Complications of traumatic brain injury

Traumatic brain injury (TBI, physical trauma to the brain) can cause a variety of complications, health effects that are not TBI themselves but that result from it. The risk of complications increases with the severity of the trauma; however even mild traumatic brain injury can result in disabilities that interfere with social interactions, employment, and everyday living. TBI can cause a variety of problems including physical, cognitive, emotional, and behavioral complications.

Symptoms that may occur after a concussion – a minor form of traumatic brain injury – are referred to as post-concussion syndrome.

Generally, there are six abnormal states of consciousness that can result from a TBI:

Disorders of consciousness affect a significant number of people who suffer severe TBI; of those with severe TBI discharged from a hospital, 10-15 are in a vegetative state, and of this number only half regain consciousness within one to three years.

Most patients with severe TBI who recover consciousness suffer from cognitive disabilities, including the loss of many higher-level mental skills. Cognitive deficits that can follow TBI include impaired attention; disrupted insight, judgement, and thought; reduced processing speed; distractibility; and deficits in executive functions such as abstract reasoning, planning, problem-solving, and multitasking.Memory loss, the most common cognitive impairment among head-injured people, occurs in 20–79% of people with closed head trauma, depending on severity.Post-traumatic amnesia (PTA), a confusional state with impaired memory, is characterized by loss of specific memories or the partial inability to form or store new ones.

Alzheimer's disease (AD) is a progressive, neurodegenerative disease characterized by dementia, memory loss, and deteriorating cognitive abilities. Research suggests an association between head injury in early adulthood and the development of AD later in life; the more severe the head injury, the greater the risk of developing AD. Some evidence indicates that a head injury may interact with other factors to trigger the disease and may hasten the onset of the disease in individuals already at risk. For example, head-injured people who have a particular form of the protein apolipoprotein E (apoE4, a naturally occurring protein that helps transport cholesterol through the bloodstream) fall into this increased risk category.

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