Tiny molecule may help battle depression

Toronto: A tiny molecule may provide a marker for depression and help detect individuals who are likely to respond to antidepressant treatment, a new study has found.

Researchers at McGill University and the Douglas Institute in Canada discovered that levels of a small molecule, called miR-1202, found only in humans and in other primates are lower in the brains of depressed individuals.

Depression is a common cause of disability, and while viable medications exist to treat it, finding the right medication for individual patients often amounts to trial and error for the physician.

"Using samples from the Douglas Bell-Canada Brain Bank, we examined brain tissues from individuals who were depressed and compared them with brain tissues from psychiatrically healthy individuals," said Dr Gustavo Turecki, a psychiatrist at the Douglas and professor in the Faculty of Medicine, Department of Psychiatry at McGill.

"We identified this molecule, a microRNA known as miR-1202, only found in humans and primates and discovered that it regulates an important receptor of the neurotransmitter glutamate," said Turecki.

Turecki and colleagues conducted a number of experiments that showed that antidepressants change the levels of this microRNA.

"In our clinical trials with living depressed individuals treated with citalopram, a commonly prescribed antidepressant, we found lower levels in depressed individuals compared to the non-depressed individuals before treatment," said Turecki.

"Clearly, microRNA miR-1202 increased as the treatment worked and individuals no longer felt depressed," Turecki said.

"Although antidepressants are clearly effective, there is variability in how individuals respond to antidepressant treatment," said Turecki.

"We found that miR-1202 is different in individuals with depression and particularly, among those patients who eventually will respond to antidepressant treatment," he said.

The study was published in the journal Nature Medicine.