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Scientists find microRNA in brain that may be associated with depression

October 1, 2014

Depressed Man

A growing number of studies on the brain are pinpointing various neurotransmitters and molecules that are tied to psychiatric conditions such as schizophrenia or major depressive disorder. Recently, one team of scientists from McGill University and the Douglas Institute found a microRNA that is present in abnormally low amounts among individuals who are living with depression. This research may ultimately lead to more effective medications and therapies for the psychiatric disease.

For their investigation, the scientists analyzed cadaver brain tissue obtained from the Douglas Bell-Canada Brain Bank. Specifically, they compared samples from the brains of both depressed and healthy individuals. They discovered the microRNA miR-1202, which was of interest to them because of its function as a receptor of the neurotransmitter glutamate within the brains of humans and other primates.

"In our clinical trials with living depressed individuals treated with citalopram, a commonly prescribed antidepressant, we found lower levels [of microRNA miR-1202] in depressed individuals compared to the non-depressed individuals before treatment," said Gustavo Turecki, M.D., Ph.D., a psychiatrist at the Douglas Institute and professor at McGill University's Department of Psychiatry. "Clearly, microRNA miR-1202 increased as the treatment worked and individuals no longer felt depressed…We found that miR-1202 is different in individuals with depression and particularly, among those patients who eventually will respond to antidepressant treatment."

Significant number of patients may be affected
According to the National Institute of Mental Health, 6.7 percent of American adults and 3.3 percent of adolescents aged 13 to 18 are affected by major depressive disorder every year. This makes the condition the most common psychiatric disease in the U.S. Women are 70 percent more likely than men to develop this problem and the average age of disease onset for both sexes is 32.

While depression is commonly associated with persistent feelings of sadness, other symptoms include irritability, restlessness, insomnia, changes in appetite and thoughts of suicide.

Although there are several antidepressants available for the treatment of depression, not all patients will respond to the same drug in a similar way. Today, there is little way to know which medication will work best for a patient and individuals sometimes have to try several drugs before finding one that works. Research using brain bank tissue, such as the one conducted by the Douglas Institute and McGill University, is opening the door for studies to develop better treatments and associated companion diagnostics. Ideally, these future companion diagnostics will work with more easily collected specimens such as blood or urine. Biospecimen procurement services can help investigators find these badly needed samples to help accelerate mental health research.

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