Recent Developments in Genetic Studies Examining ADHD

In this video, Psych Congress Steering Committee member Vladimir Maletic, MD, MS, answers the question "Have genetic studies shown a correlation between ADHD and any other mental health disorders?"

Dr. Maletic is Clinical Professor of Psychiatry, University of South Carolina School of Medicine, Greenville. He is presenting a session titled "Trees or the Forest? Advances in Neurobiological Understanding of ADHD and Novel Treatments," at the 2021 Psych Congress Regionals meeting series.

Read the transcript:

What an excellent question. Indeed, I will attempt to summarize some of the more recent findings related to genome-wide association studies examining ADHD.

A lot of surprises. One of the surprises is that ADHD actually has robust genetic association with increased BMI, with obesity. How did we determine this? A large number of candidates, of genetic faults, and these are single nucleotide polymorphisms, in excess of 300,000, were studied. Not all of them have association with ADHD. There was a certain screen set. Only the tiny genetic faults that have more pronounced association with ADHD were taken into account.

They were all added up. When all these tiny genetic faults were summarized, we come up with something that's called polygenic risk score. What we're finding out is that having higher polygenic risk score for ADHD is also associated with risk of developing an anxiety disorder.

It is associated with risk of developing depressive disorder. It is associated with increased risk of alcohol use and having diagnosis of substance use disorder. 

There are also some personality traits that accompany risk for ADHD. Those would include mood swings and emotional ability, propensity to feel lonely and isolated, likelihood of displaying irritability and being high-strung, and finally, relatively exquisite sensitivity to stress. These are individuals who can have their feelings easily hurt.

All of these, believe it or not, are genetically based. As a matter of fact, they can be quantified. One of the more recent publications looked at polygenic risk score in quintiles, so bottom 20 percent, between 20 and 80 percent, and upper 20 percent in terms of cumulative polygenic risk score.

Here are some of the findings. It was associated with greater substance abuse, and it was associated with greater perception of stress. Indeed, having ADHD has these manifestations that have been up to now neglected and are really important because they deserve treatment. If not appropriate treatment is initiated, there will be greater functional impairment, reduced quality of life, and greater comorbidity and morbidity overall.

Looking at the closest relatives genetically of ADHD, genetically, the closest relative of ADHD is major depressive disorder.

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