Significant findings in largest ever study of bipolar affective disorder
One of the largest ever genetic replication studies of bipolar affective disorder has resulted in a significant discovery. It has found compelling evidence that the chromosome known as the 3p21.1 locus contains a common genetic risk for bipolar disorder, the PBRM1 gene. This means, from using a separate dataset of over 34,000 subjects, that there appears not to be an association of this same variant with schizophrenia.
Scientists at King's College London - Institute of Psychiatry performed the study with 28,000 subjects recruited from 36 research centres and replicated the association of the marker with bipolar disorder, but not with schizophrenia. This new research contrasts with the majority of studies which have found that schizophrenia risk genes also contribute to the risk for bipolar disorder. However, this finding distinguishes the heritable risk for bipolar disorder and schizophrenia.
One of the biggest challenges in psychiatric genetics has been to replicate findings across large studies so 'this study will add to the recent rapid progress in identifying genes for mental illness', says first author Dr Evangelos Vassos. He continues: 'The last few years have seen the identification of about two dozen genetic loci for bipolar disorder and schizophrenia. About half of these are shared between these two disorders, indicating they share some, but not all, genetic causes.'
It is estimated that more than 30 million people worldwide are affected by bipolar disorder (also known as manic-depressive illness), which causes unusual shifts in mood, energy, activity levels and the ability to carry out day-to-day tasks. It is among the top 20 leading causes of disability, with up to 2 % of Europeans diagnosed as having a bipolar disorder at some point in their lives.
It is a disorder that 25 years ago affected a middle-aged adult; however, today, the average person identified as having bipolar disorder is between the ages of 18 and 22. Bipolar disorder is notoriously difficult to diagnose and treat, and has a rate of up to 20%. Studies suggest that half of people living with bipolar disorder have attempted to kill themselves.
The exact causes of bipolar disorder are not known. However, it is thought that several things can trigger an episode. Extreme stress, overwhelming problems and life-changing events are often thought to contribute, as well as genetic and chemical factors. But bipolar disorder can be treated with mood stabilisers, ensuring that people with this illness can take better control of their mood swings and go on to lead full and productive lives.
The outcome of this scientific study of the disorder is significant for those affected but, due to the conflicting results, more work needs to be done to determine the role this locus plays in psychosis. However, scientists are confident that the evidence seems solid that this locus is associated with bipolar disorder.
'There is growing interest in epigenetic mechanisms that might contribute to the development of bipolar disorder. The implication of a gene involved in chromatin remodeling in bipolar disorder risk adds fuel to this fire,' comments Dr John Krystal, Editor of Biological Psychiatry.
Dr Vassos concludes: 'Future studies may be able to use this information to develop new treatments for these disorders.'
For more information, please visit:
King's College London:
Data Source Provider: Elsevier; Bipolar Aware; Lundbeck
Document Reference: Based on information from King's College London
Subject Index: Medicine, Health