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Other types of dementia

Visit us (http://www.khanacademy.org/science/healthcare-and-medicine) for health and medicine content or (http://www.khanacademy.org/test-prep/mcat) for MCAT related content. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video. Created by Tanner Marshall.

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Video transcript

- [Voiceover] So, Dementia is this general term we use when someone starts having trouble remembering, communicating, and understanding. And Alzheimer's Disease is a specific type of dementia that accounts for about 60 to 80% of all dementia cases. But what about the other 20 to 40%? Well, the second most common type, accounting for about 20 to 30% of dementia cases, is called Vascular Dementia. So, what do all the cells in your body, regardless of what they do, need to survive? Oxygen. They all need oxygen. Your brain cells are definitely no different. Actually, they are probably the biggest oxygen hogs in the body. Every time our heart beats, we pump about 20 to 25 % of that blood straight to our brain cells. So, if there are so many brain cells, or neurons, that need so much oxygen, you can imagine that the brain is especially vulnerable and sensitive to a lack in blood flow. So, when they don't get that oxygen. or get less of it, they can be damaged, or even start to die off. So, if, for example, your cells in your temporal lobe don't get enough oxygen and start to die off, it's going to be more difficult to remember things and form new memories because that's the area of your brain that controls those things. And so this is why we call it Vascular Dementia, where the Vascular part refers to the blood supply and the blood vessels supplying the brain. If there's any lack in blood flow to the brain as a result of a lowered blood supply, then loss of brain cells can follow and loss of certain mental functions. With Vascular Dementia, changes in thinking skills can happen suddenly following some sort of sudden damage, from a major stroke, maybe, which is an interruption in the blood supply to the brain. Also, though, changes in thinking skills can come about gradually due to minor strokes or a small vessel supplying the brain become blocked, leading to a more progressive damage. So, because it's related to your blood supply and your cardiovascular system, risk factors are very similar to the ones that could also raise your risk for heart diseases, blood vessel problems, and stroke. Some of these are things like smoking, high blood pressure, lack of exercise, obesity, and an unhealthy diet. Alright. So, that's the second most common type of dementia. The third most common type is called Dementia with Lewy Bodies and this accounts for about 10 to 25% of all dementia cases. And this type is caused by abnormal protein structures forming inside your neurons, called Lewy bodies, which are named after Dr. Friedrich Lewy, who discovered them in the early 1900s. Now, these Lewy bodies are actually accumulated bits of a protein called Alpha-synuclein. And you can find these guys hanging out in your brain cells, or your neurons. These Alpha-synuclein proteins are found widely throughout the brain, but their exact function isn't fully understood yet. One thing we do know is that when your cells can't properly process these proteins, they start to accumulate and sort of build up forming these Lewy bodies and, ultimately, end up damaging the cell. Symptoms of Lewy Body Dementia include problems with thinking and memory, movements and trembling, hallucinations, and even physically acting out dreams, like sleepwalking, talking or sleep kicking. Similarly to Alzheimer's, scientists have yet to figure out what the direct and specific cause for this build-up of Lewy Bodies is and research remains ongoing. On thing they do know, though, is that these Lewy Bodies can also be found in patients with Alzheimer's Disease and Parkinson's Disease, suggesting that there might be some similarities in how the brain has trouble breaking down these types of proteins. With that said, patients with Parkinson's Disease can develop dementia later on and if this happens, we call it Parkinson's Disease Dementia. And Parkinson's Disease alone usually affects your motor control, right? With this type of Dementia, the Parkinson's Disease has progressed to a point where it's started affecting mental functions in addition to your motor functions. Now, another type of Dementia is Frontotemporal Dementia, which used to be called Pick's Disease. And this type involves damage to the neurons that are specifically located in the frontal and temporal lobes of the brain. And when these neurons are damaged, things specific to those regions become affected, right? Like, spacial orientation in the frontal lobe or problems with speech from damage to the temporal lobe. Now, dementia, in general, can also be caused, or brought about, by other factors that result in some kind of accumulative damage to your brain. For example, the toxic effects of alcohol on brain cells through alcohol misuse can damage brain tissue, or repeated head injuries, like those sustained by professional boxers or football players, and we're talking about both American football and soccer, can seriously damage brain tissue over time. And it's also not uncommon for there to be more than one type of dementia present. For example, you could have Alzheimer's Disease, but also have Vascular Dementia as well.