Signs of Depression in Adolescents

Is is possible for an adolescent to show classic signs of depression such as:

-alienating herself from friends
-abrupt change in study habits/grades (from a's to d's in 4 months)
-unable to face schoolwork/classes
-increasing somatic complaints (nausea & vomiting) when anxious
-change in sleep patterns (wanting to sleep more)
-fatigue

and yet still be able to enjoy certain activities?

So my question is:
Does anhedonia always accompany adolescent depression?

I should mention that this 16 year old female has seen a physician to r/o medical causes.

Thanks.

[Kevin Kennedy, Ph.D.]

Yes, it is possible. Anhedonia is a frequent symptom of depression, but is not a necessary criterion. In addition, in adolescents an irritable or excessively grouchy mood is often typical of depression, rather than the low mood or melancholic type of depression that is often witnessed in the adult population (though teens might display this version of depression as well).

[peapufn]

A related discussion, How Young can a Child Be Depressed? was started.