Trapped In Her Mind?

My best friend, who is 17 claims that she is 'trapped' in her own mind and mood. She used to be able to open up to me about anything, now she can't talk to me about anything, even what she did during the day is beyond discussion. She claims she doesn't feel comfortable, but I've known her for four years so this sounds very strange to me. I like to think i have an excellent understanding of the human mind, and I have been able to solve many of her issues up to this point. I'm very worried about this as it feels different to what I've seen before. she has resorted to self harm before, which I helped her stop. She seems to be slowly cutting me off because she is constantly in a bad mood. This is beyond my expertise so I am appealing for the opinion of a professional in case I'm missing something major. I hope you can provide me with an insight.

Best,
Rob

Ben's Answer:

It's possible that your friend is experiencing a serious depression, or having symptoms of Bipolar Disorder. A person who used to be open and expressive and suddenly feels completely shut down and "trapped" in her own mind and mood, is definitely experiencing something beyond the usual ups and downs of life. Sometimes when a person withdraws in this way, it is a symptom of paranoid or delusional thinking (which can happen in many psychiatric disorders - including severe depression, bipolar disorder, and schizophrenia).
Often these disorders first manifest between age 17-21. Sometimes in that state, a person may feel that they are thinking "crazy" thoughts and they are afraid to share them because they feel nobody would possibly understand (and in fact, often nobody else can understand).

It's also possible that your friend is simply very depressed and doesn't have the energy, the will, or the focus to express herself to anyone right now.

It would probably be best if she could see a good therapist. If there's any way for you to talk to her, or her family about this, in order to get her some help, it may be the best you can do for her. Aside from that, just being there, and willing to listen if she does want to talk, could be some comfort to her.