Signs that your friend could be experiencing abuse

What are the signs that your friend could be experiencing abuse?

At school they've become:
Withdrawn
Distracted
Less motivated  

Around friends lately they are:
Defensive
Isolated
More insecure  

With their partner they are:
Anxious
Hyper-vigilant
Overly submissive  

They are struggling with:
Depression
Insomnia
Anxiety
Substance abuse
Wounded self-esteem