Parenting with ADHD and the Similarity-Fit Hypothesis by Ashlyn C., B.A.


Anyone who has a child with ADHD knows that they can present unique difficulties when parenting. The research backs this up: Families with ADHD report more conflict than families without, and parents of children with ADHD are often less confident in their ability to regulate their children (Park et al., 2017; Weyers et al., 2019). I knew this dynamic to be true in my own family. My brother has been diagnosed with ADHD since he was 7 years old, but the frequent battles between himself and my parents have been present in our home for as long as we can remember. Given that ADHD is a heritable disorder, there is a running joke in our family as to who is responsible for passing it down to my brother. Although made in jest, it sparked a personal interest in how ADHD has manifested itself in my family lineage, and how parenting with potentially undiagnosed ADHD may have exacerbated the tension between my brother and my parents.

Cut to today, I currently research parent-child relationship dynamics for children with ADHD, specifically in a school context. Much of the literature on these topics mirrored my own experience with my brother, both as a witness to the conflict at home and regarding my parents’ experience navigating the school system. The research almost seemed unanimous in their conclusions that ADHD always serves as a deficit to both parent and child, regardless of who is diagnosed. However, during my search, I came across the Similarity-Fit hypothesis. In their seminal paper, Psychogiou et al. (2007) discovered that in parent-child dyads where both members had ADHD, the relationship quality was somewhat improved compared to dyads where only one member displayed ADHD symptoms. This finding has been replicated in other research, especially among dyads where the parent has especially high symptom severity (Griggs & Mikami, 2011; Johnston et al., 2012; Psychogiou et al., 2008).

The authors’ explanation for this phenomenon can be traced back to the amount of empathy the ADHD parent has for their ADHD child. The theory posits that the reason parent and child can avoid increased conflict is because there is a shared understanding of each other’s minds. Especially for parents with severe ADHD, they are more likely to extend empathy to their child during times of high stress, regardless of the symptom severity of the child (Johnston et al., 2012). This is not to say that neurotypical parents don’t have empathy for their children with ADHD, but having lived experience of what they are going through every day seems to make it easier to overlook certain deficits. As a result, when parents’ ADHD symptom severity is similar to their child’s symptom severity, the shared understanding between them ameliorates the frequency of conflict and improves the closeness between parent and child.

These findings stood in contrast to just about everything I thought I knew about parent-child relationships with ADHD. It led me to re-evaluate the existing literature through a new lens: If we are to investigate ADHD in children in the context of relationship dynamics, it is potentially negligent to omit parent symptom severity when making conclusions as to how ADHD affects the relationship. Even more so, it made me re-evaluate my family’s dynamic. For parent-child dyads where both share an ADHD diagnosis and where there is high conflict, researchers refer to this as a similarity-misfit. That is, the symptoms of one member tend to worsen the symptoms of the other, resulting in increased conflict, which then leads to a more severe presentation of symptoms, and so on…  This dynamic may be more likely to be present when the parent is undiagnosed and the child has moderate to severe ADHD. It appears in my own family there is a case of a similarity-misfit between parent and child. Regardless of fitness or mis-fitness, just having an awareness of what drives conflict between parent and child has led to a more accurate understanding of one another within my family.

40-55% of children with ADHD also have a parent with the disorder (Smalley et al., 2000). However, one wonders if there is a generational divide at play hidden in this statistic. Rates of ADHD diagnosis are rising (Abdelnour et al., 2022), and more and more women and girls are being diagnosed as we continue to understand how ADHD presents itself depending on gender. Perhaps a significant proportion of the current generation of parents of children with ADHD are simply undiagnosed. The socio-historical landscape these parents grew up in was less likely to acknowledge ADHD unless it was obvious. I am hopeful that future generations of parents with ADHD will be more inclined to extend empathy to their neurodivergent children because they will have a better understanding of themselves and their minds. Ideally, this shift can help us reframe ADHD as having potential benefits to family life, rather than always being a deficit.

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