Table 4 Pearson correlations for the phenylketonuria groups between the metabolic measures and the variables that significantly differentiated the groups.

Variables	n‐back accuracy			n‐back speed			Flanker speed
	0	1	2	0	1	2	C	I
Off‐diet PKU group
Mean Phe level age 1–4†	–0.19	–0.12	0.13	–0.58*	–0.45	–0.14	–0.36	–0.38
Mean Phe level age 5–8†	–0.05	0.04	0.02	–0.46	–0.38	–0.30	–0.40	–0.41
Mean Phe level age 9–12†	0.16	0.44	0.24	0.01	–0.19	0.01	–0.32	–0.26
Mean Phe level age 13–16‡	0.15	0.21	–0.17	–0.14	–0.14	–0.54*	–0.10	–0.11
Mean Phe level age 17–20‡	–0.09	–0.15	–0.24	–0.04	0.09	–0.53	–0.08	–0.13
Mean Phe level age 21–24§	–0.11	–0.54	–0.26	0.37	0.28	0.07	0.35	0.28
Mean Phe level age 25–28¶	–0.10	–0.12	–0.49	0.10	0.11	–0.43	0.26	0.26
Mean Phe level age 29–32**	–0.29	–0.25	–0.22	0.33	0.38	–0.11	0.43	0.25
Concurrent Phe level‡	–0.07	–0.24	–0.24	0.55*	0.38	–0.06	0.44	0.38
Recent Phe level‡	–0.08	–0.19	–0.19	0.44	0.31	–0.14	0.41	0.32
Age of stopping diet	–0.14	–0.21	–0.21	0.33	0.38	0.28	0.24	0.19
On‐diet PKU group
Mean Phe level age 1–4††	0.29	–0.47	–0.21	0.36	–0.03	–0.39	0.24	0.27
Mean Phe level age 5–8††	0.23	–0.48	–0.11	0.55*	0.19	–0.15	0.41	0.33
Mean Phe level age 9–12††	–0.41	–0.01	0.21	0.03	0.02	0.17	–0.11	–0.13
Mean Phe level age 13–16†	–0.17	0.13	0.39	0.09	0.13	0.10	0.15	0.08
Mean Phe level age 17–20†	–0.15	0.18	0.34	0.10	0.13	–0.18	0.18	0.08
Mean Phe level age 21–24‡	–0.26	0.02	0.22	0.11	0.05	–0.30	0.22	0.19
Mean Phe level age 25–28‡‡	–0.36	0.20	0.59	–0.17	–0.24	–0.01	0.17	0.03
Mean Phe level age 29–32§§	–0.56	–0.04	0.32	–0.64	–0.38	–0.29	–0.59	–0.63
Concurrent Phe level†	–0.33	–0.14	–0.07	0.22	0.26	0.23	–0.18	–0.24
Recent Phe level†	–0.38	–0.07	–0.08	–0.37	0.06	0.08	–0.20	–0.21

PKU, phenylketonuria.

* = p<0.01.

†n = 24.

‡n = 23.

§n = 22.

¶n = 17.

**n = 19.

††n = 21.

‡‡n = 16.

§§n = 12.