How do you tell if a mouse is depressed?

Because there are some things you can't ethically test on humans, human medical research involves animal models. Such models are useful and important. There is a lot we wouldn't know—and a lot of people whose lives would be much worse—if it weren't for these animals.

That said, animals models are not perfect. Especially when it comes to relatively subjective problems like mental health. We test anti-depressants on mice. But how do you know whether it's working? After all, the mouse can't tell you that it's feeling better. And you can't really watch what the mouse does and see behaviors directly relatable to the human experience of depression, either. (Does the mouse feel more like going to his job and interacting with his friends today?)

At Scientific American Mind, Robin Henig explains the three commonly used tests that give scientists a glimpse into the mouse psyche. These are flawed proxies. Given the very real questions about how effective anti-depressant drugs actually are, it's worth putting some effort into developing better ways of monitoring their effectiveness in animals. But, for now, this is what we have to go on.

Forced swimming test. The rat or mouse is placed into a cylinder partially filled with water from which escape is difficult. The longer it swims, the more actively it is trying to escape; if it stops swimming, this cessation is interpreted as depressionlike behavior, a kind of animal fatalism.

Find out about the other two tests at Scientific American Mind

Image: Mouse, a Creative Commons Attribution Share-Alike (2.0) image from iboy's photostream


    1.  Could be exhaustion. But fatigue/lack of energy is also a symptom of depression and may be close enough to exhaustion to also be indicative :)

      1. Exercise is an antidote for depression. So, while we’re anthropomorphising: maybe the little guy swims his blues away, perks up, realises he’s drowning, back to square one.

          1. You raise a good point: if it’s inconsistent amongst da hoomans, how do we reliably extrapolate to meeses? Exercise and good diet are my lodestars, YMMV @blueelm and I wish you all the best with yours.

    2. It’s not just one mouse. You’d have to do that test with a fair quantity of mice, some with the drug and some not, and take averages or do other statistical stuff on their times-to-giving-up.

    3. How fast can you run if you’re 10 minutes early?
      How fast can you run to catch a bus?
      How fast can you run if I’m chasing you with a very big knife?

      Effort depends on motivation.

  1. TEST #4: “The mice seem to have started listening to Morrissey”
    “We’ve gone too far.”

    1. Tempting block of cheese
      On a hillside mice can’t reach
      Will science make a man of me yet?

  2. If advertisements for antidepressant medicines can be believed, depressed mice should be followed around by little black clouds, or tiny blue nightgowns with eyes on them.

  3. Well, the first two tests are kind of horrifying. Let’s see if this mouse is depressed by making it think it’s going to die?

  4. “Because there are some things you can’t ethically test on humans, human medical research involves animal models.”

    I’ve never understood this thinking.  If anything I think it’s less ethically sound to test a product for a person on an animal.  I understand the complex legal and social reasons for it, but I don’t think it’s more ethical.

  5. It’s nonsense to say that animal experiments tell us stuff about us that we wouldn’t otherwise know; we have to do the same tests on people to see if they react the same way. The only reason animal experiments are used is because different animals react differently and  the lawyers use this as a get out clause when things go wrong. Animals are very bad models for humans. How many potentially live saving drugs are dismissed because they can’t get them to work on animals? 

    1. It’s nonsense to say that animal experiments tell us stuff about us that we wouldn’t otherwise know; we have to do the same tests on people to see if they react the same way.

      But if a new experimental medication kills 100% of the animals it’s tested on then it probably won’t get to the “let’s try it on humans now” phase.

        1. Whether animal testing is ethical or not is open for debate. I just take issue with the idea that “it doesn’t tell us stuff that we wouldn’t otherwise know.”

          1. Sorry, I see your point, and agree.  Animal testing has definitely advanced medicine; whether or not we needed to kill other species to further our currently overpopulated one is certainly up for debate, but it definitely works.

  6. Maybe there could be some sort of “let us experiment on you in exchange for free meds and therapy” program for depressed humans. I’d volunteer. My health insurance sucks.

    1. me too – thankfully i don’t have to pay (much) for my meds (yay nhs!) but how i feel right now, i’d happily do tests like this all day for a bunch of researchers instead of having to go to work or be around people. maybe they’d know if the meds were working when i wouldn’t want to be on the programme any more?

  7. Maybe the ‘depressed’ mouse is just really smart:

    “Screw all that swimming… The big bastards will fish me out anyway…”

    1.  I, too,  often wonder whether I’m depressed or really smart… probably just depressed

  8. “Because there are some things you can’t ethically test on humans, human medical research involves animal models.”

    The same argument has been made to justify experiments on humans who were considered to be less worthy of protection. I assume I don’t need to provide examples. Testing on unwilling subjects is inherently unethical. Science was supposed to free us from the ignorance of religion. But we continue to create a hierarchy of value where we determine one life to be more important than another. In other words, we keep playing God.

  9. “But how do you know whether it’s working? After all, the mouse can’t tell you that it’s feeling better.”

    I don’t know; the poor little guy in the pic sure looks pretty danged bummed out. I just want to pet him and tell him everything will be OK. But it won’t now, will it?

  10. Another behavioral indication by the mouse was he wearing his bathrobe all day.

    On-thread: I knew a zen-y guy who felt an ant had as much right to life as a human. I understand that viewpoint, but I don’t share it. I reject testing eye make-up on rabbits, but have no such notion regarding serious medical research.

    1.  do no evil, but when unavoidable, do as little evil as possible.  They call it “skill”.

  11. *Why* try to test efficacy on another species? Especially if it’s so open to interpretation. Just keep animal testing for safety concerns and save the efficacy tests for backpackers.

  12. Reminds me of when I was with my partner at a Clinique concession and she asked if their stuff was tested on animals: “Oh no! No, no no no no. Of course no. No, we test on students in New York”

    1. Ah, now cosmetics are a very different game.

      Medicine is a more shaky area; but any human being that thinks the suffering of an animal is justified for the sake of their shampoo choice or mascara doesn’t deserve to live.  

      In fact those that test cosmetics on animals would make great candidates for testing human medicine.  I think we’ve found an ethically sound source of test subjects!

  13. YesYes…all the good for “us” BUT… I ABHOR animal testing. It is vile and cruel and, even worse, so very often unnecessarily vile and cruel. It’s heartbreaking.

    1. Word.

      Animal testing is a cause of depression in compassionate humans. 

      Between Jersey Shore, The Kardashians and Justin beiber fans I’m sure we can find enough human test-subjects there…

  14. A mouse cannot speak. The psyche consists of those imaginative/philosophical functions which are used to imagine possible worlds and find meaning out of apparent meaninglessness when learning to speak and performs body/brain communication functions. The mind is the creation of a process of suppression of the psyche as language is acquired. This is a recent development in human ‘consciousness’. Apart from that a mouse simply has a brain and a body. It has no psyche and no mind. Isn’t depression a mind/psyche problem? Experimentation can only be ethically sound if the reasoning behind it is sound.

  15. I’m enjoying the concept of Animal Fatalism, as if these mice have read too-much Thomas Hardy.

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