If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Alzheimer's disease and Korsakoff's syndrome

Learn about how Alzheimer's Disease and Korsakoff's Syndrome affect memory.
.
Created by Carole Yue.

Want to join the conversation?

  • male robot hal style avatar for user Shaun Hall
    Are professional athletes, e.g. football players and boxers, more prone to suffer for Alzheimer's at a later age?
    (6 votes)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user Fred Hicks Jr.
    Why were these 2 diseases talked about specifically? Are there any more dementia related diseases we should know for the MCAT? Or any more details about these two? Thanks.
    (2 votes)
    Default Khan Academy avatar avatar for user
    • mr pants teal style avatar for user medstudent4life
      These are the two most important dementia related diseases and the two that the MCAT focuses on specifically, if at all. You should know the physiological changes that occur. For AD, (outside the cell) beta-amyloids (that are usually cut off of APP and recycled) aggregate into beta-amyloid plaques. Inside the cell, the Tau protein becomes hyperphosphorylated causing the proteins to become aggregated into insoluble neurofibrillary tangles. As a result, the brain as a whole shrinks, but esp. the temporofrontal and frontal cortexes and the hippocampus (also, the ventricles increase). For Korsakoff's, you mainly just need to know that it results from severe thiamine deficiencies. Hope this helps! Good luck on your MCAT! :)
      (11 votes)
  • old spice man green style avatar for user Nancy✨✴
    my grandmother has dimentia and we trying to help her but she lies sometimes and then my dad gets mad, what can we do to help get her short term memory back, without the use of a lot of medication.
    (2 votes)
    Default Khan Academy avatar avatar for user
    • leaf blue style avatar for user Tim
      The first thing to do is to go see a Doctor. If medical advice is to be had, they are the first place to go.

      Besides the first suggestion, probably the best thing they could do is exercise. Exercise has been show to reduce cognitive decline. Eating healthy always helps too. That means not consuming more calories than needed, and getting proper nutrition (daily value), Include the dark leafy greens. Blue Berries are good too. A little bit of something from each food group is a simple way to do this.

      You might also consider dancing sessions, music, or positive social interaction. And go to a Doctor, if you haven't already.
      (8 votes)
  • blobby green style avatar for user Gem
    Hi,

    So I'm trying to understand this in the simplest way so that way I can remember it. I'm not really good with this. What exactly is thiamine for? you mentioned that thiamine is used up in order for the carbohydrates to be used. So when a person lacks thiamine, does that mean that the brain is unable to use the glucose leading to damage to the brain?
    (1 vote)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Joanne
      Thiamine, or vitamin B1, is in the enzyme, TPP, that converts Pyruvic acid (from the break down of glucose in glycolysis) to Acetyl CoA so it can enter the Krebs cycle. If a person has been starving and not taken in adequate vitamin B1, this reaction can’t occur. People that are starving are frequently given carbohydrate rich food unfortunately. But without TPP, the pyruvic acid builds up, which in turn increases the amount of lactic acid. In the brain this causes Wernicke-Korsakoff syndrome which are a variety of signs of brain damage, such as nystagmus and it may lead to long term problems such as memory deficits, confusion etc. Yes, if the person is lacking thiamine and given sugar, the brain can be damaged. So, when treating people that may have not eaten well, such as alcoholics, people with anorexia nervosa, cancer etc.. it makes sense to give them thiamine. Beriberi is another term meaning Thiamine deficiency. http://emedicine.medscape.com/article/116930-overview
      (7 votes)
  • leaf blue style avatar for user Ethan Mehalchick
    Who first discovered Alzheimer's disease?
    (3 votes)
    Default Khan Academy avatar avatar for user
  • female robot grace style avatar for user OpenMinded737
    At When she says thiamine is responsible for converting carbohydrates into glucose to give the cells energy. is she referring to catabolism or anabolism? its confusing. I expect her to be referring to anabolism if we are going from a large carbohydrate to a glucose, but the cells get energy by breaking down glucose not making it.
    (2 votes)
    Default Khan Academy avatar avatar for user
    • leaf green style avatar for user Joanne
      Yes, you are close. First let's check definitions. Anabolism means to build up. (think anabolic steroids build up muscles- and no, I am not encouraging their use.) Catabolism means to break down. (think 'cut'abolism). If she said that carbs have to be converted to glucose, then she is referring to catabolism the break down of carbohydrates to glucose molecules. Thiamine is in an enzyme required to break down pyruvate (often from glucose) in cellular respiration to ATP, CO2 and H2O. Carbohydrates, starches and sugars are made up of many sugars. Glucose is a single sugar molecule.
      To break down pyruvate, TPP is required, a thiamine containing enzyme. If this enzyme is not available then ketone acids accumulate which change the body pH and may damage the brain. This maybe more than you want but here is a link to the Krebs Cycle. https://en.wikibooks.org/wiki/Structural_Biochemistry/Krebs_Cycle_(Citric_Acid_cycle)
      (2 votes)
  • starky ultimate style avatar for user Darknessthedevil
    I didn't get the planning part. Could someone explain what she meant by planning?
    (0 votes)
    Default Khan Academy avatar avatar for user
  • blobby green style avatar for user Fran Cueto
    I can't see this video... I press it and I get the aging and cognitive decay video.
    (0 votes)
    Default Khan Academy avatar avatar for user
    • duskpin sapling style avatar for user 12
      Are you sure? Did you try to reload the page multiple times and it still didn't work? How about trying to go to google and type KhanAcademy. Click on KhanAcademy and go to this video. Does it still not work?
      (1 vote)

Video transcript

Although everybody forgets, excessive forgetting can be a sign of a more serious problem. Dementia is the term for a decline in memory and other cognitive functions that gets to the point of interfering with daily life. Dementia results from excessive damage to brain tissue, which can be from multiple strokes or other causes. The most common form of dementia is Alzheimer's disease, or AD. Now, the exact cause of AD is still unknown, but we do know that in people with AD, their neurons die off over time. As people with AD lose their neurons and synapses, their cerebral cortex shrinks in size. The earliest symptoms of AD are memory loss, specifically the inability to encode or retrieve recent memories. Subsequent problems include difficulty with attention, planning, semantic memory, and abstract thinking. As the disease progresses, more severe language difficulties may appear, as well as greater memory loss, such as the inability to recognize close family and friends. As the disease continues to progress, people with AD may experience emotional instability and loss of control over their bodily functions. While there are many theories as to the exact cause of the disease, a definitive answer is still unknown, and the disease is terminal. We do know that people with AD experience a buildup of proteins called amyloid plaques in the brain, but how or why those plaques start to build up and exactly what role they play in the disease is still uncertain. Another neurological disorder affecting memory is Korsakoff's syndrome, which is caused by a lack of vitamin B1, or thiamine, in the brain. This disorder is strongly linked to severe malnutrition, eating disorders, or especially alcoholism, because these groups often don't ingest or are unable to process all the nutrients their bodies need, including thiamine. Thiamine is important because it's responsible for converting carbohydrates into the glucose your cells need for energy, and it's especially important for the normal functioning of your neurons. At first, a person developing Korsakoff's syndrome might have damage to certain parts of the brain, resulting in poor balance, abnormal eye movements, mild confusion, and/or memory loss. At this stage, it's actually called Wernicke's encephalopathy, which is the precursor to Korsakoff's syndrome. If Wernicke's encephalopathy is diagnosed in time, then it's possible to reverse the damage, or at least prevent more of it. If untreated, however, the disease will progress into full-blown Korsakoff's syndrome. The main symptom of Korsakoff's syndrome is severe memory loss, and this symptom is often accompanied by confabulation, which is when the patient makes up stories, sometimes to fill in the gaps in his or her memory. Unlike AD, Korsakoff's syndrome is not necessarily progressive. If diagnosed and treated, people can get better. People are often treated with thiamine injections or other medication, and they have to stay on a healthy diet and abstain from alcohol. And some people may also need to re-learn some things. The effectiveness of this treatment really depends on how early the disease is diagnosed and how well the patient follows the treatment guidelines.