What are the different types of concussion?

There are three grades of concussion. In Grade One, a concussion causes temporary disorientation. The person remains conscious and the symptoms are gone within 15 minutes.

With a Grade Two concussion, the symptoms are the same as a Grade One concussion, only the symptoms last about a half-hour.

With a Grade Three concussion, sometimes referred to as a classic concussion, there is a loss of consciousness - no matter how brief.

Regardless of the type of concussion, a person?s brain remains highly vulnerable for at least the next few days. Any additional concussions, which are sometimes called "mini-concussions", can compound the damage that was inflicted by the first concussion.

In fact, another concussion can be fatal - which is sometimes what happens with second impact syndrome, which happens when the brain and its arteries swell to dangerous levels.

Symptoms that remain after a concussion are sometimes called post-concussion syndrome. These can include headaches, nausea, anxiety, lapses, dizziness and difficulty with sleeping and concentrating.

A substantial number of professional athletes have been forced to retire because of persistent symptoms of post-concussion syndrome. Complicating matters, the effects of post-concussion syndrome often are not evident on a CT scan or an MRI.

There also is increasing evidence that repeated concussions can lead to early-onset dementia and similar disorders.

When someone has experienced at least three concussions, the risk of the early-onset Alzheimer's disease becomes five times more likely.