Inhibition, flexibility, working memory and planning in autism spectrum disorders with and without comorbid ADHD-symptoms

Table 1 Previous studies comparing executive functions in ASD vs. ADHD

	Ozonoff et al. 1999	Nyden et al. 1999	Geurts et al. 2004	Goldberg et al. 2005	Happé et al. 2006	Johnson et al. 2007
Sample (n)	n = 93	n = 30	n = 136	n = 70	n = 94	n = 62
-Autism	40	10	41	17	32	21
-ADHD	24	10	54	21	30	23
-TD	29	10	41	32	32	18
ASD diagnosis (%)
- HFA	40 (100)	-	41 (100)	17 (100)	6 (19)	21 (100)
- AS	-	10 (100)	-	-	26 (81)	-
ADHD subtype (%)	?	?		?	?
- Combined s.			36 (67)			22
- Inattentive only s.			16 (29)			1
- Hyperactive/Impulsive s.			2 (4)			-
Inclusion of ADHD in ASD group	?	?	Yes,	no	no	no
			only inattentive subtype
Age at testing (years)	12.1	10.0	9.3	11.2	10.1	11.2
Min-Max	(6–18)	(8–11)	(6–13)	(?)	(8–12)	(?)
IQ	103.4	95.6	103.1	107.6	101.8	101.2
Neuropsychological measures
-Inhibition	Stroop CWT	Go-No-Go, RIT	CT, CDT, TEA-Ch	Stroop CWT	Go-No-Go	SART
-Working Memory	-	-	S-OPT	C SWM	C SWM	-
-Planning	TOH	-	TOL	C SOC	C SOC	-
-Flexibility	WCST	WCST	WCST	C ID/ED	C ID/ED,	-
					Verbal Fluency

Note: CDT = Circle Drawing Task; C ID/ED = CANTAB Intra-dimensional/extra-dimensional shift task; C SOC = CANTAB Stockings of Cambridge; C SWM = CANTAB Spatial WorkingMemory; CT = Change Task; RIT = Response Inhibition Task; SART = Sustained Attention to Response Task; S-OPT = Self-Ordered Pointing; Stroop CWT = Stroop Colour Word Test; TD = Typically developing group; TEA-Ch = Test of Everyday Attention for Children; TOH = Tower of Hanoi; TOL = Tower of London; WCST = Wisconsin Card Sorting Test;

ISSN: 1753-2000