Research Review: Past, Present, and Future of ADHD

Below are highlights of an Oct. 2022 review: https://acamh.onlinelibrary.wiley.com/doi/full/10.1111/jcpp.13696.

ADHD Over Time

For most individuals diagnosed with ADHD, symptoms first appear during childhood even if the diagnosis comes later.

For most, disappearance of symptoms for good is rare. It seems to persist though it may at various times appear to fade (i.e., you may no longer meet criteria for the diagnosis at various times over the course of your life).

What factors determine persistence are still unclear.

Current debate includes whether ADHD includes a late-onset variant. Estimates vary widely regarding how many people first present with ADHD as adults: from 30% to 87% (see how widely they vary?).

Still, it’s become clear that fluctuating symptoms and impairment are common. Moreover, there’s a lot of heterogeneity when it comes to ADHD (think of variants having overlap but also differences when it comes to how they present, their particular combination of causal factors, their courses/trajectories, and their outcomes).

Finally, we still know relatively little about later-life ADHD.

Co-travelers

Emotion Regulation Difficulties (ERD), as the researchers call them, are estimated to affect 40-50% of children with ADHD, presenting as being susceptible to anger/irritability/low frustration tolerance. One question then is whether it’s part of a particular ADHD variant/profile of ADHD.

Sleep Difficulties commonly travel with ADHD at ALL AGES. Kids, teens, and adults with ADHD have higher odds of getting too little or poorer quality of sleep compared to their peers. Some researchers are exploring the causal role that inadequate/poor sleep may play.

This may be surprising, but the authors note that for females there are no increased odds of anxiety or depression, as females already have higher rates of anxiety and depression than males even without ADHD being added to the mix.

Living with ADHD

What is noted to be true across cultures? A negative impact on relationships with peers and siblings, higher rates of teen pregnancy, gambling, accidents, and premature death, with impairment persisting into adulthood for over 50% of individuals. The researchers admit, however, that research and practice have neglected “the performance and capacity of” individuals with ADHD. It focuses on shortcomings versus strengths, on disadvantages versus advantages.

Heritability

It’s high: estimated to be 74% for general population twin samples. So, if your identical twin has ADHD, there’s about a 75% chance you do, too. What gives? It’s believed that ADHD arises from an interplay between genetic and environmental factors.

“New Leads” Regarding Genes

1. Different genes may account for childhood, persistent adult, and late-onset ADHD.
2. Genetically-based sex differences may exist.

Environments

The paper references an “umbrella review of meta-analyses” that “identified nine associations as having high credibility (random effects p < .000001, or p < .000001, n > 1,000; Kim et al., 2020).”

Most were “maternal pre- and perinatal factors including prepregnancy and pregnancy overweight and pregnancy hypertension, gestational hypertension, preeclampsia, acetaminophen use, and smoking.”

“Two were child factors – childhood eczema and low serum vitamin D.”

All were of “modest” effect size “(Odds Ratio(OR) < 2.0).”

“Several other smaller associations were also deemed reliable (p < .001) including child blood lead level, child blood magnesium level, maternal stress during pregnancy, and maternal selective serotonin reuptake inhibitor (SSRI) exposure during pregnancy.”

Concluding Remarks

After going through “new leads” across various areas of research, including on the brain, the scholars acknowledge a shift of perspective that has mostly come from outside academia and research labs as the “most radical challenge to the ADHD paradigm.”

“Perhaps the most radical challenge to the ADHD paradigm comes […] from a new socio-cultural rights-based concept that has emerged outside the clinical and scientific sphere – neurodiversity (Pellicano & den Houting, 2022). This both casts ADHD as part of a wider spectrum of naturally occurring variation and challenges the DSM assumption that ADHD is a disorder caused by dysfunction within the individual – replacing it with the assumption of ADHD as neuro-divergence (Sonuga-Barke & Thapar, 2021).

May you find this reading of use.