depressive symptomatology” in the behavioral group. The authors attributed this to the “temporal proximity of their diagnosis”—those in the behavioral group had learned of their diagnosis within 4 years of study participation, whereas those in the perinatal group had lived with HIV for most if not all their lives (average age 21 years)—though it’s worth noting here that this study included just 34 subjects, all HIV-positive women between 16 and 29 years of age. However, the findings are still significant.

Indeed, there are indications that a more holistic, “mind-body” approach to care among clinicians treating patients with infectious diseases can yield positive results. Researchers in Denmark, for example, published a study in the Journal of Alternative and Complementary Medicine, which enrolled half of the HIV-positive subjects in a 3-day educational program that included teachings on “Native American philosophy” and “how changes affect human beings and create imbalance.” They found that those patients who participated in the education program had reduced risk for depression and stress and stronger coping skills.

To be clear here, we’re not suggesting that Native American medicine can cure infectious diseases such as influenza or HIV, and we doubt the researchers in Denmark are either. However, remembering the links between mental health and infectious diseases diagnoses during the course of care is obviously important.

After all, the goal of all treatment is to make patients “feel better,” isn’t it?

Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.