You know you should get things done. Start exercising, call the friend you haven’t spoken to in a long time, or clean out the storage room. But it’s as if the start button isn’t quite working. Researchers have, however, found a possible—and somewhat unexpected—explanation for why motivation can sometimes disappear, even when the desire remains.
We often think of motivation as something mental, but in recent years, research has shown that motivation is also affected by what is actually happening biologically in the body.
One aspect concerns how the immune system communicates with the brain. When the immune system is activated, various signaling molecules are released to help coordinate the defense against bacteria or viruses. Researchers have discovered that these signals can also affect the dopamine system—and therefore how easy or difficult it feels to get started on things.
Dopamine Is About More Than Reward
Dopamine is often called the brain’s reward chemical, but that describes only part of its role. Dopamine also helps us take initiative, feel drive, and mobilize energy for things we want to do.
This is especially apparent in the gap between appreciating a reward and actually being willing to make an effort to obtain it. You may still know that a workout, a phone call, or a cleared-out storage room would feel good. Yet that little extra push that gets you to take the first step is missing.
This distinction has become an important area of research into how inflammation affects the brain.
Signals from the Immune System Reach the Brain
Inflammation is a natural and important part of the immune system. It helps the body respond to infections, injuries, and other stressors so that the body can protect and rebuild itself.
However, inflammatory processes can also continue more subtly over a longer period without you noticing them.
When the immune system is activated, signaling molecules called cytokines are released. They help the immune system coordinate its work, but they can also affect how the brain’s neurotransmitters function.
In controlled studies in which researchers temporarily activated the immune systems of healthy people, they observed reduced activity in the brain’s reward system. Participants also became less motivated to make an effort for a reward, even though they still appreciated it.
This suggests that inflammation, through signals sent to the brain, can affect the dopamine system in a way that changes drive rather than desire.
The Dopamine Signal Can Become Weaker
Research also shows that inflammatory signals can affect the dopamine system in several different ways. Among other things, they can impair the brain’s ability to produce dopamine and affect how efficiently dopamine signaling works between nerve cells.
The result may be a less efficient dopamine system, making it harder for the brain to create the drive that helps you get started.
A Smart Strategy—in the Short Term
During an acute infection, this is a smart strategy. The immune system needs a great deal of energy to do its job, so it is beneficial for the body to temporarily prioritize things that are not essential.
In other words, having less desire to exercise, socialize, or tackle major projects may be part of the body’s way of conserving energy while dealing with invading viruses or bacteria.
The problem arises when the inflammatory signals remain for a longer period. In addition to chronic inflammation not being good for the body overall, it can also cause low motivation to persist—even though there is no obvious illness that you need to rest and recover from.
Low Motivation Can Have Several Causes
It is important to remember, however, that low motivation can of course be caused by many different things: stress, sleep deprivation, depression, hormonal changes, nutritional deficiencies, or difficult life circumstances.
But a lack of motivation caused by chronic inflammation may be a cause that many people are unaware of, because low-grade inflammation is not always easy to detect.
References
- Felger JC, Treadway MT. Inflammation Effects on Motivation and Motor Activity: Role of Dopamine. Neuropsychopharmacology, 2017.
- Dantzer R. Behavioral and Motivational Changes Induced by Cytokines. Novartis Foundation Symposium, 2002. (Alternatively, his classic Cytokine-induced sickness behavior from the same period.)
- Eisenberger NI et al. Inflammation-Induced Anhedonia: Endotoxin Reduces Ventral Striatum Responses to Reward. Biological Psychiatry, 2010.
- Harrison NA et al. Inflammation Causes Mood Changes Through Alterations in Subgenual Cingulate Activity and Mesolimbic Connectivity. Molecular Psychiatry, 2015.
- Harrison NA et al. Effects of Inflammation on Hippocampus and Substantia Nigra Responses to Novelty in Healthy Human Participants. Molecular Psychiatry, 2015.
