Neuroscience of Depression


Emotions are a critical part of the human experience. We laugh and we cry. But sometimes our emotions get out of hand. Sometimes the sadness we feel isn’t just the blues. Sometimes it’s depression. It turns out that depression is more than just feeling kind of sad. It’s actually a neurological condition that can really affect your everyday life. Depression is common. It’s actually the leading cause of disability among American adults. According to the National Institutes for Mental Health, in 2015, about 16 million people had at least one major depressive episode. Just during that year. That’s almost 7% of the US population. Depression comes in many forms, but most of those forms have the same symptoms. They just vary in severity and length. Common symptoms of depression include sadness, feeling empty, hopeless, or worthless, fatigue, changes in sleeping patterns, irritability, changes in appetite, and thoughts of suicide. When a person experiences these symptoms for at least two weeks and it’s interfering with their daily life, it’s called major depressive disorder. This is the one you probably think of when you think of depression. But if those symptoms go on for more than two years, it’s called persistent depressive disorder. And depression can be brought on by specific situations and life changes. Like postpartum depression, which can occur after a person has a baby. And seasonal affective disorder, when the lack of sunlight in the fall and winter can trigger symptoms. Because depression can look like normal sadness, and because it’s not always obvious what’s caused it, sometimes it’s hard for people to believe that it’s real. That’s why some people argue that if you just try hard enough, you can break the cycle. You’re in control of your own emotions, so you can choose to feel better. Anyone who’s suffered from depression knows that that’s not true. We’re still trying to figure out what causes it, and what exactly it does to our brains. And it’s important for doctors and scientists to keep working at understanding the condition so they can patients get back on their feet. There’s definitely a genetic component to
depression. If your parent or sibling has the condition, it’s more likely that you might end up with it too. But it can also be linked to environmental factors. Things like abuse, neglect, and severe life stressors like financial instability or a death in the family all make it more likely that a person might develop depression. So what’s actually going on in your brain? Up until recently, scientists were pretty sure that depression was caused by an imbalance of certain chemicals within the brain. Dubbed the monoamine hypothesis of depression, this theory said that a lack of neurotransmitters like serotonin and dopamine, two chemicals associated with feelings of pleasure and reward, would lead to depression. This theory is supported by a couple of things. First, scientists found that people with a particular genetic variation in the gene that codes for the serotonin receptor 5-HTT are more susceptible to depression after stressful life events when compared to people who don’t have that mutation. This mutation is thought to reduce the production of serotonin receptors in the
brain, leading to a decrease in serotonin signaling. There’s also evidence, mostly from post-mortem brains, that people with depression have changes in the dopamine signaling in their brains. Some research has found that, in patients with a family history of depression, deliberately reducing levels of the proteins required to make neurotransmitters like serotonin and dopamine does decrease their mood. And, finally, there’s the fact that antidepressant medications like selective serotonin reuptake inhibitors, or SSRIs, work. These medications function by altering the release of serotonin at the synapse, adjusting serotonin signaling throughout the
brain. But scientists are no longer positive that depression is a direct result of a simple chemical imbalance. Some of the research and treatments have been inconsistent with that idea. And the condition is really complex. So researchers are also exploring a lot of other possible explanations. Brain imaging studies have found that patients with depression generally have less gray matter in several different brain
regions. Like the cingulate cortex, the hippocampus, and the amygdala. Gray matter, made up mostly of neuronal cell bodies, dendrites, synapses, and glia, is the place where most neuronal signaling
happens, so changes in gray matter volume can affect all kinds of things. Like emotions, memory, and decision making. This has led some scientists to theorize that depression is more related to structural differences than neurochemical
ones. Basically, depression shrinks the parts of the brain that are important for controlling our emotions and making choices to take care of ourselves, making it hard for patients to recover from feelings of sadness. Some scientists think that depression could be related to changes in brain plasticity. That’s the process that lets your neurons change and adapt their signaling in response to new information. It might even be related to a reduction in neurogenesis, the growth of new brain cells. Even though it’s uncommon in the adult brain, there are some brain regions that create and connect new cells throughout our
lives. This theory points out that chronic stress has a negative impact on neuroplasticity. And a similar change in neuroplasticity is seen in patients with depression. Treating the condition with antidepressants might increase the formation of new brain
cells. And depressed patients taking antidepressants have higher levels of BDNF, a chemical that supports neurogenesis. Yet another theory about depression links it to our immune system. Research has found that patients with depression have unusually high levels of cytokines, small proteins that play a big role in the inflammatory response that kicks off when your body is responding to an injury. Cytokines are involved in sickness behavior. You know how, when you’re sick, you’re usually not very hungry, and have trouble concentrating, and really just want to sleep a whole bunch? Hey…those symptoms sound an awful lot like depression, don’t they? This theory proposes that high cytokine levels, caused by stress, can impact normal neurotransmitter signaling, leading to the symptoms of depression. This is why some doctors may encourage their patients to take antiinflammatory medications like ibuprofen alongside an antidepressant. Therapy can be very effective at treating
depression. About one in every three people will find that cognitive behavioral therapy
alone can improve their symptoms. Micah is making a video all about the psychology of depression. And how it’s treated in a clinical setting. There are also a number of antidepressants available on the market. Medications like SSRIs, SNRIs and tricyclic antidepressants function by increasing the levels of neurotransmitters like serotonin and norepinephrine at the synapse. Monoamine oxidase inhibitors, or MAOIs, block the enzymes that break down those same neurotransmitters. In all cases, they’re primarily aimed at enhancing neuronal signaling involving those neurotransmitters. But not every antidepressant is the same. Even different SSRIs can affect different people in different ways. And it takes a few weeks for the medications to really start having an effect. Sometimes it takes a while to find the right medication, which can be stressful and frustrating for a patient who’s really needing help. Because depression is pretty common, and because it’s complex, it could be that the underlying cause of depression varies from person to person. Whatever the cause, scientists are getting closer and closer to finding better solutions. And luckily, treatments do exist. They’re not perfect, but they can definitely
help. That’s why it’s so important to keep working on answering these questions, even when some medications are already available on the market. If you or a loved one has experienced depression, I hope that this video has helped you understand the condition a bit better. Please check out the description box below for resources on understanding and living with depression. Thanks for watching this episode of Neuro
Transmissions. If you liked it, hit that thumbs up button. And subscribe so you can catch Micah’s video all about how psychologists treat depression with therapy. You can also head on over to Patreon if you want to help support us making more videos like this in the future. Until our next transmission, I’m Alie Astrocyte. Over and out.

65 comments

  1. Thank you so much for this video! I have depression since I was a teenager and this video explains so good this condition. Just one advice: change the music, it’s like listen about an illness from the end of the world. I love your channel, guys!

  2. Hey guys, thanks a lot for this video, it's good to see some "real" info about this disease, which (as far as I know in my country) is still stigmatized. You're doing a really good job, keep going! 😀

  3. Oh that was great ! I thought I knew a good bunch of things on the matters but there were LOTS you brought up that I never heard ! Nice job, thank you.

  4. Great video! It's absolutely true that depression is more than just being "sad", and I think a lot of people don't understand that unless they've gone through it themselves.

  5. This is a great video, I had no idea about all the different possible causes of depression. While I have not experienced depression I have experienced anxiety attacks (most likely brought on by my thyroid disease). Personally I think the scary part is not knowing what is causing these unexplained emotions. When sadness or anxiety are caused by traumatic events – it's definitely not an easy thing to deal with, but at least you are aware of the cause. But when you are experiencing emotions without apparent cause, or disproportionate to the cause it can be really hard to deal with and makes you feel even more out of control. So when people tell you to just "snap out of it" it is even more frustrating. Thanks for a super informative video!

  6. I always wonder jf Im really depressed or I just want sympathy from the people and its just easier for me to self pity, than to feel enjoyment from life

  7. I was about to sleep when I suddenly scrolled and saw this video. GUYS! YOU ARE THE BEST!

    I can now shove this video down their throat when they are telling me it's all in my mind or just snap out of it. Hahahahahaha! #SadReality But seriously, thank you!

  8. Excellent video. Really good. This is a review that explains how CBT and ADM affect the brains of people suffering depression, it could be a good reference.
    https://www.nature.com/articles/nrn2345

  9. la vamos llevando, haciéndola parte de uno
    "Would you like to be sad
    would you like me to teach you
    well, you can learn to be sad
    but you must practice
    like I do
    "
    Thank you por el video

  10. Just stumbled across your channel, and I LOVE what you're doing. I have a mental health channel as well, and I talk about neuroscience quite a bit. Have any of you read the new book Lost Connections by Johann Hari about depression? It's really fascinating. There's a lot of talk about anti-depressant medications and how the success rates aren't nearly as high as people think. It goes over a lot of the other environmental and societal causes of depression as well as solutions.

    Anyways, I just subscribed and would love to collab with you some time if you're interested! I'm a recovering drug addict and do a lot of research on the neuroscience of addiction, so I'd be down to do a guest video on that if you'd like!

  11. great video 😀 I like your channel pretty much! But the background music affects my concentration and is disturbing… at least for me.

  12. If I have depression symptoms and cry everyday for two months straight does that automatically mean I have MDD fore ever?

  13. Nearly 40 Trillion Human cells make up the body but hardly make up the majority of mass. The number of cellular Microbial non-human cells that are facilitated by the body are estimated to outnumber human cells 10:1. Why is this important? This strongly suggests that health and nutrition might heavily lean upon the proper cultivation and support of these host communities. As a professional beekeeper I have been lead to understand some amazing things about natural nutrition as it applies to the hive and the body. Hit me up if you have anything to share on this topic.

  14. It's unfortunate this is so purely scientific. SSRIs don't work for many people actually. They help people to function but the feeling of depression often remains. You can't chemically erase trauma..abuse..neglect.. attachment issues etc. Psychiatry is also not the right answer. Depending on where you're from due to interchangeable terms.. usually psychologists or psychotherapists can help people through depression. This video seems really shallow in it's level of understanding of depression.

  15. I was diagnosed yesterday with Anxiety Disorder after a couple of days of chest pain, difficulty in breathing and throat pain and insomnia. The doctor prescribed me 5mg of clonazepam sleeping pills for 4 days and a whole 10 mg of it in the 5th day just for me to sleep. That's for 5 days. And oscitalopram oxalate 1/2 tablet that's 5mg for 4 days then a whole of it 10 mg after for 2 weeks.
    My concern is i have looked all those meds up in the internet and I kinda the worried about the side effects that may occur especially that withdrawal syndrome side effect. I have also read some where that oscitalopram oxalate should be taken months or years thats almost part of a person's life and the side effects for me is pretty scary.
    Does this drug really is safe? I mean I can probably control my self without anti depressant drugs but the doctor requires me so. I dont want to be tied up with any of this drugs for a long period of time or even for a lifetime. Please if you have any advises that would be much appreciated.

  16. I had some major depression a few years ago after ending a relationship. Getting dumped was fairly normal for me and I had strategies for dealing with it, but knowing what I put my ex-partner through by splitting with them pushed me over the edge. I was distracted and irritable for almost half a year until I went to my old pen&Paper group and took some time off work

  17. Thank you so much for this video!! Such a beautiful explanation of scientific theories!! And I loved the soundtrack! Haha ❤️

  18. depression is caused by emotional wounds as the person is emotionally hurt but in a hypnotic state of believeing he is just depressed and that there is no cause of the depression. i have experienced deep depression myself and know how that feels and know, someone injured my feelings in more than one way.

  19. "SSRIs work"

    ehh… I mean they tend to do more than nothing, but not enough that I wouldn't consider that statement false. They commonly have debilitating side effects like preventing virtually any sleep from occurring(and for anyone with a sex life, you can kiss that shit goodbye with a 50/50 chance), and shopping around to find one that isn't going to debilitate you just as much if not more than your depression can truly be hell if you're not lucky. They have legitimate uses, but we definitely overprescribe the hell out of them, and I'd recommend anyone to try non-drug therapy before getting pilled up.

    Also MAOIs are just horrible. They've been rarely prescribed for several decades for a reason, that reason being they violently interact with damn near anything, including several types of food. like there's a reason why virtually any ad for a drug will have "do not take X if you're currently taking MAOIs" in the fast speaking legal liability section.

  20. Because of depression I lost everything I worked hard for. I worked hard and arrived in the USA. Then my depression was so severe I had to return to my home country to my family.

  21. Why do we act like depression is not caused from our toxic society or a shitty life situation? We should be more wary of people who aren’t depressed.

  22. Great video! Definitely a solid introduction to the literature and handled with a lot of empathy. As someone who both researches and lives with depression neurobiology, it makes me glad that you guys are doing good work spreading knowledge!

    Do you think you'll ever cover the excitatory synapse hypothesis of depression? That's definitely my favorite explanation of MDD pathophysiology.

  23. SSRI’s work?? Really? There are so many misleading things you have presented that it’s disheartening because people may take some credence in your assertions. Please look at some of Irving Kirsch’ work.

  24. I have depression it’s hard the worst it’s like a dark whole and you feel like nothing I once thought I could kill myself I’m 12 I have had it for 9 years

  25. Thank you for taking your valuable time to educate people. Many still having hard times to understand why some people differ about this disease that it is not nice to handle it. 💕

  26. Thumbnail: Doctor, I don't feel so good.
    Imagine depression as a car with a failing engine! It drives suboptimal, but ok… Makes weird noises or fumes from time to time… You don't realize how much some parts struggle until they suddenly break. Depression comes from misconceptions and similar effects. Everything is fine! They say…
    When I realized my depression at 11yrs, of course people didn't believe me – and I believed them. So I searched for my problems elsewhere…
    Now I'll get 30yrs. And I realized how often I was right…
    This unintended gaslighting almost destroyed my life 😬

  27. I was wondering if their truly is a chemical imbalance in the brain why can't they prove it to me ……pharmaceutical companies are making 12 billion dollars off putting people on meds …….and they diagnose to quickly ..like how they diagnosed me with depression ,Gad in a matter of an hour .so ridiculous ..now supposedly I have Bipolar 2 .Again diagnosed. Me in an hour ….they are FINALLY gonna do an MRI….good video tho …maybe in the yr 2060 they'll maybe figure it out .

  28. Depression is so debilitating. It makes you apathetic and tired all the time causing a lot of responsibilities and even basic hygiene to become neglected. This of course just makes depression worse and is really easy to get caught in a cycle. It's the worse.

  29. Doctors and scientists can't understand it because it isn't about rationality and objective medical knowledge. It can be a reaction to shitty life conditions created by capitalism and is therefore political. Shifting the responsibility to individuals to "fix" themselves and reintegrate into consumer society is part of capitalist ideology.

  30. C b d oil is cure depression but your evil Americans cow boy drug company control all over the world this trade becuse it is billion dollar trade

  31. Multiculturalism made me depressed, SSRI's could actually make people more depressed as it will reduce the amount of serotonin receptors

  32. good, informative video !…sub'd :-)……though just before hitting the like button, I had "Achy Breaky Heart" starting to play in my head….I have no idea why, though my MDD is better accepted than thought about sometimes 😉

  33. very few people ACTUALLY suffer from the neurological condition depression which is mainly caused by a lack of monoamines and a lack of neurogenesis. most people who claim that they are depressed have developed learned helplessness which is simply not the same as the neurological condition depression. im not depressed but i would consider it offensive for one to claim that they suffer from depression when they dont actually have the neurological condition

  34. I have ADD and feel that I have depression based of online tests and occasionally the episode. Sometimes it's just random and others it is triggered by just making a little mistake. I have very low self confidence/worth. Do you think you could help by potentially doing a diagnosis since you seem like you know what you're talking about. If you have any questions that would help I will answer them.

  35. Routinely do not sleep well at night and wake up feeling very depressed. I ate two hamburgers and a banana right before bed last night. Slept better and woke up feeling amazingly better. (More energy, eager to get up and virtually no depressed feeling.) Any clue as to why?

  36. Depression is almost always situational. Peeps just don't want to admit that, because they would need the courage to change their situation, either from within, ending toxic relationships, or their environment. Also, when we stop thinking of our petty problems and stop being the problems for countless innocent beings everyday, there is something called karma. God is love, not power from above, and love isn't biased. i can also attest to natural medicine such as Cannabis (anti depressants are also tested on animals!), yoga, exercise….. And, love, not dependency 💚 Poor babies….

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