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

Abstract

Gonadal hormones may exert permanent organizational effects on sexually dimorphic finger-length ratios and sexually dimorphic behavior expressed in childhood attention deficit-hyperactivity disorder (ADHD). This study extended recent work examining associations between finger-length ratios (specifically, 2D:4D) and ADHD in a well-characterized, clinically diagnosed, communityrecruited sample of boys and girls. A multistage, diagnostic procedure was utilized to identify 113 children with ADHD and 137 non-ADHD comparison children. Right-hand digit ratios showed significant mean differences by gender, as well as associations with ADHD diagnosis. Boys with ADHD had more masculinized digit ratios than control-group boys. More masculine right 2D:4D and 3D:4D ratios were correlated with parent-and teacher-rated inattentive and hyperactiveimpulsive symptoms in boys but not in girls. Masculinized finger-length ratios were associated with hyperactive-impulsive and oppositional-defiant symptoms, but associations were largest with symptoms of inattention. It is concluded that prenatal, organizational effects of gonadal hormones may play a role in the development of ADHD and contribute to explaining sex differences in the prevalence rates of this childhood disorder. Keywordstestosterone; finger-length ratio; 2D:4D; ADHD; sex differences Males are more vulnerable than females to developing a range of learning and behavioral disorders during childhood. Attention deficit-hyperactivity disorder (ADHD) is one of the most common and impairing sexually dimorphic clinical psychopathologies, with boys about three times more likely to be identified with ADHD than girls in population samples (American Psychiatric Association, 2000;Pastor & Reuben, 2002;Wolraich, Hannah, Baumgaertel, & Feurer, 1998). In addition, there may be sex differences in the correlates of the disorder. Although boys with ADHD appear to be more inattentive and hyperactive-impulsive than girls with the disorder, particularly in school (Gaub & Carlson, 1997;Gershon, 2002;Hartung et al., 2002), girls with ADHD may have worse cognitive impairment than boys with the disorder (Biederman et al., 1999;Gaub & Carlson, 1997;Newcorn et al., 2001). The precise neurobiological mechanisms underlying sex differences in the prevalence rates of developmental learning and behavioral disorders are complex and underresearched.The male sex bias in ADHD and its precursor behaviors is apparent during early preschool years (Hart, Lahey, Loeber, Applegate, & Frick, 1995), a period marked by rapid neural organization (Breedlove & Hampson, 2002). Males are typically exposed to testosterone perinatally, whereas females develop in the relative absence of testosterone (Morris, Jordan, & Breedlove, 2004). This differential exposure to steroid hormones produces specific malelike and/or female-like brain-behavior patterns . Therefore, these prenatal events may be related to sex differences in prevalence rates of ADHD. However, research on hormonal effects in ADHD is sparse, despite conse...

Executive Functioning in Children with Congenital Adrenal Hyperplasia

“…Our results are also consistent with previous studies supporting associations between prenatal testosterone exposure and difficulties inhibiting impulses in boys but not in girls during childhood 8. For certain types of EF difficulties, such as inhibition, prenatal and postnatal effects of other hormones, such as estrogen, may play a role in shaping behavioral manifestations of EF.…”

“…Similar associations were not found in girls,8 suggesting sex differences in effects of androgen exposure on EF deficits such as inhibition. A further study of children with CAH found higher rates of ADHD (which can include EF difficulties such as inattention and impulsivity) in boys compared to girls 10.…”

“…Past studies support associations between prenatal testosterone exposure and EF difficulties, specifically impulsivity and inattention, in boys during childhood and young adulthood 8 9. Similar associations were not found in girls,8 suggesting sex differences in effects of androgen exposure on EF deficits such as inhibition.…”

Biological factors underlying sex differences in neurological disorders

“…Right hand digit ratios (length of the index finger to the length of the ring finger) are a proxy measure of foetal testosterone exposure, where smaller ratios are associated with high levels of prenatal testosterone exposure (Manning et al, 1998). Despite this measure of testosterone being somewhat controversial (Berenbaum et al, 2009), multiple studies reported that males diagnosed with ADHD or ASD have lower finger-length ratios, indicating an abnormally higher level of prenatal testosterone exposure (de Bruin et al, 2006;Martel et al, 2008). Similarly, a significant positive relationship was found between foetal testosterone levels and number of autistic traits in children by comparing foetal testosterone levels in the mother's amniotic fluid with their respective children's cognitive assessment results (Auyeung et al, 2009).…”

2D:4D Orani ve Parmak Boylari Acisindan Obsesif Kompulsif Bozukluk, Yaygın Gelisimsel Bozukluk Tanisi Konulan Cocuklar ve Saglikli Kontrollerin Karsilastirilmasi

“…Bu oransal farklılıkta prenatal sex steroidlerinin etken olduğunu gösteren kanıtlar mevcuttur (13). Bu oran depresyon, şizofreni, dikkat eksikliği hiperaktivite bozukluğu gibi psikiyatrik bozuklukların yanı sıra meme kanseri, prostat kanseri gibi hastalıklarda da incelenmiştir (14,15,16,17,18).…”