I'm a TCK who grew up in a third world country with a lot of other TCKs. My mother runs programs for TCKs to help them grieve and close the stress loops caused by no longer living in their home culture and having to lose friends and family.

Kids that partially grew up in one culture and then moved to another are particularly at risk for depression and loneliness. For example, imagine the cruelty of fellow children to a child who doesn't speak the language very well. Even a slight accent is cause for mockery by peers. Also grades will plummet as they can't keep up to the curriculum in a new language (a common thing many youth use as a proxy for self worth).

The biggest advice my mother teaches is to learn to properly grieve for lost friends (truly a skill all humans need anyway) and how to complete stress loops in healthy ways like exercise, crying, and yelling. Stress loops that don't complete can become deep emotional wounds for years.

As a TCK, I prefer the company of other TCKs, and often form deep bonds with them quickly. We've both "seen things" and can relate to each other, even if we both grew up in totally different countries. I married a TCK, and find most of my friends as TCKs.

The good news is it really does give a person a life long perspective that more people deserve. The more socially fluent TCKs become excellent at casually blending into a culture. Many grow to become really good at making friends. Few take politics too seriously. Many work with people, striving to better the world we live in by helping others as teachers, doctors, social workers, and volunteers. Quite a few found comfort in the armed services, because those turn recruits into third culture adults.

The bad news is it does increase risk of depression at all ages, because you can't ever go back and unsee things. You will have opinions that are uncomfortable to locals no matter where you live. You will have sometimes grown up in a much less safe environment and have a hard time adjusting to a safer environment. I had a few incidents that caused some minor PTSD from crimes towards me and my friends growing up. White people are often considered all rich in poorer countries, so white children are more often targets for crimes ranging from small like getting ripped off at the corner store or muggings to kidnapping for ransom. Several of my friends growing up had armed robbers break in and rob their family at gunpoint. My high school crush was almost kidnapped had her Dad not jumped in the van to save her. I've been robbed a bunch of times. Growing up where it's not safe to walk to school alone causes a person to see the world very differently even long into adulthood.

In all, I wouldn't trade it for a "normal" upbringing. There was some bad, and I had to deal with some emotional issues from it. But overall I felt like I was given a very powerful gift of perspective and social skills that would enable me to thrive as an adult.

Outside perspective can be a tricky thing, because once you have it, it's very hard to lose it. I consider it a very important part of myself, and actively seek ways continue to see things from new perspectives.

If you've got TCKs, I highly recommend finding a good grief counselor for them, so they can learn how to close the stress loops. A dozen sessions could make a huge difference in their quality of life as adults, even if they seem perfectly happy and well adjusted. Many TCKs are masters of disguise and can hide away pain and sadness behind a mask for decades until a mid life crisis. Tools to deal with it as children is a fantastic help.