Table 3.

Absolute mean (SD) brain volume at baseline and 18-months expressed as a percent of total intracranial volume.

Brain volume	Low risk		High risk
	High PA	Low PA	High PA	Low PA
	(n = 24)	(n = 34)	(n = 22)	(n = 17)
HIPPOCAMPUS
Baseline	0.456 (0.061)	0.480 (0.081)	0.447 (0.065)	0.460 (0.073)
18 months	0.451 (0.059)	0.478 (0.083)	0.445 (0.069)	0.447 (0.078)
THALAMUS
Baseline	0.789 (0.062)	0.829 (0.091)	0.800 (0.090)	0.826 (0.093)
18 months	0.773 (0.070)	0.822 (0.093)	0.787 (0.099)	0.811 (0.085)
CAUDATE
Baseline	0.504 (0.063)	0.542 (0.067)	0.499 (0.063)	0.508 (0.063)
18 months	0.502 (0.066)	0.535 (0.070)	0.493 (0.061)	0.496 (0.065)
AMYGDALA
Baseline	0.178 (0.024)	0.191 (0.028)	0.177 (0.027)	0.187 (0.026)
18 months	0.178 (0.025)	0.194 (0.033)	0.176 (0.030)	0.187 (0.029)
CAUDAL MIDDLE FRONTAL g.
Baseline	0.834 (0.108)	0.815 (0.125)	0.823 (0.126)	0.828 (0.129)
18 months	0.842 (0.115)	0.824 (0.137)	0.824 (0.130)	0.836 (0.143)
PRECENTRAL g.
Baseline	1.76 (0.15)	1.82 (0.18)	1.73 (0.17)	1.85 (0.17)
18 months	1.76 (0.13)	1.81 (0.21)	1.72 (0.18)	1.83 (0.21)
TOTAL GM
Baseline	38.6 (2.8)	40.4 (4.1)	38.6 (2.5)	40.6 (3.0)
18 months	38.5 (2.8)	40.2 (4.3)	38.5 (3.0)	40.1 (3.2)
CORTICAL WM
Baseline	30.5 (2.8)	31.2 (3.4)	30.2 (3.5)	30.6 (2.6)
18 months	30.1 (3.2)	31.1 (3.5)	30.0 (3.5)	30.5 (2.6)

PA, physical activity; GM, gray matter; WM, white matter; g., gyrus.