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Dementia in Head Injury

Dementia in Head Injury Overview

Head injury occurs when an outside force hits the head hard enough to cause the brain to move violently within the skull. This force can cause shaking, twisting, bruising (contusion), or sudden change in the movement of the brain (concussion).

  • In some cases, the skull can break. If the skull is not broken, the injury is a closed head injury. If the skull is broken, the injury is an open head injury.
  • In either case, the violent jarring of the brain damages brain tissue and tears nerves, blood vessels, and membranes.
  • The severity of this damage depends on the location and force of the blow to the head.

Damaged brain tissue does not work normally.

  • The brain has many different functions in the body, and any of them can be disrupted by this damage.
  • Not all brain damage is permanent. Like all body organs, the brain can heal to a certain extent.
  • Even this healing may not bring the brain’s function back to what it was before the injury.

Even a relatively mild head injury can cause prolonged or permanent declines in cognition. (Cognition is the processes of thinking, remembering, understanding, reasoning, and communicating.) Head injury can also cause changes in emotions or behavior.

  • Together, these changes are known as dementia.
  • The nature of dementia in head-injured persons varies greatly by type and location of head injury and the person’s characteristics before the head injury.

After head injury, a person may have symptoms such as changes in personality, emotional problems, and difficulty making decisions or solving problems.

  • The exact symptoms depend on the parts of the brain that are injured.
  • Likewise, the severity of symptoms can be related to the severity of the brain injury, but this is not always true.
  • If the injury is not too severe, these symptoms may get better over time.

Direct damage to brain tissue and surrounding areas accounts for only part of the problems in head injury. The resulting bleeding (bruising), fluid collection (hydrocephalus), and infection can also damage the brain. A common complication is epilepsy (seizures).

Dementia after head injury is a significant public health problem.

  • In the United States, roughly 2 per 1000 people each year have some kind of head injury. Many do not seek medical care.
  • Between 400,000 and 500,000 people are hospitalized in the United States every year for head injury.
  • Younger people are more likely to have a head injury than older people. Head injury is the third most common cause of dementia, after infection and alcoholism, in people younger than 50 years.

  • Older people with head injury are more likely to have complications such as dementia. Children are likely to have more severe complications.
  • Men, especially younger men, are more likely than women to have a head injury.
Medically Reviewed by a Doctor on 12/23/2015
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