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Studying for a test? Prepare with these 2 lessons on Nervous system diseases.
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- [Voiceover] So we know that in multiple sclerosis the immune system is attacking the central nervous system, but we don't really know why it's doing that. So in other words, we don't really know what the true cause of the disease is. Because we don't know the true cause of the disease, there is no known cure for it. However, there are a lot of treatment options available for people. A really common class of drugs that people take are the disease-modifying drugs. So how do these act? Well, remember that in multiple sclerosis, we can really track the way that the disease progresses over time. So on the X axis we have time, right, in terms of the lifespan of the individual and on the Y axis we have the severity of the disease, that is how much damage does the brain accumulate. There are four different types of multiple sclerosis, each characterized by the way that they progress over time. The most common type is the relapsing-remitting form. So you can tell here, you know, there's a relapse over here and relapse is really when the brain starts to accumulate a lot of damage and the symptoms start to flare up and the severity increases. And you have a remission over here. This is when the brain kind of starts to heal itself and the symptoms go away for a bit and the disease itself starts to improve. This type affects about 80% to 85% of those who have multiple sclerosis. Because it's so common, most of the treatment options that we have, right, those disease-modifying drugs, address this type. There are other types of multiple sclerosis, but unfortunately they don't really respond well to these drugs. So what are these disease-modifying drugs going to do? Well, they're actually going to modify the course at which this disease progresses. So what do I mean by that? Well, if you take these drugs, then it's most likely that the graph will probably look something like this instead. So you can already tell some of the major differences, right? One, that the severity of these relapses is decreased and two, the remission time has also increased so what you're doing is you're slowing the progression of the disease. That's why we call them disease-modifying drugs because they modify the progression of the disease. So what are some disease-modifying drugs? Well, most of them are immunosuppressants and I think this word is actually pretty self explanatory. These guys are going to suppress the immune system. So one example of an immunosuppressant are the corticosteroids. These are steroid hormones that are actually released by the adrenal glands above your kidneys, but they can also be given to a person as medication and then you also have the beta interferons. So an interferon is a chemical that's released by the immune system to manage inflammation. A beta interferon will suppress the inflammation. So how do these work? What's going on at the cellular level? Well, we kind of have to understand the pathophysiology, right? So let's say we have a neuron over here. As usual, this neuron will have myelins surrounding the axon and then next to this neuron you may have a blood vessel. Around this blood vessel is kind of a wall, right, known as the blood brain barrier. This blood brain barrier is gonna stop immune cells like this T-cell over here from crossing over and entering the brain. So this guy's ordinarily trapped in the blood vessel, but in multiple sclerosis this blood brain barrier becomes pretty leaky and this guy is able to make his way across. This is actually one of the first points in which these immunosuppressants can act. They can actually stop that T-cell from crossing the blood brain barrier and in doing so he's not even gonna interact with the brain at all to begin with. So now the immune system has limited access to the brain, but this isn't the only site where the immunosuppressants can act. Maybe the T-cell actually manages to make his way across the blood brain barrier. The T-cell will look at that myelin and it'll recognize it as foreign. In doing so, this will trigger an alarm. So this T-cell is gonna release a whole bunch of chemicals called cytokines. These cytokines are going to alert a whole bunch of other immune cells so maybe you have a B-cell over here that responds to those cytokines or maybe even a macrophage and this will lead to inflammation. The one thing your immunosuppressants can do is it can ensure that the T-cell doesn't react so vigorously to the myelin. If it doesn't react as much, it may not release so many cytokines. If it doesn't release as many cytokines, then those cytokines won't really be able to recruit the other cells of the immune system so ultimately what we have is a dampened immune response. The immune system isn't really able to act as vigorously and as aggressively anymore. So, of course, these disease-modifying drugs will kind of relieve some of those symptoms, but they do so by addressing the pathophysiology. But there are alternative ways to really address those symptoms. So what we want to do is we want to think of different types of symptom management. So instead of kind of just taking those medicines, you can also do a number of other alternative things to really address those symptoms directly. So let's say we have a person over here and let's say this person has multiple sclerosis. What are the symptoms they may experience? Well, one, they may have a lot of fatigue, right, so they may just be really physically exhausted all the time. In addition to that, they may also have this stiffness of their muscles where their muscles are contracting too much and this can lead to a lot of pain. They may also have muscle weakness and numbness in their arms. So these are a lot of symptoms, right, so how do we address them? Well, we can have the person visit a physical therapist. So here we have a physical therapist and really what they're gonna do is they're gonna have this person perform a number of different physical tasks. Maybe they'll help them do some stretching exercises. Maybe they'll help them walk a little bit more normally and ultimately this will kind of help relieve those symptoms. But there are still other symptoms that maybe a physical therapist might not be able to help out with. So remember that in multiple sclerosis, a lot of people may actually experience cognitive dysfunction and just as a brief review, remember that cognition includes functions like attention, working memory, and decision making. These functions can be pretty heavily impaired in multiple sclerosis and this can be really problematic because cognitive dysfunction is really one of the major reasons why people have to leave their jobs. So how can we address this? Well, we can have the person undergo what's called cognitive rehabilitation therapy. So in cognitive rehabilitation therapy, the primary goal is to kinda restore these functions and the way to do that is to have the person perform a set of mental tasks, right, so they may play a few games where they try to remember a few things and all sorts of things that will really help them kind of strengthen their cognitive abilities and in doing so, their cognition will start to improve, right. So it's kinda like physical therapy, except instead of working with your body you're working with your mind. So these are some of the alternative ways to manage your symptoms without taking those disease-modifying drugs.