Amantadine for the Treatment of Traumatic Brain Injury Irritability and Aggression: A Multi-site Study

Inclusion Criteria

• Closed head injury (defined as impaired brain function resulting from externally inflicted trauma without penetrating injury) at least 6 months prior to enrollment
• Irritability that is either new or worse than the level of irritability before the traumatic brain injury, by report of the Observer or person with TBI
• Age at time of enrollment: 16 to 75 years
• Voluntary informed consent and authorization of participant and informant
• Subject and informant willing to comply with the protocol
• Informant-rated NPI Irritability Domain score 6 or greater (moderate-to-severe irritability)
• Medically and neurologically stable during the month prior to enrollment
• If taking antidepressant, anxiolytic, hypnotic, or stimulant medications, no change anticipated in these medications during the month prior to enrollment or during the 90-day participation
• No change in therapies or medications planned during the 90-day participation
• No surgeries planned during the 90-day participation
• Vision, hearing, speech, motor function, and comprehension sufficient to complete interviews
• Observer (e.g.: family member, close friend, employer) with whom subject interacts sufficiently to observe occurrences of irritability. The observer interacts with the participant for a period long enough and of a nature to be able to judge the participant's irritability. The interactions would need to be adequate to judge observer distress over the irritability, severity of irritability and frequency of irritability on the following scale: < once weekly; once per week; several times per week, but not every day; essentially continuous.

Exclusion Criteria

• Previous participation in the Carolinas TBI Model System amantadine irritability study
• Ingestion of amantadine hydrochloride during the month prior to enrollment
• Potential subject without a reliable informant
• Penetrating head injury as defined by head injury due to gunshot, projectile or foreign object
• Injury < 6 months prior to enrollment
• Inability to interact sufficiently for communication with caregiver
• Clinical signs of active infection
• Diagnosis of seizure in the month prior to enrollment
• Creatinine clearance <60 mL/min
• Pregnancy (Beta-HCG + females of child-bearing potential) and lactating females
• Concurrent use of first generation neuroleptic agents or phenelzine
• History of schizophrenia or psychosis
• Active concern of schizophrenia or psychosis
• Diagnosis of progressive or additional neurologic disease that affects brain function, except stroke that occurs at th same time as the TBI
• Previous allergy or adverse reaction to amantadine hydrochloride