Last month, the American Academy of Pediatrics (AAP), the American Academy of Child and Adolescent Psychiatry (AACAP), and Children’s Hospital Association declared a national emergency in children’s mental health. Exacerbated by the COVID-19 pandemic, mounting challenges across the spectrum of childcare have deepened disparities in pediatric primary care and are particularly evident in racial and ethnic minority groups. At the same time, pandemic conditions have led many children to lose their caregivers and forced them into increased social isolation – all of which has culminated in a mental health crisis among the youngest of the population.

Current statistics reveal the urgency of the problem at hand. According to the latest data from the Centers for Disease Control and Prevention, emergency department visits for mental health emergencies rose by 24% in children aged between 5 and 11 years and by 31% in children aged between 12 and 17 years during March through October of 2020. In early 2021, emergency department visits for suspected suicide attempts increased by 51% among girls aged between 12 and 17 years as compared to data from the same period in 2019.

Loneliness has long been identified as a risk factor for psychiatric disorders and recognized as a serious threat to mental health. While digital platforms and opportunities for online connection are abundant in the 21st century, these substitutes are often lacking and leave many people feeling a growing sense of isolation regardless of their age. Social distancing practices, school shutdowns, and business closures implemented in the face of the pandemic furthered feelings of social disconnection which has evidently had a profound effect on children.

Impact of Social Isolation on Children

Today, the context of social isolation has been made more complex as we navigate necessary societal shifts for the benefit of global public health; the neuropsychological consequences of such distancing cannot be avoided but need to be better comprehended.

Understanding the mental health implications of social isolation and feelings of loneliness is paramount; prior research has shown that social isolation during childhood can be detrimental to adult brain function and behavior in mammals. However, the underlying neural circuit mechanisms and significance of the long-term repercussions remain largely unknown.

Brain Cells and Sociability 

Emerging research has identified sub-populations of brain cells in the pre-frontal cortex – a key region responsible for regulating social behavior – required for normal sociability in adulthood which are profoundly vulnerable to juvenile social isolation. In a 2020 study published in Nature Neuroscience, researchers at the Icahn School of Medicine at Mount Sinai evaluated the damage to brain circuitry caused by social isolation in childhood using mice subjects. They hoped to explain the role of specific brain cells – medial prefrontal cortex neurons projecting to the paraventricular thalamus – in sociability deficits.

Long-Term Consequences of Social Isolation

The study’s authors found that in male mice, two weeks of social isolation immediately following the weaning phase led to the long-term failure of the medial prefrontal cortex neurons projecting to the paraventricular thalamus in activating during social exposure in adulthood.

The effects of juvenile isolation were multi-fold, leading to both reduced excitability of the pre-frontal neurons as well as an increase in inhibitory input from other related neurons. This suggests that the brain circuit mechanism underlying sociability deficits may be caused by juvenile social isolation.

To determine whether acute restoration of prefrontal projections to the paraventricular thalamus would be sufficient to ameliorate sociability deficits in adult mice that had undergone social isolation, the researchers used optogenetics to selectively stimulate the prefrontal projections to paraventricular thalamus. The optogenetic method enabled researchers to stimulate particular neurons in the freely moving mice with pulses of light. Further, the team employed chemogenetics – a technique that allows for the non-invasive control over cell populations. By employing both optogenetics and chemogenetics, the study’s authors were able to quickly increase social interaction in these mice once light pulses or drugs were administered.

If the latest findings can be replicated in humans, the discovery could lead to breakthroughs in treatments for psychiatric disorders related to isolation and loneliness, according to the research team.

Therapeutic Potential

“In addition to identifying this specific circuit in the prefrontal cortex that is particularly vulnerable to social isolation during childhood, we also demonstrated that the vulnerable circuit we identified is a promising target for treatments of social behavior deficits,” Hirofumi Morishita, MD, PhD, Associate Professor of Psychiatry, Neuroscience, and Ophthalmology at the Icahn School of Medicine at Mount Sinai and senior author of the paper told ScienceDaily.

Interestingly, the researchers found that social behavior deficits could be reversed in the mice.

“Through stimulation of the specific prefrontal circuit projecting to the thalamic area in adulthood, we were able to rescue the sociability deficits caused by juvenile social isolation, ” he added.

In the future, the brain circuit identified by the latest findings could be modulated using transcranial magnetic stimulation and other techniques as part of novel treatment approaches to psychiatric disorders, per the study’s authors.

As social behavior deficits are a common factor underlying neurodevelopmental and psychiatric disorders, identifying the specific pre-frontal neurons involved in their development could point toward therapeutic targets for the improvement of social behavior deficits across a range of illnesses.

Key Takeaways

Feelings of loneliness, social isolation, significant loss, and widespread disparities in pediatric primary care have culminated in what experts have declared a national emergency in children’s mental health. Understanding the neuropsychological implications of social isolation in children is critical, as is an urgent systemic response to the evolving crisis.