Effects of the common cold on mood and performance.

Smith, A., Thomas, M., Kent, J., & Nicholson, K. (1998). Effects of the common cold on mood and performance. Psychoneuroendocrinology, 23(7), 733–739. https://doi.org/10.1016/s0306-4530(98)00042-0

This month’s journal club is a little close to home. Why? Because I’m sick. Yes, even doctors get sick. Actually, my medical secretary told me I should slow down before I collapse—and turns out, she was right. I’ve got the full works: flu, pounding sinus headache, and one of the worst sore throats I’ve ever had. And that’s saying something, because I used to get sore throats all the time (before I had my tonsils out).

Side note: I am a huge sufferer of “man-flu.” When I get a cold, I honestly feel like I’m dying. God help me if I ever develop something truly serious. My psychiatrist colleagues will have their work cut out supporting me—and I’ll be sure to give them plenty to analyze, haha.

What I’ve noticed (and this isn’t the first time) is that my mood starts to dip a few days before I actually get sick. For years, I thought this was because being grumpy somehow made me more prone to infections—maybe because I cared less about dressing warmly or slacked off on sleep hygiene. But over time, I’ve come to suspect the opposite: that the low mood is actually an early symptom of getting sick.

Now, I’m not talking about a full-blown diagnosable mood disorder. More like feeling “off”—a bit tired, not enjoying things as much, cranky, rundown. You know, that pre-flu malaise.

So this month, we’re throwing it back to 1998 (almost the year Charli XCX sang about in 1999 with Troye Sivan). And here’s the cool thing: people were doing research into colds, flu, and mental health long before COVID. Looking back, it feels pretty pioneering. Also, for the record, 1998 wasn’t that long ago—though the way research articles were formatted back then definitely makes them feel a bit old school. It took me longer to get through the paper simply because it wasn’t packaged the way we’re used to now. Still, that doesn’t make it any less valid.

The article in question is by Smith et al., published in Psychoneuroendocrinology. The team included two psychologists and two microbiologists—an early example of true interdisciplinary collaboration, which I love. No conflicts of interest, no flashy grants. Just solid university researchers chasing good science.

The study opens by reminding us that colds and flus (aka upper respiratory tract infections) are extremely common and often lead to people missing work. They even wrote about absenteeism almost like it was a diagnosis in itself—which it isn’t! (And for the record: you should take time off when you’re sick. Sorry to my patients who had to be rescheduled while I was out of action!)

The authors noted that these illnesses don’t just cause runny noses—they can also impair mental functioning and wellbeing. At the time, most of this evidence was anecdotal. There had been studies of experimentally induced influenza showing it could affect mental performance, psychomotor skills, and stimulus detection. But no one had really compared different viruses. Fascinatingly, this paper already mentioned coronaviruses as a leading cause of reduced alertness, while rhinoviruses seemed to have the mildest effect. (This was back in 1998, mind you!)

So, what did they do? They ran two experiments.

Experiment one: A cross-sectional study comparing healthy people to people with colds. Participants were mostly university students (classic guinea pigs), which limits generalisability since they’re young, relatively healthy, and similar in lifestyle. To qualify as “having a cold,” participants had to show increased nasal symptoms without systemic effects—basically a runny, blocked nose and sneezing. They even weighed used tissues to measure nasal secretions (gross, but effective). I can’t help but wonder if the researchers themselves caught colds along the way!

They also did viral swabs, blood samples, and assessed mood through questionnaires, plus cognitive and performance tasks. The results? People with colds were less alert, less happy, and less sociable (what they called “hedonic tone”). The worse they rated their mood, the worse they performed on cognitive tasks. Interestingly, there was no correlation between the amount of snot (tissue weight) and mental state.

Experiment two: A longitudinal design. They took baseline data from 187 students, then waited to see who got sick. Seventy participants eventually caught colds of unknown origin, 16 had coronavirus colds, and 14 had rhinovirus colds. Again, those who got sick reported being less alert, less happy, and less sociable, regardless of which virus they had.

The conclusion? Good old-fashioned experimentation confirmed what we all feel: colds affect not just the body, but the mind. Alertness, psychomotor performance, and enjoyment of life all take a hit.

So I’m not alone!

The reasons are likely complex. The virus could directly affect our nervous system, or it might be an indirect effect through immune response, fatigue, or disrupted routines. The authors called for more neuroimmunological research to explore causes and treatments—not just for cold symptoms, but also for the mental health effects. And after the surge of COVID-19 research, we’re finally seeing that work unfold.

For me, this was a nostalgic little trip back to the late 90s, and a reminder that sometimes simple, careful experiments can show us truths we already intuitively know. And more importantly, it proves that when I get the flu and feel low—it’s not just me being dramatic. Science agrees.

Who knows—maybe one day the “cure for the common cold” will include treating its psychological symptoms too.

P.S. I’m getting better now.