Table 2. Tests of Fixed Effects for Longitudinal Fractional Anisotropy Analyses^a.

Dependent Variable	Age		Diagnostic Group				Age × Group		Decrease, %c
	F Score	P Value	F Score	P Value	q Valueb	β (SE)	F Score	P Value
Left ALIC	224.18	<.001	13.68	<.001	.002	−.028 (.007)	0.14	.71	−6.25
Right ALIC	190.82	<.001	7.97	.008	.01	−.021 (.008)	0.74	.39	−6.69
Left PLIC	225.12	<.001	3.61	.06	.09	−.015 (.008)	0.01	.91	−3.01
Right PLIC	187.69	<.001	2.82	.10	.12	−.014 (.008)	0.11	.74	−3.42
Left ATR	172.07	<.001	4.36	.04	.06	−.018 (.008)	0.80	.37	−2.58
Right ATR	157.54	<.001	2.60	.11	.13	−.014 (.009)	0.01	.94	−3.18
Left ILF	276.87	<.001	16.90	<.001	.001	−.029 (.007)	0.03	.87	−7.44
Right ILF	524.64	<.001	19.87	<.001	.001	−.028 (.006)	1.69	.20	−5.14
Left uncinate	255.94	<.001	10.85	.002	.005	−.019 (.006)	0.68	.41	−3.84
Right uncinate	278.16	<.001	9.53	.004	.008	−.016 (.005)	0.58	.45	−3.45
Left SCP	129.13	<.001	15.48	<.001	.002	−.029 (.007)	0.27	.60	−6.91
Right SCP	162.09	<.001	24.00	<.001	.001	−.038 (.008)	1.13	.29	−7.92
MCP	137.01	<.001	3.31	.07	.09	−.020 (.011)	0.03	.85	−3.76
Corpus callosum
Section I	510.48	<.001	19.98	<.001	.001	−.035 (.008)	0.17	.68	−7.59
Section II	471.95	<.001	14.75	<.001	.002	−.032 (.008)	0.18	.67	−6.96
Section III	333.09	<.001	6.42	.01	.02	−.025 (.010)	1.61	.21	−7.77
Section IV	153.25	<.001	2.23	.14	.15	−.016 (.010)	2.54	.12	−6.73
Section Va	231.19	<.001	5.62	.02	.03	−.020 (.008)	0.34	.56	−5.62
Section Vb	154.42	<.001	1.18	.28	.28	−.013 (.012)	0.75	.39	−4.20

Abbreviations: ALIC, anterior limb of internal capsule; ATR, anterior thalamic radiation; ILF, inferior longitudinal fasciculus; MCP, midcerebellar peduncle; PLIC, posterior limb of internal capsule; SCP, superior cerebellar peduncle.

^aClinical site included as a model covariate.

^bThe q Values are false discovery rate–corrected P values.

^cPercentage decrease compares least squares means in fractional anisotropy across all time points in patients with fragile X syndrome compared with controls.