Physiological evidence of hypermasculinization in boys with the inattentive type of attention-deficit/hyperactivity disorder (ADHD)

Masculinized finger-length ratios of boys, but not girls, are associated with attention-deficit/hyperactivity disorder.

“…However, the present findings contradict several studies that found these relations in girls but not boys (Fink et al, 2007;Stevenson et al, 2007;Williams et al, 2003). It should be noted that studies finding relations in girls utilized nonclinical samples that relied on rating scale variation in the normal population and examined younger, preschool-age children (Fink et al, 2007;Williams et al, 2003) or older, college-age adults (Stevenson et al, 2007 Two notable differences were seen between the results of the present study and that of McFadden et al (2005). The present study did not replicate McFadden et al's (2005) finding that children with the inattentive subtype of ADHD had significantly more masculine digit ratios as compared with children with the combined subtype.…”

“…Fourth, masculinized finger-length patterns appeared to be more specific to the domain of inattention than hyperactivity-impulsivity in boys and girls when the shared variance between the two symptom domains was eliminated. Controlling for, or covarying, ethnicity did not alter the results.These findings are consistent with recent studies in humans indicating that ADHD symptoms may be related to more masculinized finger-length ratios (de Bruin et al, 2006;Fink et al, 2007;McFadden et al, 2005;Stevenson et al, 2007;Williams et al, 2003). However, the present findings contradict several studies that found these relations in girls but not boys (Fink et al, 2007;Stevenson et al, 2007;Williams et al, 2003).…”

“…Boys with ADHD had more masculine digit ratios than control boys, F(3, 144) = 2.78, p < .05, η 2 = 0.06), whereas the effect in girls was trivial in size (η 2 = 0.02) and nonsignificant. This last finding was consistent with studies that examined these associations in clinically diagnosed samples (de Bruin et al, 2006;McFadden et al, 2005), but it contradicts other work utilizing rating scale data in nondiagnosed samples (Fink et al, 2007;Stevenson et al, 2007;Williams et al, 2003). We conducted bivariate correlations, shown in Table 3, to examine whether more masculine (i.e., lower) finger-length ratios were related to more inattentive or hyperactive-impulsive ADHD symptoms in the total group of children (i.e., boys and girls examined together).…”

“…Children (ages 7-15) with the inattentive subtype of ADHD (n = 61) had smaller CEOAEs and smaller finger-length ratios -specifically right 2D: 5D, 3D:5D, and 4D:5D-than children with the combined subtype of ADHD or typically developing control children, suggesting higher prenatal androgen exposure in the inattentive group. Thus, two studies utilizing diagnosed child samples (de Bruin et al, 2006;McFadden et al, 2005) found that children with externalizing disorders had more masculinized finger-length ratio patterns, findings that are consistent with the idea that higher levels of prenatal testosterone exposure are related to increased incidence of externalizing disorders and increased inattentive symptoms in childhood.We sought to replicate and extend recent work examining associations between finger-length ratios and ADHD by investigating distinct effects on inattentive and hyperactive-impulsive symptoms and ADHD subtypes in a large, well-characterized, clinically evaluated sample of children with ADHD. In addition, handedness and number of older brothers were examined in relation to finger-length ratios and ADHD symptoms in a more exploratory fashion.…”

“…McFadden et al (2005) defined the inattentive subtype more strictly than specified in the DSM-IV and in the present study, requiring the inattentive subtype to have four or fewer hyperactiveimpulsive symptoms, rather than less than six hyperactive-impulsive symptoms. In the present study, more masculinized digit ratios were related most to inattentive symptoms, after controlling for hyperactive-impulsive symptoms; thus, it was not surprising that subtype differences did not emerge between the inattentive and combined subtypes, as both subtypes are defined by six or more inattentive symptoms.Another notable difference between the two studies was the predominantly strong effects seen for right 2D:4D in the present study, as compared with the strong effects seen for right 2D:5D, 3D:5D, and 4D:5D in McFadden et al (2005) study. It should be noted that measurements of finger-length ratios were conducted differently in the two studies (photocopy images and ruler measurements in the present study vs. photocopy/scanner images and canvas measurements in the McFadden et al study).…”