Depression, Anhedonia, and the Brain

Brain with locked chain around it
Image by 3D Animation Production Company from Pixabay

Anhedonia, which refers to decreased ability to experience pleasure in normally pleasurable things, is a core symptom of depression; in fact, you can get a diagnosis of major depressive disorder without depressed mood if you have anhedonia. Anhedonia is a part of the melancholic features specifier for depression, as opposed to atypical features, which involves mood reactivity to pleasurable stimuli. It can also be one of the negative symptoms of schizophrenia. People with major depressive disorder who experience anhedonia tend to respond less favourably to treatment than those who don’t.

While serotonin circuits in the brain play a role in mood, dopamine and the nucleus accumbens region play a big role in pleasure and reward. I was curious to see what science has to say about how anhedonia happens in the brain, and this post is the result.

Pleasure and anhedonia

Anhedonia can affect different aspects of how we relate to pleasure. The reward pathway involves three phases: anticipatory (the motivation to seek out rewards), consummatory (finding experiences pleasurable in the moment), and satiety (learning after the consummatory phase). The graphic below illustrates these phases. The appetitive phase is dominated by wanting a reward experience, the consummatory phase is dominated by liking the experience, and the satiety phase is dominated by learning to associate consumption with pleasure. We make predictions for future experiences based on these learned associations.

pleasure phases: appetitive, consummatory, and satiety
Rømer Thomson et al., 2015, Frontiers in Behavioral Neuroscience

In people with depression, there tends to be a reduction in capacity in the wanting and liking phases, as well as impairment in reward learning. Essentially, the whole kit and caboodle is affected, although some studies have shown that the liking phase isn’t impaired to the extent that the wanting and learning phases are.

That actually corresponds fairly well with my own experience. Something that’s normally yummy to eat may still taste reasonably good when I’m anhedonic, but I’m not very interested in seeking that reward out in the first place or trying to repeat it once it’s happened.

Pleasure and the brain

There are multiple areas of the brain that are involved in the appetitive/wanting phase, including areas of the cortex (the more advanced part of the brain) and the limbic system (a more primitive part of the brain). The consummative/liking phase appears to be more focused in a small area of the nucleus accumbens, which is part of the limbic system.

Both dopamine and opioid circuits play a role (the brain makes natural opioids known as endorphins). The neurotransmitters glutamate and acetylcholine may also play a role, which might explain some of the benefit that the drugs ketamine and scopolamine have shown in people with depression.

I’ve included the diagram below, not because I expect the details of it to be meaningful to anyone, but rather to give a general sense that reward circuitry is complex and there are a whole lot of different places where things could go wrong. The complexity is one of the reasons why there’s a lot that science hasn’t figured out yet; another issue is that animal models don’t necessarily translate that well to the human experience of anhedonia.

diagram of brain's complex reward pathways
The complexity of the brain’s reward pathways – Sternat & Katzman, 2016, Neuropsychiatric Disease and Treatment

The nucleus accumbens

A recent study found changes in functional connectivity of the nucleus accumbens, a key part of the reward system, in people with major depressive disorder vs. healthy control subjects. Neural activity involves both wiring and firing, and functional connectivity is the firing part. Researchers observed reduced connectivity to several brain regions. In particular, people with more severe anhedonia had reduced functional connectivity between the nucleus accumbens and an area called the anterior cingulate cortex compared to people with less severe anhedonia.

Medications

Some researchers have suggested that the amotivation that SSRI (selective serotonin reuptake inhibitor) antidepressants can cause is related to the way that they affect the striatum, an area of the brain that’s involved in reacting to both aversive and pleasurable stimuli. It can be a good thing if antidepressants are lowering our reactivity to negative stimuli, but not so good if they’re also lowering our reactivity to positive stimuli.

For me, the pattern of anhedonia over time has been consistent with it being illness-related rather than being negatively affected by medication.

What does any of this mean?

The TL;DR is that anhedonia in depression is complicated, and science has some ideas but hasn’t figured it out yet. I feel like anhedonia is something that can make a substantial difference in quality of life. It’s not as painful in the moment as low mood, but it can suck all the light right out of life. It seems like a difficult thing to address, too, because the absence of positive feelings doesn’t give you a lot to seek your teeth into. When doing supposedly positive things doesn’t generate a reward, continuing to do them seems a bit like pissing in the wind, which is perhaps why I’ve never found the CBT concept of behavioural activation to be particularly useful for me.

Is anhedonia something you experience, and if so, what is that like for you?

References

34 thoughts on “Depression, Anhedonia, and the Brain”

  1. Thank you for the post. This may be me being confused. I find that anhedonia is present in my life for basic things that bring happiness like spending time with my husband, spending time with my daughter, exercising and so on. But the one cycle that hasn’t changed with my bipolar depression is the cycle associated with eating. I am a stress eater and I find that the 3 phase cycle above pretty much captures how I feel looking forward to a meal, during a meal and after a meal. I am wondering why the pleasure cycle is in tact for eating but not as prevalent for other activities.

    1. That’s interesting. One of the papers that I read mentioned people with depression still tending to get a pleasure response to sweet things, so I wonder if there’s something about consuming food that can generate a response in a way that over activities can’t.

  2. I don’t know the answer. I believe though that psychotropic drugs present a big part of the problem. It will be great when the pharmaceutical companies can do something to bring to market drugs that work but don’t enhance appetite or weight gain. Waiting for that day (no pun intended).

  3. Your last paragraphs matches my experience near-exactly. I can make myself do things (if I have some external accountability like a friend or therapist having told me to do them) but if I don’t enjoy even pleasurable things, then what’s the point?

    What you say about the liking phase being less affected than the anticipatory phase also makes sense for me: if I can make myself do something (like watch a film) it’s usually better than I think it will be, but it’s hard work actually picking what activity to do when none of them make me feel as thought they will be good, if that makes sense.

    I wish I knew what the solution was.

  4. I definitely experience this. Everything just feels dull and pointless, even once enjoyable things just don’t feel worth the effort when it gets bad like that. It’s frustrating, and it isn’t something I know how to resolve really once it shows up either.

  5. I am knee deep in anhedonia right now. I don’t know how long it’s truly been going on for, but it’s been awhile and I derive little pleasure out of all the things I used to ie hobbies. So, I am going back to watching movies, whereby I haven’t watched them like I am now for 25 years! It is helping to pass the time, yes, but the anhedonia is still present. What do you do?

  6. Not exactly. I want things, and I like things, but I don’t necessarily have a desire to repeat them, meaning my wanting is over. This doesn’t apply to everything, and certainly not cupcakes, but it does apply to social events and also sexual ones. Just because I liked a thing doesn’t mean I want to do it again! A lot of people don’t understand this, but I’m perfectly fine with many things I once enjoyed simply to be pleasant memories now…

      1. I agree, it is weird to describe. Especially since it seems like even many depressed people can at least watch TV or something. Not all, of course, including those with anhedonia.

  7. Is anhedonia something you experience, and if so, what is that like for you?

    don’t fully experience anhedonia, except to a small degree. Usually that’s when my depression is at a very low point (i.e. getting worse) especially in the Autumn and Winter months when SAD takes it’s share of good moods. I have experienced a lessening of enjoyment in things that I usually enjoy, and as to emotions regarding romantic attachments that does not happen any more. But aside from those areas, I still cry at sad movies, go ‘awwww’ at cute baby animal pics (and pics and vid clips of piggos) and feel a bit of joy in simple things. Ziggy evokes a lot of emotion. I only recently heard the term anhedonia (although I believe you’ve blogged about it in the past) and I had it definitely at one point when I was severely suicidal. But there was nothing to feel anything about save my fur kids at the time. I certainly continued to feel a lot of pain I will say.

  8. Had to look this up: TL;DR. Never seen it before

    Nature is about the only thing we seem to predictably enjoy. It’s not always “fun,” but it can be relaxing, less stressful than live indoors, and life with people.

    It’s not always easy to motivate us to get outside and into a natural environment, but afterwards we’re often glad we did

    Sex would be awesome if it weren’t for shame 😞

    Passing time isn’t pleasurable. Tv, movies, and books can on rare occasion be interesting but they also dissociate us and their themes can upset us.

    We are intolerant of sugar (maple syrup is okay) and gluten and lactose and sugar alcohols so that sweets are not in our diet at all

  9. “it can suck all the light right out of life.”
    What a great line, Ashley. It expresses not only anhedonia, but depression in general. At least, that’s the way it feels to me when depression has me in its grip.

  10. This was very interesting. I find great pleasure in all aspects of food – anticipation and enjoying the moment. But there are some experiences which have lost any appeal to me. Recently a friend wanted to treat me to a spa weekend with a group of close friends. Maybe it is just the wrong time of year (this time of year is tough for me) but I had absolutely no desire for it. I don’t want a stranger to touch my body. I don’t want to be in a pool with strangers. Jack was wondering why I did not want to go. I said to him that I sensed zero desire and I did not think I would enjoy it at all. In the past it was something I would have enjoyed, now – not at all.

  11. This is not the main point of your post at all, but I feel like that top image of the brain in chains is really fitting for this post. This is also a well-researched and interesting post – I didn’t only look at the pictures! But I think that picture is really well-chosen.

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