Anxiety and depression might be controlled by a MicroRNA (a non-coding RNA molecule that regulates cellular activities) says a new study published in Neuron. According to the World Health Organization, mood disorders like depression affect about 10% of the population. Yet, not many advancements have been made towards understanding the biological reasons behind depression and anxiety. This study breaks new ground in the treatment of mood disorders by identifying a possible cause, and, consequently, giving scientists the potential to treat anxiety at the source.
Researchers from the Weizmann Institute of Science investigated the molecular mechanisms of the serotonin system, which could cause anxiety and depression. They did so by genetically modifying the MicroRNA that create serotonin in mice and examining its effects. By combining bioinformatics methods and experimentation, researchers identified MicroRNA 135 (miR135) and two proteins that play a role in serotonin regulation and production.
By manipulating the production levels of miR135, researchers discovered they could control the anxiety and depression levels of the mice. For example, mice that were genetically engineered to make more miR135 were resistant to constant stress and did not develop anxiety or depression. Mice with low levels of miR135 expressed more behaviors associated with anxiety and depression. The mice with lower levels of miR135 also were not as affected by antidepressants. Scientists concluded that the brain needs to have miR135 levels low enough to enable healthy stress and high enough to avoid mental health issues.
Scientists then moved on to testing miR135 levels in humans. After testing blood samples of a score of humans, they found that subjects with depression had lower miR135 levels in their blood. They also found that three of the genes involved in producing miR135 were also associated with bipolar mood disorders.
These findings could mean big breakthroughs in the treatment of anxiety and depression. Current medications for this disorder are only effective in 30 to 40% of patients, and for many of these patients, the effects are often not enough. Selective serotonin reuptake inhibitors (SSRIs), which are the most commonly prescribed antidepressants, treat the effects of microRNA production. When a patient stops taking an SSRI, he or she might go back to unhealthy serotonin levels. This new research will help scientists go to the source of depression and anxiety in order to more effectively treat patients for their mental health problem.