The human brain consists of 80-100 billion neurons, each one making 10-20 thousand connections. It is one of the most complex entities in the known universe, and we all have one. But our brains are also very vulnerable, particularly early in life. Neuroscientists estimate that at birth, the human brain is unique among mammals in that it is only 10% developed. That means 90% of brain development occurs outside the womb. As a result, newborns, young children, and even teenagers need continuous attention from adult caregivers as their brains grow to full maturity sometime in the third decade.
Thus, we should not be surprised that our brains are endowed with networks of neurons that compel us to form strong social bonds. We form early attachments with caregivers that influence our future relationships; we make friends who influence what we watch, wear, and buy; we work in groups that build societies and amazing technologies; we stay connected to people we love for most of our lives.
One key area of our unique brains necessary for social connection is the prefrontal cortex. Sitting behind our forehead and eye sockets, the prefrontal cortex is the most evolved and interconnected part of the human brain. Its main purpose is to orchestrate different neuronal regions in an elaborate dance of conscious and nonconscious processing often referred to as executive function.
And while it does not generate emotion nor trigger rewards that give color and meaning to life and motivate us to move forward, its vast networks of neurons connect to our emotion and reward systems putting the prefrontal cortex in the privileged position of helping us interpret and regulate our emotions and keep our reward system in check.
A healthy prefrontal cortex needs more than two decades to mature and is the difference between impulse and insight, distraction and focus, reaction and reflection—and is our best defense against mental illness. It underlies our capacity to focus, learn new skills and filter out unnecessary information. It helps us visualize our future and interpret our past and gives rise to prosocial skills like empathy and self-sacrifice. A healthy prefrontal cortex is key to forming strong social bonds and to success at school and at work. And it's under siege in the Digital Age.
Our world is changing. Fast. The ways we work, travel, and entertain ourselves—and most important, the ways we communicate and interact—are all altered by new habits inspired by the supercomputer in our pockets.
One of many changes is the massive shift in the amount of media we consume as a society. In 2002, the average American adult consumed six to eight hours of media per day—mostly TV, radio, and videocassettes. Today, enabled by new internet-connected devices and always on streaming services, that number is nearly double. There are similar figures for children of every age.
When we spend that much time with our smartphones consuming media, regardless of whether it is gaming, video content, checking the news or making social comparisons, we begin to use media as a mood and emotion regulator.
By relying on an external source to help us alter our moods and emotions, we lose the ability to use social interaction and internal mechanisms of regulation. We also no longer tolerate boredom, and we lose our capacity to manage negative emotions, because we don’t have to—stimulation and reward are just an arm’s reach away. Over time, distant online social media and other external applications begin to displace more intimate offline human social interactions. This disrupts attachment with family and weakens relationships with friends.
And as I document in my book, Rewired: Protecting Your Brain in the Digital Age, this is a direct result of the diminished capacity of an exhausted and overwhelmed prefrontal cortex that cedes the balance of power in our brains to our emotion and reward centers.
We become more distracted, divided, and depressed as a society.
To understand how this occurs, we must think developmentally. As young children march through milestones, their immature brains grow and change in fundamental ways that inform how we should think about media use and abuse at every age.
For example, from 0-3 years, the ability of a very young child to learn from most video content is extremely limited due to the lack of maturity in their brains. This is well illustrated by the failure of the Baby Einstein videos. Despite their wild popularity with parents, research shows that infants are unable to learn meaningful concepts from them. Worse, the more infants watch, the further they fall behind in language acquisition and the higher their risk for ADHD as they grow older.
We now know that the failure of Baby Einstein and similar series results from the “video transfer deficit”: Very young children simply lack the size and neural connectivity in their prefrontal cortex and other critical brain areas to take information from a two-dimensional screen into their three-dimensional reality. This neurobiological fact is why the American Academy of Pediatrics recommends zero screen time (including background television) for children less than 2 years.
Fast forward to the teen years, and the brain enters a new phase of growth characterized by another developmental vulnerability. As hormones are released during puberty, the emotion and reward centers race ahead of the prefrontal cortex, which needs another decade to fully mature. Despite significant growth and improvement in the size and interconnectivity of their brains, this developmental lag explains the impulsive nature of many teenagers.
Enter social media platforms, with instant feedback on highly curated images and the proverbial “best time ever.” Social pressure to communicate constantly through multiple apps complicates evolving peer dynamics and puts pressure on the teen prefrontal cortex. The resultant social media seesaw comes with impossible expectations about body image and wealth juxtaposed with online discrimination and microaggressions that confuse the teen brain already struggling with issues of self-identity. Research shows that while there are some upsides to social media in terms of social support, the downsides are real and contribute to social isolation, low self-esteem, fear of missing out, and massive increases in teenage ADHD, anxiety, depression, and, tragically, suicide.
Even adults, with their mature prefrontal cortex, are not immune to the temptations of every app ping and message ring. The seduction of media multitasking at home, work, and in our cars undermines our relationships, and research shows it clearly decreases our productivity, and puts us and others at risk on the roads. Our overwhelmed brains can’t control our impulses and our reward centers take control. We become irritable and petty as our emotion centers fatigue. Our weakened prefrontal cortex contributes to political divisiveness and rising rates of adult loneliness, narcissism, anxiety, depression, and substance abuse.
There are many causes for worry about the corrosive effects of mobile devices in our lives and in our brains. But we have managed new technologies in the past. We are capable of change, and there are signs we will survive the many threats and consequences of our smartphone habits.
But there is a difference between surviving and thriving.
To thrive, we need to be more proactive than reactive to protect our prefrontal cortex. We need to create a common expectation that new technologies can and should support and help us, not divide and depress us. As adults, we need to develop digital literacy for our children and tech-life balance for ourselves. And we need to use the same brain science that informs our understanding of the consequences of too much media consumption and unhealthy smartphone habits to inform recommendations about how to move forward.
To that end, below are ten scientifically supported recommendations that can help strengthen and protect the prefrontal cortex.
Dr. Carl Marci is a physician, scientist, entrepreneur, and author of Rewired: Protecting Your Brain in the Digital Age. He is part-time Assistant Professor of Psychiatry at Harvard Medical School and staff Psychiatrist at Massachusetts General Hospital. He is also the Chief Psychiatrist and Managing Director of Mental Health and Neuroscience at OM1, a venture-backed health data company, and he advises multiple early-stage companies focusing on substance use and treatment-resistant depression. Dr. Marci is a graduate of Columbia University, Oxford University, and Harvard Medical School.