By Sola Ogundipe

Five of the most common psychiatric disorders share genetic risk factors, an international study published in the Lancet has found. These disorders include; autism, attention deficit hyperactivity disorder (ADHD), clinical depression, bipolar disorder and schizophrenia.

In the largest genetic study of mental illness to date, researchers compared the genomes of 33,000 people with one of five common psychiatric disorders to nearly 28,000 unaffected controls. All participants were of European ancestry. Genetic variations called single nucleotide polymorphisms (SNPs) identified in four regions of the genome were significantly associated with the psychiatric disorders. Two of these regions were involved in regulating the flow of calcium in nerve cells – a process that regulates brain activity.

These findings hint at a possible shared mechanism in the development of several mental disorders. Marjorie Wallace, chief executive of mental health charity SANE, noted. ‘The findings highlight the need to understand the genetic and biological factors of these life-changing conditions, in order that more effective treatments and therapies may be found’.

The identification of shared genetic risk factors for different psychiatric disorders may help explain previously observed connections between certain disorders. For instance, those in families with a history of bipolar disorder are suggested to have an increased risk of schizophrenia.

Although the SNPs identified in this study cannot predict or diagnose the mental disorders investigated, as their effects are too small, the findings have fuelled the hope that a better understanding of the genetic contributions to these conditions could impact diagnosis in the future. Currently, the diagnosis of psychiatric disorders is based entirely on symptoms.

Experts from Cardiff University, who was involved in the study, told the BBC: ‘It signals the opening of a potential new era for psychiatry and mental illness. This is a scientific method that helps understand what is going wrong in the brain’.