Active duty service members who sustain a traumatic brain injury have chronically elevated peripheral concentrations of Aβ40 and lower ratios of Aβ42/40

Figures & data

Table I. Demographics and clinical characteristics for TBI– and TBI+ groups (n = 71).

	TBI– (n = 18)	TBI+ (n = 53)	Significance
Mean age in years (SD)	28.91 (5.49)	30.56 (8.78)	F1,70 = 1.38, p = 0.41
Gender, % (n)
Male	100.0% (18)	98.1% (52)	χ^2 = 0.89, p = 0.89
Race, % (n)			χ^2 = 1.19, p = 0.66
Caucasian	83.3% (15)	88.7% (47)
African American	5.2% (1)	7.5% (4)
Mixed Race	5.2% (1)	1.8% (1)
Hispanic/Latino	5.2% (1)	1.8% (1)
PTSD (PCL-M), Mean (SD)	24.33 (10.84)	36.21 (13.05)	F1,68 = 7.32, p < 0.01
n (% PTSD Dx)	5 (27.78)	13 (24.52)	χ^2 = 0.79, p = 0.86
Depression (QIDS), Mean (SD)	7.00	12.85 (4.08)	F1,67 = 6.52, p < 0.01
n (% Depression Dx)	5 (27.78)	14 (26.41)	χ^2 = 0.74, p = 0.79
PCS (NSI), Mean (SD)	26.33 (13.55)	38.39 (14.20)	F1,58 = 6.84, p < 0.01

SD, standard deviation; PTSD, post-traumatic stress disorder; PCL-M, PTSD Checklist Military Version; QIDS, Quick Inventory of Depression; PCS, post-concussive syndrome; NSI, Neurobehavioral Symptom Inventory.

Table II. TBI characteristics according to the WARCAT.

	n	%
Severity of TBI
Dazed/confused/seeing stars	22	41.51%
Not remembering injury	20	37.73%
LOC < 1 minute	26	49.05%
LOC 1–20 minutes	11	20.75%
LOC > 20 minutes	5	9.43%
TBI symptoms after injury
Headache	33	62.64%
Memory problems	24	45.28%
Balance problems	20	37.73%
Irritability	26	49.05%
Sleeping problems	31	58.49%

Figure 1. (a) Concentrations of Aβ40 were significantly different (F_1,68 = 6.948, p = 0.009), with higher concentrations in the TBI+ group compared to TBI– controls. (b) Concentrations of Aβ42 tended to be different (F_1,64 = 2.979, p = 0.089), with a tendency to have higher concentrations in the TBI+ group compared to TBI– controls.

Figure 2. The ratio of Aβ42/Aβ40 was also significantly different between the groups (F_1,62 = 5.671, p = 0.020), with the ratio being significantly lower in the TBI+ group compared to TBI– controls.