An international study of around 2,700 children, adolescents, and adults has demonstrated that some variations in the gene LPHN3, which is associated with attention deficit/hyperactivity disorder (ADHD), could favor likelihood to smoke, consume alcohol, cannabis and other addictive substances, according to an article published in the journal Translational Psychiatry.
The study, led by researchers from the National Institutes of Health, was conducted in the United States, Colombia, and Spain, and it will likely contribute to provide new genetic tools to improve prevention of addictive behaviors in people with ADHD.

In the study, researchers applied a statistical method (Recursive-partitioning Frameworks) that integrates clinical, demographic, and genetic information on a specific disorder, in this case, ADHD, to predict another comorbid disorder, such as addiction.

Within the group of Spanish patients with ADHD, a specific variation of the LPHN3 gene increased by 40% the risk of nicotine dependence. According to the researchers, results were similar in the cases for alcohol and illegal drugs. 

Not all those affected by ADHD show behaviors with an addictive profile, the researchers noted. Seventy-five percent of ADHD has a genetic base and the remaining 25% is related to environmental factors which can vary, according to the data. Therefore, external factors can be relevant in the appearance of addictive behaviours in people with ADHD. For example, certain lifestyles or social interactions can play an important role. 

Psychological and pharmacological treatment and psychopedagogical intervention are the combined strategies that are most efficient in ADHD treatment. In the future, the researchers urged new clinical studies to analyze the importance of genetics in ADHD susceptibility and addictive behaviors that can affect the patient’s health. 

 Velez JI, Muenke M. ADGRL3 (LPHN3) variants predict substance use disorder. Translational Psychiatry. 2019; 42.