When you look at the numbers, it’s easy to gape in horror.

In Ghana, a nation of 32 million people, there are only 62 psychiatrists.

Zimbabwe, with a population of 15 million, has only 19 psychiatrists.

And in Uganda, there are 47 psychiatrists serving a country of 48 million — less than one single psychiatrist for every million people.

These are staggering ratios. To get your head around them, take the US as a comparison. There are around 45,000 psychiatrists for all 333 million Americans, which translates to about 135 psychiatrists for every million people. That’s still not enough — experts are actually warning of an escalating shortage — and yet it’s a whopping 135 times more coverage than exists in Uganda.

These numbers have very real, and sometimes very brutal, implications for people’s lives. When psychiatry and other forms of professional mental health care are not accessible, people suffer in silence or turn to whatever options they can find. In Ghana, for instance, thousands of desperate families bring their ailing loved ones to “prayer camps” in hopes of healing, only to find that the self-styled prophets there chain their loved ones to trees. Instead of receiving medical treatment for, say, schizophrenia, the patients receive prayers.

For emergency room doctors, they are a dispiriting and familiar sight: Children who return again and again in the grip of mental health crises, brought in by caregivers who are frightened or overwhelmed.

Much has been written about the surge in pediatric mental health emergency visits in recent years, as rates of depression and suicidal behavior among teens surged. Patients often spend days or weeks in exam rooms waiting for a rare psychiatric bed to open up, sharply reducing hospital capacity.

But a large study published on Tuesday found a surprising trend among adolescents who repeatedly visited the hospital. The patients most likely to reappear in emergency rooms were not patients who harmed themselves, but rather those whose agitation and aggressive behavior proved too much for their caregivers to manage.

In many cases, repeat visitors had previously received sedatives or other drugs to restrain them when their behavior became disruptive.

About a year ago, teenager Anastasia Vlasova started seeing a therapist. She had developed an eating disorder, and had a clear idea of what led to it: her time on Instagram.

She joined the platform at 13, and eventually was spending three hours a day entranced by the seemingly perfect lives and bodies of the fitness influencers who posted on the app.

“When I went on Instagram, all I saw were images of chiseled bodies, perfect abs and women doing 100 burpees in 10 minutes,” said Ms. Vlasova, now 18, who lives in Reston, Va.

Around that time, researchers inside Instagram, which is owned by Facebook Inc., were studying this kind of experience and asking whether it was part of a broader phenomenon. Their findings confirmed some serious problems.

The review, which synthesizes over 60 pre-existing, peer-reviewed studies on topics spanning isolation, loneliness and mental health for young people aged between 4 and 21 years of age, found extensive evidence of an association between loneliness and an increased risk of mental health problems for children and young people.

"As school closures continue, indoor play facilities remain closed and at best, young people can meet outdoors in small groups only, chances are that many are lonely (and continue to be so over time)," said lead author, Maria Loades, DClinPsy, Senior Lecturer in Clinical Psychology at the University of Bath, UK.

"This rapid review of what is known about loneliness and its impact on mental health in children and young people found that loneliness is associated with both depression and anxiety. This occurs when studies measured both loneliness and mental health at the same point in time; when loneliness was measured separately; and when depression and anxiety were measured subsequently, up to 9 years later," Dr. Loades added. "Of relevance to the COVID-19 context, we found some evidence that it is the duration of loneliness that is more strongly associated with later mental health problems."