The journal Science publishes the largest study that has been done so far about the common genetic bases between different brain disorders and in which researchers from three research groups of Vall d'Hebron have participated. One of the main conclusions is that migraine shares some risk genetic variants with some disorders such deficit hyperactivity disorder (ADHD).

This is a study of the Brainstorm Consortium, in which the data of all the GWAS studies performed on brain diseases have been analyzed jointly and with complex statistical methods. With regard to migraine, they have included almost 60,000 samples of patients and 300,000 controls, and in the case of ADHD, 12,645 patients and 84,435 controls.

Brain disorders can exhibit considerable epidemiological comorbidity and share symptoms, which has always inciting debate about their origins or causes. In this work, mainly statistical, were studied the genetic basis of 25 brain disorders starting from genome studies of 215.683 patients and 657.164 controls, and their relationship with 17 phenotypes (expression of genetics depending on the environment) and environmental factors (smoking, tobacco, years of education, body mass index, among others) of 1.191.588 individuals.

Thus, while psychiatric disorders (especially schizophrenia, bipolar disorder, ADHD and major depression) share risk variants, that is, there is a genetic correlation between them, neurological disorders (epilepsy, Alzheimer's or Parkinson's) seem to be different between them and also from psychiatric disorders. "The exception is migraine, a neurological disorder that significantly correlates with ADHD, major depression and Tourette syndrome (psychiatric disorders)", explains Dr. Patricia Pozo, neurologist responsible for the Unit of Headache Hospital Vall d'Hebron, head of the Research group in Headache and Neurological Pain of VHIR and one of the authors of the study.

Detailed analysis of the heritability of brain disorders has demonstrated the key role of shared genetic variations between neurological and psychiatric disorders and the environmental factors studied with substantial overlaps in genetic risk.

On the other hand, it has also been shown that psychiatric disorders, ADHD in particular, and migraine have strong correlations with cognitive parameters (years of education and achievement of the university stage) and personality traits (neuroticism or emotional instability). "In the field of psychiatry this study is very important because it highlights the importance of the common genetic bases in many disorders such as autism, schizophrenia, ADHD or bipolar disorder as a predisposing factor for the onset of the disorder in function of certain external agents, that is, that genetic variants play a fundamental role in explaining why each person's brain behaves differently from the same external conditioner", says Dr. Josep Antoni Ramos-Quiroga, head of the Service of Psychiatry of Vall d'Hebron, principal investigator of the Research group in Psychiatry, Mental Health and Addictions of VHIR and one of the authors of the study. On the other hand, at the genetic level, ADHD has been associated with an increased risk of obesity, fewer years of academic training and higher tobacco consumption. According to Dr. Ramos-Quiroga, "this study again demonstrates the health and social problems that patients with ADHD may suffer".

In this study, promoted by the Brainstorm Consortium, an international consortium that brings together prestigious institutions related to research in neurological and psychiatric diseases, more than 500 experts from around the world have participated. Some of them belong to catalan research centers such as the Institute of Biomedicine of the UB (IBUB) and the Network Biomedical Research Center of Rare Diseases (CIBERER), the Institut de Recerca Sant Joan de Deu (IRSJD), the Center for Genomic Regulation (CRG), the Hospital Universitari MútuaTerrassa, the Hospital de la Santa Creu i Sant Pau, the Institut Català de la Salut (ICS), the Institut Català de Neurociències Aplicades and the Universitat Internacional de Catalunya (UIC).

Migraine

Migraine is a neurological disease that is characterized by the presence of episodic and recurrent attacks of headache associated with other symptoms such as discomfort to light, noise and nausea. According to the WHO it is the second most disabling neurological disease and the seventh in a global way that causes more disability. It can affect all ages of life since childhood.

Migraine is three times more common in women than in men, and usually begins before the age of 30 and no later than age of 50. Family history is common. It can be triggered by various stimulus and changes in the environment, especially stress, hormonal changes, and also by the presence of intense odors, bright lights, changes of time, disturbances of sleep rhythm, hormonal variations or stress.

Regarding migraine in childhood, Dr. Alfons Macaya, head of the Service of Pediatric Neurology of Vall d'Hebron, head of the research group of the same name of VHIR and one of the authors of the study, explains that "it is usually that migraine starts before the age of 10 in children and around puberty in girls. At the age of 14, up to 10% of the pediatric population will have suffered an episode of migraine". Symptoms are less defined than in the adult and can even manifest as episodes of vomiting or vertigo without headache. The modern lifestyle may have increased the frequency and it is a disorder with a high impact in the school environment, an even more significant fact if we consider the association to ADHD that is described in the present study.

Attention deficit hyperactivity disorder

ADHD is a neurodevelopmental disorder that affects 5% of the population during childhood, and is maintained in more than half of patients during adulthood. It is the most diagnosed mental pathology in Catalonia among children and adolescents, according to the latest data from the Department of Health. Of the cases diagnosed, 25% are girls and 75% boys. The most common symptoms are lack of attention, disorganization, lack of control of impulses, emotional instability and hyperactivity.

The persistence of ADHD throughout life is associated with poor academic performance, difficulties in maintaining interpersonal relationships, drug abuse and risk in driving and in sexual relationships.