Lack of resources to run the trial

The purpose of this research is to determine whether athletes with concussion have changes in cortical excitability.

Single and paired transcranial magnetic stimulation (TMS) can be used as reliable neurophysiological marker of motor cortex reorganization in athletes with concussions.

This study also aims to determine whether modulation of cortical activity by a powerful technique of noninvasive brain stimulation (tDCS) results in a different cortical response as compared with sham tDCS.

This study is a multicenter study with investigators from other institutions (Dr. Alvaro Pascual-Leone and Dr. Hugo Theoret).

Inclusion Criteria:

• Student-athletes at risk for traumatic brain injury (collegiate football, ice hockey)
• Age between 18 and 30 yr.
• Concussion as defined by the American Academy of Neurology: trauma-induced alteration in mental status that may or may not involve loss of consciousness (confusion and amnesia are the hallmarks of concussion)
• Concussion that occurred > 6 months
• All head injuries classified as minor with a Glasgow Coma Scale of 13 to 15 at the time of the trauma
• Participants are cleared for full sport participation based upon neurological and neuropsychological (NS) assessments Classified as symptomatic based on Post-concussion Symptom List

Exclusion Criteria:

• Previous significant neurological history
• Use of tricyclic anti-depressants such as amitriptyline, nortriptyline and imipramine within the past six months.
• Use of anticonvulsants such as carbamazepine, phenytoin, valproic acid and gabapentin within the past six months
• History of seizures, depression or PTSD
• Presence of post-concussion symptoms such as complaints of loss of concentration, dizziness, fatigue, headache, irritability, visual disturbances, and light sensitivity.
• Contraindications to single pulse TMS (TMS will be used to measure cortical excitability) such as metal head implants
• history of seizures
• unexplained loss of consciousness
• metal in the head
• frequent or severe headaches or neck pain
• implanted brain medical devices.
• Contraindications to tDCS:
• metal in the head
• implanted brain medical devices

For the control group (subjects with no concussion) we will select subjects according to the previously stated list of exclusions as well as the following criteria: Subjects who are athletes (similar to the concussed group) with the same age range and also similar level of education; however these subjects will have no prior history of concussion or neurological insult as self reported. They should also have no contraindications to TMS or tDCS.