Teenagers with issues related to social isolation seems almost an oxymoron . During adolescence teenagers are all quite extroverted, even those that are more on the introverted end of the continuum.
Recently I have seen a number of teenagers that present with the parents' complaint of social isolation. They don't seem to have a very active peer group. They are not doing things with peers on the weekends or talking much to peers. They may have on line peers but not the kind that allow face to face interactions. Like many teenagers they spend a great deal of time in their rooms away from family but don't have the other part of needing to be with their peers.
There can be many reasons for this. Sometimes these teens are struggling with social anxiety. In these instances they find it too difficult to seek out others. They may not have any idea what is happening to them and often they feel defective. They see others having fun that seems unattainable to them.
Sometimes they have been or are a victim of harassment. This is so common today in schools and we can't depend upon the schools to monitor this form of abuse. These teens have developed a poor sense of self worth and isolate to avoid the pain of the abuse.
Others have poor social skills. They just have not developed the skills necessary to "fit in". This could be teens that have struggled with this since elementary school or ones that did not make the transition into the adolescent culture. You will at times find here that they describe themselves as above all of this.
No matter what has triggered this, it is a issue worth addressing. The teens that present in my office often have been told by their family that there is something wrong with them and by the time I see them they are defensive. The earlier parents intervene the better. If you are dealing with social anxiety it would be reasonable to seek professional assistance. If your teen is a victim of harassment that needs to be addressed with the school and professional help may be indicated. ( A few year ago I visited the Tolerance Museum in LA. There was a interactive exhibit about bullying. At the time I participated 73% of the people in the room reported having been bullied in their life time. I was appalled at that high number.) If your child needs social skills, participation in some leadership activities would be helpful. It can be a community or church activity that would help them develop those skills.
In any case, approach your child carefully. They are likely already feeling defective they need to feel support from you. These are important issues with teens since this is the beginning of learning how to create an adult peer group so they can make the launching they will need to do in the near future.
If you find this related to your teen good luck and tread lightly. Sherri