A brain network linked to attention is larger in people with depression

Symptoms of depression fluctuate over time, but many brain imaging studies of the condition simplest learn about one point in time. That’s made it difficult to connect networks of brain activity to reasonably a range of symptoms and mood changes. Now, a new learn about using long-term brain imaging data shows one brain network curious about guiding attention is almost twice larger in patients with depression than in people now no longer experiencing depression symptoms, and stays larger even as depressive symptoms ebb and flow.

“Honestly, after we started this project, we weren’t waiting for necessarily to search out stable, traitlike differences in brain [activity patterns] in those with depression,” says Charles Lynch, a neuroscientist at Weill Cornell Medical College. “We were more focused on seeking out things that would most likely change over time as their symptoms fluctuate.” The outcomes, published September four in Nature, may lend a hand toughen reasonably a range of sorts of brain stimulation therapies for depression (SN: 9/21/23).

Lynch and his team hoped to uncover the driving forces in the back of mood changes in depression by mapping brain networks over time. Existing functional MRI datasets allowed the team to try the activity, across multiple days, of greater than 100 people’s brains, including those with and without depression. The dataset also included patients’ rating scales of their depression symptoms at the time of each scan.

The team identified the networks of brain areas with the foremost coordinated activity and found that the salience network — known for identifying relevant stimuli and guiding attention — was once nearly twice larger in those with depression. The network also directs the activity of two other networks; one that controls self-focused thinking and every other that facilitates working memory at some stage in goal-directed tasks. Previous work hinted that the salience network would most likely be curious about depression, however it the findings were unclear. The brand new learn about showed that though the final shape of the network was once similar across both groups, its borders extended farther outward in patients with depression.

Though the boundaries of the salience network remained stable over time and across reasonably a range of moods, some changes in connectivity between specific nodes of the network corresponded with worsening symptoms. By analyzing network changes in two patients who were scanned over many months, the team found that connectivity between the nucleus accumbens, which is curious about reward-seeking, and the anterior cingulate, which plays a part in decision-making, weakened when patients reported experiencing less joy.

Two individuals with bipolar II disorder also had expanded salience networks, but those with autism or obsessive-compulsive disorder did now no longer. “The specificity of salience network expansion to depression will thus be an incredibly intriguing question to explore in future studies using transdiagnostic samples,” says Lucina Uddin, a neuroscientist at UCLA who was once now no longer curious about the learn about.

To examine out whether an important salience network may precede depression altogether, the team analyzed a neuroimaging dataset of children over time. They curious about fifty seven teenagers who did now no longer have depressive symptoms when they were scanned between the a long time of 10 and 12 years old, but developed symptoms within a pair years. These teenagers had significantly larger salience networks than those who did now no longer develop depression, and the size of the network stayed stable over time in both groups.

A bigger salience network is now no longer the outcome of depression; it precedes depression, the implications suggest. The authors have self belief the enlarged network also may perhaps be related to childhood stressors or genetics, but more research has to be done before anyone can say of course.

A stronger understanding of the neural components driving depression may lead the style for more precise therapeutic interventions, which may well be specifically helpful given the unreliable effectiveness of current medications.

“We predict there's a chance to include small print about how functional brain networks are organized spatially in individuals with depression to tell how we administer brain stimulation therapies,” Lynch says.