Is the contemporary mental health crisis among youth due to DMN disruption?

Abstract

The human brain is comprised of multiple large-scale networks that are functionally connected and control feelings, thoughts, and behaviors. As clinical neuroscientists, psychiatrists must consider the profound impact of a massive societal shift in human behavior on the functional connectivity of brain networks in health and disease. The advent of smartphones, social media, and video game addiction may have disrupted the developing brain networks in children and adolescents, leading to the current escalating epidemic of mental disorders in youth. The major networks in the human brain include the default mode network (DMN), the salience network, the limbic system, the dorsal attention network, the central executive network, and the visual system.1 Each network connects several brain regions. Researchers can use functional MRI to detect the connectivity of those networks. When blood flow increases concurrently across 2 or 3 networks, this indicates those networks are functionally connected. There was an old “dogma” that brain regions use energy only when activated and being used. Hans Berger, who developed the EEG in 1929, noticed electrical activity at rest and proposed that the brain is constantly busy, but his neurology peers did not take him seriously.2 In the 1950s, Louis Sokoloff noticed that brain metabolism was the same whether a person is at rest or doing math. In the 1970s, David Ingvar discovered that the highest blood flow in the frontal lobe occurred when a person was at rest.3 Finally, in 2007, Raichle et al4 used positron emission tomography scans to confirm that the frontal lobe is most active when a person is not doing anything. He labeled this phenomenon the DMN, comprising the medial fronto-parietal cortex, the posterior cingulate gyrus, the precuneus, and the angular gyrus. Interestingly, the number of publications about the DMN has skyrocketed since 2007. DMN deactivation by excessive use of social media may explain the mental health decline in youth Henry A. Nasrallah, MD, DLFAPA Editor-in-Chief