London, Oct 26 : Researchers at University of Cambridge have identified a brain region linked to higher heart disease risk in depressed and anxious people.
The new study, published today in the journal Nature Communications, suggests that the brain region called the subgenual anterior cingulate cortex (sgACC) -- a key part of the emotional brain -- is a crucial region in depression and anxiety, and targeted treatment based on a patient's symptoms could lead to better outcomes.
"We found that over-activity in sgACC promotes the body's 'fight-or-flight' rather than 'rest-and-digest' response, by activating the cardiovascular system and elevating threat responses," said Laith Alexander, one of the study's first authors.
"This builds on our earlier work showing that over-activity also reduces anticipation and motivation for rewards, mirroring the loss of ability to experience pleasure seen in depression." Using marmosets, a type of non-human primate, the team of researchers infused tiny concentrations of an excitatory drug into sgACC to over-activate it.
Marmosets are used because their brains share important similarities with those of humans and it is possible to manipulate brain regions to understand causal effects.
The researchers found that sgACC over-activity increases heart rate, elevates cortisol levels and exaggerates animals' responsiveness to threat, mirroring the stress-related symptoms of depression and anxiety.
The researchers used brain imaging to explore other brain regions affected by sgACC over-activity during threat.
Over-activation of sgACC increased activity within the amygdala and hypothalamus, two key parts of the brain's stress network.
By contrast, it reduced activity in parts of the lateral prefrontal cortex - a region important in regulating emotional responses and shown to be underactive in depression.
"Our research shows that the sgACC may sit at the head and the heart of the matter when it comes to symptoms and treatment of depression and anxiety," said Professor Angela Roberts.