A study conducted by researchers at the Vall d'Hebron Research Institute (VHIR) and the Psychiatry Service of the Vall d'Hebron University Hospital (HUVH) confirms the relationship of the LPHN3 (Latrophilin 3) gene with ADHD, which combines attention deficit hyperactivity disorder, the most common subtype of this disorder. The research therefore provides evidence of the link between this genetic variant and the persistence of the disease in adults. The results of the study, published in the journal Genes, Brain and Behavior, show that genetics plays an essential role as a substrate in the development of ADHD and corroborate the existence of common genetic bases between ADHD in children and ADHD in adulthood.

Genetic influence on ADHD

Previous results from this research group confirmed the association between the LPHN3 gene and ADHD in the contrasted analysis of 2627 cases and 2531 controls from different populations: Colombia, the United States, Germany, Spain and Norway. The work of the Vall d'Hebron Research Institute is important because it corroborates this link between LPHN3 and ADHD and demonstrates that genetics can influence the development of the disease. And especially because it proves that this gene increases the patient's susceptibility to continue suffering from this disorder in adulthood and, in particular, the combined ADHD subtype. Thus, the results of the research, obtained from the study of samples of 334 patients and 334 adult controls between 2004 and 2008, "could be key in the future in the prevention and prognosis of the disease", explains Dr. Josep Antoni Ramos-Quiroga, member of the Psychiatry and Mental Health group at VHIR. The head of the ADHD research line adds: "They could allow us to identify a priori in which young people affected by ADHD the disease will persist when they grow up".

Genetics is one of the most important factors in explaining the origin of ADHD. Thanks to the results of the Vall d'Hebron Research Institute study, the LPHN3 gene extends the list of genes that increase an individual's susceptibility to the disorder. This, moreover, gives greater strength to the hypothesis that ADHD is not a disease confined to childhood, but persists into adulthood because the person is a carrier of this gene.

However, although the origin of ADHD is mostly genetic and having the gene predisposes the person to suffer from the illness, this does not necessarily imply that the individual will end up developing it. Not only does the genetic load have an influence, but its origin is multifactorial: environmental factors (smoking during pregnancy, for example) or developmental factors (alterations in the levels of some neurotransmitters in the brain such as dopamine) which, in combination with genetic factors, can cause the disease to ‘awaken’.

About ADHD

ADHD (attention deficit disorder with or without hyperactivity) is a neurobiological disorder with obvious consequences on the child's behaviour: he/she is hyperactive, impulsive and easily distracted. For this reason, ADHD, which affects between 7% and 8% of school-age children, is one of the most frequent causes of school failure and social problems in childhood. In adults, ADHD appears as a ‘hidden’ disorder that can affect interpersonal relationships and the person's work efficiency, making them more prone to depression, anxiety or drug use.