Cornell University Team Finds Abnormal Salience Network in Depression Patients

On September 5, 2024, a research team led by Conor Liston and Charles J. Lynch of Weill Cornell Medicine published an important study in the journal Nature. By analyzing a large volume of human brain imaging data, the team found that, compared with healthy people, some depression patients have a salience network in the prefrontal-striatal cortex that has expanded by more than twofold. Moreover, the size, shape, and spatial location of the expanded salience network do not change over time, nor do they fluctuate with the patient's emotional state. Patients whose depressive symptoms emerged in adolescence had already shown expansion of the salience network in early childhood.

This finding reveals the neurobiological basis of depression. The salience network is an important part of the nervous system involved in reward processing; it is the brain's built-in regulator, continuously monitoring the outside world and carefully deciding how other brain networks respond to new information and stimuli. The salience network plays an indispensable role in processing sensorimotor information, in overall cognition, and in coordinating among emotion, pain, and bodily action. An abnormal salience network indicates that, because the brain's physiological structure differs from that of healthy people, some of a depression patient's feelings and perceptions are not entirely the same as those of healthy people.

This is also why many depression patients feel their close relatives cannot understand what they are going through. Their own feelings, like those of healthy people, are "real"; it is just that human joys and sorrows are not mutually shared, so the experiences of depression patients and those of healthy people differ to some degree.

This also shows that depression is not "imagined ailment" or the patient "faking it"; rather, their physiology determines that they react to external stimuli more sensitively than healthy people. This research provides important new ideas for developing future drugs to treat depression.

On the other hand, this may also be a result of human genetic diversity: a well-developed salience network can raise alertness in the face of potential danger and help humans adapt better to a nature full of crises. Perhaps in the future, as psychiatry advances, people will no longer regard those with a well-developed salience network as unhealthy; a change in public understanding and greater social inclusiveness could also improve the quality of life of such people.