Sex‐specific manifestation of genetic risk for attention deficit hyperactivity disorder in the general population

Background

Attention deficit hyperactivity disorder (ADHD) is more commonly diagnosed in males than in females. A growing body of research suggests that females with ADHD might be underdiagnosed or receive alternative diagnoses, such as anxiety or depression. Other lines of reasoning suggest that females might be protected from developing ADHD, requiring a higher burden of genetic risk to manifest the disorder.

Methods

We tested these two hypotheses, using common variant genetic data from two population‐based cohorts. First, we tested whether females and males diagnosed with anxiety or depression differ in terms of their genetic risk for ADHD, assessed as polygenic risk scores (PRS). Second, we tested whether females and males with ADHD differed in ADHD genetic risk burden. We used three different diagnostic definitions: registry‐based clinical diagnoses, screening‐based research diagnoses and algorithm‐based research diagnoses, to investigate possible referral biases.

Results

In individuals with a registry‐based clinical diagnosis of anxiety or depression, females had higher ADHD PRS than males [OR(CI) = 1.39 (1.12–1.73)] but there was no sex difference for screening‐based [OR(CI) = 1.15 (0.94–1.42)] or algorithm‐based [OR(CI) = 1.04 (0.89–1.21)] diagnoses. There was also no sex difference in ADHD PRS in individuals with ADHD diagnoses that were registry‐based [OR(CI) = 1.04 (0.84–1.30)], screening‐based [OR(CI) = 0.96 (0.85–1.08)] or algorithm‐based [OR(CI) = 1.15 (0.78–1.68)].

Conclusions

This study provides genetic evidence that ADHD risk may be more likely to manifest or be diagnosed as anxiety or depression in females than in males. Contrary to some earlier studies, the results do not support increased ADHD genetic risk in females with ADHD as compared to affected males.     

Aetiology of neonatal conjunctivitis evaluated in a population‐based setting

Aim

Our aim was to study prospectively the aetiology of neonatal conjunctivitis in a population‐based setting.

Methods

Altogether 173 neonates with clinical conjunctivitis aged on average 20 (SD 10) days were recruited from child welfare clinics in Oulu, Finland, in 2010–2015. Conjunctival specimens were collected from 167 neonates for multiplex polymerase chain reaction to detect 16 respiratory viruses, from 163 for polymerase chain reaction to detect Chlamydia trachomatis and Neisseria gonorrhoeae and from 160 for bacterial culture studies. The cases were followed up until the age of 18 months.

Results

Viral conjunctivitis was diagnosed in 8/167 (4.8%; 95% CI 2.1–9.2%), chlamydial or gonococcal conjunctivitis in 0/163 cases (0%; 95% CI 0–2.2%) and other bacterial conjunctivitis in 58/160 (36%; 95% CI 29–44%). Rhinovirus was found at the ocular site in 4/167 (2.4%) neonates, adenovirus in 3/167 (1.8%) and bocavirus in 1/167 (0.6%). The most commonly isolated bacteria included Staphylococcus aureus (16%), Moraxella catarrhalis (9.4%) and Streptococcus pneumoniae (3.1%). None of these pathogens was associated with the 4/173 (2.3%) cases later operated on for persistent nasolacrimal duct obstruction.

Conclusion

Chlamydia trachomatis was a rare pathogen in neonatal conjunctivitis in a population‐based setting, but respiratory viruses were detected more frequently than indicated earlier.