To investigate the associations between infectious diseases and the long-term risk of death by suicide, a team of researchers from Denmark and the United States analyzed data contained in Danish registers on more than 7 million people 15 years or older over a 32-year follow-up period. The study authors defined a history of infection as one or more infection diagnoses listed in the national hospital register.
Of the 7.22 million individuals observed in the study, 809,384 had a hospitalization with infection, and 32,683 died by suicide. Of those who died by suicide, 7,892 (24.1%) had previously been diagnosed as having an infection during a hospitalization.
The authors found that the relative risk of suicide was increased among individuals with any hospitalization with infections by 42% compared with individuals without prior infection; the greater the number of hospital contacts for infections and days spent in treatment, the greater the risk of death by suicide. With the exception of pregnancy-related infections, all other infections examined were linked to an increased risk of suicide, which was most pronounced for HIV or AIDS, hepatitis, respiratory tract, and sepsis infections.
“Although psychiatric disorders and previous suicide attempts might constitute stronger predictors of suicide, we found that hospitalization with infection accounted for a population-attributable risk of 10.1%,” Helene Lund-Sorensen, B.M., and colleagues wrote. If the association between infection and the risk of death by suicide is determined to be causal, “identification and early treatment of infections could be explored as a public health measure for prevention of suicide,” they concluded.
“There is an imminent need to develop better biomarkers indicating patients at risk for suicide and improved treatment options that are personalized for persons vulnerable to suicidal behavior,” wrote Lena C. Brundin, M.D., Ph.D., and Jamie Grit, B.Sc., of the Van Andel Research Institute in Grand Rapids, Michigan, in a related editorial. “It will be important to understand how milder and long-term infections contribute to depression and suicidality.” Such infections, they noted, often go untreated and remain latent in the body for years.
For related information, see the Psychiatric News article “Researchers Consider Infection as One Cause of Depression.”