Can Covid change your personality?

When you ask people what experiences have shaped them, they commonly mention being bullied at school or an unkind offhanded remark a parent or teacher made. In my experience, people are much less likely to mention an infection or physical injury as part of their narrative.

I just recovered from Covid19. And I feel different.

In January I contracted a very mild case of Covid. I only really felt sick for 3 days but I slept for 14 hours a day for almost two weeks after my fever subsided. Luckily, I was exposed only hours before a planned isolation of several weeks.

Getting Covid has reminded me of how much disease can change a person.

Read below to learn more about how disease alters a personality and check out this interview I did on Modern Wisdom on Covid19 and personality.

The connection between the immune system and psychology, was largely the topic of my dissertation research. But a personal experience made it seem like it was possible to just breathe the wrong air and be changed forever.

On a rainy evening in 2013 I met my new roommate out for a beer. She was classy, conscientious, educated, well traveled, sociable and had been living in our city for decades. I thought I was signing up to live with someone who’d only be around half the time and could introduce me to other great local people. But, unexpectedly after we started living together, she turned down several jobs. For months, she stayed at home alone, resting, drinking tea and watching TV. Later, she told me about her life the year before: globetrotting, dating, exercising and planning on writing a novel. But everything changed after she contracted mononucleosis. Many believe that inflammation, heightened activation of the immune system, often in response to infection, can cause depression and other psychological suffering.

The Evolution of Lassitude

We propose that lassitude also has distinct qualia – profound tiredness, greater relative preference for close social allies, reduced overall appetite but stronger relative preference for particular food items, greater feelings of vulnerability, increased pain sensitivity, greater susceptibility to nausea, and altered perceptions of ambient temperature. Not all of these qualia are present in all cases of infection – the presence of each component depends on context-sensitive regulation of the underlying motivational system.

Lassitude– Schrock, J. M., Snodgrass, J. J., & Sugiyama, L. S. (2020).

From an evolutionary perspective, it’s in a disease’s interests to change your behavior, as I wrote about here. Generally, diseases interests are not going to be aligned with your interests, they want you to be a vector for their genes, you want to be a vector for your own genes. One recent paper hypothesizes that some of the less well understood apsects of our brains may be designed to prevent manipulation from pathogens.

When you’re sick, your strategies for survival and reproduction change- it might make sense to completely isolate yourself from others, or it might make sense to try to make one last offspring before you die. We also evolved to significantly change our behavior when we have an infection. There is evidence that our brains can monitor immune activation, and, like our other senses, this can tell us a lot about the environment and how we need to change to survive.

“The immune system —just like the body’s other sensory organs—provides the brain with important information about the body’s condition, which is used to compute psychological and behavioral choices that are likely to optimize survival given its internal, physical condition” (Gassen & Hill 2019).

Lassitude and sickness behavior are both ways of describing the many changes that humans and animals experience when they are sick. Some of these are probably very familiar to you. Feeling tired or sleepy means that your body is motivating you to conserve energy for your immune system. Feeling the chills makes you pile on blankets so it’s easier for your body to produce a fever. Fever makes your body less hospitable to viruses and bacteria and helps your immune system work faster to eradicate the infection.

Covid and other diseases commonly changes people’s appetites. Given what I’ve just told you about preserving energy to use for the immune system, you might be wondering why we don’t eat as much as possible when we’re sick. Throughout our evolutionary history foods often contained parasites and other pathogens. It’s better not to risk getting infected by something else if your immune system is already busy. But also, 5-15% of our daily energy expenditure goes to digesting food- from this perspective your body’s fat stores are safe and they don’t need to be digested. One interesting exception to this is honey- because it’s antibacterial and easily digested some groups try to get more of it when they are sick.

Is there any benefit to SARS-CoV-2 of removing your sense of taste and smell? I didn’t lose my sense of taste and smell until 10 days after my infection. When I first came down with symptoms, everything smelled disgusting and I didn’t eat for 4 days. One speculation is that losing taste and smell keeps the host eating food that wouldn’t seem appetizing otherwise. Again, speculation, but when some of your energy is shunted to digestion or fending off any bacteria that might be in your food, it means that there is less energy to fight Covid19.

Perhaps most interestingly, our social behavior and psychology change when we’re sick. Our social behavior, including much of our personalities, are calibrated to get benefit out of our social relationships. For humans, it’s especially important that they have other people to take care of them when they are sick or injured.

Many personality characteristics are really not “affordable” in an evolutionary sense unless we are strong and in good health. Studies have shown that extraversion is associated with physical strength and attractiveness in men and attractiveness in women. If we think about the costs of meeting new people, doing new things and taking on new ideas, it seems that these can be difficult to afford if you’re not healthy and strong. A disease may want you to meet and infect as many new people as possible, but when lassitude takes over your body is telling you that you need to prioritize relationships with familiar people, the kinds of people who might take care of you.

As an aside, we don’t think that much about how vulnerability might change our social lives and relationships. I know a few examples of people with chronic diseases or injuries that have gotten married or involved in serious relationships very quickly.

Sexual relationships also are expensive- men don’t change that much when they get sick, they still want to have sex. But studies have shown that women and other female mammals reduce their sexual drive when they’re sick. This makes sense, as I wrote about here, women are much more susceptible to sexually transmitted infections than men are, and because eggs and pregnancy are expensive, they need their bodies to be in good working order to carry a baby to term. Over the past few years there has been discussion of whether or not asexuality, which is more common among women, is a disorder or a sexual orientation. I’ll speculate that asexuality is one possible manifestation of long term illness.

All of this is important because Covid seems to cause “cytokine storm” in many sufferers. And it’s possible to have long term inflammatory effects of covid long after it’s over. There are likely millions of people whose relationships, personality, and behavior will be changed for months or years after Covid- lassitude and sickness behavior maintained in the face of the sense that your body is still fighting an infection.

For a couple of weeks I didn’t feel like myself- I had no desire to get on social media, My “openness to experience” was reduced- I watched familiar things, clips and movies over and over again. I felt more anxious when I heard strangers. And, most weirdly of all, I talked to my Mom every day.