Table 1.

Baseline Participant Characteristics by Treatment Group

Variable	Category	Placebo (n=86) Number (%)	Amantadine (n=82) Number (%)	p value
Sex	Male	74.4%	80.5%	0.3473
Race	Caucasian	87.2%	89.0%	0.9359
	Black	5.8%	6.1%
	Other	7.0%	4.9%
Hispanic	Yes	9.3%	3.7%	0.1394
Education	Less than HS	16.3%	6.1%	0.3472
	HS diploma	30.2%	37.8%
	Some college	51.7%	48.3%
	Bachelors or toward masters	45.5%	54.6%
	Masters and above	7.0%	7.3%
Cause of injury	Vehicular	61.6%	69.5%	0.5513
	Fall	18.6%	13.4%
	Assault	10.5%	6.1%
	Sport-related	3.5%	1.2%
	Pedestrian	3.5%	7.3%
	Other	2.3%	2.4%
Loss of consciousness duration	<1 h	27.9%	23.1%	0.6845
	≥1 h but <24 h	15.1%	12.8%
	1–6 d	16.3%	24.4%
	7–13 d	8.1%	6.4%
	14–20 d	9.3%	12.8%
	21–29 d	10.5%	9.0%
	30–59 d	9.3%	6.4%
	≥60 d	3.5%	5.1%
Post-traumatic amnesia duration	<24 h	9.6%	11.5%	0.9685
	1–6 d	22.9%	11.5%
	7–13 d	4.8%	10.3%
	14–20 d	9.6%	14.1%
	21–29 d	12.1%	10.3%
	30–59 d	15.7%	23.1%
	≥60 d	25.3%	19.2%
History >1 TBI	Yes	18.6%	13.4%	0.3599
Total Glasgow Coma Scale score	3–8	30.8%	22.5%	0.4672
	9–12	1.3%	4.2%
	13–15	25.6%	23.9%
	Chemically paralyzed, chemically induced coma, or intubated	42.3%	49.3%

	Mean (SD)	Mean (SD)
Age at enrollment	38.23 (12.36)	40.18 (12.67)	0.2814
Age at injury	31.88 (12.07)	33.85 (12.87)	0.3803
Observer NPI irritability Most Problematic	8.35 (2.13)	8.56 (2.36)	0.7859
Participant NPI irritability Most Problematic	6.17 (3.54)	6.15 (3.18)	0.8593
Observer NPI irritability Most Problematic Distress	3.77(0.95)	3.65 (1.06)	0.5421
Participant NPI irritability Most Problematic Distress	3.00 (1.41)	3.05 (1.28)	0.9427
Beck Depression Inventory–II Total	18.36 (11.09)	17.39 (9.76)	0.6705
Glasgow Coma Scale–Extended	5.05 (1.38)	5.51 (1.19)	0.0492*

HS, high school, TBI, traumatic brain injury; SD, standard deviation; NPI, Neuropsychiatric Inventory.

^*Statistically significant.