Have you ever experienced not wanting to do anything when you are stressed, not even the things you normally love to do? Like spending time with friends or on hobbies? Such loss of pleasure, or anhedonia as scientists and medical doctors would call it, is an important and serious symptom of too much stress and stress-induced depression.
The impact of stressors on pleasure
Scientists have found that stress reduces the feelings of pleasure, both in laboratory animals and in humans. The loss of pleasure seems thus to be something common during stress. However, at first sight a connection between stress and anhedonia is quite perplexing. After all, doing something you enjoy may take your thoughts away from the stress you are experiencing, and may give you even fresh energy to face the stressor (the problem that gives you stress).
Indeed, for short-term stress, seeking distraction in doing things you love or being with friends or family may bring you joy, whether you are stressed or not. Anhedonia arises especially when stress becomes repetitive or chronic. For example, students who were preparing for their medical exams, reported decreased pleasure in their daily activities. This observation, along with many others, have demonstrated that chronic stress can promote anhedonia, although not everybody who is under chronic stress will develop it.
There is also a clear link between stress and a medical condition that is characterized by loss of pleasure. This condition is depression. Anhedonia is therefore an important symptom of chronic stress, and could indicate that a stressed person is on his or her way to develop depression.
Role of the brain in stress and anhedonia
Researchers have identified many regions within the brain that are involved in motivation and reward. When these regions are less active due to chronic stress, motivation and reward diminish. This manifests itself as a loss of pleasure, or anhedonia. We will not go over all of these brain regions, but just mention a few, as they are important for the reward and stress systems in the brain. This would help to understand what is actually happening to you when you lose pleasure when you are under chronic or repetitive stress.
Reward, energy and stress systems in the brain. Dopamine signals reward. It is produced in the brainstem (orange) and released in many brain areas, including the prefrontal cortex (green) that is involved in emotional control. Dopamine production is reduced under the influence of GLP-1, synthesized in another part of the brainstem (yellow green). The stress hormone CRF from the hypothalamus (blue) does the same thing. Both inhibit the feelings of pleasure and motivation by reducing dopamine signaling in the brain.
Dopamine signaling: reward and motivation
The first system that we will briefly discuss is the dopamine system in the brainstem. Dopamine is a molecule that looks a lot like the stress hormones adrenaline (or epinephrine) and noradrenaline (or norepinephrine). They are chemically related. Dopamine is also known as the “pleasure hormone”.
Cells in the brain that produce dopamine have two functions. The first is to detect the salience of a stimulus, so that they help to decide whether something is pleasurable or not. The second is to encode a reward prediction error. This means that dopamine cells are sensitive to unpredicted rewards (Surprise! You won the lottery!), or the difference between what is expected and what is actually happening. When expected rewards are not coming, then the activity of the dopamine neurons will diminish, and feelings of pleasure will go away. Stress has a negative influence over dopamine signaling, and this contributes to the development of anhedonia.
Dopamine cells release dopamine in many areas of the brain, including those that are important for reward and stress. The effects of stress on dopamine signaling has therefore major consequences for how the rest of the brain functions.
Prefrontal cortex: control of emotions
The second structure on the list is the prefrontal cortex. This region is located at the front of the brain,right above the eyes. It is a structure that is involved in stress responses, anxiety and fear, and emotional memory.
Several studies in mice have shown that stress causes structural changes to cells in the prefrontal cortex. They become smaller. Brain scans in humans have shown something similar, in that the volume of the prefrontal cortex decreases. These structural changes alter the activity of the prefrontal cortex. One of the consequences of this is that the communication between the prefrontal cortex and the dopamine system changes. The precise processes through which altered communication leads to anhedonia are still under study, but it is clear that abnormal prefrontal cortex - dopamine interactions play a role in the onset of anhedonia under stress.
The hypothalamus: stress responses
The hypothalamus is where the stress responses begin. One of these is a rapid stress response through the sympathetic nervous system, leading to the secretion of adrenaline (epinephrine) in the blood. The second is a hormonal stress system that operates slower than the one through the sympathetic nervous system, and leads to the secretion of cortisol into the blood. Adrenaline and cortisol are the major stress hormones in the body, and serve to prepare you for immediate action (the “fight-or-flight” response) and to direct energy to those organs that need to be activated to deal with the stressor.
An important signaling molecule in the hypothalamus that is at the basis of both stress responses is a small protein. This protein is known as CRF. CRF not only activates the stress responses. It also has an inhibitory effect on the dopamine system. CRF will thus reduce the feelings of pleasure and reward.
Stress, energy and reward
Overall, it seems that many brain regions work together to bring about feelings of pleasure. Dopamine is a central signaling molecule in this network of different brain areas. Scientific research is still in full swing to better understand how stress reduces pleasure precisely. One of the directions in which this research is going at the moment concerns energy.
One of the hallmarks of stress is the redistribution of energy across the body. There is a clear link between stress, energy and pleasure. This is because eating (getting more energy into the body) is in itself a rewarding activity, in which dopamine plays an important, motivating, role. When you have eaten to satiety, food becomes less rewarding, and dopamine signaling drops.
How are stress, anhedonia and energy precisely linked? The answer to this question may be found by looking at a protein in the brain, which is called GLP-1. GLP-1 is produced in the brainstem, and is released after eating in the dopamine system. As a result, the dopamine system becomes less active, so that eating becomes less rewarding and stops.
GLP-1 is also released in the dopamine system following stress, with the same result: less reward, less pleasure and less eating. Eating is indeed suppressed during stress, and energy is liberated from the liver by adrenaline (epinephrine) and cortisol. In this way, all attention can be on the stressor (the thing that causes stress), without having the need to eat.
The release of GLP-1 in the dopamine system during stress could be at the basis of anhedonia during stress. Also, GLP-1 can activate the stress responses in the hypothalamus, so that GLP-1 could coordinate stress, energy and pleasure/anhedonia.
Symptoms and examples of anhedonia
As mentioned before, anhedonia is not only a symptom of stress, but also of depression. Stress can lead to depression. Depression is difficult to treat, and recovery will take a serious amount of time. Stress-induced anhedonia should therefore be recognized early, before stress turns into depression.
Some of the symptoms include the following:
- Diminished pleasure in daily activities
- Social withdrawal
- Lack of relationships or disrupting existing relationships
- Loss of libido
- No more interest in hobbies
Examples of anhedonia could be:
- You used to love playing basketball in the evenings, but now you no longer have the desire to play the game or interact with your teammates
- You have lost pleasure in cooking, a favorite hobby of yours, and you have to remind yourself to eat
- You don’t like to go out with friends anymore
- You feel indifferent to your partner, or even withdraw from him or her, and have a severely reduced libido
- Activities that you love to do and fill you with happiness, so as going to the cinema, no longer gives you pleasure
Treatment of anhedonia
Anhedonia can be quite challenging to treat. This is because most treatments focus on anhedonia in depression. We will discuss some treatment options that are related to anhedonia caused by stress.
If you recognize (some of the) symptoms and examples that you have read above, then it is time to assess for yourself whether you are under chronic stress or not. It is advisable to keep a diary to keep track of feelings of stress and loss of pleasure. You could write down under which conditions you feel stressed (place, other persons, stressful things you have to do, deadlines, etc.) and you could keep a list of things that you don’t feel like doing anymore.
If it turns out from your diary that you find yourself in a condition of chronic stress, then you would have to talk with your medical doctor or a psychiatrist. Your doctor will ask you questions about your symptoms and your general mood, and may also perform a physical exam to determine if you have any physical problems.
A psychiatrist can help you to find out the causes of your stress more precisely. This makes it possible to improve the conditions or events that stress you out. And if the causes of stress are taken away, then anhedonia will follow and disappears as well.
The treatment of anhedonia related to depression is typically much harder to treat. Your psychiatrist may prescribe an antidepressant. Other techniques include electroconvulsive therapy to provoke a small seizure (under general anesthesia), transcranial magnetic stimulation to stimulate brain cells, and vagus nerve stimulation to stimulate the brain indirectly through activation of this nerve. The vagus nerve is part of the parasympathetic nervous system that counteracts the stress responses.
As mentioned above, stress-induced anhedonia can be treated indirectly and effectively by designing an adequate strategy to deal with the problems that cause stress. Here at Stressinsight we provide information about how to ameliorate work conditions to reduce and prevent stress, and put an end to anhedonia in the process.
A disclaimer: our advice and strategies will in general produce excellent results, but cannot always substitute for medical consultation. So if you think you are losing pleasure in things you used to like, seek medical advice sooner rather than later.
