Aphasia: The disorder that makes you lose your words - Susan Wortman-Jutt

1,437,610 views ・ 2016-09-15

TED-Ed


Please double-click on the English subtitles below to play the video.

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Language is an essential part of our lives that we often take for granted.
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With it, we can communicate our thoughts and feelings,
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lose ourselves in novels,
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send text messages,
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and greet friends.
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It's hard to imagine being unable to turn thoughts into words.
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But if the delicate web of language networks in your brain
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became disrupted by stroke, illness, or trauma,
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you could find yourself truly at a loss for words.
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This disorder, called aphasia, can impair all aspects of communication.
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People who have aphasia remain as intelligent as ever.
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They know what they want to say,
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but can't always get their words to come out correctly.
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They may unintentionally use substitutions called paraphasias,
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switching related words, like saying "dog" for "cat,"
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or words that sound similar, such as "house" for "horse."
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Sometimes, their words may even be unrecognizable.
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There are several types of aphasia grouped into two categories:
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fluent, or receptive, aphasia
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and non-fluent, or expressive, aphasia.
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People with fluent aphasia may have normal vocal inflection
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but use words that lack meaning.
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They have difficulty comprehending the speech of others
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and are frequently unable to recognize their own speech errors.
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People with non-fluent aphasia, on the other hand,
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may have good comprehension
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but will experience long hesitations between words and make grammatical errors.
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We all have that tip-of-the-tongue feeling from time to time
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when we can't think of a word,
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but having aphasia can make it hard to name simple, everyday objects.
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Even reading and writing can be difficult and frustrating.
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So how does this language loss happen?
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The human brain has two hemispheres.
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In most people, the left hemisphere governs language.
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We know this because in 1861,
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the physician Paul Broca studied a patient
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who lost the ability to use all but a single word, "tan."
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During a postmortem study of that patient's brain,
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Broca discovered a large lesion in the left hemisphere
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now known as Broca's area.
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Scientists today believe that Broca's area is responsible in part for naming objects
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and coordinating the muscles involved in speech.
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Behind Broca's area is Wernicke's area near the auditory cortex.
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That's where the brain attaches meaning to speech sounds.
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Damage to Wernicke's area impairs the brain's ability to comprehend language.
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Aphasia is caused by injury to one or both of these specialized language areas.
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Fortunately, there are other areas of the brain
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which support these language centers
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and can assist with communication.
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Even brain areas that control movement are connected to language.
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FMRI studies found that when we hear action words, like "run" or "dance,"
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parts of the brain responsible for movement light up
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as if the body was actually running or dancing.
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Our other hemisphere contributes to language, too,
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enhancing the rhythm and intonation of our speech.
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These non-language areas sometimes assist people with aphasia
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when communication is difficult.
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So how common is aphasia?
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Approximately 1 million people in the U.S. alone have it,
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with an estimated 80,000 new cases per year.
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About one-third of stroke survivors suffer from aphasia
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making it more prevalent than Parkinson's disease
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or multiple sclerosis,
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yet less widely known.
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There is one rare form of aphasia called primary progressive aphasia, or PPA,
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which is not caused by stroke or brain injury,
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but is actually a form of dementia
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in which language loss is the first symptom.
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The goal in treating PPA is to maintain language function for as long as possible
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before other symptoms of dementia eventually occur.
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However, when aphasia is acquired from a stroke or brain trauma,
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language improvement may be achieved through speech therapy.
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Our brain's ability to repair itself, known as brain plasticity,
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permits areas surrounding a brain lesion
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to take over some functions during the recovery process.
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Scientists have been conducting experiments using new forms of technology,
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which they believe may encourage brain plasticity in people with aphasia.
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Meanwhile, many people with aphasia remain isolated,
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afraid that others won't understand them or give them extra time to speak.
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By offering them the time and flexibility to communicate in whatever way they can,
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you can help open the door to language again,
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moving beyond the limitations of aphasia.
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