Screens are rewriting childhood: a new framework says the developing brain integrates experience until age 25, with profound stakes for mental illness

LAUSANNE, Vaud, SWITZERLAND, 2 June 2026 — Children are growing up inside screens. A new peer-reviewed Thought Leaders Invited Review in Brain Health argues that neuroscience has been missing the word for what those screens are touching. The synthesis, by Michel Cuenod and Kim Q. Do at the Center for Psychiatric Neuroscience at Lausanne University with Julio Licinio at SUNY Upstate Medical University, names it: the criticome. The complete record of sensory, motor, social, cultural, and environmental experience the brain integrates during critical periods of synaptic plasticity, from before birth through approximately age twenty-five.

What enters during those windows becomes load-bearing. What does not enter, or enters wrong, cannot easily be added back. The authors do not claim to know what screen-saturated childhoods are producing. They offer something more useful for a field that has been groping for the question: a framework precise enough to study it.

From adult dysfunction to developmental disorder

The synthesis is at its most consequential when it points the framework at psychiatry. Autism spectrum disorders, schizophrenia, post-traumatic stress, major depressive disorder, and culture-bound syndromes are recast as developmental rather than purely synaptic conditions. The clinical question shifts. It is no longer only what is broken in the adult brain. It is what could not be integrated, or was integrated incorrectly, during the windows when integration was possible. Schizophrenia, in this lens, is bound up with disrupted maturation of parvalbumin-positive interneurons in the prefrontal cortex during the late adolescent window. Autism reflects altered critical-period timing across multiple sensory and association systems. Early trauma alters stress responsivity for life.

“The data have been telling us for years that schizophrenia is a disorder of development, not a disorder of the adult synapse,” said Dr. Michel Cuenod, co-author at the Center for Psychiatric Neuroscience, Lausanne University. “The difficulty has always been articulating what went wrong, and when. The criticome gives us a frame for that question.”

Major depression receives the review’s most carefully argued case, drawing on a striking natural experiment by Kenneth Kendler and Lindon Halberstadt. They interviewed fourteen monozygotic twin pairs reared together but rigorously discordant for lifetime major depression. With genotype identical and the rearing family shared, the affected twin almost always carried the weight of a relational rupture, sometimes by chance, sometimes channeled there by a slightly more impulsive temperament that hardened across decades into a divergent life. Kendler and Halberstadt called the slow magnification cumulative continuity. The criticome lens places that finding in a mechanistic frame: the social scaffolding integrated during the protracted late-adolescent prefrontal window is itself load-bearing for adult mood regulation.

Six mechanisms, one machinery

Six neurobiological mechanisms anchor the framework: GABAergic regulation through parvalbumin-positive interneurons, perineuronal nets around fast-spiking cells, progressive myelination of cortical circuits, experience-dependent epigenetic regulation, neuromodulatory maturation, and developmental synaptic pruning. The authors treat pruning as a sixth pillar rather than an afterthought. Up to half of cortical synapses are eliminated across childhood and adolescence, with microglia and complement-mediated tagging doing much of the work. What is pruned cannot be recovered. What is preserved becomes the substrate of adult cognition.

There is an old Brazilian proverb that folk wisdom got to long before the molecular biologists did. Papagaio velho não aprende a falar. An old parrot does not learn to speak. Hubel and Wiesel showed it in the cat visual system. Language acquisition, birdsong, attachment, the rough geography of moral feeling: the same logic runs through all of them. A window opens. A code is absorbed. The window closes. After that, acquisition is effortful and incomplete.

The same plasticity, in two directions

Critical periods are double-edged. The same machinery that allowed Mozart to emerge from a childhood saturated in harmonic relationship is the machinery that produced the developmental delays documented in Romanian orphanages. The progression from a toddler’s first steps to Roger Federer on Centre Court rests on motor experience integrated during plastic windows. So does the contemplative architecture established when Lhamo Dhondup was recognized as the Dalai Lama at age two and immersed in meditative training from early childhood. The review also names the dark uses without flinching. The Nazi Hitlerjugend exploited critical-period plasticity by design. Current conflicts are integrating violence and displacement into the criticomes of children in real time, with consequences that will outlive their causes.

The unsettled question of screens

The review treats the screen question as the central open problem of its framework. Contemporary children and adolescents are absorbing screen-mediated experience at scales no previous generation has known, during the precise windows when the criticome is most malleable. The authors do not claim to know what kind of criticome is being assembled under those conditions. They argue, persuasively, that the question is now urgent, and that the framework gives researchers a way to formulate it as a testable empirical problem rather than a moral panic.

“We wrote this for the clinician asking the right questions without quite having the vocabulary,” said Dr. Julio Licinio, co-author and SUNY Distinguished Professor at the State University of New York, Upstate Medical University, and Publisher of Genomic Press. “It is also for the educator wondering why second-language instruction works so much better at five than at fifteen, and for the policymaker trying to understand why early-childhood investment yields the returns it does. They are the same question.”

Two people going to the bottom of the same river

One of the review’s most evocative passages is also one of its most clinically useful. The authors set a sentence from Finnegans Wake beside a sentence from the letters of Lucia Joyce, James Joyce’s daughter, diagnosed with schizophrenia. On the surface, the two read the same: ruptured syntax, coined words, associations that skip the rails of ordinary logic. One writer is among the most celebrated novelists of the twentieth century. The other was a patient. Carl Jung, who briefly treated Lucia in 1934, gave the sharpest answer on record. Father and daughter, he said, were like two people going to the bottom of a river, one falling and the other diving. The criticome offers a neurobiological reading of that asymmetry. Joyce composed from a criticome integrated under intact critical-period regulation, then chose, as an adult, to navigate its depths. Lucia’s late-adolescent prefrontal window closed on a disrupted integration, and the same depths drew her down without her consent.

What the framework does not claim

The authors are explicit about limits. The criticome is a conceptual framework, not a measurement tool. It does not deliver a method for quantifying integrated content in a living brain. The conditions it reframes are heterogeneous, and the developmental lens is offered as productive rather than complete. Translating the synthesis into testable interventions will require measurement methods that do not yet exist, and the authors say so.

“We were not looking for a new term. We were looking for a way to talk about something we kept failing to name,” said Dr. Kim Q. Do, corresponding author at the Center for Psychiatric Neuroscience, Lausanne University. “Our students would ask what the brain actually integrates during a critical period, and we would reach for memory, or for cultural learning, or for epigenetic marking, and none of those words quite fit. The criticome is our attempt to fit.”

The framework will not resolve every dispute it touches. It is not meant to. What it does is convert a scattered literature into vocabulary precise enough to support the next round of experiments. Decades of work on critical periods have given neuroscience the parts. The criticome offers a name for the whole.

The peer-reviewed invited review in Brain Health titled “The criticome as the window of becoming: Toward a novel and comprehensive framework for understanding the critical period of information integration in human development,” is freely available via Open Access, starting on 2 June 2026 in Brain Health at the following hyperlink: https://doi.org/10.61373/bh026i.0021.

The full reference for citation purposes is: Cuenod M, Licinio J, Do KQ. The criticome as the window of becoming: Toward a novel and comprehensive framework for understanding the critical period of information integration in human development. Brain Health 2026. DOI: https://doi.org/10.61373/bh026i.0021. Epub 2026 Jun 2.

About Brain Health: Brain Health is a peer-reviewed medical research journal published by Genomic Press, New York. The journal publishes original research, reviews, and perspectives across the full breadth of brain health and longevity, integrating neuroscience, psychiatry, neurology, public health, and the social and behavioral sciences. Brain Health serves as a forum for work that addresses how the brain is shaped, sustained, repaired, and burdened across the lifespan, from molecular and cellular mechanisms through clinical, societal, and policy dimensions.

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