Understanding the basic biology of bipolar disorder
Scientists know there is a strong genetic component to bipolar disorder, but they have had an extremely difficult time identifying the genes that cause it. So, in an effort to better understand the illness’s genetic causes, researchers at UCLA tried a new approach.
Instead of only using a standard clinical interview to determine whether individuals met the criteria for a clinical diagnosis of bipolar disorder, the researchers combined the results from brain imaging, cognitive testing, and an array of temperament and behaviour measures. Using the new method, UCLA investigators — working with collaborators from UC San Francisco, Colombia’s University of Antioquia and the University of Costa Rica — identified about 50 brain and behavioural measures that are both under strong genetic control and associated with bipolar disorder. Their discoveries could be a major step toward identifying the specific genes that contribute to the illness.
A severe mental illness that affects about 1 to 2 percent of the population, bipolar disorder causes unusual shifts in mood and energy, and it interferes with the ability to carry out everyday tasks. Those with the disorder can experience tremendous highs and extreme lows — to the point of not wanting to get out of bed when they’re feeling down. The genetic causes of bipolar disorder are highly complex and likely involve many different genes, said Carrie Bearden, a senior author of the study and an associate professor of psychiatry and psychology at the UCLA Semel Institute for Neuroscience and Human Behavior.
‘The field of psychiatric genetics has long struggled to find an effective approach to begin dissecting the genetic basis of bipolar disorder,’ Bearden said. ‘This is an innovative approach to identifying genetically influenced brain and behavioural measures that are more closely tied to the underlying biology of bipolar disorder than the clinical symptoms alone are.’
‘These findings are really just the first step in getting us a little closer to the roots of bipolar disorder,’ Bearden said. ‘What was really exciting about this project was that we were able to collect the most extensive set of traits associated with bipolar disorder ever assessed within any study sample. These data will be a really valuable resource for the field.’
The individuals assessed in this study are members of large families living in Costa Rica’s central valley and Antioquia, Colombia. The families were founded by European and native Amerindian populations about 400 years ago and have a very high incidence of bipolar disorder. The groups were chosen because they have remained fairly isolated since their founding and their genetics are therefore simpler for scientists to study than those of general populations. UCLA Health System
