Table 2.

Main Effects and Interaction for Traumatic Brain Injury and Apolipoprotein E-ε4 Status on Age of Symptom Onset of Alzheimer Disease

	n	M (SD)	F	p
Main Effect for APOE Status			19.27	< .001*
APOE ε4 +	2,798	69.6 (8.8)
APOE ε4 –	1,946	71.9 (10.3)
Main Effect for TBI Status			26.06	< .001*
TBI +	386	68.2 (10.6)
TBI –	4,358	70.7 (9.4)
Interaction for TBI and APOE ε4			0.93	0.34
TBI + APOE ε4 +	228	67.1 (9.9)
TBI + APOE ε4 –	158	69.9 (11.3)
TBI – APOE ε4 +	2,570	69.8 (8.7)
TBI – APOE ε4 –	1,788	72.1 (10.2)

Note. * p < .05. n = 4,744. df = 1. TBI+ = presence of a history of traumatic brain injury with any loss of consciousness and no chronic deficits occurring more than one year prior to the initial visit. TBI− = absence of a history of traumatic brain injury with loss of consciousness. APOE ε4+ = presence of at least one apolipoprotein E-e4 allele. APOE ε4– = absence of an apolipoprotein E-e4 allele.