Table 2 Irritability descriptive statistics and associations with ADHD symptom levels and sex

From: Investigating the genetic underpinnings of early-life irritability

(a) Population sample: ALSPAC

Age 7

Age 10

Age 15

Sample N

7963

7558

4602

Frequency

3.9%

4.0%

4.2%

Frequency in males

5.2%

5.1%

3.8%

Frequency in females

2.5%

2.9%

4.5%

Sex difference (χ2(1))

40.20, P<0.001

23.72, P<0.001

1.26, P=0.262

ADHD symptoms (OR)

1.17 (1.16–1.19) P<0.001

1.18 (1.17–1.20) P<0.001

1.18 (1.16–1.20) P<0.001

(b) Population sample: NCDS

Age 7

Age 11

Age 16

Sample N

8201

8011

7063

Frequency

10.4%

13.1%

9.4%

Frequency in males

10.9%

14.1%

7.7%

Frequency in females

9.9%

12.0%

11.1%

Sex difference (χ2(1))

1.97, P=0.160

7.78, P=0.005

24.47, P<0.001

ADHD symptoms (OR)

1.90 (1.80–2.02) P<0.001

1.79 (1.70–1.89) P<0.001

1.78 (1.67–1.90) P<0.001

(c) ADHD sample: SAGE

 

(Age 6–18)

 

Sample N

 

678

 

Frequency

 

90.9%

 

Frequency in males

 

89.0%

 

Frequency in females

 

91.2%

 

Sex difference (χ2(1))

 

0.54, P=0.461

 

ADHD symptoms (OR)

 

1.25 (1.16–1.35) P<0.001

 
  1. Abbreviations: ADHD, attention-deficit/hyperactivity disorder; ALSPAC, The Avon Longitudinal Study of Parents and Children; NCDS, The National Child Development Study; SAGE, The Study of ADHD, Genes and Environment.
  2. N=sample with irritability data.
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