What are the long-term problems associated with traumatic brain injury?

In addition to the immediate post-injury complications other long-term problems can develop after a TBI. These include Parkinson's disease and other motor problems, Alzheimer's disease, dementia pugilistica, and post-traumatic dementia.

Alzheimer's disease (AD) - AD is a progressive, neurodegenerative disease characterized by dementia, memory loss, and deteriorating cognitive abilities. Recent research suggests an association between a 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.

Parkinson's disease and other motor problems - Movement disorders as a result of TBI are rare but can occur. Parkinson's disease may develop years after TBI as a result of damage to the basal ganglia. The symptoms of Parkinson's disease include tremors, rigidity, slow movement (bradykinesia), inability to move (akinesia), a shuffling walk, and a stooped posture.

Dementia pugilistica - Also called chronic traumatic encephalopathy, dementia pugilistica primarily affects professional boxers. The most common symptoms of the condition are dementia and parkinsonism caused by repetitive blows to the head over a long period of time. The symptoms begin anywhere between 6 and 40 years after the start of a boxing career, with an average onset of about 16 years.

Post-traumatic dementia - The symptoms of post-traumatic dementia are very similar to those of dementia pugilistica, except that post-traumatic dementia is also characterized by long-term memory problems and is caused by a single, severe TBI that results in a coma.

This Answer is based on source information from the National Institute of Neurological Disorders and Stroke.