Infectious mononucleosis as a risk factor for depression: A nationwide cohort study, 2021, Vindegaard et al

I wonder whether ME/CFS would be a better primary diagnosis for some of these people?

https://www.sciencedirect.com/science/article/abs/pii/S0889159121000398

Brain, Behavior, and Immunity
Volume 94, May 2021, Pages 259-265
Infectious mononucleosis as a risk factor for depression: A nationwide cohort study
Nina Vindegaard
Liselotte V. Petersen
Bodil Ingrid Lyng-Rasmussen
Søren Dalsgaard
Michael Eriksen Benros



https://doi.org/10.1016/j.bbi.2021.01.035Get rights and content

Abstract
Background
Infectious mononucleosis is a clinical diagnosis characterized by fever, sore throat, lymph node enlargement and often prolonged fatigue, most commonly caused by Epstein-Barr virus infection. Previous studies have indicated that infectious mononucleosis can be followed by depression; however, large-scale studies are lacking. We used nationwide registry data to investigate the association between infectious mononucleosis and subsequent depression in this first large-scale study.

Methods
Prospective cohort study using nationwide Danish registers covering all 1,440,590 singletons born (1977–2005) in Denmark by Danish born parents (21,830,542 person-years’ follow-up until 2016); where 12,510 individuals had a hospital contact with infectious mononucleosis. The main outcome measures were a diagnosis of major depressive disorder (ICD-8: 296.09, 298.09, 300.4; ICD-10: F32) requiring hospital contact.

Results
Infectious mononucleosis was associated with a 40% increased hazard ratio (HR) for a subsequent depression diagnosis in the fully adjusted model (HR: 1.40, 95% CI: 1.26–1.56;n = 358), when compared to unexposed individuals. The increased risk of being diagnosed with depression was significant to the periods one to four years after the infectious mononucleosis diagnosis (HR: 1.40, 95% CI: 1.17–1.67;n = 121) and ≥ five years (HR: 1.40, 95% CI: 1.22–1.61;n = 207). We did not find any differences according to age (p = 0.61) nor sex (p = 0.30).

Conclusion
In this largest study to date, infectious mononucleosis in childhood or adolescence was associated with an increased risk of a subsequent depression. Our findings have important clinical implications and identifies youth with infectious mononucleosis as a group at high risk of later depression in young adulthood.

 

I have always understood that depression could be triggered by any viral infection and this was in part a chemical balance issue, though I don’t know if this is based on any formal research.

Many years ago a friend in his mid twenties with a successful business and an apparently happy marriage, shot himself some three or four weeks after a bout of influenza. (Sorry one of our regular n=1 reports).

Unfortunately, though this is prospective study with a large sample, without any control group we do not know if this apparent association between EBV and clinical depression is specific to mononucleosis/glandular fever or not, nor if it is a direct causal factor or not.

As @Dolphin points out what we are seeing here could at least be partially due to glandular fever triggered ME/CFS being misdiagnosed as depression or alternatively undiagnosed and/or unsupported ME/CFS being in turn a trigger for depression.

It would be interesting to know if there was any relationship between the severity of the glandular fever or the duration of the active EBV infection, given the apparent risk of depression is primarily in the first few years (less than five years) after the (onset?) of the glandular fever.

 

Too bad we can't track ME/CFS accurately using the International Classification of Disease (ICD).

 

Unfortunately, this is a study of medicine's long-standing habit of misdiagnosing chronic illness, it says nothing about either mono, depression, or anything, really. It only shows that invalid input leads to invalid data, but hardly anyone understands this, making this study compound the very problem it unwittingly reveals.

Nearly all of us have a label of depression on our records, whether it's accurate or not, and I doubt even 5% of physicians would care to tell the difference, let alone manage to. In hindsight, mindlessly adding invalid labels only leads to... invalid labels. It's exactly as valid as finding mental illness labels in gay populations back when homosexuality was in the DSM and it was heavily discriminated against, a lesson that clearly no one has learned.