Does Birth Order Affect ADHD Risk?

Quick Spoiler: Maybe, but probably not.

“I have two kids. My younger child is the wild one. He has trouble focusing and paying attention. He is very, very active – often bouncing off the walls from sun up to sun down, never running out of energy. He is also very emotional. If he’s faced with even the slightest discomfort, he cries loudly and throws a tantrum. I spoke with other parents at his school, and many of them said their second child acts exactly the same.”

As parents, we’re often trying to understand our kids better. This is especially true if we suspect, or have confirmed, that one of our children has ADHD. We don’t like uncertainty when it comes to our kids, and often that is projected onto our curiosity about why some children seem to have developed ADHD, and others do not.

As researchers seek to better understand the potential environmental and genetic factors associated with ADHD, one question does birth order play a role in ADHD risk? Are first born, second born, or third born children any more or less at risk than others?

ADHD and its Birth Order Risk Factors

Most likely, there is no *true* link between birth order and ADHD risk, at least not when it comes to genetic factors. Research is still not entirely clear, so nothing can be ruled out, but there does not appear to be a sizeable difference between ADHD risk in siblings.

In fact, despite the story above that was shared to us by one of our readers, if there is a link between birth order and ADHD, research suggests that it is the first born that is the highest risk. Some studies have found that firstborn children may have 2x the risk of second and third born children.

Still, others studies have not been able to confirm this, so early research is mixed.

With that in mind, anecdotal stories about younger siblings being more likely to have [suspected] ADHD are fairly common. There are many possible reasons for this, and it might be helpful to go over what they may be. Potential reasons may include:

  • Older Sibling Advantage – Some studies suggest that firstborn children may receive more parental attention and resources, potentially reducing their risk of developing ADHD. Early parental involvement has been linked to better emotional and behavioral regulation, which could mitigate ADHD symptoms (but not prevent ADHD), making ADHD less apparent in older children with ADHD than younger children with ADHD.
  • Tablet Time – Modern parenting is hard, as most people have less family support than they did in the past, less options for childcare, and more demanding workloads. That means that children are more likely now to have screen time, especially on tablets and phones. This si especially true when there is more than one child, as it is often harder for parents to manage the needs of both. This type of screen time has been associated with the development of ADHD symptoms.
  • Advanced Material Age – Children born to older mothers (>40) have been shown to be more likely to have ADHD than children born to younger mothers between 25 and 39.

Still, it’s also important to remember that the reverse also has a science basis. For example, children born to especially young parents (under 24 years old) may be more at risk for ADHD. This would imply that first born children (who’s mothers would be younger than they would be for subsequent children) may be at higher risk.

Birth Order’s Influence on ADHD Diagnosis

Birth order may, however, exhibit an influence on the diagnosis of ADHD – making it less likely that older siblings receive a diagnosis than younger siblings, regardless of risk. For example, firstborn children often develop coping skills earlier as they receive direct attention and are generally tasked with more responsibilities at a young age. These factors could contribute to lower ADHD diagnoses, as early-developed self-regulation can reduce ADHD-like behaviors.

Later-born children might exhibit more risk-taking behaviors or require more attention to compete with older siblings, potentially leading to behaviors that are mistakenly associated with ADHD. This does not necessarily indicate a higher prevalence of the disorder itself, but rather differences in behavioral expression and, potentially, diagnosis.

Lastly, younger children learn a lot from older siblings. Yet older siblings are often also in the process of learning the world themselves. This means that younger siblings may exhibit more wild behaviors simply by modeling their behaviors more after the first born, while first born siblings may be attempting to model behaviors after their parents.

The Role of Genetics and Environment

Despite some associations between birth order and ADHD, research consistently points to genetics and environmental factors as more prominent influences. Genetic studies estimate that ADHD has a heritability rate of up to 70-80%, making it a primarily genetic disorder. Prenatal factors, such as maternal stress or exposure to toxins during pregnancy, also significantly impact ADHD risk, regardless of birth order, and many, many children with ADHD have no discernable cause at all.

How Much Does Birth Order Matter?

In the context of ADHD, birth order is not terribly important. It does not appear to have a strong correlation with symptoms, and while there is some evidence that firstborn children may be at higher risk, second and third born children are the ones that many parents “report” showing signs of ADHD. Overall, the risk is likely low.

Instead of focusing on birth order, it is better to focus on providing your child with the techniques and tricks that can help them manage their ADHD symptoms better, as well as how you can parent them in a more successful way. For more information, reach out to our team at ADHD Training Center, today.

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