Table 2.

GAM of the slopes for each composite.

Composite	N	Age at Baseline		Baseline Performance		SESa		Ethnicity		Sex		Site		Family History		Group mean practice slope = % group mean observed slope
		variance	p	variance	p	variance	p	variance	p	variance	p	variance	p	variance	p
Accuracy Composites
General Ability	545	0.0030	0.0918	0.0513	0.0000	0.0183	0.0027	0.0109	0.1046	0.0023	0.2549	0.0119	0.1335	0.0013	0.3909	29.17
Abstraction	542	0.0263	0.0000	0.2534	0.0000	0.0185	0.0001	0.0219	0.0012	0.0009	0.4169	0.0145	0.0266	0.0017	0.2452	76.49
Attention	553	0.0129	0.0004	0.4691	0.0000	0.0002	0.6248	0.0053	0.1200	0.0001	0.7150	0.0043	0.3090	0.0000	0.9083	67.33
Emotion	551	0.0040	0.0509	0.2509	0.0000	0.0026	0.1783	0.0098	0.0642	0.0071	0.0220	0.0097	0.1218	0.0004	0.5915	62.67
Episodic Memory	549	0.0000	0.9999	0.1643	0.0000	0.0015	0.3203	0.0095	0.1018	0.0012	0.3796	0.0058	0.4375	0.0010	0.4106	94.96
Working Memory	548	0.0033	0.0447	0.4553	0.0000	0.0016	0.2176	0.0104	0.0149	0.0001	0.7514	0.0063	0.1907	0.0015	0.2139	87.65
Balance	540	0.0446	0.0000	0.1709	0.0000	0.0031	0.1524	0.0069	0.1953	0.0032	0.1406	0.0102	0.1443	0.0092	0.0126	NAb
Total	519	0.0166	0.0012	0.1577	0.0000	0.0052	0.0765	0.0192	0.0080	0.0028	0.1881	0.0066	0.3986	0.0000	0.9415	68.32
Speed Composites
General Ability	549	0.0089	0.0195	0.3357	0.0000	0.0066	0.0185	0.0029	0.4999	0.0017	0.2377	0.0121	0.0416	0.0002	0.7073	75.05
Abstraction	542	0.0000	0.9999	0.2823	0.0000	0.0000	0.9082	0.0069	0.1554	0.0011	0.3576	0.0082	0.1858	0.0023	0.1866	∼100
Attention	550	0.0000	0.9999	0.1432	0.0000	0.0005	0.5519	0.0052	0.3330	0.0002	0.7443	0.0116	0.1081	0.0008	0.4570	NAc
Emotion	550	0.0053	0.0283	0.2743	0.0000	0.0002	0.7095	0.0119	0.0260	0.0031	0.1187	0.0226	0.0014	0.0007	0.4647	93.48
Episodic Memory	549	0.0076	0.0136	0.2156	0.0000	0.0001	0.7495	0.0093	0.0770	0.0000	0.9296	0.0130	0.0507	0.0114	0.0038	85.51
Working Memory	548	0.0000	0.9999	0.2242	0.0000	0.0000	0.9043	0.0039	0.3926	0.0017	0.2792	0.0138	0.0379	0.0003	0.6297	99.99
Motor	536	0.0000	0.9999	0.1969	0.0000	0.0017	0.2698	0.0040	0.4199	0.0052	0.0557	0.0351	0.0001	0.0001	0.7555	68.09
Total	519	0.0066	0.0261	0.1987	0.0000	0.0007	0.4909	0.0069	0.2054	0.0002	0.7424	0.0338	0.0002	0.0025	0.2016	69.58

Family-wise Bonferroni correction for 8 comparisons = 0.0063 (α = 0.05, 2-tailed).

practice slope = observed slope − predicted group GAM fit baseline developmental slope from baseline age to 1-yr followup age.

site effects measured against UCSD.

^aSES = socioeconomic status determined from the highest education of one parent.

^bNA: The mean developmental slope was nonmonotonic, whereas the practice slope was monotonic, resulting in invalid ratios.

^cNA: The mean developmental slope was nonmonotonic, whereas the average practice is negative and expected development is positive, resulting in invalid ratios.