Breakthrough in psychology may lead to new treatments for depression

A new study has shown the link between noradrenergic neurons and susceptibility to depression for the first time.

The study was published by Bruno Giros’ team, a researcher at the Douglas Mental Health University Institute and Professor of psychiatry at McGill University, in the journal ‘Nature Neuroscience’.

“We know that a small cerebral structure, known as the ventral tegmental area, contains dopaminergic neurons that play a key role in vulnerability to depression,” said Bruno Giros, whose team is part of the CIUSSS de l’Ouest-de-l’Île-de-Montréal research network.

By mimicking stressful events in animal models, the researchers found out that an increase in dopaminergic activity increases cases of depression.

The dopaminergic neuron is controlled by the noradrenergic neuron. “It is this control that steers the body’s response toward resilience or toward vulnerability to depression,” said Giros.

Giros’ team showed, animals incapable of releasing noradrenaline, are more likely to develop depression following chronic stress. However, this is not the case if the situation is reversed ; Increasing noradrenaline production does not lead to higher resilience and less depression.

The noradrenergic neurons are found in a Cerebral structure called the Locus Coeruleus. These neurons connect with each other via a neurotransmitter molecule called noradrenaline. It regulates emotions, sleep and mood disorders – and now, Giros believes, it is also involved in resilience and depression.

Stressful life events like  job loss, accident and death of a loved one can cause  major depression in some but not in others. A determining factor is resilience, a biological mechanism that enables an individual to snap out from a traumatic or stressful event. However, researchers are still working on how resilience plays a role.

“Beyond this discovery about the brain mechanisms involved in depression, our results help explain how adrenergic drugs may work and could be used to treat major depression,” said Giros.