Neurodevelopmental disorders: prevalence and comorbidity in children referred to mental health services

Figures & data

Table 1. ND, non-ND psychiatric disorders, and no psychiatric disorder in 407 consecutive referrals aged 7–13 years.

	N	% of 407	Gender distribution (% boys)	Age, years Mean (SD)
ND	226	55.5	69.9	10.32 (1.94)
ADHD	181	44.5	68.5	10.24 (1.87)
Tic disorders	72	17.7	77.8	10.34 (2.07)
Autism spectrum disorders	25	6.1	76.0	10.97 (1.91)
Non ND psychiatric disorders^a	114	28.0	59.6	10.62 (2.01)
No psychiatric disorder	67	16.5	65.7	10.45 (2.08)^b

ND: neurodevelopmental disorders.

^a Non-ND psychiatric disorders include anxiety disorders (16.0%), depressive disorders (3.2%), ED (elimination disorders: enuresis and/or encopresis) (3.7%), DBD (disruptive behavior disorder: oppositional behavior disorder and conduct disorder) (6.9%) and OCD (obsessive compulsive disorder) (6.9%).

^b Age missing in one patient.

Figure 1. Homotypic comorbidity (neurodevelopmental disorder, ND) in 226 children aged 7–13 years with ND according to parent interview with Kiddie-SADS-PL (DSM IV version). ASD: autism spectrum disorders; TD: tic disorders.

Table 2. Homotypic comorbidity (neurodevelopmental disorder, ND) and heterotypic (non-ND) comorbidity in 226 children aged 7–13 years with ND according to parent interview with Kiddie-SADS-PL (DSM IV version).

		Homotypic comorbidity			Heterotypic comorbidity
	No Comorbid condition	ADHD	TD	ASD	Anxiety disorders	Depressive disorders	Elimination disorders	DBD	OCD	No. of diagnoses, median (range)
ADHD, n = 181	61 (33.7%)		36 (19.9%)	9 (5.0%)	48 (26.5%)	9 (5.0%)	33 (18.2%)	42 (23.2%)	6 (3.3%)	2 (1–5)
TD, n = 72	7 (9.7%)	36 (50.0%)		11 (15.3%)	25 (34.7%)	8 (11.1%)	11 (15.3%)	19 (26.4%)	5 (6.9%)	2 (1–5)
ASD, n = 25	2 (8%)	9 (36.0%)	11 (44.0%)		9 (36.0%)	2 (8.0%)	1 (4.0%)	5 (20.0%)	1 (4.0%)	2 (1–5)

ND: neurodevelopmental disorders; ASD: autism spectrum disorders; TD: tic disorders; OCD: obsessive compulsive disorders; DBD: disruptive behavior disorder. Numbers in parenthesis are percentages by row, which exceed 100 due to more than one comorbid disorder.

Table 3. Gender distribution and mean age by comorbid status in 226 children aged 7–13 years with a ND.

Comorbidity	Boys, n = 158 (69.9 %)	Girls, n = 68 (30.1%)	χ^2	p	Mean age^a (SD)	t	p^b
Homotypic comorbidity	n = 37 (23.4%)	n = 11 (16.2%)	1.49	.288	10.31 (1.91)	0.03	.976
Anxiety disorder	n = 38 (24.1%)	n = 30 (44.1%)	9.10	.003**	10.75 (1.98)	−2.21	.028*
Depressive disorder	n = 9 (5.7%)	n = 7 (10.3%)	1.53	.216	11.63 (1.71)	−2.79^c	.005^d**
OCD	n = 5 (3.2%)	n = 6 (8.8%)	3.29	.070	10.67 (2.00)	−0.62	.536
DBD	n = 39 (24.7%)	n = 14 (20.6%)	0.44	.505	9.91 (1.95)	1.76	.080
ED	n = 28 (17.7%)	n = 10 (14.7%)	0.31	.578	9.88 (1.85)	1.52	.129

ND: neurodevelopmental disorders.

^a Mean age in children with comorbid disorder.

^bStudent’s t-test comparing age with and without comorbid disorder.

^c z-value.

^d Mann–Whitney U-test (median: 11.8 and interquartile range: 10.6–12.8).

* Statistical significance at p < .05 level.

** (bold figures) Statistical significance after Bonferroni correction. Homotypic: other ND; OCD: obsessive compulsive disorder; DBD: disruptive behavior disorder; ED: elimination disorder.