. 2023 Jul 21;14:1155691. doi: 10.3389/fneur.2023.1155691

Table 2.

Chronological age and mental age at each visit.

	Group	Chronological age (years) M (SD) range	Nonverbal mental age (years)¹ M (SD) range
Visit 1	ASD-O	8.27 (2.90)^a 3.24–13.27	6.11 (1.8)^a 2.33–10.50
	FXS-ASD	10.56 (2.47)^b 6.58–15.07	5.00 (0.56)^b 3.50–6.25
	FXS-O	9.34 (3.24)^a,b 5.59–14.98	5.64 (1.42)^a,b 3.67–9.17
	DS	10.94 (2.07)^b 6.81–14.86	5.33 (0.81)^b 4.33–8.25
	TD	4.74 (1.10)^c 3.15–7.07	5.23 (1.21)^b 3.58–7.67
Visit 2	ASD-O	10.31 (2.20)^a 6.41–13.92	6.34 (1.57)^a 4.42–10.25
	FXS-ASD	12.02 (2.53)^b 7.95–16.75	5.07 (0.58)^b 3.25–6.58
	FXS-O	11.47 (3.56)^a,b 7.50–16.40	5.72 (1.29)^a,b 4.50–9.17
	DS	12.39 (2.03)^b 7.93–16.09	5.66 (1.09)^a,b 3.08–8.25
	TD	6.41 (1.54)^c 4.60–10.33	6.80 (1.65)^a,c 5.58–11.67
Visit 3	ASD-O	11.69 (2.34)^a 7.54–15.77	6.94 (1.71)^a 4.42–10.25
	FXS-ASD	13.10 (2.55)^a,b 9.10–17.90	5.15 (0.55)^b 4.42–6.67
	FXS-O	11.64 (2.87)^a,b 8.73–16.38	5.11 (0.75)^b 4.00–6.00
	DS	14.14 (2.51)^b 9.63–17.93	5.99 (1.33)^a,b 4.58–9.58
	TD	7.73 (1.70)^c 6.15–11.55	8.49 (3.11)^c 6.00–17.08

Leiter International Performance Scale-Revised.

ASD-O, autism spectrum disorder only; FXS-ASD, fragile X syndrome with ASD; FXS-O, FXS only; DS, Down syndrome; TD, typical development. Per visit, different superscripts within a column indicate significant differences at p < 0.05. If groups share the same letter, differences were not significant.