Table 1.

Characteristics of the Groups

	TD N=50		ASD N=56		ADHD N=45		Group Comparisons			Post-Hoc

	M	SD	M	SD	M	SD	F	df	p

Age	10.7	1.8	10.1	1.8	9.9	1.8	2.71	2, 148	0.07	-

Full IQ	115	13	108	16	110	13	3.30	2, 148	0.04	TDC>ASD
Verbal IQ	116	13	107	15	111	13	5.21	2, 147	0.01	TDC>ASD
Performance IQ	112	14	108	18	108	13	0.96	2, 147	0.39	-

CPRS-R:L T scores
DSM-IV Inattentive	45	5	64	11	68	9	87.1	2, 144	<0.00	TDC<ASD=ADH
DSM-IV H-I	47	6	66	12	71	11	73.7	2, 144	<0.00	TDC<ASD=ADH
DSM-IV Total	46	6	66	11	71	9	100.43	2, 144	<0.00	TDC<ASD<ADH
Anxious/Shy	45	5	61	13	52	8	33.9	2, 144	<0.00	TDC<ADHD<AS

CTRS-R:L T Scores
DSM-IV Inattentive	46	5	57	9	62	11	31.6	2, 130	<0.00	TDC<ASD<ADH
DSM-IV H-I	47	8	57	11	65	13	24.3	2, 130	<0.00	TDC<ASD<ADH
DSM-IV Total	47	6	58	9	64	12	35.6	2, 130	<0.00	TDC<ASD<ADH
Anxious/Shy	50	11	63	14	56	10	13.9	2, 130	<0.00	TDC<ADHD=AS

SRS-Parent	43	6	78	12	53	6	199.	2, 143	<0.00	TDC<ADHD<AS

SRS-Teacher	44	5	62	10	54	11	39.6	2, 124	<0.00	TDC<ADHD<AS

ADOS Module 3^*
ADOS Total	-		14	5	-		-			-
Social Affect Total	-		10	4	-		-			-
Restricted Repetitive Behaviors	-		3	1	-		-			-
Scaled Severity Score	-		7	2	-		-			-

	N (%)		N (%)		N (%)		χ²	df	p

Males	37 (74)		49 (88)		37 (82)		3.2	2	0.20	-

SES (class 4 or 5)	36 (72)		40 (71)		34 (76)		0.5	2	0.77	-

Race^**
Caucasian	19 (38)		33 (59)		23 (51)		6.3	4	0.18	-
African-American	14 (28)		8 (14)		6 (13)
Other^***	13 (26)		11 (20)		10 (22)

Medication Status
Medication naïve	-		29 (52)		28 (62)		5.69	3	0.13	-
Not naïve but off	-		12 (21)		9 (20)
Current Stimulant Treatment^{^}	-		9 (16)		8 (17)
Current Non-Stimulant	-		6 (11)		0 (0)

Note: ADOS: Autism Diagnostic Observation Schedule; df=degrees of freedom; CPRS-R:L: Conners’ Parent Rating Scales Revised Long Version (one parent of ADHD and three parents of TDC did not complete the CPRS-R:L); CTRS-R:L: Conners’ Teacher Rating Scales Revised Long Version (CTRS-R:L were not completed for 15, 1, and 2 of the TDC, ADHD, and ASD, respectively); DSM-IV: Diagnostic & Statistical Manual-4th edition; H-I: Hyperactivity/Impulsivity score; IQ: Intelligence Quotient (Verbal IQ and Performance IQ were not available for one TDC for whom only two scales of the WASI were administered); M=group mean; SD=standard deviation of the group mean; SES: Socio-economic status; SRS: Social Responsiveness Scale Total T-score (all but three parents of TDC, 1 parent of ASD, and 1 parent of ADHD completed the SRS; SRS teacher scores were available for 33, 54, and 40, TDC, ASD and ADHD, respectively);

Only data for research reliable ADOS administrations (n=53) are reported; the remaining were based on clinical administrations only.

^**

Self (parent) reported race was missing in 4 TDC, 6 children with ADHD and 4 children with ASD.

^***

“Other” includes Asian, Pacific Islander, Hawaiian, American Indian, Alaskan Native, other races, or mixed races.

^****

Not taking psychoactive medications for periods ranging from 1 week to >12 months prior to scanning.

^{^}

Those currently treated with psychostimulants had medication discontinued for 24–48 hours prior to scanning.

^{^^}

Three were treated with selective serotonin reuptake inhibitors and one each with guanfacine, desmopressin, or melatonin.